IPM-11

INTEGRATED CROP MANAGEMENT FOR

KENTUCKY CABBAGE

SCOUT MANUAL

Prepared by

John Strang; Extension HorticulturistTerry Jones; Extension HorticulturistRic Bessin; Extension Entomologist

Brent Rowell; Extension HorticulturistWin Dunwell; Extension Horticulturist

April, 1997

This manual was produced with support of the Kentucky IPM Program

TABLE OF CONTENTS

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

PRODUCER-SCOUT RELATIONSHIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

SCOUTING PROCEDURES FOR CABBAGE INSECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4HOW TO SCOUT A FIELD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4CUTWORMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4FLEA BEETLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5APHIDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6BEET ARMYWORM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6IMPORTED CABBAGEWORM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7DIAMONDBACK MOTH LARVA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8CABBAGE LOOPER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8CROSS-STRIPED CABBAGEWORM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9THRIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

EFFECTIVENESS OF COLE CROP INSECTICIDES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

CABBAGE INSECTS PICTURE SHEETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

BENEFICIAL INSECTS PICTURE SHEET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

SAMPLING TECHNIQUES AND SIGHT I.D. CHARACTERISTICS FOR CABBAGEDISEASES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

CABBAGE DISEASES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15SCOUTING FOR CABBAGE DISEASE PESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15DECISION-MAKING FOR CABBAGE DISEASE PEST MANAGEMENT . . . . . . . 16

DAMPING-OFF OF SEEDLINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16WIRESTEM, BOTTOM ROT AND HEAD ROT . . . . . . . . . . . . . . . . . . . . . . 16ALTERNARIA LEAF SPOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17DOWNY MILDEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17BLACK ROT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18CLUBROOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18BACTERIAL SOFT ROT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19BLACK LEG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19WHITE ROT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19MOSAIC OR VIRUS DISEASES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

SCOUTING FOR EARLY SEASON CABBAGE DISEASES . . . . . . . . . . . . . . . . . . 20

TIPBURN AND OTHER PHYSIOLOGICAL DISORDERS . . . . . . . . . . . . . . . . . . . 21TIPBURN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21EDEMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21SOIL COMPACTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

CABBAGE DISEASES PICTURE SHEET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

CABBAGE CULTURAL REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23FIELD SELECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23CROP ROTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23VARIETY SELECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23SOIL TESTING AND FERTILIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23FOLIAR APPLICATION OF NUTRIENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24TRANSPLANTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25HANDLING CABBAGE TRANSPLANTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26CARE OF TRANSPLANTS PRIOR TO PLANTING . . . . . . . . . . . . . . . . . . . . . . . . . 26TRANSPLANTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27IRRIGATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27WEED MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27HARVEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

KEY TO CABBAGE NUTRIENT DEFICIENCY SYMPTOMS UNDER FIELD CONDITIONS28

APPENDICES INSECT TRAPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30USING PHEROMONE TRAPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31CABBAGE INTEGRATED PEST MANAGEMENT FORM . . . . . . . . . . . . . . . . . . . 32ROTATION FROM VARIOUS CROP GROUPS FOR PLANTING CABBAGE . . . . 33ROW SPACING AND PLANT POPULATIONS PER ACRE . . . . . . . . . . . . . . .33

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INTRODUCTION

Agriculture is the world's most Much of the information in thisimportant industry because of rapidly manual was adapted from other sources,expanding populations which demand including scouting procedures from theincreased amounts of food and fiber. Crop Kentucky Integrated Pest Managementprotection problems associated with this program, as well as from other states.increased production have become more Decision guidelines for the cabbagewormcomplex. A simplistic approach to pest control complex were adapted from a similar programleads to serious environmental complications developed by the New York State Integratedand economic losses. A truly successful pest Pest Management Program.management program must take amulti-disciplinary approach in order to supply We have found that the mostthe farmer with reliable pest control economical methods of controlling pests at theinformation. An approach to crop production lowest cost and least risk do not involve abased on economic, ecological, technical and regular spray schedule. The most economicalsocial considerations is needed to assist the approach is Integrated Pest Managementfarmer to achieve the production and quality (IPM). The cabbage IPM program is based onlevels needed to satisfy increasing world regular monitoring, correct identification ofdemand. pests and diseases, estimations of percentage

Current economic conditions mandate economic thresholds. To reduce the number ofthat farmers be provided with the information unnecessary sprays, pest infestations andneeded to manage pests while maximizing infected plants are only treated when anprofits. This manual describes the information economic threshold is reached. This is thethe farmer needs to make important point at which the pest population is almostmanagement decisions. Your sound judgment high enough to cause economic damage. Theand dedicated effort will directly affect the economic threshold takes into account thesuccess of this program. We welcome your value of the crop, the amount of damage to beparticipation and look forward to working expected, the cost of the control, and thewith you in the coming growing season. amount of damage that can be prevented by

of infected or infested plants, and the use of

using the control.

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PRODUCER-SCOUT RELATIONSHIP

In an Integrated Management Program, it is fences.imperative that the scout enjoy a goodrelationship with the producer-cooperator. Thefarmer must have confidence that the scout isdoing his or her job. In some cases hundredsor even thousands of dollars may rest upon thescout's report. The scout's report will weighheavily on whether or not control measures forcertain insects, diseases or weeds areemployed.

The following points will assist scouts indeveloping a harmonious relationship betweenIPM scouts, cooperators and supervisorypersonnel. These points were developedduring conversations between cooperators, thePest Management Supervisor and a CountyAgent.

1. Let the grower know that you feel this job isimportant.2. Be courteous and friendly.3. Present a good appearance.

a. Dress appropriately for thejob--short or long sleeve shirt, longpants, cap and shoes. No athleticshirt, cut off pants or sandals.b. Be and look busy.

4. Go about your work in a businesslikemanner.5. Keep a neat legible record.6. Do not be a "know it all". Be tactful.7. Answer the grower's questions to the best ofyour knowledge. Do not be afraid to say "I donot know".8. NEVER make a recommendation forcontrol measures.9. Do not discuss other grower's problems orcontrol measures.10. Do not block drives or lanes with yourvehicle.11. Keep all gates closed or open as thecooperator has left them. Do not ride down

12. Do not trample or otherwise damage crop.13. Let cooperator know the type vehicle orvehicles you will be using and approximatetime that you will be on farm.14. Place report in location agreed upon withcooperator.15. Let the cooperator know where you can bereached by phone.16. Use tact in dealing with cooperator's dog.17. ALWAYS follow recommended sanitationpractices in regard to diseases, insects andweeds. Clean shoes are a must. Washableboots are preferred.18. Remarks regarding the pest managementprogram, fellow scouts, cooperators andsupervisory personnel should be positive. Ifyou cannot say anything good about theprogram and/or people involved, do not sayanything19. Always keep in mind that you are scoutinghis acreage. He expects you to do a good job.20. Do not spend excessive time talking withthe cooperator or others.21. If asked to have lunch with the cooperator,do so, but make it clear that your time islimited.22. Carry your own water supply so that youdon't have to ask for water.23. Keep vehicle on solid ground.24. Be on time to begin work.25. Do not get involved with jobs oncooperator's farm unless there is someemergency. STAY OFF MACHINERY.26. You are not to scout crops not in program.Make sure you scout the right field.27. You are not to take anyone with you whilescouting unless instructed to do so bysupervisory personnel.28. You are not to be on farm after dark.29. Do not go in farm buildings unless invitedor caught in rain.30. Do not scout when you are miring to shoe

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tops unless advised to do so by supervisor. When in doubt about proper procedures,consult with supervisory personnel.

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SCOUTING PROCEDURES FOR CABBAGE INSECTS

HOW TO SCOUT A FIELD

Specific survey procedures are described foreach insect. In general, you will EXAMINE 5PLANTS PER LOCATION and record thenumber of insects or percent of damagedplants. Fields will be monitored on a weeklybasis. Select locations randomly so that theywill be representative of the entire field. Don'tsurvey along field margins unless specificallydirected to do so. Don't limit surveys to oneside or end of a field. IF YOUR SURVEY ISNOT RANDOM IT IS NOTREPRESENTATIVE OF THE WHOLEFIELD and you may find a lot of problems onyour return visit. Do not bias your sample bylooking for damaged or undamaged plants.Because IPM for fresh-market cabbage is newfor Kentucky, we will use 8 locations per acre.

For most of the season, the primary pests willbe the lepidopteran larvae (importedcabbageworm, diamondback larvae, cross-striped cabbageworm, and cabbage looper).These larvae cause similar types of damageand they are combined when using theeconomic thresholds. On each plant, we usepresence/absence sampling to determine thepercentage of plants infested and the types ofinsects found. As soon as the first larva of anylepidopteran species is found, that plant isconsidered “infested” and the scout moves tothe next plant. Thresholds are based on thepercentage of plants infested and the growthstage of the plant, so growth stage of the plantmust be recorded during each visit.

Plant Stage Number of leavesCotyledon No true leavesPrecupping Up to 19 leavesCupping 20 to 28 leavesHead fill 29 to 35 leaves

If the percentage of plants is less than thethreshold, then the field does not need to betreated. If the field percentage if affectedplants is greater than the threshold, then thefield probably needs to be treated. If thepercentage of plants is very close to thethreshold, treatment may be required soon.Consider the size of the larvae, predictedtemperature and current and forecastedspraying conditions before making a decision.

CUTWORMSOccurrence: From setting of the transplantsuntil the 8 to 10 leaf stage. These are moreoften a problem with fall cabbage production.Fields having one or more of the followingcharacteristics should be watched verycarefully:

# history of cutworm damage # excess surface litter# fair to poor drainage or overflow land # fall production # excessive annual weeds prior to tillage

When to scout: Cabbage plants should bemonitored weekly from emergence until theyreach the 10-leaf stage. Watch for missingleaves or plants, or removed leaves at the baseof the plant. Infestations are often spotty socheck carefully for damage. Make counts onlyif cutworm damage is noticed in the field.Continue to scout damaged fields once aninfestation is found.

Description: Larvae are light gray to nearlyblack and may have a faint, narrow mid-dorsal

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stripe. Larvae vary from 1/4 inch long afterhatch to 1-3/4 inches long when full grown.

Damage: Larger worms (about ½ inch orlonger), cut small plants and may pull partsinto their burrow. Symptoms are cut off leavesor cut plants.

Preventive management: Eggs and larvae arefrequently in the field prior to planting.Prepare fields and eliminate weeds at least 14days before planting to destroy eggs, larvaeand egg-laying sites.

How to scout: Begin making counts whenevidence of cutworm damage is found. 1)Randomly determine a starting point andexamine 5 consecutive plants per location andwrite down the number of cut plants.Determine the percent plants cut by dividingthe total plants cut by the total number ofplants inspected. Multiply this figure by 100and record the percent infestation on the reportform. 2) Look for live cutworms aroundfreshly damaged plants. They will generally becovered or underground during the day. Firstcheck under clods near the base of the plant.Then, dig up an area three inches in diameterand three inches deep around the damagedplant. Record the average number and length(inches) of "live" cutworms per 5 plant sampleand whether they were found near the soilsurface or deep.

Record: Record the number of cut plantsfound per 5 plants examined at each site.Record the average length of "live" cutwormsfound. Note if they were found near the soilsurface or deep.

Economic Threshold: 3% or more cut plantsand 1 or more cutworms (1 inch or smaller)per 40 plants. Inform the growerimmediately. If conditions are borderline,check the field again in 24 to 48 hours or untila final decision is made.

FLEA BEETLE

Occurrence: Cotyledon through seedlingplant stage. Flea beetles are not usually aproblem on larger plants, except that they canreduce the marketability of the cabbage duringthe early head stage.

When to scout: Check cabbage seedlingscarefully. Flea beetle may be numerous onyoung plants.

Description: Flea beetles are very small, darkinsects that jump readily when disturbed.Several species may attack cabbage. They maybe black, black with yellow stripes, or metallicblue-green depending on the species.

Damage: These beetles are leaf feeders. Theymake small, circular, feeding scars on theleaves. Damage can be serious on smallplants. While the larvae feed on the roots, theyare not usually harmful.

How to scout: On small plants (less than 4leaves), examine 5 plants at each location andrecord the number of flea beetles. This mustbe done carefully because the beetles willjump at the slightest disturbance.

Record: Record the average number ofbeetles on each 5 plant sample in yourcomments.

Economic Threshold: An average of 2 fleabeetles per plant.

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APHIDS

Occurrence: Can be found on cabbage atanytime, but are more common with fallproduction. These aphids can becomenumerous during prolonged cool wet periods.Infestations often begin in localized areas ofthe field.

When to scout: Cabbage should be scouted an occasional invader of vegetable crops infor aphids during the precupping stage. Kentucky. It is only a potential problem for

Description: Two aphid species are commonon cabbage, the cabbage aphid and the tobaccoaphid. The pale-green cabbage aphid lookslike other aphids but with a grayish waxy coat When to scout: Late July, August andsimilar to cigarette ash. Tobacco aphids are September.pale green to red insects. Aphids occur ingroups or colonies on the undersides of leaves.Both winged and wingless aphids may bepresent.

Damage: These aphids infest the undersides and a broader stripe along each side. There isof leaves and suck sap. Infested plants may usually a distinctive dark spot on each sideshow signs of curling, wrinkling, or cupping just above the second pair of true legs.of the leaves. Some plants may be stunted and Females lay masses of up to 80 eggsproduce unmarketable heads. Aphids may get underneath a covering of cottony-white scales.under the leaves of older plants and become acontaminant. They may also carry viruses tothe cabbage from nearby weeds.

How to scout: Look at the undersides of the small transplants. Often a fine webbing isleaves for wingless aphids. Do not count the produced by smaller larvae near these feedingnumber of aphids. sites. Plants can become rapidly defoliated.

Record: Of the 5 plants observed at each How to scout: Examine 5 plants in each of 8sample site, record the number of aphid locations per acre for the presence of beetinfested plants observed at each site. Calculate armyworm only when beet armyworm mothsand note the percent infestation. Note the type are found in pheromone traps. Inspectof aphid found. pheromone traps for beet armyworm once a

Economic Threshold: With fall production,cabbage aphid infestations can spread rapidlyduring prolonged periods of cool, wet Trapping: Pheromone traps are available forweather. Treat if cabbage aphids are found. beet armyworm. These traps are very sensitive

Comments: Parasitism of aphids can be high.If aphids appear gold, silver or black they havebeen parasitized. Ignore these aphids duringyour scouting.

BEET ARMYWORM

Occurrence: The beet armyworm is a majorpest in the southwestern and southern US and

fall production. Peppers, tomatoes and sweetcorn are more susceptible to beet armywormthan cabbage.

Description: The beet armyworm is alight-green to black larva with four pairs ofabdominal prolegs and a dark head. There aremany fine, white wavy lines along the back

Damage: Beet armyworm damage is similarto that of the other cabbageworms. Feeding onyoung tender growth can be very damaging to

week.

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and moths may be captured long before larvae front wing.are found in the field. Decision to treat forbeet armyworm should be made solely onlarval counts.

Record: The percentage of plants infested often concealed next to veins or the midrib onwith beet armyworm. Keep the beetarmyworm percentage separate from thatof the other larvae.

Economic Threshold: Timing of insecticideapplications is very important. Once larvae are½ inch or longer, they become very difficult tokill with insecticides. So treatment must betargeted against young larvae. Use thefollowing threshold table to make decisions:

Plant Stage Percentage of infested plants locations per acre for the presence or absenceCotyledon 10 % of imported cabbageworms, diamondbackPrecupping 15 % larvae, cabbage loopers, or cross-stripedCupping 10 % cabbageworms.Head fill 5 %

IMPORTEDCABBAGEWORM

Occurrence: Entire season.

When to scout: Begin checking for eggs andlarvae as soon as the white butterflies are seenflying about during the day.

Description: The bullet-shaped eggs have Cotyledon 20 % distinct ridges and are initially white when Precupping 30 %laid but turn dark yellow as they mature. The Cupping 15 %larvae are velvety green with an narrow, light Head fill 5 %yellow stripe down the middle of the back andhave four pairs of prolegs in addition to thethree pairs of legs toward the head. Whenmature the larvae reach 1-1/4 inches in length.The pupae is greenish-brown in color andattached to the undersides of cabbage leaves.The adult is a white butterfly about 1-3/4inches long tinged with yellow on theundersides of the wings and black spots on the

Damage: Imported cabbageworms causedamage similar to that of loopers, but feedcloser to the center of the plant. Larvae are

the underside of the leaves. Feeding is notrestricted to between leaf veins. Large larvaecan be particularly damaging to young plantsand can cause significant yield reductions.

Preventive Management: After springharvest is complete, plants and field debrisshould be disced under to reduce problems forfall production.

How to scout: Examine 5 plants in each of 8

Record: Of the 5 plants examined at each siterecord the number of plants infested with anyof these four larvae. Note the species of thelarvae found.

Economic Threshold: The threshold is basedon the percentage of plants infested with anyof these four species of larvae. Use thefollowing table to make treatment decisions.

Plant Stage Percentage of infested plants

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DIAMONDBACK MOTHLARVA

Occurrence: Entire season.

When to scout: Monitoring should begin following table to make treatment decisions.when the plants are young. During cupping,larvae that feed on heart leaves are difficult to Plant Stage Percentage of infested plantsfind unless the outer leaves are pulled back. Cotyledon 20 % Heart leaves of preheading plants should be Precupping 30 %examined, if feeding damage is present. Moths Cupping 15 %found in pheromone traps indicate that egg Head fill 5 %laying is occurring.

Description: Eggs are laid singly or in smallgroups on the undersides of lower leaves.Eggs are small, yellowish-white andsomewhat football-shaped. Larvae are small,yellowish-green, spindle shaped, and have aforked tail. When mature, larvae are 5/16 inchin length. The pupae are found in a gauze-likecocoon attached to leaves or stems of thecabbage plant. The moth has a small, slender,grayish-brown body with folded wings. Thewings of the male form three yellowdiamond-shaped spots where they meet.

Damage: Diamondback moth larvae, despitetheir small size, can be very destructive to colecrops. Their feeding on the bud may causemalformation of the cabbage head.

Preventive Management: After springharvest is complete, plants and field debrisshould be disced under to reduce problems forfall production.

How to scout: Examine 5 plants in each of 8locations per acre for the presence or absenceof imported cabbageworms, diamondbacklarvae, cabbage loopers, or cross-stripedcabbageworms.

Record: Of the 5 plants examined at each siterecord the number of plants infested with any

of these four larvae. Note the species of thelarvae found.

Economic Threshold: The threshold is basedon the percentage of plants infested with anyof these four species of larvae. Use the

CABBAGE LOOPER

Occurrence: From May through September

Description: The larvae are light green incolor with a pale white stripe along each sideand two thin white stripes down the back. Thebody tapers toward the head. There are threepairs of slender legs near the head and twopair of club-shaped prolegs toward the otherend. When mature, the larvae reach 1-1/2inches in length. Because the larvae have nolegs in the middle area of their body, this areaarches when the insect moves. All larvalstages of the insect move with this loopingmotion. The ridged, white, round eggs areusually laid singly on the underside of theouter leaves. The pupae are brown, about 3/4inch long and wrapped in a delicate cocoon ofwhite tangled threads. The adult moth is amottled, grayish-brown moth with a 1-1/2 inchwing span and a small silvery spot resemblinga sock in the middle of each front wing.

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Damage: They can cause serious damage toyoung transplants as well as causing seriousleaf feeding damage to older plants. Damage Description: The larva is bluish-gray in colorto the head or wrapper leaves often reduces with numerous black stripes runningmarketability. cross-wise on its back. Below the transverse stripes on each side is a black and yellowPreventive Management: After springharvest is complete, plants and field debrisshould be disced under to reduce problems forfall production.

How to Scout: Watch for cabbage loopersparticularly on the undersides of leaves alongleaf margins, but they can be found anywhereon the plant. Examine 5 plants in each of 8locations per acre for the presence or absenceof imported cabbageworms, diamondbacklarvae, cabbage loopers, or cross-stripedcabbageworms.

Record: Of the 5 plants examined at each siterecord the number of plants infested with anyof these four larvae. Note the species of thelarvae found.

Economic Threshold: The threshold is basedon the percentage of plants infested with anyof these four species of larvae. Use thefollowing table to make treatment decisions.

Plant Stage Percentage of infested plantsCotyledon 20 % Record: Of the 5 plants examined at each sitePrecupping 30 % record the number of plants infested with anyCupping 15 % of these four larvae. Note the species of theHead fill 5 % larvae found.

CROSS-STRIPEDCABBAGEWORM

Occurrence: Entire season. This insect ismore common in the mountainous region ofeastern Kentucky. Because eggs are laid inclusters, individual plants scattered over afield may be infested with large numbers of

cross-striped cabbage worms.

stripe along the length of the body. Whenmature, the larvae reach 3/4 inch in length.The larvae drop to the soil to pupate in a tightcocoon just below the soil surface. Thescale-like eggs are light yellow and laid inmasses of 20 to 30 on the undersides of theleaves. The moth is yellowish-brown to brownwith dark zigzag markings and has a wingspanof about 1 inch.

Damage: Larvae feed on all tender parts ofthe plant, but prefer terminal buds. Youngleaves and buds are often riddled with holes.

Preventive Management: After springharvest is complete, plants and field debrisshould be disced under to reduce problems forfall production.

How to Scout: Examine 5 plants in each of 8locations per acre for the presence or absenceof imported cabbageworms, diamondbacklarvae, cabbage loopers, or cross-stripedcabbageworms.

Economic Threshold: The threshold is basedon the percentage of plants infested with anyof these four species of larvae. Use thefollowing table to make treatment decisions.

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Plant Stage Percentage of infested plants Heavily infested leaves may have brown,Cotyledon 20 % leathery patches. Thrips often get inside thePrecupping 30 % head and damage layers in the outer third ofCupping 15 % the head.Head fill 5 %

THRIPS

Occurrence: these are sporadic pests that maymigrate to cabbage when surrounding fields ofsmall grains ripen or when alfalfa is cut.Injury from thrips is most severe during hotdry weather.

Description: Thrips are slender, tiny insectsabout 1/25" long and range in color from lightyellow to brown. They have 4 long, fringedwings that are held flat over the back.

Damage: Thrips feed by rasping the plantsurface and sucking up the exuding sap.Thrips cause whitish scratches on the leaves.

Preventive Management: Some varieties aremore susceptible to thrip damage. In general,thrips prefer varieties with tight heads overthose with loose heads. Unfortunately, themarket demands varieties that have tightheads.How to Scout: examine the bud area of youngplants and underneath the leaves of olderplants for the presence or absence of thrips.

Record: The percentage of plants infestedwith thrips.

Economic Threshold: treatment is advised ifmore than 20% of the plants are infested withthrips.

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Effectiveness of Cole Crop Insecticides

Insecticide Cabbageworm Moth LooperImported Diamondback Cabbage

Ambush G* G G

Ammo G G G

Asana G F G

Bacillus G G Fthuringiensis

Guthion G G F

Lannate G G F

Larvin G G -

Lorsban G G -

Mustang G G G

Orthene G G G

Pounce G G G

Thiodan G G G

Warrior G G G

*G= Good control, F=Fair, - = Insufficient information

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CABBAGE INSECTS PICTURE SHEET

DIAMONDBACK MOTH BEET ARMYWORM MOTH

IMPORTED CABBAGEWORM CABBAGE LOOPER MOTHBUTTERFLY

CABBAGE APHID CABBAGE LOOPER

CROSS-STRIPED CABBAGEWORM DIAMONDBACK LARVA

13

IMPORTED CABBAGEWORM BEET ARMYWORM

CUTWORM THRIPS

PARASITIZED APHIDS THRIPS DAMAGE

DISEASED CABBAGE LOOPER

14

SAMPLING TECHNIQUES AND SIGHT I.D.CHARACTERISTICS FOR CABBAGE DISEASES

CABBAGE DISEASES

In commercial plantings of cole crops, it isstrongly recommended that growers have allinitial diagnosis of diseases confirmedthrough the Plant Disease DiagnosticLaboratories. Few "new" growers havesufficient experience to scout and identifydiseases properly. Therefore, it is moreimportant for growers to be walking theirfields and looking for any of the symptomsdescribed here, then submitting typicalsamples of whole plants for diagnosis; whilethey wait, they can shorten the interval ontheir spray schedule or if no sprays have beenmade start with a broad spectrum fungicidesuch as Bravo.

Black Rot: Look for V-shaped yellow lesionsat the margins of the leaves, particularly theupper leaves. Inside the yellow lesions lookfor black veins. Cut through a vein at least3/8" from the bottom edge of the yellow "V",if it's black rot the vein will be as black as ink.

Club Root: Look for stunted, wilted plantswith swollen, deformed roots. Some plantdeath.

Alternaria: Look for round, dark lesions withconcentric rings inside on the leaves or head.Alternaria leaf spot can be a problem duringwet periods, it is especially favored by hightemperatures and becomes more prevalent ascabbage heads age.

Downy Mildew: Look for yellowed leaf for places in the field where plants appearlesions, especially on lower leaves. The tanlesions are often rectangular-shaped, boxed inby veins. White to purplish gray mold may be

seen on the undersides of lesions duringhumid weather. Downy mildew may alsobecome systemic and be found throughout thecabbage plant.

Black Leg: Round, sunken, black lesions onthe stem and lower leaves that eventuallycoalesce into larger black lesions arediagnostic. Small pepper-like specks in thelesions are strongly suggestive of the funguscausing Blackleg.

Wirestem, Bottom Rot And Head Rot: Thesediseases are caused by the fungus Rhizoctoniawhich invades at the soil line (girdling youngplants at that point and moves up the plant inhot, wet weather causing a bottom and side rotof the heads. Infected areas may be slimy ordry and papery, but are almost always dark.

Other Diseases: Sclerotinia - heads arecovered with white mycelium and hard, brownsclerotia. In KY, this disease mainly causeslesions on the stem and lower leaves similar tothose of Blackleg, rather than the head rotphase. It is more common in spring than fallcrops.

SCOUTING FORCABBAGE DISEASEPESTS

1. Examine at least five (5) cabbage plants in8 locations of a V-shaped transect across thefield. Examine a total of 40 plants. Look

“abnormal”. If such places are seen, go thereand determine the cause(s) of any differenceseen.

15

2. As you walk, survey constantly for disease the name wirestem. Most pythium speciessymptoms, weeds, and any unusual problems. infect when temperatures are low and soil isLook for “disease spots” in the field.Examine abnormal plants carefully. Look fordisease symptoms on the upper and lowersurfaces of each plant leaf, stems and roots.For each area examined, record the presenceor absence of disease pests or problems. Management Guidelines: The following

DECISION-MAKING FORCABBAGE DISEASE PESTMANAGEMENT

Fungicides are available to help control manyof the diseases important in cabbage in KY.See ID-36 "Commercial Vegetable CropRecommendations" for details. Specifically,fungicides are available for control ofDamping-off fungi, Alternaria, Blackleg,Downy Mildew, White rot, and Wirestem.Most fungicides need to be in place inpreventative roles rather than as rescuetreatments. In nearly all cases, fungicidesapplied after a disease becomes active aredesigned to reduce spread and have littleeffect on symptom development in plantsalready infected; therefore, frequent scoutingand early diagnosis is critical to themanagement of cabbage diseases.

DAMPING-OFF OFSEEDLINGS Pythium sp. and Rhizoctinia solani are theusual causes of damping-off. Pythium canalso cause seed to rot before it germinates.Seed rot and damping-off occur primarilyduring cool, wet conditions. For infectionsafter germination lesions usually occur on thelower stems at or near the soil line. Stemtissue collapses and becomes dark andshriveled because there is little structuraltissue in stems while they are young.Sometimes seedlings remain alive and growslowly, with the infected areas giving rise to

wet. Pythium can be a serious problem infloat bed production. Rhizoctonia is favoredby warmer soils and may be a major problemin fall cabbage.

practices can all help reduce damping-offproblems. Preparation of good seedbedswhich have been fumigated, use of newsoilless media for transplant production, useof fungicide treated seed, careful watermanagement, drenching outside beds withrecommended fungicides after planting, andchoice of planting time.

WIRESTEM, BOTTOM ROT,AND HEAD ROT These diseases are caused by Rhizoctoniasolani. This fungus also causes damping-off inthe field, in plant beds and in floatbeds.Wirestem is characterized by stems that aredarkened and girdled near the soil line (seefigure). Plants beyond the 3 or 4 leaf stageusually are resistant to wirestem. Infectedplants are weak, produce small heads, andsometimes wilt and die. Bottom rot developson plants after they have been transplanted tothe field. Dark slightly sunken spots developon basal leaves near the soil. Under moistconditions the rot spreads to adjacent leavesand causes a head rot. The causal fungus ispresent in all field soil. Disease is promotedby moist conditions and fresh decomposingorganic matter. Green manure crops ploweddown just before planting (within 2-3 weeks)may contribute to this problem.

Management Guidelines: Plow under allgreen manure crops and fescue sod early sothat they have time to decay before planting.Raise transplants in fumigated soil, newsoilless media or use Terraclor to controlRhizoctonia in seedlings. In the field a band

16

application of Terraclor or a Rovral first are yellowish-white and later turn brownapplication may help reduce disease problems with bluish-black lace-like markings. In moist(See ID-36). weather, a white downy mold develops on the

ALTERNARIA LEAF SPOT Alternaria leaf spot is caused by the fungusAlternaria brassicae. It is characterized bydistinct spots with concentric rings (bull’s eyepatterns) on the lower leaves; the dark velvety,dusty fungus growth develops on these spotsduring moist periods (see figure). There are,however, no tiny dark bodies as in blackleglesions. A good hand lens or microscope isrequired to see the growth. Spores are spreadfrom plant to plant by the wind and rain underfavorable conditions. During unfavorableperiods, the fungus can survive in plant debrisor on seed. This disease can become aproblem on cabbage heads held in the field forlong periods of time after reaching maturity.Alternaria leaf spot may be an economicproblem on Chinese cabbage and cabbageduring warm, rainy months. Soft rot bacteriamay enter through dead leaf spots. Thefungus overwinters in seed and in residuefrom diseased plants. Warm, wet conditionspromote disease development. Certainfungicides applied as foliar sprays will controlAlternaria leafspot.

Management Guidelines: A 2 - 4 yearrotation will greatly reduce severity of thisdisease. Apply protective fungicidesbeginning with the seed bed or shortly aftertransplanting when the weather is wet. Duringdry weather a spray program can be delayeduntil the first symptoms are seen. A 7 - 10 dayinterval is recommended.

DOWNY MILDEWDowny mildew is caused by the fungus Management Guidelines: A few cabbagePeronospora parasitica, is most serious in varieties are now available that are tolerant toearly spring or under cool fall conditions (46 - downy mildew. Fungicide treatment of61 F). It appears as small leaf spots which susceptible varieties is needed when the

underside of the leaf spots. Vascular tissuemay become discolored. The causal fungusoverwinters on seed, in crucifer weeds, andperhaps in soil. Disease is promoted by cool,wet weather. Downy mildew predisposesplants to bacterial soft rot. Economic damagemost often occurs during transplantproduction, where infections may kill largenumbers of plants, especially in plant or floatbed situations. Severe leaf infections or steminfections can stunt older plants, reducingyield and quality of a commercial crop. Thedowny mildew fungus may become systemicand move throughout the cabbage plant andhead by way of the vascular system. In thestems and heads of cabbage, downy mildewproduces dark purplish spots visible beneaththe cortical tissue when the heads are cutopen. These spots or lesions may be invadedby bacterial soft rot resulting in complete headdecay. Occurrence of systemic downy mildewmay result in rejection of the cabbage by thebuyer. Seasonal Development: The fungus survivesfrom season to season on overlapping crucifercrops or as thick-walled resting spores, calledoospores. These sexual spores can survive inthe soil for extended periods and producesporangia under favorable environmentalconditions. During the growing season, thefungus produces sporangia on the underside ofthe leaf at night when conditions are moist.The sporangia are carried primarily by aircurrents and, to a lesser extent, by rain. Underfavorable conditions the sporangia germinate,producing germ tubes that directly penetratethe leaves causing new infections.

17

disease occurs early in crop development; beds or in production fields.repeated applications may be required, 4. Preplant fumigate all plant beds.depending on the weather. Crop rotation to 5. Purchase hot water treated seed that hasnoncruciferous hosts is recommended. See been certified as disease free.ID-36 Commercial Vegetable Crop 6. Check transplant grower’s certificationProduction in Kentucky for recommended records.fungicides. 7. Plant several small plant beds rather than 1

BLACK ROTThis disease is caused by the bacteriumXanthomonas campestris and affects young,as well as mature plants. Infected seedlingsturn yellow and die. On older plants, yellowwedge or “V” shaped areas appear at leafmargins and expand toward the center of theleaf; infected areas later turn brown and die.Vascular tissue (veins) is black within infectedareas. This discoloration develops from leafmargins toward the base of the plant. Whenplants are infected as seedlings, heads aredwarfed and lower leaves fall off. Frequentlysymptoms are most severe on one side of thehead. Soft rot often develops in infectedheads. If the disease spreads extensively, thecabbage field will have a scorched appearanceand plant growth will be inhibited. The blackrot bacterium overwinters on seed and inresidue from diseased plants; it can persist inplant residue for 2 to 3 years. Plowing underdebris so that it rots quickly is recommended.As with the blackleg fungus, the black rotbacterium is seed-borne and is spread onseedlings and by movement of contaminatedwater. All cole crops are susceptible,especially cauliflower and weeds like wildmustard. Cabbage varieties differ insusceptibility to black rot.

Management Guidelines:1. Rotate transplant beds and do not locate atransplant bed near production fields orgardens with crucifers.2. Raise or trench production beds. Floodingof plant beds can result in widespreadinfections.3. Eliminate wild crucifer weeds near plant

large one.8. Use seed from different lots and sources foreach bed.9. Do not top or mow transplants.10. Do not wet down or dip transplants toremove soil.11. Do not work in or handle wet plants.12. Spray to slow disease spread when notedin the field.

CLUBROOTClubroot is caused by the fungusPlasmodiophora brassicae, which causesstunting, wilting and yellowing ofabove-ground parts. Plants often die beforemaking heads. The diagnostic symptom is thepresence of large spindle-shaped galls onroots. Clubroot can infect wild mustard andshepherd’s purse. The causal fungus issoil-borne and persists in soil for at least 7 -10 years. Soil pH of less than 7.2 favorsdisease development, as does wet, poorlydrained fields. Optimum soil temperature forinfection is 64-77 F. The fungus spreadso

from one field to another in soil clinging totools, field equipment, transplants.

Management Guidelines: Clean transplants,and crop rotation help reduce diseaseproblems. Seed beds should not have been incrucifers for 6 - 8 years or must be fumigated.If club root is a problem and fields are notavailable to rotate to, broadcast and disc in1500 lb of hydrated lime per acre 2 to 3 daysprior to transplanting if the soil pH is not over7.5. This should not be done more than onceevery 3 years. Otherwise the soil pH shouldbe over 6.5.

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BACTERIAL SOFT ROT This disease is caused by Erwinia carotovoraand some other bacteria. Infected areas appearto be water-soaked, develop a soft decay, andhave a foul distinctive odor. Infected cabbageheads decay rapidly and turn dark. Thebacteria usually infect plants through surfaceareas injured by insects, cold, other diseases ormechanical means. Warm, wet conditions White rot is caused by the fungus Sclerotiniapromote disease development. sclerotiorum. This disease is expected to

BLACK LEG Black leg is caused by the fungus Phoma(Plenodomus) lingam. Symptoms begin asdark sunken cankers at the base of the stemand as light brown circular leaf spots. Stemcankers enlarge and girdle stems, causingplants to wilt. A diagnostic feature ofblackleg is the presence of distinct blackpycnidia (speck-size fungus reproductivestructures) within stem cankers and leaf spots.Infected seed is the major source of disease.The greatest spread occurs in the seed bed orseedling stage. Weather conditions during thegrowing season determine severity. Fungalspores are carried by splashing rain or insectsto nearby plants. Fruiting bodies may developon the leaves. The causal fungus overwinterson seed and in residue from diseased plants,and can persist in residue for 3 to 4 yearsdepending on how quickly the roots and stemsdecay. The fungus can be carried on seed andon transplants; it can be spread within fieldswhen diseased and healthy plants are dippedin the same water, when workers andimplements move through fields that containdiseased plants, and by splashing and runningwater.

Management Guidelines: Blackleg can be usually do not cause significant damage.managed by combining preventive measures. However, on the related crops ChineseAlways use disease-tested, fungicide treated cabbage or bok choy, they can significantlyseed. Fumigate seed beds under a reduce yield and quality.polyethylene tarp with a mixture of methyl Leaves of infected plants are mottled in abromide and chloropicrin. Do not locate plant mosaic of light green or yellow to dark green

beds in or near fields that were planted to colecrops the year before. Harvest any field withdisease symptoms last. Plow under debris indiseased fields to allow for more rapid andthorough decomposition. Rotate infestedfields out of cruciferous crops for 3 to 4 years.

WHITE ROT

increase with the use of float beds fortransplant production. Symptoms appear onleaves, petioles or stems nearest the ground oron the top of cabbage heads. The fungus isfavored by high humidity and temperatures(77-81 F). Infected areas appear aso

water-soaked spots; these enlarge toirregular-shaped areas which become coveredby white mold. The white colored fungusgrows upward over the maturing plant, oftenproducing a soft water-soaked mass.Numerous black sclerotia (seed-like fungusreproductive structures) form on and indiseased parts. Often float bed plants sufferthe greatest loss. Severely infected plants maywilt or topple. Sclerotia produced by thefungus can survive in soil for many years.The fungus can infect and survive on wildmustard. Spores from wild mustards can beblown to nearby cabbage.

Management Guidelines: Rotate to grasscrops. Avoid beans, potatoes and tomatoes inrotations. Deep plowing of debris buriessclerotia.

MOSAIC or VIRUS DISEASESCauliflower and turnip mosaic virusesoccasionally occur on cole crops, but they

19

and may have varying amounts of necrosis, transplants from the same source or in seedsdepending on the virus strain and other from the same seed lot. A 3-4 year rotationfactors. Some plants show vein clearing. with control of cruciferous weeds is required.Plants may be stunted if infection occurs early.Cauliflower and turnip mosaic can cause aproblem known as pepper spot on maturecabbage heads. Initially the spots are on theinterveinal tissue of the outer leaves but intime will infect leaves in the head. The mostimportant time of infection is in the seedlingstage. Plants infected then may suffer yieldreductions, whereas plants infected later mayshow little effect. Aphid control in the plantbed is recommended as is control of weedsaround the bed. The viruses cannot survive inthe absence of a living host; they depend forsurvival on perennial and annual plants. Theyare spread from plant to plant by aphids. Avoid planting next to old virus-infectedcrucifer fields, and control such weed hosts aswild mustard.

SCOUTING FOR EARLYSEASON CABBAGEDISEASESControl recommendations for production areaswill be based on diseases found in scoutedfields in that area. All diseases should beconfirmed by the plant diagnostic lab.

1. Black Rot Copper fungicide sprays shouldbegin if presence of this disease is confirmed.If only an occasional plant is infected, removalmight slow spread. If greater than 10% sprayand pray. Black rot is often carried in seedlots or transplants from the same productionsource. Alert all growers using that seed lot ortransplant producer to begin a spray programif the infection source is transplants or seed.

2. Blackleg If this disease is found in isolatedplants in the field, remove these and destroy.Blackleg is often found in fields with wildmustard populations. It may be carried on

3. Downy mildew Begin a Bravo sprayprogram with the first tobacco blue mold alert.

4. Rhizoctonia Wirestem is often seen infields with a freshly turned green manure crop.It may get its start on transplants that havebeen injured due to pulling and/or shipping.Wet soils may aggravate this problem.

5. Sclerotinia If white rot is found in isolatedplants, pull these and remove them. This mayoccur in fields with or near high wild mustardpopulations. It is sometimes found in fieldswhere wild mustard was recently ploweddown.

20

TIPBURN AND OTHERPHYSIOLOGICALDISORDERS

TIPBURNTipburn is a serious physiological disorder ofcabbage, involving death of leaf tissue in thedeveloping head. Tipburn may involve a fewspots along the leaf margin or the entire edgeof the leaf may be affected. The tissue turnsbrown and eventually black and may continueto decay. Tipburn is caused by calciumdeficiency in this leaf tissue. This deficiencymay be due to low Ca levels in the soil (pH)++

and/or poor uptake of Ca by the plant and++

distribution to the leaves in the head. Theproblem is often associated with fields whichreceived excess nitrogen, especially theammonium (NH ) forms of nitrogen or4

+

potassium (K ) fertilizers. Competition+

between NH , K , and Ca for uptake by4+ + ++

cabbage plant roots results in less Ca++

reaching the head leaves. Anything thatreduces size of the cabbage plant’s rootsystem will also reduce the level of Ca++

reaching the head leaves, simply because therewill be fewer sites for uptake. Excess soilmoisture can also induce the problem byreducing calcium uptake. All plant nutrientstaken up by the roots are carried by waterthroughout the plant. Dry soil conditions canincrease the possibility of tipburn because lesswater is available to carry nutrients to theleaves. When weather conditions are hot anddry, most plant transpiration is highest throughthose leaves directly exposed to the air.Interior head leaves do not require as muchwater, so Ca flow to these leaves is less.++

Varieties may also differ in susceptibility totipburn.

Control Recommendations: 1) Maintain uniform plant growth throughoutthe season. 2) Fertilize according to soil tests. Applyingmostly nitrate forms of nitrogen rather thanammonium forms. 3) Maintain uniform soil moisture withirrigation where possible and avoid poorlydrained fields. 4) Maintain good soil tilth (no compaction, orhard pans) to promote root growth. 5) Avoid excess cultivation (root pruning).

EDEMAEdema appears as small brownish graywart-like growths on the leaf surface. Thesegrowths are thought to be initiated by leafinjury caused by sand or insects. Edemausually develops during cool nights followingwarm muggy days. Under these conditionswater uptake is faster than water loss;consequently, the leaf epidermis bursts andexpanding leaf cells are exposed and becomecorky.

SOIL COMPACTION Signs of soil compaction include: slow plantgrowth, variable stands, variable plant size inthe field, off-color leaves, shallow rootsystems. Plowing, disking and planting whenthe ground is too wet can lead to serious yieldlosses. Compare soil penetrometer readings inaffected areas with normal areas.

21

CABBAGE DISEASES PICTURE SHEET

ALTERNARIA BLACK ROT

BACTERIAL SOFT ROT DOWNY MILDEW

FREEZE DAMAGE

22

CABBAGE CULTURAL REQUIREMENTS

See ID-36, Commercial Vegetable Crop cold periods below 50E F encountered inRecommendations for specific cultural and spring plantings and some have morevariety recommendations. resistance to head splitting. Ideally the variety

FIELD SELECTIONSandy, silt or loam soils are more desirablethan clay soils. Soils with high organic matterlevels are also preferred. Avoid wet or poorlydrained soils. The field should be free ofweeds, particularly perennial weeds. A southor southwest exposure allows earlier plantingand promotes earlier crop harvest. Select fields where deer and ground hogs arenot a problem or put control measures intoeffect prior to crop planting. Both or thesecan cause considerable crop loss. Follow agood crop rotational program.

CROP ROTATIONNever grow cabbage, related cole crops orrelated weeds in the same field more thanonce every 3 years and preferably 4 years.Cole crops include cabbage, broccoli, Brusselssprouts, cauliflower, Chinese cabbage, kale,kohlrabi, mustard, radishes, rutabagas, andturnips. Related weeds include, wild radish,shepherds purse, wild mustards etc. There canalso be some rotational problems from cropsthat are outside the cole crop family. (SeeAppendix 4.)

Fescue sod plowed down in the fall, soybeans,corn, wheat and grasses are good rotationalcrops. Be sure that there are no carry-overherbicide residues.

VARIETY SELECTIONSelect varieties that are desired by theintended market. It is preferable that thevarieties have black rot tolerance/resistance,as well as yellows resistance. Some varietiesare less prone to bolting, caused by prolonged

should have a small core and produce hardcompact heads. Varieties that produce smallerheads in the 2-3 lb range are desired for thefresh market, while large head sizes aredesired for the slaw or processing market.

SOIL TESTING ANDFERTILIZATIONTest the soil the year before planting for pH,phosphorus (P), potassium (K), calcium (Ca),Magnesium (Mg) and boron (B). Adjust thepH to 6.5 to 7.0 with lime preferably in thefall or very early spring and work into the soil.A pH in this range promotes optimumavailability of most nutrients needed toproduce a good cabbage crop. A minimum of2,000 lb of calcium per acre is recommended.

On soils with a history of club root, adjust thesoil pH to over 6.8. Broadcast and disc in1,500 lb per acre of hydrated lime 2-3 daysprior to transplanting if the soil pH is less than7.5 for club root control. Do not do this morethan once every 3 years.

Apply P and K based on the soil testrecommendations and plow these in prior toplanting.

Cabbage yields are increased by higher ratesof nitrogen (N). However, N levels that aretoo high increase internal tipburn. Prior toplanting broadcast and plow down 50 lb of Nper acre. Sidedress with 50 to 100 lb of N peracre when heads begin forming (150-300 lb ofammonium nitrate or 330-660 lb of calciumnitrate). Make a second sidedressing of N 2 to3 weeks later. Late N applications can lead tohead bursting. Use calcium nitrate where

23

tipburn has been a problem.

If the soil test indicates that magnesium (Mg)is low and if lime is recommended, applydolomitic limestone. The soil test shouldshow 100 lb Mg per acre as a minimum. Ifmagnesium is low and lime is notrecommended, apply enough magnesiumoxide or other source of magnesium such asEpsom Salts (MgSO ) to achieve 100 pounds4

of elemental magnesium per acre. Cabbagehas a fairly high Mg requirement. If a Mgdeficiency develops in the field, spray with 10lb of Epsom salts in 100 gallons of water peracre.

Apply a minimum of 10 pounds of sulfur peracre using a fertilizer such as potassiumsulfate, K SO (0-0-50) which is 18% S.2 4

Apply up to 50 lb S if it is necessary. Sulfateof potash magnesia (Sul-Po-Mag or K-Mag)may also be used to supply a portion of therecommended K 0 and to supply Mg and S.2

Most tobacco ground probably has plenty of S.

For cole crops, one to two pounds of actualboron (B) per acre is recommended,particularly if your area of the state tends to below in B or your soil test shows less than 1 lbof B per acre. Two pounds of B is equivalentto 18 lb of Borax which is 11% B. Boron canalso be applied to the leaves as Solubor at 1.5lb per acre. Be careful when applying boron,since the range between deficiency andtoxicity is very narrow. Too much boroncauses serious problems.

If the soil test indicates that zinc (Zn) is low(see corn recommends in AGR-1), apply fivepounds of actual Zn as zinc sulfate, ZnSO .4

Growth responses are likely when the soil testshows less than 2.5 lb/acre.

FOLIAR APPLICATION OFNUTRIENTSThe fact that plants can absorb a number offertilizer elements through their leaves hasbeen known for some time. However, leavesof many vegetable plants are not especiallywell adapted for absorbing nutrients becausethey have a waxy cuticle. In fact, plants mayappear to benefit from foliar uptake when theactual cause of improvement may be from thatcomponent of the nutrient spray which reachesthe soil and provides essential nutrients forsubsequent root uptake. Foliar application isbeneficial if soil nutrient levels are low or ifnutrients are unavailable to the plants andthe plants are showing a deficiency. Foliarapplications are often effective in rapidlycorrecting micronutrient deficiencies.

The effectiveness of applying macronutrientssuch as nitrogen, phosphorus, and potassiumto plant leaves is questionable, high rates oftencause damage to plant tissues. It is virtuallyimpossible for greens (waxy leaved cabbage,collards and kale) to absorb enough N, P or Kthrough their leaves to meet their nutritionalrequirements, furthermore, it is unlikely thatthey could absorb sufficient amounts ofmacronutrients to correct major deficiencies.Although nitrogen may be absorbed within 24hours after application, up to four days arerequired for potassium uptake and seven to 15days for phosphorus to be absorbed fromfoliar application.

The crucial question is whether foliar N, P, orK actually increase yield and/or enhancequality. Although some growers feel thatfoliar fertilizer should be used to supplementa soil-applied fertilizer program, researchfindings do not support this practice. If properfertilizer management of soil-applied nutrientsis used, supplementation by foliar fertilizationis not usually required.

24

Foliar nutrients often are expected to cure a expected. Foliar applications are usually avariety of plant problems, many of which may poor substitute for proper soil testing prior tobe unrelated to nutrition, such as reducing planting.stress, aiding in healing frost or hail damagedplants or increasing plant resistance to variousstresses and pests. Nutrients are effective aslong as they are supplying a nutritional need.

Following a damaging frost or hail, somecabbage and leafy greens growers apply foliarnutrients to give the plants an "extra shot" topromote rapid recovery. However, if a properfertilizer program is being used before foliagedamage occurs, it becomes evident that theplants don't need additional fertilizer. Whatthey do need is time and the properenvironment for the normal recoveryprocesses to occur. The likelihood of derivingsignificant nutritional benefits from a foliarapplication of fertilizer to plants that have lostsome of their leaves (or have a largeproportion of their leaves severely damaged)is questionable.

Foliar application of sulfur, magnesium,calcium and micronutrients (based on a soiltest) may help alleviate deficiencies. Anapplication of water-soluble boron such asSolubor (approximately 0.25 lb of actual B peracre) can be used when a deficiency occurs.However, foliar nutrient sprays should beapplied only if there is a real need for themand only in quantities recommended for foliarapplication. Application of excessive amountscan cause fertilizer burn and/or toxicityproblems. Once deficiency symptoms occur,some yield loss can be

TRANSPLANTSIf plants are purchased from the south,purchase certified disease free bare rootplants. A better alternative is to purchase plugplants, preferably locally grown. A third andeven better option in most cases is to growyour own transplants. If you grow your own,use western grown, hot water treated seed andtreat this with a fungicide prior to planting.Seed for the spring crop should be seededaround January 20 and seed for the fall cropshould be planted from late May to July 1.

When growing your own transplants for a fallcrop in a seedbed, choose a site where colecrops have not been grown before or fumigateprior to seeding. Four to 6 ounces of seedwill sow a standard 9' X 100' seedbed andproduce enough plants for an acre. Drill seeds1" apart in rows 6" apart and 5/8 inch deep, 5-6 weeks before transplanting. Seeds should beplanted in late afternoon or evening toimprove germination. A light layer of strawover the bed will also improve germinationand frequent light irrigations are absolutelynecessary for success.

To grow your own transplants in agreenhouse, precision seed into 200 cell flatscontaining a peat vermiculite mix or othersuitable growing media. Seed will germinatein 3-6 days, approximately 4 days at 70E F. Temperatures should be maintained above 45EF at night and below 85E F during the day.

25

Transplants should be hardened off when B. Put the graded plants back in separategrown in a greenhouse before going to the crates. Mark each crate according to plantfield. A transplant taken directly from a size so you can easily plant all the large andgreenhouse and set in a field on a hot sunny small plants in separate locations. If you areday will sunburn and die. Hardening off not going to plant within a few hours keep theinvolves slowing the plant growth to toughen crates in the shade or place them in a barn.the plants up so that they will withstand fieldconditions. This is achieved by decreasing the C. If the cabbage plant count was short or iftemperature 5-15E F, reducing watering you feel you have diseased plants tell yourfrequency, increasing light exposure, county agent or Coop director immediately!increasing ventilation, and/or reducing Nlevels. Too great a reduction in N will causeyellowing, stop growth, delay maturity, andreduce head size.

Most Kentucky growers progressivelyincrease the amount of sunlight exposure ontheir transplants over a period of time toharden them off. This can be done by placingthe transplants on a wagon and moving themout of a barn for progressively longerintervals.

HANDLING CABBAGETRANSPLANTSSoon after you get your cabbage plants home, extra plants in a separate box or crate.they should be prepared for field setting. Youwill receive field packed plants in wooden B. If plants become wilted the crates can becrates or boxes. Plant counts will vary from set in 1-2 inches of water for several hour.crate to crate based on plant size at the time of The crate should be packed so that only theharvest and packing but you should receive cabbage plant roots are in the water. Do notenough to plant your intended acreage. leave them in the water for more than two

A. Open the crates as soon as possible,remove the plants and gently pull theentangled roots apart. Plants should be gradedinto two size groups, large and small, forseparate planting. The larger cabbage plantsnormally will produce heads first, so plantingthem separately will make harvesting easier.Check the plants for diseases as you sort not leave the plants outside where the tops canthem. Contact your county agent if you feel get wet if it rains.you may have a disease in your cabbagetransplants. E. Many growers place sawdust, straw, hay or

D. When your plants arrive get them in theground as soon as possible without workingwet soil.

CARE OF TRANSPLANTSPRIOR TO PLANTING

You may not have the ground ready or it maybe too wet to plant immediately. Transplantscan be held safely for 10 to 14 days ifnecessary by doing the following.

A. Remove some of the plants from each crateso they are not packed too tightly. Place the

hours. Be sure that only the roots are touchingthe water. DO NOT WET THE LEAVES!

C. Set the crates in a well-ventilated and shadyplace (a barn, crib, or any well ventilatedbuilding).

D. Do not wet the tops of the plants! and Do

any similar material on the floor of the barn,

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then wet the area thoroughly with a water hosebefore setting the crates on the moistenedmaterial. If it is necessary to hold the plantsmore than 5 days it may be necessary to movethe crates and remoisten the sawdust or straw.This is an easy, safe method to keep the plantsin good condition. There is less chance ofaccidental disease spread with this methodthan soaking the roots in water.

TRANSPLANTINGPrior to transplanting prepare a good firmseedbed by discing. Transplant by mid-March for the spring crop and from June toAugust 1 for the fall crop. Set plants 8-10inches apart for fresh market cabbage and 12-14 inches apart for slaw cabbage in rows 32-42 inches apart. (See Appendix 5 for variousplant spacings and plant populations per acre.)

Apply 1 cup of starter solution that is high inP per plant to the root system at transplanting.The starter solution is made by adding 3 lb ofa starter fertilizer such as 10-52-17 to 50gallons of water. It is important to apply thestarter solution immediately aftertransplanting. These nutrients are veryimportant to get the cabbage off to a good startin the spring, because the soil is cold andnutrient uptake is slow. The water isparticularly important in combination with thedilute nutrients to get the transplantsestablished under hot dry conditions for thefall crop. For the fall crop increase theamount of solution applied, but make it halfstrength to avoid burning the plants.

IRRIGATIONIrrigation is important to achieve high cabbageyields. Growers can often get by withoutirrigation for the spring crop, particularly ifthe spring is a wet one. However, irrigation isa must for fall cabbage. Plants should receive1" of water per week either as rain orirrigation.

WEED MANAGEMENTSurvey the field that will be planted tocabbage the year before and identify andcontrol problem weeds. This may involvespot sprays of a systemic herbicide or sprayingthe entire field to kill problem perennialweeds. Plant a crop or covercrop with theintent of reducing weed populations in thefield the year before.

Do not let weeds go to seed in fields,alleyways, and roadways. Keep fence rowsclean and mow field margins on a regularbasis. This will avoid the production ofunwanted weed seeds that blow into the field.Regular mowing will avoid the build up ofproblem insects such as aphids and theirforced movement into the cabbage field whichoccurs with infrequent mowing.

Cabbage has a shallow root system andcultivation should be shallow (2 inches orless) and should only be used as needed tocontrol weeds. See ID-36, CommercialVegetable Crop Recommendations for thelatest chemical weed controlrecommendations. Plan on using at least onepreemergence herbicide and do not dependsolely on post emergence materials. It is agood idea to rotate the materials that are usedto avoid building up populations of certainweed species.

HARVESTHarvest while heads are cool and after theyhave dried off. Keep harvested heads shaded.Avoid rough handling and maintain a highhumidity during storage.

Harvest heads for the fresh market when theyare firm. A 2 to 3 pound head is the sizedesired by the fresh market. Harvest with 2

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to 3 wrapper leaves leaving ½ inch of basil Harvest 5 to 8 pound heads for the processingplate below the head. Get cabbage out of the (slaw) market and remove the wrapper leaves.sun to avoid sunburn. Slaw cabbage is hauled in bulk bins.

KEY TO CABBAGE NUTRIENT DEFICIENCY SYMPTOMS UNDER FIELD CONDITIONS

In a large field the symptom of any deficiency usually occurs in spots so plant growth should becompared between areas. The first symptom is usually a slowdown of growth which may goundetected. Sometimes soil characteristics, crop characteristics and cultural practices can give clueswhen a problem is seen.

I. Slow plant growth with slow developing visual symptoms. Leaf shape is normal.

A. Entire plant is involved.

1. Generally dark green, stunted plant with dark purple on leaves, leaf veins and stems. Some yellowing on older leaves in severe cases. Phosphorus

2. Pale green or yellowish stunted plant with woody stem and tough leaves. Gradual dying of older leaves. Bright purpling on stems and leaves in some plants. Usually only seen when soils are wet and cold. Nitrogen

B. Older leaves showing symptoms with progressively milder symptoms on younger leaves.

1. Yellowing of leaf margins, moving inward in large blotches, followed rapidly by death of yellow tissue. Affects oldest leaves first and upper part of plant may be normal in appearance. Potassium

2. Yellowing in interveinal areas with veins remaining green. May be blotchy or in stripes but leaf stays yellow without necrosis for sometime. Oldest leaves are affected most and often puckered. Sometimes magnesium deficiency occurs when excessive applications of potassium have been made. Magnesium

3. Plants stunted with a purplish cast to the older leaves. Deficiency symptomsfrequently occur during cold weather when temperatures are below 50F. Phosphorus

II. Rapidly developing symptoms with yellowing of younger leaves, deformed leaves, or death ofterminal buds or older plant parts.

A. Leaf shape normal.

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1. Chlorosis most severe on young leaves, severe stunting of plant.

a. Young leaves uniformly golden yellow. Usually on alkaline or overlimed soils. Iron

b. Young leaves with severe yellowing but green veins. Plant growth may be stunted. Usually on alkaline or over limed soils. Manganese

2. Chlorosis over most of plant, moderate to slight stunting.

a. Leaves with alternate yellow and green stripes, yellow blotch at base of leaf, some white or necrotic spots. Zinc

B. Young leaves deformed.

1. Symptoms on leaves only.

a. Twisting of young leaves with chlorotic spots on older leaves. Zinc

b. Younger leaves progressively more strap-like and brittle, usually with slight to moderate chlorosis. Molybdenum

c. Young leaves deformed, cupped with some chlorosis and terminal bud death. Boron

d. Young leaves suddenly water soaked turning black rapidly. Calcium

e. Margins of young leaves cupped downward; brown to black preceded by water soaking. Calcium

2. Death or abnormalities on plant parts other than the leaf blades.

a. Cracking or blistering of petioles or midribs, sometimes turning black and hard. Boron

b. Water soaked areas on stems, storage organs followed by red or brown colorthen turning black and hard. Internal discoloration of the stem may occur. Boron

c. Tips of leaves in heads turn brown then black (Tipburn). Calcium

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Appendix 1

INSECT TRAPS

The basic principle of pest management is We are interested in catching many insectsthat you do not take action against a pest when they are in the moth stage of their lifeunless you are certain the pest is present and cycle because this is when they will be layingwill be a threat to your crop. Insect traps are a eggs and males will be attracted by the odor ofgood method of determining if an insect is the pheromone. The moths lay eggs whichpresent and can also give an estimate of their develop into worms that feed on crops. Toconcentration and distribution. Food, light, complete their life cycle the worms change tocolor or chemicals can be used to attract moths that in turn lay more eggs thusinsects to a trap. However, if you are producing more worms. By knowing that theinterested in only one species of insect, such moth stage of a pest is present the farmer canas only the beet armyworm or only cabbage be on the look out for damaging worms thatlooper, a pheromone would be the best choice are sure to follow.to attract the insect. A pheromone is asecretion from an unfertilized female insectthat attracts only male insects of the samespecies. The male insects are attracted by theodor of the pheromone. The traps consist of aplastic top and bottom that are held togetherby a wire hanger. The tops of the traps can bereused and the disposable bottoms are coatedwith a sticky gel to hold the insects once theyland in the trap. The trap can be mounted to afence post.

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Appendix 2

USING PHEROMONE TRAPS

The following are guidelines to be followed # If you cannot identify a particular insect inwhen using pheromone traps in cabbage: a trap, send it to your county CES office or to

# Store replacement lures in freezer orrefrigerator when not in use. Lures can bestored from one season to the next in thefreezer. Write the date the lures were placed inthe freezer on each package.

# Change gloves or wash when handlingpheromones for different species of insects toprevent cross-contamination. Minute traces onone pheromone contaminating another willrender the second completely ineffective.

# Begin pheromone trapping as soon as thecabbage is set in the field.

# Mark the type of insect that the trap attractson the outside of the trap and be sure to placethe correct pheromone lure into the correcttrap.

# Hang traps on field margins and separatethe traps by at least 15 to 20 yards..

# Use 1 trap of each type per each 5 acres.

# Monitor traps at least once a week,particularly during peak flight periods.

# Record trap catches on IPM scouting log. Ifind it helps to keep a running graph of theinformation.

# Remove moths collected in trap during eachvisit and dispose of them away from field.

# Change pheromone lures every 4 weeks.DO NOT dispose of any lures in the field,these will compete with the traps and affecttrap catches.

UK Lexington for identification.

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Appendix 3CABBAGE INTEGRATED PEST MANAGEMENT FORM

COOPERATOR: SCOUT: FIELD #:

ADDRESS:

CITY: ZIP: VARIETY: ACRES:

COUNTY: PHONE: DATE PLANTED:

SOIL CONDITIONS WEATHER TIME/DATE:

WET MOIST DRY COOL WARM HOT NO LEAVES:

LOOSE HARD LIGHT CRUST CALM LIGHT STRONG WINDSUNNY CLOUDY RAINY

GROWTH STAGE:

INSECTS/DISEASES: 1 2 3 4 5 6 7 8 TOTAL AVG % INFESTATION

PHEROMONE TRAP INFORMATION

LURE TYPE LAST VISIT THIS VISIT (LAST + THIS VISIT) DATE LURES CHANGED# MOTHS # MOTHS TOTAL FOR 2 WEEKS

BEET ARMYWORM

DIAMONDBACK MOTH

CABBAGE LOOPER

PESTICIDES APPLIED RATE/ACRE DATE APPLIED

FERTILIZER APPLIED RATE/ACRE DATE/APPLIED

COMMENTS:

WEEDS:PREDOMINANT SPECIES

LOW MEDIUM HIGHPRESENCE OF WILD MUSTARD IN FIELD G G G NEARBY G G G

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Appendix 4

Rotation from Various Crop Groups for Planting Cabbage

Crop Group Probability of Disease Overlap

Cabbage, Broccoli, Cauliflower Very High

Tobacco, Tomato, Pepper Medium*

Soybean, Alfalfa, Peas Low/Medium

Pumpkin, Melon, Cucumber Low

Corn, Wheat, Grasses Very Rare

* Root Knot Nematode

Appendix 5

Row Spacing and Plant Population Per Acre

Row Spacing Plant Spacing in Row Per AcrePlant Population

32" 8" 24,540

32" 10" 19,666

32" 12" 16,376

34" 8" 23,084

34" 10" 18,481

34" 12" 15,375

36" 8" 21,801

36" 10" 17,493

36" 12" 14,520

38" 8" 20,644

38" 10" 16,519

38" 12" 13,758

42" 8" 18,695

42" 10" 14,969

42" 12" 12,446