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Prevention and Control of Common Olive Insects and Diseases
Bill Krueger, UC Cooperative Extension, Glenn County
Life Cycle
• Overwinters in margins of old lesions• Spores spread by wind and rain• Infections-fall winter-spring• Symptoms-spring and summer
Peacock Spot Variety Susceptibility
• Very susceptible -Blanqueta, Cornicabra,Empeltre,Mission, Picual
• Susceptible -Aglandou, Arbequina, Ascolano, Hojiblanca, Kalamata, Sevillano, Manzanillo, Pendolino, Picudo
• Resistant-Beauteillan, Cayon, Coratina, Leccino, Maurino, Moraiolo
• Very Resistant -Arbosana, Frantoio, Koroneiki
Cercospora Leaf SpotMycocentospora cladosporioides
• North Coast • Sooty mold like symptoms on underside of
leaf from sporulation• Yellowing and leaf drop – no spots• Life cycle similar to Peacock spot• Control measures are the same
Cultural Control
• Variety Susceptibility• Consider variety susceptibility• Cultural
– Contributors to disease• High humidity- heavy dew, fog, low lying areas• Dense canopies-low light• Excessive sprinkler irrigation
Control continued
• Copper sprays– Bordeaux, Fixed coppers
• Preventative applied before infection– Central Valley table varieties, post harvest
before significant rain, 1 to 2X– Coastal Areas ? Oil varieties?, post harvest
and spring– Consistent program important
Life Cycle
• Bacteria survive in galls• Spread by wind and rain• Infect openings in tree
– Leaf scars, pruning wounds, freeze cracks• Infection-fall, winter, spring• Symptoms-late spring, summer
Olive Knot Variety Susceptibility
• Very susceptible – Arbequina, Manzanillo, Picudo
• Suceptible – Empeltre, Sevillano, Hojiblanca, Koroneiki, Moraiolo, Pendolino, Picual
• Resistant – Ascolano, Blanqueta, Frantoio, Leccino, Mission
Average Rainfall by Month for Orland, California
0102030405060708090
100
Rai
nfal
l (m
m)
JAN. MAR. MAY JULY SEPT. NOV.
Olive Knot Wound Study4 Wounds/tree
11 replicates 2-15-91 to 6-30-92 10 replicates 3-29-93 to 11-24-93
0
20
40
60
80
100
120
2/15
/199
1
3/22
/199
1
4/18
/199
1
5/25
/199
1
9/13
/199
1
11/2
3/19
91
12/3
/199
1
2/27
/199
2
4/6/
1992
6/30
/199
2
3/29
/199
3
5/3/
1993
5/21
/199
3
6/16
/199
3
7/26
/199
3
9/14
/199
3
10/1
5/19
93
11/2
4/19
93
Wounding Date
% In
fect
ion
Olive Knot Pruning Wound Study
Manzanillo Variety
0102030405060708090
100
% Infected (10 shoots)
Con
trol
5/22
- 0
5/20
- 2
5/18
- 4
5/15
- 7
5/13
- 9
5/11
- 11
5/8
- 14
Date / Days From Pruning to Inoculation 3.175 mm rain
Pruning Dates: 5-8-92 to 5-20-92
Inoculated 5-22-92
Cultural Control
• Variety susceptibility• Prune out during dry period (late spring)
– Reduces risk of freeze injury– Allows wounds to heal before infection period
Control-Continued
• Materials are at the same as Peacock Spot– Copper Sprays
• Timing-preventative• More sprays are better• Central Valley recommendation- 2 sprays,
fall and spring.• Spring spray is the most important
Verticillium WiltSoilborne fungusSurvive in the soil as microsclerotiaGrow into root and plug vascular tissue resulting in wiltInfections in cool moist soil in winterSymptoms in spring and summerMuch more prevalent in Southern San Joaquin Valley
Verticillium Wilt Variety Susceptibility
• Very Suceptible – Arbequina, Cornicabra, Hojiblanca, Picual, Picudo
• Susceptible – Kalamata, Leccino, Manzanillo, Mission, Moraiolo, Pendolino, Picholine
• Resistant – Aglandou, Ascolano, Koroneiki,
• Very Resistant – Empeltre, Frantoio
Control
• Site selection– Avoid that are known to have high levels of
Verticillium• sites that have previously grown susceptible hosts
• Solarization- inconsistant results• No resistant rootstock.
Black ScaleSaissetia oleae
• Soft Scale• One to two generations
(coast) generations per year
• Overwinter as 3rd instarnymph
• Mature spring summer• Lay eggs• Egg hatch May,
June,complete by July• Crawlers develop to 2nd
or 3rd instar by fall
Damage• Suck sap from
tree- honeydew• Suity mold• Reduces
photosynthesis and respiration
• Can reduce fruit bud formation, cause leaf drop and dieback
Cultural Control
• Pruning- Open airy canopy promotes heat mortality
• Most reliable control for Central Valley
Biological Control
Scutellistacyanea
Metaphycus helvolus
Control ants-deny access to tree
Cool environment is preferable
Treatment Thresholds
• May sample– Light population (0-1 per branch) no treatment– Moderate (1-4 per branch)- prune or prune
and spray– Heavy (4-10) Prune and Spray
Oil and/or Insecticide Treatment
• Crawler emergence (July 1) to Aug. 1– To prevent damage to subsequent crop
• Post Harvest– Until scale develops to rubber stage– Light to moderate populations
Armored Scales
• Olive, Oleander, Latania, Greedy and Red
• 2 to 3 generations per year• Damage-reduce yield and downgrade fruit
Control
• Biological– Don’t disrupt– Promoted by open airy canopy
• Spray crawlers with oil and/or insecticide– Monitor for crawler emergence with 2 sided
sticky tape