May 13, 2019 VOLUME 28, No. 8 Geneva, NY

1

IN THIS ISSUE...

DISEASES v Bacterium that causes blister spot v Weekly Scab update v Weekly Blossom Blight update

CHEM NEWS v NYS Bans Lorsban

UPCOMING PEST EVENTSPEST FOCUSINSECT TRAP CATCHESPHENOLOGIES

continued...

scaffoldsF R U I T J O U R N A L

Update on Pest Managementand Crop Development

by frequent rains during bloom (which is currently the case this spring in

the Hudson Valley) and continu-ing into mid- to late June, when the fruit have developed stomata. Fruit start being susceptible when stomata first form on them. If the

weather is rainy during bloom and for several weeks after petal fall, al-

most 100% of 'Mutsu' fruit can be infect-ed.

However, the fruit losses in NY usually range from 5–60%. This is an issue not only in eastern but in western NY, too. Once blister spot appears in the orchard with highly suscep-tible cultivars, it cannot be eradicated. In the Hudson Valley, both 2017 and 2018 have seen 11–71% more rain than the yearly average and were extremely favorable for blister spot out-breaks. In 2018, P. s. pv. papulans was diag-nosed at the Hudson Valley Research Laborato-ry from this author's own research resources as

A BACTERIUM,Pseudomonas syringae pv.papulans,COULDCAUSE

BLISTER SPOT ON APPLEFRUIT IN 2019(Srdjan Aćimović, Plant Pathology and Plant-Microbe Biology, Highland;acimovic@cornell.edu)

vv Apple blister spot is a bacterial dis-ease that affects fruit and leaves. It is caused by a Gram-negative bacterium, Pseudo-monas syringae pv. papulans. During the growing season, this pathogen is very like-ly present in most of the apple orchards as an epiphyte – i.e., living on the surface of leaves, flowers and fruit. It survives over the winter in apple buds, in leaf scars and on dis-eased fruit left on the orchard floor. Blister spots lead to economic damage by impacting the fruit cosmetic quality, thus preventing it to be sold for a top price on the fresh fruit market. Yield weight is not reduced but the fruit can only be sold for juice, severely re-ducing the profits. The most affected culti-vars are 'Mutsu' ('Crispin'), 'Fuji' and 'NY-1', where 'Mutsu' is extremely susceptible, but other cultivars such as 'Golden Delicious', 'Red Delicious', 'Cortland', 'Gala' and 'Jona-gold' are also susceptible to this disease, but much less than 'Mutsu'. Other cultivars can get infected, usually when planted near the infected trees of 'Mutsu', which serve as the inoculum source ('Idared', 'Mclntosh', 'Rome Beauty'). The pathogen is spread by rain and insects. Blister spot infections are favored

AVOIDBEING

SPOTTED

DISEASES

scaffolds No. 8 May 13, 2019

2

scaffoldsis published weekly from March to September by Cornell University—Cornell AgriTech at the NYS Agricultural Ex-periment Station (Geneva) and Ithaca—with the assistance of Cornell Cooperative Extension. New York field reports welcomed. Send submissions by 2 pm Monday to:

scaffolds FRUIT JOURNAL Dept. of Entomology Cornell AgriTech at NYSAES 15 Castle Creek Dr. Geneva, NY 14456-1371 Phone: 315-787-2341 FAX: 315-787-2326 E-mail: ama4@cornell.edu

Editor: Art Agnello

This newsletter available online at: http://www.scaffolds.entomology.cornell.edu/

continued...

a cause of this disease in a limited outbreak on NY-1 ('SnapDragon'). The grower lost 20% of his crop to this disease. Blister spot has been known to occur on NY-1 (Agnello et al. 2017).

Blister spot symptoms usually express first around 2 to 3 months after petal fall. In the lower Hudson Valley, we detected the first symptoms in 2018 around mid- to late July (petal fall occurred around 14 May in 2018). Early blister spots are very small (1–2 mm), dark green to black, raised blisters with wa-ter-soaked margins that develop at fruit stoma-ta (Figure 1A). With time, blister spots turn to purplish black (Figure 1A) and develop a cork tissue in the lesion center at the end (Fig-ure 1B). With fruit growth, the spots expand to becoming even more corked and pronounced. P. s. pv. papulans can also cause leaf petiole and mid-vein necrosis and curling on 'Mutsu' leaves, and usually occurs prior to fruit blister spot expression (Fig. 2, left; Bonn and Bedford 1986).

Rarely, this pathogen also causes curling of terminal growth (e.g., 'Red Cort', Fig. 2, right). It seems that 'Mutsu' is extremely favorable for

Figure 1A. Advanced blister spots with wa-ter-soaked margins on apple cv. NY-1 (aka ‘SnapDragon’) caused by a bacterium Pseudo-monas syringae pv. papulans.

Figure 1B. Cork tissue appearance of blister spots in its final stage on apple cv. NY-1 (Photo by Aćimović S. G. 2018).

scaffolds No. 8 May 13, 2019

3

this pathogen to maintain the highest plant sur-face populations of P. s. pv. papulans. Never-theless, this bacterium has also been found to maintain its populations on the leaf, flower and fruit surfaces of other apple cultivars, as well as on the leaves of some orchard weeds such as dandelion, clover, quackgrass, leafy spurge and common mallow. Young 'Mutsu' fruit are highly susceptible to infections for roughly 6 weeks, starting from around 14–17 days after petal fall, and stay susceptible for 4–5 weeks more; i.e., until stomata on fruit have devel-oped into lenticels. Afterwards, the fruit lenti-cels are no longer susceptible to infections.

The best control can be achieved by spray applications of streptomycin, with the first ap-plication made at 10–14 days after petal fall, and two additional spray applications made at weekly intervals after the first one, especially if more rains have occurred. If the first appli-cation is made too late, efficacy is not guar-anteed. It is essential not to apply more than 2–3 sprays of streptomycin in total for this

disease. Summer sprays of streptomycin are NOT recommended, except after a hailstorm, so as not to promote antibiotic resistance in Erwinia amylovora and P. s. pv. papulans. Di-lute sprays are highly recommended to secure good leaf and fruit coverage where popula-tions of P. s. pv. papulans reside and multiply. It is recommended to mix streptomycin with Phostrol or StarPhite or Aliette WDG (fose-tyl-Al) in these applications. Use of strepto-mycin must be reserved only for the years with very favorable conditions for blister spot, stat-ed above, primarily to avoid development of streptomycin-resistant strains of P. s. pv. pap-ulans, which have been detected in the past. Resistance to this antibiotic can be quickly acquired by P. s. pv. papulans and lead to anti-biotic-control failures. Resistance can emerge in only a few years after consecutive antibiotic use. Monitoring of P. s. pv. papulans popula-tions for streptomycin resistance emergence is highly recommended to prevent this problem from increasing. On farms where no resistant

continued...

Figure 2. Left and Middle: Typical leaf midvein necrosis and curling on apple cv. ‘Mutsu’ (Image source: Bonn, W. G., and Bedford, K. E. (1986): Midvein necrosis of Mutsu apple leaves caused by Pseudomonas syringae pv. papulans. Canadian Journal of Plant Pathology 8:2, 167–169. Right: Curling effect of blister spot pathogen on terminal growth of ‘Red Cort’ apple tree (Image source: Plant Health Progress article by M. A. Ellis, L. V. Madden, and T. J. Burr (2000): Effectiveness of Fosetyl-Aluminum and Streptomycin Alone and In Combination for Control of Blister Spot on Mutsu Apples in Ohio and New York).

4

scaffolds No. 8 May 13, 2019

strains of this pathogen are detected, use of this antibiotic is an option, especially after recent history of the disease. In the classic planting systems, where other less susceptible cultivars are interplanted with or are near 'Mutsu', the disease can spread to these other cultivars. In spring, a 2–4 lb Kocide per 100 gal, from green tip and 1/2-inch green bud growth stage, may reduce the overwintering populations of P. s. pv. papulans that can emerge from overwin-tering pockets and overall effect some small degree of control. During pink bud, petal fall and early cover sprays, application of Aliette WDG or phosphorous acid; i.e., phosphite ma-terials (e.g., StarPhite, Phostrol, ProPhyt) can reduce infections. vv

Aćimović, S. G. (2019): Protect Your Most Precious: Apple Blister Spot (Pseudomo-nas syringae pv. papulans) Can Occur on NY-1. Cornell Blog Posts for 2019 Grow-ing Season. Fruit Tree Pathology at Cor-nell University's Hudson Valley Research Laboratory. http://blogs.cornell.edu/aci-moviclab/2019/01/30/protect-your-most-precious-apple-blister-spot-pseudomonas-syringae-pv-papulans-can-occur-on-ny-1/

Agnello et al. (2017): 2017 Cornell Pest Management Guidelines for Commercial Tree Fruit Production. Chapter 6, Disease Management, 6.2.2 Orchard Sanitation for High-inoculum Orchards. p. 60.

Bonn, W. G., and Bedford, K. E. (1986): Midvein necrosis of Mutsu apple leaves caused by Pseudomonas syringae pv. pap-ulans. Canadian Journal of Plant Patholo-gy 8:2, 167–169, Available at: https://doi.org/10.1080/07060668609501822

Burr, T. J. (1982): Blister Spot of Apple, New York's Food and Life Sciences Bulletin, Number 95, ISSN 0362-0069, New York State Agricultural Experiment Station, Ge-neva: https://ecommons.cornell.edu/bit-stream/handle/1813/5102/FLS-095.pdf?se-quence=1&isAllowed=y

M. A. Ellis, L. V. Madden, and T. J. Burr (2000): Effectiveness of Fosetyl-Aluminum and Streptomycin Alone and In Combina-tion for Control of Blister Spot on Mutsu Apples in Ohio and New York ,Plant Health Progress: doi:10.1094/PHP-2000-1204-01-RS.

Kerkoud, M., Manceau, C., and Paulin, J. P. 2002. Rapid Diagnosis of Pseudomonas syringae pv. papulans, the Causal Agent of Blister Spot of Apple, by Polymerase Chain Reaction Using Specifically Designed hrpL Gene Primers. Phytopathology 92:1077–1083.

OMAFRA Staff (2011): Blister spot Excerpt from Publication 310, Integrated Pest Man-agement for Apples:

http://www.omafra.gov.on.ca/english/crops/facts/blistersp.htm

T. van der Zwet, K. S. Yoder, and A. R. Biggs (2011): Blister Spot of Apple, The Mid-Atlantic Orchard Monitoring Guide (NRAES-75), https://articles.extension.org/pages/60624/blister-spot-of-apple

Plantwise Technical Factsheet – blister spot of apple (Pseudomonas syringae pv. papu-lans), Plantwise Knowledge Bank: https://www.plantwise.org/KnowledgeBank/Data-sheet.aspx?dsid=44982

Highland:Lesser Appleworm and Codling Moth 1st catch today, 5/13.

PEST FOCUS

5

scaffolds No. 8 May 13, 2019

scaffolds No. 8 May 13, 2019

6

UPCOMING PEST EVENTS

43°F 50°FCurrent DD* accumulations (Geneva 1/1–5/13): 292.6 124.1 (Geneva 1/1–5/13/2018): 339.5 183.2 (Geneva "Normal"): 392.0 202.0 Geneva 1/1-5/20, predicted): 369.8 167.8 (Highland 1/1–5/13): 520.3 251.7 Coming Events: Ranges (Normal ±StDev):Comstock mealybug 1st gen crawlers in pear buds 215-441 80-254European red mite egg hatch complete 368-470 182-280Green fruitworm flight subsides 267-499 123-271Lesser appleworm 1st catch 276-564 129-305Lesser appleworm 1st flight peak 364-775 183-444Oriental fruit moth 1st flight peak 331-533 166-284Pear psylla 1st egg hatch 174-328 60-166Redbanded leafroller 1st flight peak 232-382 105-201Spotted tentiform leafminer 1st flight peak 267-405 124-212Spotted tentiform LM sapfeeding larvae present 343-601 165-317Spotted tentiform leafminer mines forming 367-641 170-342White apple leafhopper nymphs on apple 302-560 146-308McIntosh bloom 344-415 168-218

*all DDs Baskerville-Emin, B.E.

NYS BAN ON LORSBAN(Peter Jentsch, Entomology, Highland; pjj5@cornell.edu)

In New York State, the use of chlorpyrifos (Lorsban; Dow/DuPont) is limited to a single application per season. Two types of applica-tions can be made, directed either to the tree canopy to manage San Jose scale, beetles (in-cluding borers and plum curculio), rosy apple aphid, lepidopteran and plant bug or Lygus pests; or as a coarse trunk spray directed to the lower 4 ft of the tree to manage trunk bor-ing pests such as dogwood borer and black stem borer. Lorsban can still be used in NY during 2019–2020.

On April 30, NYS legislators approved Senate bill S5343 and Assembly bill A2477B, which will bring about a ban on chlorpyrifos in New York beginning in 2021. This legislation is part of a larger environmental package and requires the approval of Gov. Andrew Cuomo to put the new law into effect. The bill would ban all use of chlorpyrifos except for on apple tree trunks by Jan. 1, 2021, and would ban the pesticide altogether by December 2021.

CHEM

NEWS

scaffolds No. 8 May 13, 2019

7

NOTE: Every effort has been made to provide correct, complete and up-to-date pesticide recommendations. Nevertheless, changes in pesticide regulations occur constantly, and human errors are possible. These recommendations are not a substitute for pesticide labelling. Please read the label before applying any pesticide.This material is based upon work supported by Smith Lever funds from the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

PHENOLOGIES

Geneva: Apple Current 5/20, Predicted (McIntosh): pink bloom (Red Delicious): pink king bloom (Empire): pink bloom (Idared): pink bloomPear (Bartlett): bloom bloom (Bosc): white bud/king bloom bloomSweet Cherry petal fall petal fallTart Cherry bloom bloomPeach petal fall fruit setPlum petal fall/shuck split fruit setApricot petal fall/shuck split fruit set

Highland:Apple Pear (McIntosh): 50% petal fall (Bartlett): early fruit set (Ginger Gold): fruit set 5 mm 49% (Bosc): 87% fruit set (Red Delicious): 62% petal fall Cherry (Smoothie): 53% petal fall (Black Pearl): 87% fruit set (Empire): fruit set 5 mm 44% (Ebony Pearl): 89% fruit set (Zestar): fruit set 7 mm 58% (Regina): 90% fruit set (Jersey Mac): 58% petal fall Peach fruit set/shucks on (Honeycrisp): 58% petal fall 66-71% (Brookfield Gala): 60% bloom

INSECT TRAP CATCHES(Number/Trap/Day)

Geneva, NY Highland, NY 5/6 5/9 5/13 4/29 5/6 5/13Redbanded leafroller 7.0 35.5 3.0 Redbanded leafroller 57.5 59.0 42.0Spotted tentiform leafminer 14.5 26.5 5.5 Spotted tentiform leafminer 51.5 65.5 0.0Oriental fruit moth 0.5* 9.0 13.5 Oriental fruit moth 21.5 30.5 0.0 Lesser appleworm 0.0 0.0 134.0* Codling moth 0.0 0.0 2.0* * first catch