July 27, 2020 VOLUME 29, No. 19 Geneva, NY

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IN THIS ISSUE...INSECTS v August insect checklist v Dock sawfly

HORTICULTURE v Keeping squirrels out of apricots

CHEM NEWS v Bifenthrin Section 18 approval for BMSB

PEST FOCUS TRAP CATCHESUPCOMING PEST EVENTS

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

Update on Pest Managementand Crop Development

for Cyd-X granulosis virus applications against codling moth, or Madex HP or

ViroSoft CP4 against both OFM and codling moth.

European Corn Borer This late season moth can be active

until the middle of September, so lar-vae can be a threat, particularly to lat-

er varieties. Delegate is a good option for control, and 1-2 sprays of a B.t. product can also be a useful alternative.

Mites Our warm temperatures are still capable of promoting flare-ups of mites. The 7.5 mites/leaf threshold (sampling chart on p. 77 in the Recom-mends) would apply at this point in the season. There are several good rescue materials available, if needed; check the acaricide efficacy table on p. 66 of the Recommends for ratings against TSSM vs ERM.

THE MADDING CROWD(Art Agnello, Entomology, Geneva;ama4@cornell.

edu)

vv As harvest preparations are being made, it's worth keeping in mind the late season arthropod pests that can still pop up and complicate life during the dog days of August. Take some time to ensure that your pest management program is not overlooking the following potential problems during this pe-riod:

Apple Maggot We typically get the highest trap captures during the first week of August, and having just recorded the first captures of the season in Geneva (July 24) and Wayne Co. (July 26, c/o Jim Eve), we may be in for a later than normal flight this year. Monitor your traps carefully this week, and be ready to apply a preventive spray if necessary. Options include: Imidan, Assail, Avaunt, Delegate, Exirel, certain premixes such as Endigo, Leverage, Besiege, and the pyre-throids.

Internal Lepidoptera Respectable adult numbers are being seen in traditional high-pressure blocks; 2nd brood cod-ling moth egg hatch is in progress, and the 3rd flight of oriental fruit moth is due to start soon in the Hudson Valley. Recommended options in-clude Altacor, Assail, Delegate, Verdepryn, Ex-irel, Besiege, and Minecto Pro. Pyrethroids and OPs may be less suitable because of locally re-sistant populations. This is also a suitable time

ALL HOME WEEK

I N S E C T S

scaffolds No. 19 July 27, 2020

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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/

Woolly Apple Aphids Colonies in the canopy (Fig. 1) are present and can always increase. It's probably too late for a Movento application to be effective, but Assail (plus a non-ionic surfactant), Admire Pro, Sivan-to Prime or Beleaf could be of use. For fruit not intended for European markets, baby food, or any of the eco/sustainable fruit program buyers, Diaz-inon remains the best option on the market.

San Jose Scale This old-timer refuses to fade away, and to-gether with white Prunicola scale, represents an increasing challenge to fruit quality during the late summer. We've begun catching adults of the 2nd generation SJS, both in the Hudson Valley and in Geneva; the next batch of crawlers is expect-ed 400 DD (base 50°F) from this biofix. Esteem, Centaur, and Sivanto Prime are the go-to choices for problem blocks; for more moderate pressure situations, Assail, Admire Pro (as noted for WAA above), or Venerate are appropriate; the first two options will serve double duty if they're already being used for apple maggot and/or leafhoppers.

Japanese Beetle This once invasive but now entrenched foliar feeder is having another abundant occurrence this season (Fig. 2), and continues to cause noticeable damage to apples and stone fruits; heavy infesta-tions can also result in damaged fruit. Check your trees again, and keep open the possibility of a(no-ther) application of an effective preventive/resuce spray. Options include Assail, Sevin, Endigo or Besiege (in apples) or Admire Pro, Assail, Sevin, Imidan, Endigo, Exirel, Leverage, Minecto Pro or Besiege (in cherries or peaches). vv

Fig. 1. Woolly apple aphid aerial colonies.

Fig. 2. Japanese beetles feeding on apple foliage.

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OUT OF THE WEEDS(Art Agnello, En-tomology, Geneva; ama4@cornell.edu)

vv The dock sawfly, a member of the nor-mally beneficial Hymenoptera, typically appears and causes trouble during this general time of the season. Following is a rerun of our annual write-up on this pest:

Before and during apple harvest in recent years, a number of growers and fieldmen are sometimes unpleasantly surprised by the appear-ance of neat little (2 mm) holes bored into the side of their fruit, similar in appearance to those caused by a stem puncture. Although graders sometimes attribute this damage to apple maggot or European corn borer, cutting open these apples reveals a bright green worm with a light brown head (Fig. 3), 3 pairs of true legs and 7 pairs of prolegs, not feeding but lying inactive, in the bur-row extending in from each hole. These are lar-vae of the dock sawfly, Ametastegia glabrata, a highly sporadic but nonetheless well document-ed apple pest that has been known to show up in our area since 1908.

Dock sawfly probably confines its feeding

almost entirely to plants belonging to the buck-wheat family (Polygonaceae), including nu-merous docks and sorrels, the knotweeds and bindweeds, or else wild buckwheat or alfalfa. In feeding on any of these plants, the larvae de-vour the leaf tissue and the smaller veins, eating out irregular holes in the leaves. Ordinarily, the midribs and the larger veins are untouched. This insect should not be confused with the related European apple sawfly, Hoplocampa testudinea, which has a whitish larva that lives and feeds in young apples, particularly prevalent in the eastern apple regions of N.Y.

Injury to apples by the dock sawfly is known to occur generally in the late summer and early fall, when the fruit is approaching maturity and the sawfly is searching for an overwintering site. The greater hardness of immature apples proba-bly deters the larvae from burrowing into these, so although 4 generations per year have been identi-fied, only the last one or two are of concern to ap-ple growers. The injury to apples consists exter-nally of the small round holes bored by the larvae, which after a few days show a slightly sunken, brownish ring around them and occasionally may be surrounded by a larger discolored halo. These holes may occur anywhere on the surface, but are most numerous around the calyx and stem ends, or at a point where the apple touches a leaf or an-other apple, since it is easier for the larva to obtain a foothold here. Inside, the injury is usually more serious, since the larva often burrows to the core and usually hollows out a pupal cell somewhat larger than itself. Apples may have three or four, or sometimes even eight, holes in them of vary-ing depths, but contain only one or two worms.

Since the dock sawfly does not feed upon any part of the apple tree, but must live on the above-mentioned succulent weeds, it becomes an apple pest only where these plants are growing in or around the orchard. There is little danger from this insect in orchards where the food plants

DOCKINGPROCEDURE

Fig. 3. Dock sawfly larva and feeding dam-age on apple.

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don't exist. Likewise, the possibility of the lar-vae coming into the orchard from neighboring meadows, ditch banks, or roadsides is slight, for the larvae are incapable of finding their way over any extent of bare soil. The adults, though ac-tive, are not strong fliers, and it is not possible for the insect to travel far in this stage. Now would be a good time to assess the weed situation in your orchard and make plans for such selective herbicide applications as may be appropriate re-garding this insect. Even though common wis-dom says this sawfly is a pest only every 10–12 years, this is only an average estimation, and it's not a bad idea to anticipate the unexpected when hardly any season is considered to be "average". vv

(Information adapted from Newcomer, E. J. 1916. The dock false-worm: An apple pest. USDA Bull. 265, 40 pp.)

KEEPING SQUIRRELS OUT OF APRICOTS(Dave Rosenberger, Plant Pathology [ret.], Highland; dar22@cornell.edu)

vv Apricots can be difficult to grow in NY for many different reasons. Their early bloom date leaves them subject to spring frosts that can kill the flowers, so regular cropping can be expected only on excellent sites that rarely get spring frosts after trees begin to bud. In north-eastern United States, apricots are very sensi-tive to bacterial canker that can quickly become systemic, often killing a third of trees in a plant-ing by the time trees are 5 years old. Bacterial canker is best avoided by pruning trees only on dry days during the heat of summer, right after bloom and/or after harvest, when wounds will dry out before the canker pathogen can invade the pruning wounds. Keeping trees away from hedgerows that contain wild Prunus species may also be helpful because some of the inoculum

may come from wild black cherry trees (Prunus serotina). The same pathogen that causes bacteri-al canker, Pseudomonas syringae, can also cause a spur blight and fruit spotting if sub-lethal frosts during or after bloom create micro-wounds that allow the bacteria to penetrate host tissue. Final-ly, some cultivars are highly susceptible to bacte-rial spot caused by Xanthomonas campestris pv. pruni, and the antibiotic oxytetracycline that is la-beled for control of bacterial spot on peaches and nectarines does not have a label for apricots.

To further complicate apricot production, a beautiful crop of apricots can be destroyed just days before harvest if a scurry of squirrels discov-ers that the apricots have sweet kernels inside the pits. Yes, a group of squirrels is a "scurry", unless they are all part of one family, in which case they are a "dray". When they were eating my apricots, I never inquired about family connections.

Squirrel depredation may be a minor problem in large plantings or even in smaller plantings that are well distanced from squirrel habitat. Howev-er, for homeowners or smaller growers, squirrels can remove almost all fruit from a single mature tree in just two or three days.

At the Hudson Valley Lab, I had a planting of 16 apricot trees that gradually died from bac-terial canker or were removed to make room for other plantings. In the end, we had only two trees left, one Harcot and one Harglow. Nearly every year the squirrels from a woodlot a hundred yards away would travel through a hedge row to reach our Harcot tree where they destroyed the fruit just as they began to ripen. However, squirrels nev-er appeared to touch the Harglow fruit that were even closer to the hedgerow.

It turns out that the kernels inside apricot pits have varying degrees of sweetness or bitterness, and squirrels only like seeds from cultivars with

HORTICULTURE

THEBITTERTRUTH

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scaffolds No. 19 July 27, 2020

sweet kernels. (They apparently destroy the fruit to get the kernels, not because they like the apricot flesh.) Thus, homeowners and small growers might benefit by selecting cultivars with bitter kernels if trees will be located any-where close to squirrel habitat.

Determining which cultivars have sweet ker-nels and which have bitter kernels may be dif-ficult unless your nursery supplier can provide that information. However, the variety releases published by Dr. Richard Layne who worked at Harrow, Ontario, include information about the pits. For example, Harcot is noted to have an edible sweet pit whereas Harval, Harglow, Hargrand, and Harlayne are described as having bitter pits. I have not checked to see if similar information is provided for cultivars from oth-er breeding programs. Furthermore, I am not certain that all cultivars noted as having bitter pits will be squirrel-resistant since levels of "bit-terness" can vary. My only experience is with the Harcot versus Harglow trees that we had at the Hudson Valley Lab.

Bitterness in apricot pits is due to concen-trations of amygdalin, a compound that is con-verted to cyanide in the mammalian digestive track. Apricot fruit flesh does not contain toxic amounts of amygdalin, but the seed kernels of bitter seeded cultivars contain high levels. Thus, there is a toxicological reason that squirrels do not seek out seeds from apricots with bitter ker-nels. Not surprisingly, however, humans are sometimes less intelligent than squirrels. Bitter apricot seeds are readily available as a "health food": a Google search for "buy bitter apricot seeds" will reveal numerous suppliers of "fresh, clean, organic" bitter apricot seeds.

The European Food Safety Authority says that eating more than three small or one large bitter apricot seed could exceed what is consid-ered a safe "dose" for an adult (https://www.efsa.europa.eu/en/press/news/160427).

The Canadian government has also issued warn-ings against consuming bitter apricot seeds (https://healthycanadians.gc.ca/recall-alert-rap-pel-avis/hc-sc/2017/65316a-eng.php). In 1993, New York State Department of Ag and Markets tested imported apricot kernels for cyanide con-tent and found that an adult who consumed an entire 8-oz snack bag of the tested seeds in a day would receive double the minimum lethal dose for an adult (https://en.wikipedia.org/wiki/Apri-cot_kernel).

The belief that amygdalin might have benefits for treating cancer dates back to 1845 in Russia, and was introduced into the US in the 1920s but was soon discounted as being too poisonous. A synthetic form was marketed as laetrile in the 1950s, but the United States Food and Drug Ad-ministration banned it from interstate commerce in 1977. Controlled studies never showed any benefits of Laetrile, although there was a huge backlash against the government for banning it from interstate commerce (https://en.wikipedia.org/wiki/Amygdalin#History_of_laetrile).

Sales of bitter apricot kernels are generally not regulated even today. Seems like some folks could learn a thing or two by watching squirrels. vv

[NOTE: If links in this article are broken, elim-inate spurious characters, usually dollar signs or spaces, that may occur where links have line breaks in the final text.]

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scaffolds No. 19 July 27, 2020

CHEM

NEWS

SECTION 18 APPROVAL OF BIFENTHRIN FOR BMSB(Mike Helms, PMAP, Ithaca; mjh14@cornell.edu)

The US Environmental Protection Agency has granted New York State a FIFRA Section 18 Specific Emergency Exemption for the use of Bifenture 10DF Insecticide/Miticide (EPA Reg. No. 70506-227), Bifenture EC Agricul-tural Insecticide (EPA Reg. No. 70506-57), and Brigade WSB (EPA Reg. No. 279-3108) to control brown marmorated stink bug on apples, peaches, and nectarines in Columbia, Dutchess, Monroe, Niagara, Orange, Orleans, Ulster, and Wayne Counties in New York State.

Please note the following:· The Section 18 labels restrict use to Columbia, Dutchess, Monroe, Niagara,Orange, Orleans, Ulster, and Wayne Counties. Use in any other counties is prohibited.· The exemption is valid through October 15, 2020.· Bifenture 10DF, Bifenture EC, and Brigade WSB are all restricted-use pesticides.· Aerial application is prohibited.

Users must have a copy of the appropriate Section 18 exemption in their possession at the time of use. Users must also follow all applicable directions, restrictions, and precautions on the pri-mary product label. Copies of the approved Sec-tion 18 labels are available at the DEC's NYSPAD product registration website.

INSECT TRAP CATCHES(Number/Trap)

Geneva, NY Highland, NY 7/20 7/24 7/27 7/13 7/20 7/27Redbanded leafroller 8.0 6.0 4.0 Redbanded leafroller 44.5 32.0 11.5Spotted tentiform leafminer 32.0 50.0 43.5 Spotted tentiform leafminer 133.5 380.0 359.5Oriental fruit moth 27.0 10.5 5.0 Oriental fruit moth 7.5 6.5 5.0Codling moth 34.0 36.0 14.0 Black stem borer 1.0 7.0 9.0Lesser peachtree borer 2.5 0.5 1.0 Codling moth 15.5 15.5 14.5Dogwood borer 0.5 2.0 0.5 Tufted apple budmoth 24.0 10.5 0.5San Jose scale 6.7 15.3 31.7 San Jose scale 34.5 203.5 194.5Peachtree borer 17.0 18.0 16.0 Lesser peachtree borer 9.0 3.5 6.5Obliquebanded leafroller 0.5 0.0 1.0 Brown Marm. Stink Bug (adults) 3.0 10.0 8.0Apple Maggot 0.0 4.0* 3.7 Fruit Tree Leafroller 0.0 0.0 0.0 Variegated Leafroller 0.5 0.0 1.5 7/8 7/15 7/23 Dogwood Borer 9.5 6.0 35.5Black stem borer 18.7 13.7 29.0 Sparganothis Fruitworm 0.5 0.0 0.0 Obliquebanded Leafroller 1.0 0.0 0.5 Spotted wing drosophila 61.0 58.0 199.0 (cherry) Apple maggot 8.0 16.8 31.8

*firstcatch

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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.DepartmentofAgriculture.Anyopinions,findings,conclusions,orrecommendationsexpressedinthispublicationarethoseoftheauthor(s)anddonotnecessarilyreflecttheviewoftheU.S.DepartmentofAgriculture.

UPCOMING PEST EVENTS

43°F 45°F 50°FCurrent DD* accumulations (Geneva 1/1–7/27): 2197.8 1995.0 1547.1 (Geneva 1/1–7/27/2019): 1954.8 1754.0 1290.3 (Geneva "Normal"): 1909.1 1975.8 1291.1 (Geneva 1/1-8/3, predicted): 2374.8 2158.0 1675.1 (Highland 1/1–7/27): 2486.6 1726.8 Upcoming Pest Events (Geneva): Ranges (Normal ± StDev):American plum borer 2nd flight peak 2005-2575 1351-1777Apple maggot peak flight 2139-2640 1437-1822Codling moth 2nd flight peak 1967-2677 1312-1849Comstock mealybug 2nd gen crawlers emerge 2234-2624 1505-1781Lesser appleworm 2nd flight peak 2144-3071 1433-2129Obliquebanded leafroller 2nd flight start 2212-2615 1486-1807Oriental fruit moth 2nd flight subsides 2030-2510 1818-2284 1349-1746Oriental fruit moth 3rd flight start 2244-2790 2199-2579 1515-1935Redbanded leafroller 2nd flight subsides 2144-2699 1441-1860San Jose scale 2nd flight peak 2137-2493 1440-1742Spotted tent. leafminer 3rd flight start 2221-2618 1487-1815White apple LH 1st brood adults subside 2195-2521 1564-1792

*all DDs Baskerville-Emin, B.E.

Geneva: Apple Maggot 1st catch, 7/24.Wayne Co: Apple Maggot 1st catch, 7/26.

PEST FOCUS