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May Madness…Reigning In Plum Curculio and Codling Moth

by Peter Jentsch posted on MAY 15, 2024

PC Damage during Early Fruit Set (5mm)

Synopsis: We have seen fairly consistent and strong flowering and subsequent set this season. Fuji, Golden Delicious and other varieties with biannual propensity displaying variable in flower density tree by tree. We are now seeing early set clusters with king or lateral fruit w/o kings at or above 10mm in early and mid-season varieties. Extended bloom of later apple varieties and lingering 1st wood bloom has sufficient pollination conditions in the Hudson Valley across varieties lasting for at least 10 days from the onset of bloom. (Historical Phenology Table)

It has been a slow start for the Plum Curculio (PC) this season given the cold nights and cooling rains. Plum Curculio had been found in the lower Hudson Valley orchards on the 15th of May . Egg laying scars will begin to appear first in stone fruit, most attractive being apricot and early cherry. In apple, Ginger Gold sizes early and tends to be vulnerable in years when PC emerges.

PC seem to prefer fruit in the 5 to 15mm range. As temperatures moderate this week, Plum Curculio migration will begin in earnest and egg laying will occur requiring management over the next three weeks. Using the PC model, we are presently at 39 DD50 from the biofix (90% PF in McIntosh, Milton, NY). Once we reach 308DD50 PC will no longer be migrating into orchards, at which point insecticides for PC can cease.

Codling Moth: The second focus of insect peat management for the next 3 days should be on Codling Moth (CM) as adults continue to emerge, mate and lay eggs. The 1st captures for CM was the 12th of May but no sustained captures observed to date.

The first eggs are laid at about 50 DD from the biofix, with codling moth egg hatch expected early June in Milton, NY.

To manage both Plum Curculio and Codling moth this week, insecticides that contain active ingredients effective against both insects are critical. If pre-mixes are used, be certain that the rates are appropriate for the pressure from these insects in your orchard blocks. Most, if not all pre-mixes, have lower rates then the highest rate available for the use of each specific active ingredient.

What we are seeing in commercial orchards……

* Spongy Moth (in very high numbers on developing shoots last week).

*San Jose Scale adult infestation overwintering in trees. Forecast crawler emergence on 18th May

* High numbers of Rosy Apple Aphid (RAA) in curling foliage. At this point RAA are best managed a with a neonicotinoid (Imidacloprid, Actara, Assail). Be mindful that Imidacloprid (Provado, Confidor, Admire-Pro …) can cause mite flare-up.

* Red banded leafroller, Oriental Fruit Moth, Lesser Appleworm are laying eggs, Oblique banded leafroller is now at 4th -5th instar stage, and if foliar feeding has been observed, requires a broad spectrum or specific Lep. larva material.

* Low overwintering European red mite (ERM) egg populations equate very low foliar ERM populations across the Hudson Valley.

* Over the past 15 years we’ve seen very little in the way of European apple sawfly (EAS) larva injury to developing fruit during fruit development. Yet they have been found in unsprayed orchards this season.

Post Bloom Tree Fruit Management: The petal fall management window is likely to be the most important insect pest management timing to control a very diverse complex of insects. This often requires a mix of insecticide actives with different modes of action.

The insect complex includes:
*Lep complex of green fruit worm complexobliquebanded leafrollerredbanded leafrolleroriental fruit mothlesser appleworm
*’Bug’ complex of Mullen plant bug, aphid complex of rosy, green and spirea aphid, wooly apple aphid
*Leafhopper complex of white apple leafhopper (nymphs), potato and rose leafhopper (adults)
*Beetle; specifically Plum curculio (PC)
*Primitive bee, specifically European apple sawfly
*Mite, predominately the European red mite

You should be using the best materials at the appropriate rate for each specific insect of concern. The 2023 Cornell Pest Management Guidelines for Commercial Tree Fruit Production can assist in decision making during the growing season with on-line access available.

Management: After the whole orchard petal fall application is made, border applications for PC management can made to reduce migratory adults until the whole orchard application for Codling Moth needs to be applied. This may provide you the additional time necessary to more precisely target codling moth.

Generally, the neonicotinoid class, specifically Actara 25WDG (Thiamethoxam) @ 4.5-5.5 oz/acre for plum curculio, has translaminar or systemic activity that reduce foliar feeding insects such as aphids (Green & Rosy Apple Aphid (RAA)) and leafhopper well under control. Note that of the neonicotinoid class, Thiamethoxam has the highest high bee toxicity and repellency if used in blocks at ‘early variety petal fall’.

If you are transitioning from neonicotinoid to a contact contact insecticide, such as Imidan or the pyrethriods used alone, then consideration should be made for RAA management prior to leaf curl and fruit injury before full establishment of this pest in the orchard.

The addition of the neonic’s, such as Admire Pro 4.6SC (imidacloprid) at 2.8 fl.oz./acre, Assail 30SG at 2.5-4 oz/acre, or the use of Exirel (cyantraniliprole) at 13.5-20.5 fl.oz./acre will provide the additional broad spectrum activity needed for RAA management, including green aphids and leafhopper.

The active ingredient for Exirel is cyantraniliprole, the anthranilic diamide class (Group 28), in the same class as Altacor (Rynaxypyr) with a broad spectrum of activity, which has shown efficacy against plum curculio, yet may not be as effective as high rates of pyrethroids or OP’s.

The addition of post bloom applications of Movento 240SC at 6-9 fl.oz./acre is also very effective against RAA, reduces San Jose scale residing in the trees and reduces the incidence of wooly apple aphid that can develop late into the season due to BMSB manaement use of pyrethroids that reduce predatory beneficial insects.

The use of pre-mix insecticides should be strongly considered here.

AGNELLO. ACTIVE INGREDIENT EQUIVALENTS BETWEEN PREMIX AND SINGLE A.I. INSECTICIDE PRODUCTS

In the article “All in the Mix”, Dr. Art Agnello points out that ‘the amount of chlorantraniliprole a.i. in a high-rate application of Voliam Xpress (0.078 lb) is lower than a comparable application of Altacor (0.099 lb); also, you can see the difference in thiamethoxam a.i. between the use rates of Endigo (0.046-0.055 lb) and Actara (0.070-0.086lb).

Additionally, note that Thiamethoxam is limited to a maximum seasonal total of 0.172 lb/A, regardless of the formulation, which can complicate mixing & matching of products during the season.’ It’s very important to know that if a full rate of thiamethoxam is essential for plum curculio management in high pressure blocks, then a pre-mix may not be the best option.

RAA Feeding
RAA FEEDING

Biology and control of Plum Curculio in conventional management programs: The insect to which we can attribute the highest losses in apple during the petal fall period is Plum Curculio. It is a native of North America, a major pest of pome and stone fruits in the United States and drives much of the early season pest management. As most commercial orchards are free of endemic PC populations, the migrating adult will be moving in from hedgerows and woodlands to damage fruit. This is not so for organic orchards that do harbor endemic populations of emerging adults from within orchards. The approved organic pest management tools used against the PC tend to be repellent with only moderately efficacy at reducing oviposition to fruit.

PC overwinter as adults in ground litter or the soil and become active in the spring following several days of either a mean temperature above 60°F or maximum temperatures above 75°F. This weather pattern is forecasted for this week as we near petal fall. However, if we see a temperature drop and conditions become unfavorable, the adults may return to hibernation sites. The emergence period for PC can last for several weeks, however, we can see 40-60% of the total emergence occurring on a single day with very high egg laying damage levels over a 24 hour period.

PC.GingerGold.06

With the loss of Calypso, Guthion and Lorsban, we are finding fewer broad spectrum insecticides to manage the pest complex at petal fall. The OP Imidan 70WS as mentioned earlier, used at the higher rate, is comparable to Guthion, yet without the added efficacy against the RAA or aphid & leafhopper complex of Calypso. The use of Actara 25WDG at 4.5-5.5 oz./A will provide activity against PC, the leafhopper and aphid complex. Its very important to note that Actara (Thiamethoxam) is not effective against the lep. complex. It also has been observed by growers to have bee repellency if applied near bloom. In LD50 efficacy studies thiamethoxam applied directly to pollinators was found to have high toxicity.

Avuant 30WDG at the high rate of the 5-6 oz./A range will manage PC with varying degrees of activity against the secondary pest spectrum.

Organic Options for PC Management: If you are relying on the repellency of the barrier film Surround WP (Kaolin Clay) instead of PC mortality through the use of conventional insecticides, complete coverage of fruitlets will need maintained until curculio egg laying is completed. This season it is predicted to be mid-late June. Surround WP used for organic PC management will only have marginal control of EAS. Late applications or a delay in PC management during cool years of prolonged bloom, will allow EAS larva to hatch and begin feeding, giving rise to apple injury. This is especially true in northern orchards of the Champlain Valley into New England. In years when PC populations are high, Surround WP may not reduce PC injury to viable or profitable economic injury levels.

Control of the larva and pupal form of PC is presently being investigated using entomophagous nematode introductions. Information available in PowerPoint of nematode research to reduce PC residing in organic orchards.

Adult plum curculio.
ADULT PLUM CURCULIO.

European Apple Sawfly (EAS): are primitive hymenopterous insects, related to bees, wasps, and ants having a single generation per year in NY. An introduced pest that was first noted in North America infesting Long Island crabapples in 1939. The pest is especially troublesome in the apple-growing regions of the Hudson Valley of New York with increasing levels of infestation occurring in more northerly regions of the state.

The larvae feed on apple with a preference for early or long-blooming, heavy-set varieties. Years in which there is a very late bloom typically have very few EAS present to cause damage to early and mid-pollinating varieties with small amounts of damage noted to late harvested fruit. Timely controls for PC at PF will eliminate the need for EAS management in conventionally grown fruit.

European apple sawfly egg laying during bloom
EUROPEAN APPLE SAWFLY EGG LAYING DURING BLOOM
European apple sawfly damage to apple
EUROPEAN APPLE SAWFLY DAMAGE TO APPLE

The lepidopteran complex:
Codling Moth (CM) adult males are flying. ‘In the old days’ the broad spectrum OP insecticides targeting plum curculio would prevent codling moth damage. However, with the loss of effective insecticides over the past 10 years (Calypso, Guthion & Lorsban, ) we are left with fewer broad spectrum insecticides that manage both PC and adult CM. Since CM larva emergence will occurs during the 1st – 2nd cover window (approx. June 10th ) we don’t need to address this insect yet, however, If you use Actara for PC control at 1st or 2nd cover, the lep complex can slip through the program. Using only Actara after PF will leave you open for oriental fruitworm, lesser apple worm and codling moth injury.

Loss of susceptibility by CM to conventional materials (Delegate & Altacor) appears to be on the rise. Increasing injury to fruit has been occurring over the past 5-10 years across the Hudson Valley. Utilizing degree day forecasting to predict first emergence of CM larva for the first application will target the most vulnerable life stage of this insect. Using the newer lepidopteran active ingredients of insecticides, such as Chlorantraniliprole (Altacor, Besiege, Voliam Flexi WDG), Cyantraniliprole (Exirel, Minecto Pro) and Verdepryn (Verdepryn 100SL) for first generation and rotating active ingredients such as Spinetoram (Delegate) is important to manage teh resistance potential of these pests.

For both conventional and organic production, mating disruption in orchards of 5 acres or more, is the most effective long term solution for codling moth (also OFM & DWB) management.

Organic Options for CM Management: include granulosis virus such as Cyd-X 0.06SC using high rates and applications at 5-day intervals beginning at first hatch to end of hatch has been shown to work very well in combination with mating disruption.

Scouting has shown potentially high numbers of Red Banded Leafroller (RBLR), Oriental Fruit Moth and increasing Lesser Apple Worm (LAW) adult populations that often give rise to larva that feed on flowers and developing fruit. As RBLR has been flying since early March, we have seen peak trap catch and the approximate start of egg hatch occurred in mid-March, continuing on through bloom. Larva can be observed in untreated trees in Highland and scouting should include sampling and observations for RBLR in flowering clusters. Larva of green fruit worm (GFW) or Obliquebanded Leafroller (OBLR) have been found during bloom through mid May in untreated trees, yet its likely high overwintering mortality and cool spring suppression of these insects have reduced the presence of populations to reduce the need for management of these pests during the pre-bloom period. The warming trend this week should prove this either way. Foliar feeding ‘worms’ can be held in check using Bt formulations, such as Biobit, Dipel, Javelin, and MVP (IRAC 11 B2) also have a low impact on beneficial mite and are very effective against overwintering obliquebanded leafroller (OBLR) and the green fruit worm (GFW) complex. The Bt products should be optimized employing multiple applications at 5-7 day intervals at the low-labeled rate as they easily break-down due to UV light.

1ST GEN. CM LARVA.

• Intrepid (methoxyfen-ozide) (IRAC 18A) another reduced risk insecticide very effective against the larva, acts as an insect growth regulator to imitate the natural insect molting hormone and works by initiating the molting process. Activity of the insecticide is primarily through larval ingestion of foliage, excellent coverage is necessary for effective control. Intrepid is quite safe to birds, fish, and most beneficial insects and can be applied from pink through petal fall. It is registered on pome and stone fruits for control of oriental fruit moth, lesser apple worm, spotted tentiform leafminer and leafroller, with suppression of codling moth at the highest labeled rate. REI = 4-hours; PHI = 14 days (pome fruits), 7 days (nectarine, peach and plum).

• Proclaim (Emamectin Benzoate) is registered on pome fruit for the control of leafroller, spotted tentiform leafminer and suppression of codling moth, oriental fruit moth, lesser apple worm and spider mite in apple and pear psylla in pear. It interferes with neurotransmission in insects resulting in the loss of cell function and nerve impulse. Proclaim, when used with a penetrant, has translaminar activity through ingestion and limited contact activity. Proclaim 5SG rate is 3.2 to 4.8 oz. per acre and seasonal maximum of 14.4 oz per acre. Begin application at the onset of hatch to control early stage larvae. Apply using a minimum of 40 gal. of water per acre with a horticultural spray oil or a nonionic penetrating surfactant. Do not use a sticker or any other pesticide or product containing a sticker component in its formulation as stickers can drastically reduce pest control. REI = 48-hours; PHI = 14-days.

Oriental Fruit Moth (OFM): Flight began on April 29th with 1st generation egg hatch and treatment for >50% hatch beginning mid-May.

The Tarnished Plant Bug (TPB): is a predominately a pre-bloom pest of apple, a true bug in the order Hemiptera, with piercing-sucking mouthparts such as is found in aphids and leafhoppers. The adult TPB has a color appearance ranging from dull brown to black. The rear half of the forewings are membranous and are bent downward with a distinct yellow triangle behind the head.

The adult bugs hibernate under leaf liter, clover, alfalfa, mullein and protected places of stonewalls and tree bark. Orchards with weed host density are more prone to damage. Control of weed hosts, such as common mustard weed, has been shown to reduce fruit injury. They become active at relatively low temperatures (> 46oF) with feeding becoming pronounced at temperature at or above 70oF, between tight cluster through the post bloom period of apple.

The pyrethroids (Asana, Ambush, Baythroid, Danitol, Pounce, Warrior ) are most effective, followed by the neonicotinoid group including Actara, Assail and Avaunt, which are moderately effective. If Pyrethroids and neonicotinoids were used at pink they would have had some impact on the insect pests damaging to fruit such as RAA, STLM and early immigrating PC. However, given the prolonged bloom this season (17 days and over 2.5 inches of rain in most Hudson Valley sites), its likely there is little in the way of residual activity left.

Mullin plant bug feeding to red delicious fruitlet.
MULLIN PLANT BUG FEEDING TO RED DELICIOUS FRUITLET.

Mullein Plant Bug (MPB): and apple brown bug (ABB) are occasional pests that move into trees during the pre-bloom period, feeding on fruit shortly after fruit set. In blocks where historical injury has been observed, scouting for this insect in Red Delicious, Golden Delicious, Northern Spy, and Spartan with McIntosh seldom suffering damage.

The expected 50% egg hatch date is Monday, May 9th, about 4 days before Red Delicious petal fall date. Most literature states that MPB and ABB are pests only during the period from bloom through about the time fruit are 0.5 inches in diameter. After that, they are beneficial, preying on European red mite, aphids, psylla, and other insects.

Petal fall insecticide applications will kill most of the nymphs present, with some of the damage occurring by then. However, if timely petal fall applications are omitted the MPB will continue feeding on developing fruitlets well after petal fall.

Red Delicious are especially prone to MPB feeding injury. Petal fall sprays should be applied as soon as possible after blossoms are off. Assail, Actara, and pyrethroids are quite effective against the insect.

San Jose Scale (SJS): If pre-bloom applications of 1-3% oil, Esteem or Centaur were applied effectively to blocks with know SJS populations then you can relax until nymph emergence during 3rd cover, sometime in mid June this season and too early for modeling. Scouting for nymphs in mid-June will determine if your pre-bloom applications were effective. However, you will need to consider the use of Movento 240SC at 6-9 oz./A plus a non-ionic penetrant, such as LI700 at 32oz./100 to address the San Jose Scale fruit injury at pack out last year if pre-bloom applications were omitted this season. The active ingredient in Movento, spirotetramat, is taken into the foliage, systemically moving through plant tissue to stems, roots, and leaves to be fed upon by emerging SJS nymphs during emergence and feeding. Our research has found the single application of 9 oz./A at PF or two applications at 6 oz./A at PF and 2C to effectively control the 1st generation of the insect. That said Wooly apple aphids are best managed with two applications of Movento at PF and 2-3C. Never mix a penetrant with Captan!!! and follow the label regarding the timing of Captan and use of LI700 or oils as penetrants.

SJS.female.2
SJS female under chitin coverings
SJS on empire harvest
SJS Infested apple

Organic Options for SJS: Use of Marrone Bio Innovations product Venerate XC contains the active ingredient Burkholderia strain A396. Applied at the 4 quart / A rate has been shown to significantly reduced the presence of San Jose scale in orchard trees.

Highly refined horticultural oil applied using dilute rates of 2-3% during delayed dormancy or 1% during the season also kills SJS black cap stage and crawlers when complete coverage is achieved.

About Peter Jentsch

Peter Jentsch is a graduate of the University of Nebraska with a Masters degree in Entomology. He recently retired from Cornell’s Hudson Valley Research Laboratory after 33 years and now serves the mid-Hudson Valley pome and stone fruit growers as entomologist and director of Poma Tech Inc; a 501(c)(3). This agricultural supporting not-for-profit is located in the mid-Hudson Valley of NY.

He provides regional farmers with timely information on pest management, concentrating on insect related topics and research results conducted on commercial pome fruit orchard trees. He is presently focusing on keeping growers notified of horticultural and pest issues, focusing on insect and disease development, newly invasive insect species, and monitoring the pest complex for use in pest modeling in the commercial agricultural production systems throughout the SE NY region .

Poma Tech employs weekly Zoom meetings on topics of insect and disease pest biology & management, coined the Monday Morning Brew’ which begins live at 6AM from April to September. Hope to see you there!