June 21, AppleTalk Conference Call

AppleTalk Conference Call Summary
Tuesday, June 21, 2016, 8:00 – 9:00 AM
Presenter: John Aue, Threshold IPM
Moderator: Peter Werts, IPM Institute of North America; questions or comments, pwerts@ipminstitute.org

June 21st call download: Click Here

Current degree-day (base 50°F) accumulations for codling moth biofix dates, May 23 – 27
• La Crescent, MN: 566-475 DD
• Lake City, MN: 544-468 DD
• Gays Mills, WI: 550-468 DD
• Woodstock, IL: 523-495 DD

First generation codling moth wrap up
Base the decision to reapply codling moth (CM) insecticides using degree-day accumulations from biofix and trap captures following the date of the first insecticide application. Continue to closely monitor degree days and trap captures until 650-700 DD from biofix to determine if additional flights require treatment. Most flights should occur by 700 DD.

Look at the trap captures since you applied the first application and disregard counts from the first seven days after the application. Eggs laid in first seven days will hatch in the second seven days after application. Then count 250 DD after treatment to determine if another application is required at 14-17 days. Checking traps more than once per week will allow more accuracy when determining to treat a cohort. Make note how many CM are alive when you check traps.

A high rate of Altacor (chlorantraniliprole) has been found to be effectiveness for up to three weeks when there is no rain. A high rate of Delegate (spinetoram) will not provide protection past 14 days. Lower rates will be effective, but for a shorter period of time. Rate is also a function of CM pressure. If you are treating eight moths per trap, good control can be achieved with a middle rate, on the other hand if the cohort is 30-40 in a trap, then the high rate is required.

To assess efficacy of first generation CM control, check hot spots relative to trap captures. Variable trap captures suggest CM are flying in from outside the orchard. Uniform captures suggest an in-house population with minimal external pressure. Dedicate time to scout fruit clusters or areas that may have received poor insecticide coverage.

Note: it is advised to test the pH of spray water multiple times a year. Pesticides can rapidly degrade if pH is not within acceptable range.
Obliquebanded leafroller
Obliquebanded leafroller (OBLR) are beginning to hatch in the southern half of the state. Larvae are small and green with caramel to black head capsules. Scout fruit, if cultivars have set terminals. Damage will be on the surface of the apple and at harvest will be difficult to distinguish from other lepidoptera. Large flights now, are a result of the overwintering generation not being controlled; may result in high population for second generation. These larvae are offspring from the first flight of OBLR this season. Larvae at petal fall and first cover overwintered from last year’s second generation flight. In addition to feeding on foliage, larvae will also feed on fruit and are capable of causing economic damage, in some instances. Products, i.e., Altacor or Delegate, applied for CM, except granulosis virus and mating disruption, should provide adequate control of OBLR. Beneficial insects should also aide in suppression of this pest. Second generation larvae can be more problematic and more difficult to control then first generation OBLR. High populations may cause damage to fruit and significant damage to terminals on young and non-bearing trees. It is recommended to scout and treat the larvae during this generation rather than waiting to treat second generation larvae in mid-August and early September.

Scouting for fruit and foliar feeding should begin seven to ten days after moths are caught in pheromone traps. There are no established action thresholds and trap counts do not correlate well to the potential for feeding injury to fruit or growing terminals. OBLR is resistant to many of the organophosphates and most of the neonicotinoids are not very effective on OBLR. To reduce the risk of resistance developing only expose one generation of OBLR to a specific insecticide class, e.g., overwintering larvae (Bt), first generation larvae (Delegate), second generation larvae (Altacor); Using Bt could be an excellent insecticide to include in the rotation. Look at the number of adult moths captured in traps and how long the flight is lasting as a possible indicator of resistance beginning to develop. Trap capture can vary wildly within the orchard and although OBLR has a wide host range, it is likely larger orchards could have an in-house population.

Note: Neonicotinoids, i.e., Assail (acetamiprid), have low rainfastness and does not have activity on OBLR. Altacor, Belt (flubendiamide), Delegate, Entrust (spinosad), Exirel (cyantraniliprole) are options that will offer management of OBLR. Delegate and Altacor are the most resistant to rain. Bt (Bacillus thuringiensis) products work well on OBLR but not well on CM.

Apple maggot
Larry Gut expressed concern that some of the newer insecticides we are using are not killing apple maggot (AM) adults and, rather, are only repelling them, which have allowed population to grow outside of the orchard. Organophosphates and pyrethroid alternatives for AM control include neonicotinoids and Exirel. Neonicotinoids have been used to the greatest extent and, imidacloprid has been a popular AM product for the last several years, e.g., Admire, Alias, Montana, Wrangler.

New tree management, Steve Louis, Oakwood Fruit Farm
Plant trees as early as possible so they have a full year to grow.

Maintain 0.5 lbs. of actual copper on non-bearing trees to prevent fire blight and scab. The first application should begin one week after planting, since most trees come from nurseries with a fresh application of copper.

New trees should not be allow to produce any fruit. To remove fruit on new trees apply NAA (20 ppm) + oil (1%) during bloom. If any fruit set, apply a second thinner when fruit are 5-8 mm in diameter.

There is very low tolerance for insect pests which feed on growing terminals or those which will create stress and slow growth, and include aphids, leafrollers and leafhoppers.

On new trees, irrigation is installed and watering begins as soon as possible. Before irrigation is setup, Oakwood installs the trellis to support the trees, and the bottom wire supports irrigation lines. It can take upwards of one month to complete trellis construction.

Orchard renovation steps: 1) remove old trees, 2) plant corn for a few years to level ground, 3) apply manure with lots of organic materials and fertilizer where needed. Oakwood has tried TerraClean (hydrogen dioxide) to avoid replant disorders and TerraGrow (Ascophyllum nodosum, microbial soil Inoculant, humic acid, molasses, soy protein hydrolysate) to add beneficial microbes into the soil. Following planting, Black Label or Topwire fertilizer solution are ground applied (10 gal/ acre) with an herbicide boom, twice per season, to a one foot band around the trees. Once there is enough leaf surface, a foliar fertilizer, i.e., Pro-Sol (2-3 lb. /acre), is added to all cover sprays. Calcium nitrate (0.25-0.33 lb.) is applied to second and third leaf trees, application can be easily adjusted accommodate low and high growth areas of the block. Fertilizer applications are typically discontinued by the end of July to allow the trees adequate time to set terminal buds before fall.

Dennis Norton, Royal Oak Farm Orchard, soaks new trees for 24-48 hours before planting in a small wading pool with a mixture of BioOrganics Endomycorrhizal Inoculant (BEI) and Mycorrhizal Root Dip. The soaking bridges the gap between planting the young trees and getting the irrigation and trellis installed. Dennis also has success spraying copper on trees before planting, while they soak, since they have usually already sprayed a copper+ oil spray in the orchard by planting time.

Potato leafhopper
Potato leafhopper nymphs are appearing on terminals and shoots, particularly orchards in close proximity to hay and alfalfa fields and are blown into the south and west on heat thermals. These are also often only a problem on young and non-bearing trees. Symptoms include upwards, cupping of leafs on terminal shoots. The potential for PLH causing serious damage is reduced once the terminals have set. High populations can create honeydew which can result in mold, similar in appearance to fly-speck, before harvest.
White apple leafhopper
White apple leafhopper (WALH) nymphs come from within the orchard, and at this time can be found on the undersides of leaves. Scout for white spots or stippling of leaves on the interior of the canopy. With the potential to feed into September WALH can cause a major loss of chlorophyll.

Flower thrips
Scout terminals and shoots for leaf curl, resulting from feeding. The damage is most prevalent on the midrib of the leaf. Brown, feeding scars will be present on the underside of leaves and may be of concern on young or non-bearing trees and thrips will continue to feed until terminals have set and often not a concern on mature trees.

Dogwood borer
Dogwood borer traps can still be set in orchards. Trap counts will provide information on hatching larvae in a few weeks.

European red mite
Summer populations of European red mites (ERM) should be visible in orchards. Identify hot spots now, note that a lot of lush growth usually translates to heavy ERM pressure.

Apple rust mite
Apple rust mites (ARM) function as food for beneficial mites and mite predators, and traditionally have not caused damage in established orchards. High infestations of ARM in young, non-bearing trees may result in economic damage; damage threshold on these is significantly lower than large, established trees. While scouting use a hand lens with 10x or greater magnification to scan the upper and lower surface of leaves. Visual symptoms include yellowed and distorted foliage, prolonged feeding by high populations will cause a leathery silver or bronzing and curling of the leaf. Feeding on developing fruit may damage the skin and cause russeting. ARM need to feed on new growth, and as long as shoot elongation is continuing, populations will continue to grow.

San Jose scale
Monitoring for San Jose scale (SJS) crawlers should begin in the southern half of the state. Monitor known hotspots with black electrical tape applied to suspect scaffold branches. With adhesive side towards tree, wipe a thin layer of petroleum jelly on the outside of the tape. If populations are high, concentrate a few traps in areas with greatest pressure. Increasing the number of monitoring sites may help eliminate false negatives. Note: Low trap captures do not reflect overall pressure, i.e., false negatives. Low trap captures may indicate the beginning of the hatch. First generation SJS hatches over a narrow period, while second generation hatches over a wide period. Widespread catches of 10-15 crawlers in a couple of days or 10 crawlers on one tape with zero on all other tapes, may warrant application. Conventional products for summer control include Esteem (pyriproxyfen) or Movento (spirotetramat). Organic growers are limited to summer oil and biological control.

Aphid Predator Photo Glossary
All photos taken by John Aue and Peter Werts, click pictures to enlarge.

Syrphid fly maggots feeding on woolly apple aphid (WAA) colonies.
Syrphid fly maggots feeding on woolly apple aphid (WAA) colonies.
The dark blue mummy is a WAA that has been parasitized by a parasitic wasps.
The dark blue mummy is a WAA that has been parasitized by a parasitic wasps.
Minute pirate bug on a rosy apple aphid infested leaf
Minute pirate bug on a rosy apple aphid infested leaf
Generalist predator - green lacewing larva (larva hatch from white eggs on slender stalks visible on leafs)
Generalist predator – green lacewing larva (larva hatch from white eggs on slender stalks visible on leafs)
Green lacewing larva
Green lacewing larva
Aphelinus spp. parasitized WAA.  Note level of mortality characterized by black ‘mummies’ when scouting WAA colonies.
Aphelinus spp. parasitized WAA. Note level of mortality characterized by black ‘mummies’ when scouting WAA colonies.
Cecidomyid (aka gall midge) larva and potato leafhopper nymph on leaf.
Cecidomyid (aka gall midge) larva and potato leafhopper nymph on leaf.