Leafroller Management: Finding the (re) application window.

Obliquebanded leafroller (OBLR), Choristoneura roseceana (Harris): is an insect pest in the Tortricidae family of lepidopteran insects. This family of moths has challenged New York State fruit growers since the arrival of the first European apple trees in the early 17th century. ‘Apple worms’ and surface feeding larvae continue to damage our commercially grown fruit, requiring diligent management to reduce economic loss from this insect group. With the recent loss of insecticides that effectively managed this group (Azinphos-methyl and post bloom use of Chlorpyrifos of late) the challenge becomes greater with more focus on the use of species specific insecticides targeted earlier in the development stage of the leafroller and internal lepidopteran complex for effective management.

The first OBLR adult male moth was observed in traps on May 29th followed by a sustained and peak flight this week. The predicted date of larva emergence is for the 14th of June (last Sunday). Applications made on the 14th had 1.08″ of rainfall up to this afternoon (Highland HVRL: 16th of June). We are now 2 days out from the first hatch application with loss of residual from rainfall. As we near peak egg hatch the need for a follow-up application to control the latter emergence of OBLR will likely be required toward the end of this week to early next week depending on the amount of rainfall accumulates over the next 8 days.

As heavy rains are predicted this afternoon into tonight, keep your eye on the weather gauge for local accumulations. If more then 1.5” of rainfall is measured on your Leafroller application, you will need to re-cover by weeks end.
Temperatures are predicted to be in the lower 80′s through to the end of the week with low to moderate winds Wednesday afternoon into Thursday morning. Optimum timing of insecticide applications should be made at the most opportune window for coverage (low wind, high relative humidity, good drying conditions post application). When temperatures exceed 75F, the pyrethroids in IRAC group 3 are less likely to be effective, relative to lower temperature applications of the product. Entrust, Delegate and Altacor are more stable under higher temperatures, providing excellent rainfastness.

See the article on ‘Rainfastness’ by John Wise. It will help guide you through your questions on whether to spray after a rain.

For resistance management purposes: Make multiple applications of the same material for each generation, BUT, alternate active ingredients for subsequent generations.

The rule for resistance management is to use USE THE SAME CLASS FOR EACH GENERATION whenever possible.
So, for example, if you used Intrepid or Proclaim for the overwintering OBLR larva at petal fall, followed by Altacor for the first application of the 1st summer generation this week, and using a second application of Altacor at a 10-14d interval (also applied against the 1st summer generation). Both Altacor (chlorantraniliprole) and Belt (flubendiamide) are in the same IRAC Class 28.

The next generation of OBLR occurs in early to mid-August. This application would require a different class of insecticides, such as Delegate, in IRAC Class 5.

By using Intrepid (IRAC 18) or Proclaim (IRAC 6) for the overwintering, Altacor or Belt (IRAC Class 28) for the 1st generation and Delegate (IRAC Class 5) for the 2nd generation, you are reducing the resistance potential of any one class on insecticides against this insect pest.

Tufted Apple Bud Moth (TABM), Platynota idaeusalis (Walker): is one of the most serious direct pest of apples in the mid-Atlantic region. We have seen trap captures of TABM this season, with increasing presence of this insect in the Hudson Valley over the past twenty years. Typically the adults emerge at about the same time as OBLR adults in pheromone trap captures. The damage they cause to fruit is quite similar with eggs and larva looking alike in the field. It appears these two insects will overlap with regards to larval emergence this year. So…applications targeting OBLR will also manage TABM this week.

The classes used against the leafrollers include:
• Intrepid (methoxyfen-ozide) (IRAC 18A) another reduced risk insecticide very effective against the larva, imitates the natural insect molting hormone and works by initiating the molting process. Intrepid is quite safe to birds, fish, and most beneficial insects.
• Proclaim (emamectin benzoate) (IRAC 6), a second-generation avermectin insecticide related to Agri-Mek, is also an excellent insecticide against the OBLR while having a low impact on beneficial mites. Used with a penetrant such as 0.25% horticultural oil, Proclaim will provide effective mite management.
• The Bt products such as Biobit, Dipel, Javelin, and MVP (IRAC 11 B2) can be used during apple bloom, also has a low impact on beneficial mite and are very effective against young OBLR used at low rates at tight intervals (5d). Bt residual is prolonged under low UV or cloudy conditions yet likely not to have strong residual from rain events.
• Altacor (chlorantraniliprole) or Belt (flubendiamide) (IRAC Class 28) and Delegate (spinetoram) or Entrust (spinosad) (IRAC Class 5), have been used successfully against the leafroller complex prior to the leaf rolling stage during early instar larval development. These materials are also very effective against the codling moth (continuing to emerge this week), oriental fruit moth and lesser apple worm. These insecticides have also been shown to have strong rainfastness.
• Lannate, a carbamate in IRAC Class 2, is an older class of insecticide with systemic properties. It provides good efficacy against the insect when used against all life stages of OBLR larva. However, the broad spectrum activity of of this insecticide may cause reduced predator activity and increased aphid and mite populations.

The placement for these materials at the onset of hatch, followed by a second application at 10-14d to manage the summer generation of OBLR larva, has provided excellent results in Eastern NY State pome fruit production.