When Obliquebanded Leafroller (OBLR) Fly: OBLR Management at 1st Hatch

We are at the period of the season when obliquebanded leafroller (OBLR) adults have just begun to emerge, are now on the wing and will be beginning their egg laying in earnest this week.

OBLR Pheromone Trap
OBLR Pheromone Trap

If we capture them over two to three successive days (sustained flight) we will establish the biofix date and begin calculating heat accumulations using 45DD to help us determine, using the NEWA model, the early period of emergence for optimum timing of insecticide applications. If you find OBLR in your traps prior to or after our trap findings you can use the NEWA site to fine tune your application window.

Late season fruit feeding Fruit injury caused by second brood obliquebanded leafroller larvae
Late season fruit feeding Fruit injury caused by second brood obliquebanded leafroller larvae

Over the past ten years, growers have been able to control OBLR larva through the use of effective insecticide programs targeting three periods of larval activity. These include:
* employing applications against the overwintering generation during either the pre-bloom / bloom or petal fall periods
* 1-2 applications against summer generation
* and in high population years, 1 application against late summer generations.

We recommend using three distinct yet very effective active ingredient groups or IRAC classes. In this way we hope to reduce the resistance potential of the insect over time.

The classes used against the leafrollers include:
• The Bt products such as Biobit, Dipel, Javelin, and MVP (IRAC 11 B2) also have a low impact on beneficial mite and are very effective against OBLR.
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.
Altacor (chlorantraniliprole), Belt (flubendiamide) (IRAC Class 28) and
Delegate (spinetoram) and Entrust (spinosad) (IRAC Class 5), have been used successfully against the surface feeding and internal Lep. complex. The placement for these materials has been predominately at the onset of hatch of the summer generation larva of OBLR, providing excellent results in NY State.

Since the development of insecticide resistance is dependent on the volume and frequency of applications of insecticides and the inherent characteristics of the insect species, we should limit one insecticide class to a single generation of pest for resistance management purposes. The present model for insecticide resistance management (IRM) practices then is to use a single insecticide class for a single generation of insect pest.

For example, an IRM program against the lepidopteran complex, specifically OBLR, would use effective insecticides listed above (X, Y, Z) in three different IRAC classes (A, B, C) throughout the season.

Insecticide X (Class A) 1 application @ TC-P or PF for overwintering OBLR
Insecticide Y (Class B) 2 applications @ 14d; first emergence of 1st brood OBLR larva
Insecticide Z (Class C) 1 application @ first emergence of 2nd brood OBLR larva if needed.

Given the historic failures the apple industry has experienced managing the leafroller and internal worm complex, we should consider designing programs to maintain the effectiveness of these excellent IPM tools beginning early in the season, before the heat of the battle begins.

About Peter J Jentsch

Peter J. Jentsch serves the mid-Hudson Valley pome fruit, grape and vegetable growers as the Senior Extension Associate in the Department of Entomology for Cornell University’s Hudson Valley Laboratory located in Highland, NY. He provides regional farmers with information on insect related research conducted on the laboratory’s 20-acre research farm for use in commercial and organic fruit and vegetable production. Peter is a graduate of the University of Nebraska with a Masters degree in Entomology. He is presently focusing on invasive insect species, monitoring in the urban environment and commercial agricultural production systems throughout the state
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