Components of an Insecticide Resistance Management Strategy for Grape Berry Moth

Andy Muza, Penn State Extension – Erie County

In this blog I will discuss insecticide resistance management pertaining to grape berry moth control.  But first, information concerning insecticide classification and modes of action is necessary.

Insecticides are classified based on the similarity of the chemical structures of their active ingredients. Therefore, all insecticides in a certain group/class have similar characteristics. It is the chemical structure of the insecticide’s active ingredient that defines how it works (i.e., mode of action, MoA) at the target site.  The target site is the location within the insect where the insecticide acts.

Understanding modes of actions can be difficult due to the complex biochemical processes that occur within insects upon exposure. Fortunately, due to the efforts of the Insecticide Resistance Action Committee (IRAC) in classifying the Mode of Action (MoA) of insecticides, and assigning numbers to the mode of action groups, a detailed understanding of how insecticides work is not required. However, a basic knowledge regarding modes of action and the MoA classification scheme is useful for developing an insecticide resistance management strategy.

There are at least 8 different modes of action groups [IRAC Number – 1A, 1B, 3A, 5, 11, 18, 22A, 28] that are rated good to moderate for management of grape berry moth (GBM) in the 2016 New York and Pennsylvania Pest Management Guidelines for Grapes

https://store.cornell.edu/p-193185-2016-new-york-and-pennsylvania-pest-management-guidelines-for-grapes.aspx

IRAC Number (Modes of Action – MoA – Classification) : Insecticides for management of grape berry moth

Apr 2016_Andy_Insecticide Table

Components of a Resistance Management Strategy

Cultural Practices

Maintain good weed control under the trellis. Poor weed management resulting in excessive vegetation under the vines can harbor grape berry moth (GBM) pupae. Viticultural practices that promote a more open, less dense canopy resulting in better exposure of clusters to sunlight (e.g., shoot thinning, leaf removal, judicious use of nitrogen) will not only improve quality of fruit but will enable better spray coverage.

Vineyard area maintenance such as preventing overgrown, trashy areas around the vineyard will reduce overwintering sites for GBM pupae. If possible, removal of wild grapevines near the vineyard will decrease potential reservoir sites.

Figure 1.  Weeds under the trellis can harbor grape berry moth pupae.

Figure 1. Weeds under the trellis can harbor grape berry moth pupae.

Figure 2. Overgrown areas around the vineyard can be overwintering sites for grape berry moth pupae.

Figure 2. Overgrown areas around the vineyard can be overwintering sites for grape berry moth pupae.

Figure 3. Wild grapevines near the vineyard are potential reservoir sites for grape berry moth.

Figure 3. Wild grapevines near the vineyard are potential reservoir sites for grape berry moth.

Scouting                             

Insecticides should be used only if needed. Regular scouting throughout the season is a critical component in determining if and where applications should be applied for GBM.  A scouting protocol and assigning a GBM risk rating is outlined in  “Bulletin 138, Risk Assessment of Grape Berry Moth and Guidelines for Management of the Eastern Grape Leafhopper”  –  http://nysipm.cornell.edu/publications/grapeman/files/risk.pdf

Timing of insecticide applications using the GBM Degree–Day Model

GBM Degree–Day Model is incorporated into Cornell’s Network for Environmental and Weather Applications (NEWA – http://www.newa.cornell.edu/) and many grape growers in the Lake Erie Region have adopted this model to more accurately time insecticide applications for GBM management.

Spray Application Practices

Obtaining good spray coverage on clusters is critical. Calibrate sprayers at a minimum in the beginning of each season. Preferably 2 – 3 times/season as canopy growth increases.

  • Use appropriate gallonage, speed, pressure, and nozzles for good cluster coverage as the size of the canopy increases throughout the season.
  • Spray Every Row.
  • Minimize Spray Drift.

Rotate chemical groups/classes of insecticides                                                                                                           

An important component in preventing or delaying insecticide resistance is to rotate insecticides with different modes of action into your GBM spray program. Use the MoA classification information above and consult the 2016 New York and Pennsylvania Pest Management Guidelines for Grapes   https://store.cornell.edu/p-193185-2016-new-york-and-pennsylvania-pest-management-guidelines-for-grapes.aspx  to develop a rotational plan.

Be sure to incorporate GBM selective insecticides such as (Intrepid [18]; Altacor [28]; or Delegate [5]) into your spray program which will also aid in conserving natural enemies.

Understanding insecticide modes of action may not be easy but following the IRAC MoA Classification for resistance management is as simple as rotating the numbers.

 

References:

Brown, A.E. and E. Ingianni.  Revised August 2013.  “No. 43: Mode of Action of Insecticides and Related Pest Control Chemicals for Production Agriculture, Ornamentals, and Turf.” University of Maryland. 13 pp. http://pesticide.umd.edu/products/leaflet_series/leaflets/PIL43.pdf

Insecticide Resistance Action Committee (IRAC) http://www.irac-online.org/

Suiter, D.R. and M.E. Scharf.  Reviewed January 2015. “Insecticide Basics for the Pest Management Professional (Bulletin 1352). University of Georgia. 28 pp. http://extension.uga.edu/publications/detail.cfm?number=B1352

                                                                                                     

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