Chapter 24

Pesticides for Grapevines

Strategies for Managing Pesticide Resistance

Pesticide resistance is a genetically based phenomenon. Resistance occurs when a pest population— insects, for instance—is exposed to repeated applications of a pesticide. After a period, the pest may develop resistance to a chemical so that the chemical no longer effectively controls the pest at the same rate, and higher rates and more frequent applications become necessary until eventually the chemical provides little or no control.

Monitor Pests

Scouting is one of the key activities in the implementation of an insecticide resistance management strategy.

Focus on Economic Thresholds

The decision to use an insecticide, or take some other action, against an insect infestation requires an understanding of the level of damage or insect infestation the vineyard can tolerate without an unacceptable economic loss.

Adopting Integrated Pest Management Practices

Integrated pest management (IPM) strategies involves compiling detailed, timely information about the vineyard and its pests to ensure that pest management decisions are economically, environmentally, and socially sound. IPM places emphasis on multiple means of control, rather than relying on a single management tactic.

Avoid Tank Mixes

Never combine two pesticides with the same mode of action in a tank mix.

Avoid Persistent Chemicals

Insects with resistant genes will be selected over susceptible ones whenever pesticide concentrations kill only the susceptible pests.

Use Recommended Label Rates

Using lower pesticide rates other than recommended by the manufacture increases the risk of pests surviving the initial contact, thereby increasing the potential for resistance.

Optimal Spray Coverage

Another means of retarding pesticide resistance is to increase the effectiveness of pesticide application.

Using Selective Pesticides

Using selective pesticides often have the advantage of producing less damage against harmless (and potentially beneficial) pests.

Use Different Modes of Action

When resistance to a pesticide arises, not only does this resistance render the selecting compound ineffective, but it also confers cross-resistance to other chemically related compounds. This is because compounds within a specific chemical group usually share a common mode of action (MoA).

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