Optimizing Control of Insect Pests: Reducing Insecticide Use and Minimizing Economic Injury with JMP

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 Jane Breen Pierce, New Mexico State University

Insect pests cause significant losses in agriculture. Growers frequently turn to insecticides to protect their investment in a crop but the decision to use an insecticide is often difficult and anything but straightforward. Economic thresholds are used to help make these decisions and are often calculated as (loss/insect)/ crop value. 

Clearly an understanding of the potential crop value is an essential element in determining return on investment.  Unlike some crops cotton produces harvestable yield in the form of bolls containing lint and seed over a relatively long period of time. The flower buds (squares) and bolls are only susceptible for a matter of days and represent only a portion of the total yield.  A typical season long yield of 3 bales with 480 lb/bale or 1440 lb/A is not the appropriate measure. 

The location of cotton bolls are mapped by node and position so at any point in time growers know which squares and bolls are susceptible to insect damage. In New Mexico, bollworm has historically been one of the key insect pests damaging cotton late season. If late season bolls are only a small portion of overall yield, it might be difficult to justify inputs for protection of these susceptible squares and small bolls.  Growers frequently use Bt cotton to avoid bollworm damage but as a late season pest the benefit only applies to late season bolls, also making calculations of value important in justifying the expense of expensive Bt cottons.