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Northwest Iowa Dairy Outlooks

A local discussion of current science and issues concerning dairying in northwest iowa

The timing of the insecticide application is crucial to effective casebearer control.

Ideal timing is signaled by the initial appearance of newly hatched larvae. Insecticides, currently labeled for the casebearer, kill primarily larvae. One well timed treatment when needed achieves maximum control and conserves natural enemies needed to aid in control of aphids, mites and leafminers that come later in the season.

To determine when to spray, inspect clusters for casebearer eggs. Select trees that have had heavy casebearer infestations in previous years. The nut casebearer prefers some trees over others so that if you check those trees first you will normally detect the earliest eggs laid.

Note that eggs turn from white to red in the 3 – 5 day period before hatch.

Continue monitoring and tagging until the first larvae hatch. If >1% of clusters are infested and you are at or before the Decision Window, economic damage is expected to result. If treatment is made, return 5 to 7 days later and inspect fate of eggs/larvae on treated clusters. If they are still alive, consider a need for a re-treatment.

So far I have made two checks on local pecan trees with no larvae hatch.

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