A website from UGA Cooperative Extension

The decision to terminate insect controls can be challenging in some fields but a few basic considerations will assist in that decision.  When evaluating a field a grower must first identify the last boll population which will significantly contribute to yield (bolls which you plan to harvest).  In some situations the last population of bolls which you will harvest is easy to see (i.e. cotton which is loaded and cutout).  In others, such as late planted cotton, the last population of bolls you will harvest will be determined by weather factors (the last bloom you expect to open and harvest based on heat unit accumulation).  Once the last boll population is determined the boll development or approximate boll age should be estimated.  Depending on the insect pest, bolls are relatively safe from attack at varying stages of boll development.

The table below list approximate boll age in days which bolls should be protected for selected insect pests.  Cooler temperatures will slow plant development and subsequent boll age values may increase in such environments.  It is assumed that the field is relatively insect pest free when the decision to terminate insecticide applications for a pest is made.

Insect Pest(s) Approx. Boll Age (days)
Corn Earworm

Tobacco Budworm


bolls fully sized

Stink Bugs 25
Fall Armyworm bolls near maturity
Foliage Feeders

soybean looper

beet armyworm

southern armyworm

bolls mature
Sucking Insects




(honeydew accumulation on lint)

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