Uniform Spray Deposits for Reduced Pesticide Use in Weed and Insect Control Operations

1991 Annual Report for LS91-041

Project Type: Research and Education
Funds awarded in 1991: $43,500.00
Projected End Date: 12/31/1993
Matching Non-Federal Funds: $46,830.00
Region: Southern
State: Mississippi
Principal Investigator:
David R. Shaw
Mississippi State University

Uniform Spray Deposits for Reduced Pesticide Use in Weed and Insect Control Operations


Today's pesticide dose (or rate) recommendations for row crops are nearly always in excess of the doses which have been shown to be effective when used and applied properly. The recommendations reflect a "measure of insurance" against no or poor sprayer calibration, adverse weather, and poor deposit uniformity obtained with the majority of the application equipment in current use. Past research has addressed a wide variety of factors involved in erratic pest control, including environment and pest species and size. However, little research has been conducted to evaluate potential influences of pesticide deposit variation on pest control; therefore, the proposed research addresses this question.

An electronically controlled field sprayer will be used to create three levels of variation among deposits on common cocklebur and cotton canopies. High Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC) equipment will be used to quantify the magnitudes of herbicide and insecticide deposits on common cocklebur and cotton, respectively. Deposit variation data will then be compared with actual weed and insect control data to determine the effects of deposit variation on pest control. Results from the first year's research will also be used in the second year at the farm level to demonstrate the impact of pesticide deposit variation on weed and insect control, and the potential for economic and environmental benefits through reductions in pesticide application rates. These levels of variation will be used at two or more pesticide rates in order to demonstrate the potential rate reductions possible through more uniform pesticide applications.


(1) Improve weed control and reduce environmental pesticide impact by reducing the variation of on-target herbicide deposits.

(2) Improve cotton insect control and reduce environmental pesticide impact by determining the effect of insecticide deposit variation on insect control.


Labeled pesticide rates typically are higher than what are needed to adequately control pests. This provides a margin of error for poor application techniques, larger- than-optimum pest size, and poor environmental conditions. However, under appropriate conditions, producers may be able to save money and reduce the introduction of pesticides into the environment by improving sprayer efficiency and reducing pesticide rates. Common cocklebur control at a high level of spray deposit variation required 50% more acifluorfen than at a low level of deposit variation.