Evaluating plants for herbicide injury can be difficult and determining the exact cause of injury is not always possible. However, there are options to assist with these situations.
The Iowa Department of Agriculture and Land Stewardship  (IDALS) is responsible for investigating complaints of pesticide drift and enforcing state regulations involving pesticide applications. When a complaint is filed with the Pesticide Bureau of IDALS, it then becomes an official investigation, which may result in civil penalties for the applicator. As part of the investigation, testing may occur on plant samples for the herbicides in question. For more information, contact the Pesticide Bureau of IDALS at 515-281-8591.
Iowa State University Extension also can be a valuable source of information regarding herbicide injury. Samples submitted will be visually evaluated and a report will be returned to the client. However, Iowa State University Extension will not analyze plant tissue or soil samples for pesticide residues. The form Weed ID and Herbicide Injury Diagnosis, Ag-146, available from your county extension office or online at http://extension.agron.iastate.edu/extweeds/  should accompany submitted samples.
This article originally appeared on page 96 of the IC-480(12) -- June 1, 1998 issue.