Project Overview

Reports

Commodities

• Additional Plants: Christmas trees, flowers, greenhouse, herbs, ornamentals, roses, tobacco, trees

• Agronomic: corn, cotton, peanuts, sorghum (milo), soybeans, wheat

• Fruits: small fruit, tree fruit

• Vegetables: beans, cucurbits, peppers, sweet corn, tomatoes

Target Pests

Practices

• Pest Management: chemical control, monitoring/scouting, pesticide application timing, pesticides, plant growth regulators, precision pesticide use

• Crop Production: nurseries, water storage

The problem or opportunity

Non-target herbicide injury has become increasingly problematic in agronomic and horticultural crops, and in urban landscapes. Although auxin-herbicide drift events are often in the farm press headlines, crop injury from other herbicide modes of action are also common contributors via drift, contaminated compost and hay, contaminated irrigation water, and misapplication. Crop injury from hay, manure, composts and grass clippings contaminated with auxinic herbicides have been reported throughout the region (Bush et al. 2016, Davis et al. 2020). In North Carolina vegetable and nursery crop producers have experienced crop losses from herbicide contamination of irrigation water.

Cooperative Extension agents often act as “first responders” to diagnose suspected herbicide injury, yet herbicide injury diagnosis can be challenging. Many factors affect plant responses to herbicides including innate crop sensitivity to the herbicide active ingredient, weather conditions during and after exposure, exposure dose, crop nutrition, crop growth stage (and vigor). Also, other biotic and abiotic factors may mimic herbicide injury. Furthermore, plant responses to diverse herbicides can be similar, complicating field diagnostics. A thorough understanding of herbicide injury symptoms, differential species responses to herbicides, as well as in-field diagnostic procedures is essential for accurate diagnoses.

In a survey of NC Cooperative Extension horticulture agents, >80% of respondents indicated training on herbicide injury diagnosis was a high priority (Neal, J. 2021 survey, unpublished). Furthermore, Cooperative Extension has experienced rapid staffing turnover, with 58% of Extension agents remaining in a job for less than 3 years (Zippa 2021). Thus, continuing education for newly hired agents is a high priority. In a prior herbicide injury in-service training event, participant evaluations highlighted the value of field demonstrations of injury symptoms on diverse crops. While valuable, such training events are very time consuming and expensive, and thus cannot be conducted every year. Agents and allied industry professionals need access to digital resources for on-line, asynchronous continuing education. 

The approach. Herbicide injury symptom demonstrations will be established. Diverse agronomic and horticultural crops will be planted at the NC State University Lake Wheeler research farm and postemergence herbicides representing the major mode-of-action classes will be applied and injury symptoms will be photographed. Additionally, preliminary data on the critical concentrations of herbicide contaminants in irrigation water will be generated.

Two in-person training events for Cooperative Extension agents (both horticulture and agronomic crops agents) and Department of Agriculture pesticide inspectors will be conducted.  The training content will include an overview of herbicide injury diagnostic procedures, herbicide modes-of-action and symptomology, common routes of exposure, and response strategies for growers. 

Narrated video segments will be recorded in which Extension Weed Scientists will describe principles of herbicide injury diagnostics and symptoms on diverse agronomic and horticultural crops. These video segments will be publicly available for remote or continuing education for agents and crop consulting professionals.

The anticipated impacts:

As a result of this project, county agents in North Carolina will be able to recognize and diagnose herbicide injury to crops, and will be better able to advise clients on how to avoid herbicide injury. These agents and other professionals will have access to updated on-line fact sheets on herbicide injury symptoms and diagnostics.  The video training modules will be used for continuing education by recently hired and experienced cooperative extension agents and by other crop consultants.  This targeted training program with a focused audience of NC Cooperative Extension agents will be leveraged to create educational resources for a broader audience throughout the Southeast and beyond.  A longer term impact will be establishment of a weed science outreach training infrastructure that will be capable of self-sustaining outreach educational events on a variety of topics.