One of the most difficult situations greenhouse growers may face is herbicide contamination and subsequent plant injury. Herbicide applications may occur off-site or within the greenhouse, sometimes well before symptoms are noticed. Once affected, plants are often unmarketable.
In a recent article on E-Gro, Beth Scheckelhoff, an Extension Educator for Greenhouse Systems at The Ohio State University, provides some examples and basic recommendations for mitigating and preventing herbicide contamination and injury in the future.
The examples address real-life situations from the following incidents:
• Contamination from greenhouse flooring. Whether greenhouses have been in operation for several years or several decades, significant changes in management practices and ownership often occur over time. With these changes, prior knowledge of chemical use and misuse may not be known by present day owners and/or growers. For example, new owners of a production and retail facility experienced problems with leaf distortion on geranium and tomato plants within one of their three greenhouse ranges.
• Contamination from irrigation water. A rural greenhouse using well water for irrigation consistently had trouble growing spring vegetable transplants, as well as some ornamental species. The greenhouse changed ownership, and the new owners wanted to solve the recurring issue of poor germination and growth of seedlings in the spring.
• Non-labeled herbicide application. Recently, a grower was advised by a local agricultural supplier’s sales representative to apply a nonselective post emergence herbicide labeled for application to commercial and industrial sites where bare-ground is desired. The grower applied the herbicide to weeds on the greenhouse floor while spring bedding material was actively growing on benches. All plants in the greenhouse died, weeds and ornamentals alike.
• Herbicide drift. In some cases, herbicide from a neighboring property will drift into a greenhouse and cause damage. While not fool-proof, it is beneficial for greenhouse owners to develop relationships with surrounding businesses and farms that might be applying herbicides or other chemicals throughout the growing season.
Go to the E-Gro article to check out the full article from Scheckelhoff.