Herbicide disappointments in dry weather

Commercial vegetable growers may be encountering some strange problems when using soil-applied herbicides in dry conditions.

We've been getting many calls about problems with pre-emergent and other soil-applied herbicides and it sounds like this dry weather has a role to play. Click on these links to listen in to our conversation with Dr. Thierry Besançon (Rutgers University) about the role of rainfall and/or irrigation in getting soil-applied herbicides where they need to be, and keeping them away from where they shouldn't be. We discuss two scenarios where dry weather can cause problems: 

Plasticulture Vegetables

Herbicide residue often finds its way onto plastic mulch during application to row middles. Unless rain or overhead irrigation washes this residue of the plastic, herbicide can be washed into the rootzone of newly planted transplants and cause some problems. The tomato plants in this photo grew through this damage but this is an alarming outcome, for sure!

Sweet Corn

Managing grass weed species in a grass crop, like sweet corn, can be challenging. So it's all about seedbank management and pre-emergent herbicides. For soil applied herbicides, rainfall and/or overhead irrigation is critical to getting that material below the soil surface, where the weed seeds are, before UV light degrades the material.



Jeremy Delisle
Fruit & Vegetable Production Field Specialist
Assoc Field Specialist
Phone: (603) 351-3831
Office: Cooperative Extension, Taylor Hall, Durham, NH 03824

Anna Wallingford
Extension State Specialist, Entomology & IPM
Phone: 603-862-1734
Office: Cooperative Extension, Kendall Hall Rm 330, Durham, NH 03824

Nicholas Rowley
Extension Field Specialist
Asst Field Specialist
Phone: 603-788-4961
Office: UNH Cooperative Extension, Taylor Hall, Durham, NH 03824

George Hamilton
Fruit & Vegetable Field Specialist, Emeritus
Phone: 603-641-6060
Office: Cooperative Extension, Taylor Hall, Durham, NH 03824