2024 alert - guard against herbicide carryover in fields

By Scout Nelson

The utility of herbicides in weed management is undeniable, yet their residual activity can sometimes harm the subsequent year's crop, especially under adverse environmental conditions.

The degradation of herbicides depends on moisture, temperature, and microbial activity in the soil, and is also influenced by soil pH and the application rate of the herbicide.

Given the dry conditions of the 2023 growing season, farmers should be particularly careful about the risk of herbicide carryover into 2024.

Herbicides of Concern: A few herbicides, including atrazine, clopyralid, chlorimuron, fomesafen, mesotrione, imazethapyr, and isoxaflutole, have raised alarms due to their potential for carryover.

It's crucial to adhere to the rotation restrictions detailed on their labels to avoid crop injury in the following season. Farmers are advised to consult their spray logbooks to ensure compliance with these restrictions.

Mitigation Strategies: Delaying planting in fields treated with these herbicides during dry spells can reduce the risk of crop injury. Tillage might help by dispersing herbicide residues more evenly, thereby diluting their concentration.

This also promotes aeration and microbial activity, aiding in faster herbicide breakdown. Switching to a crop that is more tolerant to the residual herbicide, if compatible with your farming practices, can be a smart move.

Detecting Herbicide Carryover: Soil testing for herbicide residues is one option, though it can be costly and may not accurately reflect field variability. A more practical approach is conducting a bioassay.

This involves planting seeds of the next crop in soil samples from the field and observing their growth for signs of herbicide injury over three weeks.

A healthy growth indicates a lower risk of carryover, while stunted or damaged seedlings suggest the opposite.

By being proactive in managing herbicide carryover, farmers can safeguard their 2024 crops against potential damage, ensuring that their fields remain productive and profitable.

Photo Credit -gettyimages-fertnig