Do's and don'ts of agricultural tank mixing

By Scout Nelson

In agriculture, efficiency is crucial. Farmers often combine herbicides, fungicides, insecticides, and even liquid fertilizers in a single tank mix to save time and resources. This practice requires careful consideration of the specific pesticide labels, which indicate whether products can be safely combined.

Most pesticides used are emulsified concentrates (ECs), consisting of an active ingredient dissolved in an organic solvent, often accompanied by surfactants that enhance uptake by plants or insects.

Mixing multiple ECs can increase the surfactant load, which under certain environmental stressors, can lead to crop injury and reduced pest control effectiveness.

These stressors include extreme temperatures or overly moist or dry soil conditions that slow down crop metabolism.

An example of such antagonism is observed in small grains where bromoxynil, a Group 6 herbicide, is used with grass herbicides from Groups 1 or 2, alongside a fungicide and an insecticide.

Under adverse conditions, the high surfactant load from this combination can impair wild oats' ability to absorb the grass herbicide effectively, reducing overall pest control.

Many wheat fields are sprayed for weeds, and conditions are favorable for tan spot and aphids, common regional pests. The forecast suggests continued cool and wet weather, making the addition of fungicide and insecticide appealing as preventative measures.

It is crucial first to scout the fields to confirm the presence of tan spot and aphids before proceeding with these additives.

Farmers are advised to refrain from adding these treatments unless the specific pests are confirmed. Following the pesticide labels and recognizing that some crop injury is possible, even with label-approved tank mixes, is essential for maintaining crop health and achieving effective pest control.

Photo Credit: istock-fotokostic