Attached as an Excel file are three tables. The two foliar insecticides tables are titled: Labeled Corn Postemergence Herbicide and Foliar Insecticide Tank Mixtures and Labeled Corn Postemergence Herbicide and Foliar Insecticide Sequential Application Restrictions. The third table is titled: Labeled Postemergence Herbicide Sequential Applications for Soil-Insecticides.

With the extended wet weather, the threat of black cutworm infestations, and the anticipated rush to "multi-task" field work activities I thought that it was appropriate to see what the herbicide labels addressed in regards to foliar herbicide and insecticide tank mix applications.

Generally the timing of postemergence weed control and insect (e.g. black cutworm) control do not sequence well, you treat each problem as it arises. However, if the opportunity should arise it is important to realize that some tank mixtures will work with little risk of physical incompatibility, reduced weed control, or herbicide-induced crop injury. Many tank mix combinations (especially with organophosphate insecticides and ALS herbicides) can enhance herbicide crop injury and that is why tank mixtures with these products should be avoided and why sequential application restrictions are presented in the second table.

As you can see in the first table, many herbicide labels do not specifically address herbicide and insecticide tank mixtures. A designation of no listed tank mixtures does not imply that a specific mixture cannot work but it would be wise to contact representatives of the specific pesticide manufactures for more details. Also, a designation of no restricted herbicide and insecticide tank mixtures does not mean that the combination can be safely applied to the crop. Often EC insecticide formulations have the potential to increase herbicide-induced crop injury because they increase the rate and amount of herbicide uptake similar to the addition of too much crop oil concentrate or other adjuvants. Again, a
consultation with the basic pesticide manufactures is a wise strategy before application of the tank mixture to the crop.

I hope that you do not need to make these type of decisions in this already stressful cropping season but I would also hate to see extensive harm done to the corn crop by trying to say time via herbicide plus insecticide tank mixtures

Finally, soil-applied insecticides can increase the crop injury potential of a number of ALS herbicides. The third table shows the relationship of soil-applied corn insecticides and postemergence corn herbicides.

Table.   Herbicide x Insecticide Interactions