Archives for April 2014

Over the past few years, a few fields have been treated with an organo-phosphate insecticide and then with an ALS-inhibiting herbicide and significant injury has occurred. A number of corn herbicides have label precautions about use of an organo-phosphate insecticide at planting due to potential crop injury. This includes the insecticides Counter (terbufos), Lorsban (chlorpyrifos), and Fortress (chlorethoxyfos). The herbicides include both soil-applied and postemergence herbicides. Some of the common products include Callisto (Halex GT); Resolve (Steadfast, Basis); Accent; Capreno, Sharpen or Kixor. Note that the list is not only Group 2 (or ALS-inhibiting herbicides). If using an organo-phosphate insecticide, a list of herbicides that have potential interactions can be found at https://extension.udel.edu/ag/files/2014/01/CornWeedguide.pdf and go to Table 19.

Unfortunately, most corn seed companies no longer designate hybrids as either IT or IR. So if you are not sure, take the cautious approach and assume the hybrid is a “standard” hybrid (no enhanced tolerance for imidazolinone herbicides); and follow the most restrictive guidelines.

I have been asked by a few people about the differences in metolachlor (the active ingredient in Dual) products. The “old” Dual in the early 1990s was two isomers of metolachlor, R and S isomers. The Dual II included a safener to improve crop safety (improves safety to corn, not to broadleaf crops; hence Dual for broadleaf crops and Dual II for corn). [Read more…]

The weather has not been favorable for maximum effectiveness of many postemergence (or burndown) herbicides. Cool weather and overcast skies are not ideal conditions for herbicide performance. And given that many fall and early spring emerging weeds can be difficult to control once the crop is planted, it is important to scout your no-till fields to determine if a follow up treatment is necessary prior to planting.