It appears there will be a great deal of late May and June planted corn in Tennessee this year. Temperatures are beginning to warm up, and this late planted corn will grow very quickly.  Moreover the Palmer amaranth with this weather can emerge and grow to 8” in just 13 days. Therefore if this late planted corn does not have a pre emerge applied it will need to be sprayed soon. Because everyone is so busy with wheat harvest which early reports indicate is a good yielding crop, some producers might find themselves needing control of larger Palmer amaranth after the period where atrazine can no longer be applied. So the question is, “What can we do to control larger Palmer amaranth after the atrazine cutoff?”

Common premixes such as Halex GT or Capreno are effective in controlling Palmer up to 6” depending on the rate of application. Halex GT is the most commonly used premix on corn  in the state. It is often tank mixed with atrazine to provide control for Palmer larger than 6”tall. However, atrazine can only be applied to corn that is 12” tall.

Halex GT or Capreno are a good options, but in fields of high pressure or with larger Palmer, these herbicides as a standalone aren’t enough. Moreover just relying on those herbicides, particularly on large Palmer, can promote resistance development in this weed to those HPPD inhibiting herbicides. An ongoing study has shown that Halex GT or Capreno in combination with Status provides effective control of larger Palmer. The recommended rate is 4 pts/A of Halex GT plus 8 ozs/A of Status. This tank mix application can be applied in corn up to 30” tall.