Serious infestations of goosegrass, junglerice and barnyardgrass have proven to be way too persistent in many cotton and soybean fields (Picture 1). Many are getting frustrated with the lack of control seen with tankmixes that contain glyphosate and/or clethodim or quizalofop. Some have asked if maybe some of these grasses have developed resistance to glyphosate, clethodim and quizalofop. Continue reading
UT’s Soybean Scout Schools will be held in July (see details below). These field-side programs cover the basics of soybean growth, scouting, pest identification, and general management. Pesticide recertification and CCA CEU points will be available. Scout Schools are offered free of charge with sponsorship from the Tennessee Soybean Promotion Board. Registration is not required. Participants will receive a scouting notebook and a sweep net while supplies last.
West TN – Madison County, July 15th, 9:00 AM – 11:30 AM. This school will be at the West TN Research and Education Center, 605 Airways Blvd. Jackson TN, 38301. Signs will be up at the station to direct you to the field.
Middle TN – Franklin County, July 16th, 9:00 AM – 12:00 PM. This school will be at 601 Cumberland St., Cowan TN 37318. Contact Matthew Deist for more information. 931-967-2741, mdeist@utk.edu. Register online at https://tiny.utk.edu/SoybeanScoutSchool
West TN– Obion County, July 17th, 9:00 AM – 11:30 AM. This school will be held at the Obion Farmers Coop, 810 Mt. Zion Rd Union City, TN 38261. Contact Garrett McDaniel for more information gartmcda@utk.edu, 731-223-1178.
JACKSON, Tenn. – The University of Tennessee Institute of Agriculture will host the annual Weed Tour this Thursday, June 20 at the West Tennessee AgResearch and Education Center. The guided tour will feature 60 weed management research tests in cotton, corn and soybean.
Weed Tour runs from 9 – 11:30 a.m., with registration opening at 8:30 a.m. Continue reading
The question of the week is on how to burndown fields that are grown up messes before planting soybeans (Picture 1). The problem is when fields are heavily infested with 3’ tall goosegrass, Palmer amaranth, horseweed and volunteer corn that is tasseling there are no good answers. Continue reading
Last fall there was a notable amount of Palmer amaranth in many corn fields in areas of the state where we had confirmed dicamba resistance. As a result, we have recently conducted some field screens on these pigweed populations to herbicides used in corn and soybean.
Figure 1
There have been numerous fields where goosegrass, junglerice and Palmer amaranth were not controlled at burndown and the crop has emerged. In some cases, the wet weather delayed burndown to where Palmer amaranth and those grasses were too large to be effectively controlled with one pass of Gramoxone (Picture 1). In other cases, tillage used to help speed up field drying or to build beds partially buried pigweed and grasses which make effective burndown from Gramoxone very problematic (Picture 2). In a few cases, dicamba and glyphosate were used for burndown and they did not control those weeds due to resistance (Picture 3). Continue reading
The call of the last week was Pre-emerge herbicide injury in soybeans. Several folks reported that their soybeans were “going backwards”. This is not a surprise as in wetter springs the probability of seeing injury from Pre-applied herbicides is greatly increased. That coupled with an increase in soybean acres this spring would increase the probability of herbicide injury in that crop. I would expect more of the same as we move into June with all the rain in the past few days.
Carryover injury from fomesafen (Flexstar, Prefix, Reflex, Intimidator, Marvel, Dawn, Rhythm, etc.) is starting to show in a few corn fields. This is because some applications in late June and July in 2023 coupled with a very dry fall allowed the herbicide to persist into winter. Recent rains then allow any herbicide carryover to more completely get into the soil solution.
Fomesafen carryover injury in corn and grain sorghum looks similar. Expect to see stunting and interveinal chlorosis as pictures below sent from crop consultants clearly shows.
