By Clint Schroeder OSU Extension
Each fall Ohio State University Extension conducts a survey of the different types of weeds present in soybean fields, as well as, the level of infestation. Weed Science State Specialist Dr. Mark Loux leads this study and uses the information gained to help develop future weed management programs. This study is conducted in each county where there is an Ag and Natural Resources Educator. The educator selects a route 80-100 miles long through the county and takes notes on one soybean field in each mile.
I was able to complete the study for Allen County on Friday, October 4th. The timing worked out perfect as most fields were nearly ready for harvest, and I did in fact see a few harvested fields on the southern and western portions of the county. The route that I selected has been saved so that it can be used in the future in an effort to maintain a level of consistent observation. In the 84 mile route I was able to observe 90 fields. The results in Allen County are similar to the rest of Northwest Ohio as marestail continues to be problem. In Allen County 37 percent of fields had some level of infestation of this weed. Marestail, also called horseweed, has continuous germination, is highly competitive, fast moving and wide spreading with wind dispersal. Many plants are also Glyphosate tolerant, and some populations have ALS and PPO-inhibitor resistance. You can find more information about managing this problem weed by following this link: https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/7/3461/files/2019/04/2019-marestail-fact-10czipq.pdf
I would also caution producers to be on the lookout for waterhemp. This will be the weed that gives us fits in the future. Here is more information on how to distinguish this pigweed from others in the same family: https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/7/3461/files/2018/12/2019-pigweed-ID-fact-25mywu8.pdf There is also a great factsheet about herbicide resistance within waterhemp populations at this link: https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/7/3461/files/2018/12/2019-WH-resistance-fact-tmmdvk.pdf