There is one guest that OSU herbicide specialist Mark Loux hopes never shows up at an Ohio State University Weed Science Field Day — Palmer Amaranth. This unusually pesky weed is beginning to make unwelcome visits at farms in southern Ohio and in some northwest parts of the state and Loux would much rather take his research teams to the weed instead of getting data from the South Charleston farm.
“What my groups are trying to do with Palmer Amaranth is work with producers with the weed individually so it does not turn into a mess if we are able to intercept it early enough,” Loux said. “It is not our goal to have a Palmer Amaranth research site. If someone’s farm gets out of control and they are battling it, we will probably end out working there.”
With ongoing Palmer Amaranth research being done in states west and south of Ohio, the last thing Loux wants to do is duplicate those tests anywhere close to home. Those studies will come up with management programs that will also work for Ohio.
For those that were welcomed to the Western Agriculture Research Station for the recent field day, there were many plots to see with many different and unique variables of weed control. Palmer Amaranth was discussed, as was pig weed, but marestail is one weed that has been on Loux’s radar for many years. This particular weed has morphed into more of a summer weed that is causing challenges for farmers.
“We have really tried to fine-tune our marestail recommendations,” Loux said. “We’ve tried to stress to everyone that there needs to be a systems-type approach to marestail that includes a fall application and a spring application.”
Loux says some of the questions about marestail are about when to apply residual in the spring, how much to use at what time and if a burndown is necessary. His research results are driving agriculture toward a more comprehensive pre-emergence herbicide program that costs an additional $5 compared to current programs being used.
One of the challenges with Loux’s research is the consistency of the results as conditions and weeds themselves are constantly changing.
“A former weed scientist at Purdue told me that it isn’t how good something is, it is how consistently good something is,” Loux said. “We know what controls some weeds, like lambsquarters for example. Other weeds, like marestail and giant ragweed, have either a long enough period of emergence or they grow fast enough or have enough resistance that if a program is a bit too simplistic there will be situations when it just won’t work.”
It has taken a weed like the dreaded Palmer Amaranth to raise the bar on the use of herbicide programs that have never had to be used in soybeans for control of any other weed to date. Loux says with 15 counties in Indiana with confirmed cases and a big area of Michigan fighting the weed off, it is just a matter of time before Ohio will see more challenges that Loux’s and his crew are prepared to meet head on, while hoping that they won’t have to.