Thursday, January 12th, 2017
Hemp, a weed to worry about
By Tom Stankard
Ohio State University Extension educator Jeff Stachler warns about the dangers o. . .
CELINA - Local farmers are seeing a "concerning increase" in waterhemp in area soybean fields, Ohio State Extension Educator Jeff Stachler said during a weed-management presentation Wednesday afternoon at Wright State University-Lake Campus.
Sightings of pigweed varieties, including waterhemp, have increased in soybean fields across the state, he said.
Waterhemp is one of the most common weeds with which Midwest farmers deal, Stachler said. As the name suggests, waterhemp thrives in wet areas but over time has adapted to varied conditions.
Waterhemp is more prevalent in Auglaize County than in Mercer County, he said. The weed is a high-prolific seeder with as many as 1.5 times as many seeds than most other pigweed species, according to information provided at the presentation.
Like most weeds, waterhemp seeds remain viable in the soil for years, Stachler said. The weed compensates for small seed size by having a higher growth rate than most weeds - typically about 1 inch per day during the growing season. This allows the waterhemp seedlings to acquire more sunlight.
Typically, waterhemp can range from 4 inches to 12 feet tall, Stachler said.
The weed also gains a competitive advantage through the sheer number of plants infesting an area, Stachler said, adding seasonlong competition by waterhemp has been known to reduce soybean yield by about 44 percent.
Waterhemp can be tough to eradicate because it's resistant to multiple herbicides, he said.
Its populations are known to be resistant to ALS-inhibitors, triazines, diphenylethers (PPO-inhibitors) and glyphosate.
To help combat this timely scouting, proper herbicide application timing and using herbicides with multiple modes of action are key components of managing the weeds, he said.
"We're going to only compete against the crop and reduce crop yield if we don't get these things managed," he said.
According to a 2015 extension office survey, 46 percent of Mercer County soybean fields were weed free. The year before, 57 percent were weed free.
In Auglaize County, 18 percent of soybean fields surveyed were weed free. In 2013, 27 percent of fields surveyed were weed free.