Weed issues caused by fields not sprayed with pre-emergent herbicide

WEST LAFAYETTE, Ind. — As the 2020 growing season gets into full swing, farmers are beginning to look toward harvest season and what steps they need to take now to ensure quality yields in a few months.

Bill Johnson, a professor of weed science at Purdue University, said despite all the issues the agriculture industry has been experiencing this year due to restrictions and regulations put in place to stop the spread of COVID-19, one of the biggest issues with weeds that crop farmers are facing is due to not spraying pre-emergent.

Johnson said he has been surprised by the number of fields he has seen that did not get sprayed.

“I’ve been pretty amazed by the number of fields that didn’t get pre-emergent herbicide,” he said.

Johnson said the weeds that farmers are seeing in their fields this year are the usual suspects, including marestail, ragweed, waterhemp and annual grasses.

“Not anything new with weeds, but surprised didn’t use pre-emergent,” he said, adding he thinks many farmers decided to not spray pre-emergent herbicide by putting it in post-emergent to try and cut down on costs.

Johnson said if farmers chose not to spray pre-emergent, it is key to spray the weeds when they are small and with the right herbicide program, otherwise the weeds could continue to grow and get out of control.

Johnson said it is now too early to tell if the weeds that were not sprayed pre-emergent and are not killed off with a post-emergent herbicide will choke out the crops.

“It’s too early to tell because in July and August rain patterns will be the determinant for weed control in June,” he said.

Johnson said good rains in July and August will determine if the weeds will take all the nutrients from the crops in the field because weeds grow better in a dry, humid climate.