Expect high weed pressure in 2020

MARKLE, Ind. — Many prevent plant acres experienced heavy weed growth this year, causing concern for high weed pressure in 2020.

Delayed or missed herbicide applications led to weed escapes. Additionally, floodwaters likely carried weed seeds — meaning growers may have to deal with weeds they’re not used to seeing in their fields.

“We need to consider increasing some of our residual herbicides next year, knowing we have more pressure from this past year,” said Chad Threewits, Syngenta agronomic service representative for Indiana. “That’s one way to combat an increased seed bank.

“I think it’s also about being diligent to catch up after a year of poor weed control — with strong fall burndown programs and strong early spring burndown programs. Any time we can start clean in fields, we’ll be ahead.

“It’s nobody’s fault except the weather — we had to plant into weeds. I think that it will be critical to get ahead of the weeds next year.”

Waterhemp and marestail are of particular concern, Threewits said.

According to Iowa State University Extension, waterhemp is a prolific seed producer and can produce abundant seed under adverse conditions.

Waterhemp plants produce about 250,000 seeds per plant. Those seeds will either take root in 2020 or lay dormant until future years.

“With waterhemp and marestail, we worked really hard the last few years to reduce the seed bank,” Threewits said. “In one year, we put it right back, and maybe even heavier than what we had previously. Especially in areas where it was already bad.

“Even if I controlled my weeds pretty well, if my neighbors didn’t — those weeds are going to spread.”

An effective herbicide program can combat weed concerns, he said.