It goes without saying that a weed allowed to compete with a growing crop is going to affect yield. How much?

A 2008 Iowa State study in corn under heavy weed pressure might provide some insight. They created differing periods of weed competition, implementing control at the V2, V4, and V5 growth stages (22, 36, or 43 days after planting) as compared to a weed-free treatment that included a pre-emerge herbicide program followed by a post program. By measuring corn shoot biomass at the time of the post emerge application, they found large differences in the amount of biomass lost from the differing application timings. A 10 percent reduction in biomass at V2 increased to 70 percent by V4. While the applications at V2 and V4 allowed for decent yield ‘recovery’ (losses were limited to five and 12 percent), waiting an additional week to the V5 stage resulted in a 63 percent increase in lost yield compared to application at the V4 stage.

We know that to be true. What challenges our weed control systems is how to design a weed control program to avoid these losses! That’s the goal of the Meadowlark Extension District Weed (Control) Week 2017 coming up on February 22nd and 24th.

Dr. Curtis Thompson, K-State Research and Extension Weed Specialist will be our guest on Wednesday, February 22nd to focus on corn weed control programs. Dr. Thompson will discuss new corn herbicides as well herbicide systems to help reduce weed pressure and herbicide resistance. We’ll kick off the morning with light refreshments in the small meeting room of the Nemaha County Community Building in Seneca at 9:45 AM followed by Dr. Thompson’s presentation from 10:00 – 11:00 AM. Dr. Thompson will be available for a question and answer session after the meeting as well.

Soybean Weed Control will be the focus on Friday, February 24th at the Knights of Columbus Hall in Nortonville. Dr. Dallas Peterson, K-State Research & Extension Weed Specialist will speak from 10:00-11:30 AM on new products in soybean weed control, including Xtend soybeans and management of the new dicamba formulations available. Come early for refreshments at 9:45 AM!

RSVP is not required, but is helpful to make insure adequate meeting materials. Please RSVP by noon on Tuesday, February 21st to any Meadowlark Extension District Office or via e-mail to dhallaue@ksu.edu . Hope to see you there!