K-State Research and Extension-Post Rock District Crop Produ ction Agent
Wow……what a blessing with the snow that most of the state of Kansas received over this last couple of weeks! This was extremely important that helped insulate the wheat crop when we experienced sub-zero temperatures and for the moisture! Let’s hope we continue to receive more moisture! You might think it is a bit early to start thinking about those weeds that can magically appear in your crop fields. Weeds compete with your wheat crop for light, water, nutrients, and space. Uncontrolled weeds in wheat decrease yields, lower quality and interfere with harvest. Stay tuned and I will share with you some weed strategies to think about.
It is important to scout fields and properly identify young weed seedlings early in the season to develop an effective weed management strategy. Understanding the life cycle of the weeds will also help with identification and control. Basically, weeds are divided into different categories depending on their emergence and growth pattern. There are winter annuals, summer annuals and perennials. Winter annual weeds generally emerge in the fall of the year, go dormant over winter, resume active growth in the spring, and then flower and set seed before dying in the summer. Winter annual weeds are generally most susceptible to herbicides in the fall or before they have begun to bolt or joint in the spring. These include grasses and broadleaves such as cheat grasses, jointed goat grass, mustards, field pennycress or henbit. Winter annual weeds are usually the most abundant type of weeds in winter wheat because they have a similar life cycle.
There are several herbicide options for controlling winter annual broadleaf weeds in wheat. Generally, fall applications will provide the best control of winter annual weeds with any herbicide, as long as the weeds have emerged. The majority of winter annual weeds usually will emerge in the fall, although you can still have some emergence in the spring, especially if precipitation after planting is limited in the fall. However, winter annual weeds that emerge in the spring often are not very competitive with the crop, at least in years when there is a good crop stand. Some of the wheat stands are okay or better than last year, so you may want to keep an eye out on how the wheat is competing against the weeds once it warms up.
Some herbicides can work well even when applied during the dormant part of the season, while others perform best if the crop and weeds are actively growing. The key difference relates to the degree of soil activity provided by the herbicide. Herbicides that have good residual activity, such as Glean, Finesse, Amber, and Rave can generally be applied in January and February when plants aren’t actively growing and still provide good weed control, assuming you have proper conditions for the application. Most other herbicides, which depend more on foliar uptake, will not work nearly as well during the mid-winter months, when the wheat and weeds aren’t actively growing, as compared to a fall or early spring application.
Spring herbicide applications can be effective for winter annual broadleaf weed control as well, but timing and weather conditions are critical to achieve good control. Spring applications generally are most effective on winter annual broadleaf weeds soon after green-up when weeds are still in the rosette stage of growth, and during periods of mild weather. Once weeds begin to bolt and wheat starts to develop more canopy, herbicide performance often decreases dramatically. Please give me a call if you have further questions on weed management.
The Post Rock Extension District will be hosting one of the KSU NC/ NW regional Weed Management Update schools on Monday, February 12, in Beloit. The meeting will be held at the First Christian Church, 321 N. Mill Street, and will start at 9:30 a.m. until 12:30 p.m. 3 credit hours for CEU 1A certification along with CCA credits have been applied for. Lunch will be served following the program thanks to sponsor CVA. No cost, however, registration is re- quested by Friday, February 9, either ONLINE at www. postrock.ksu.edu or calling any of our Post Rock Extension District Offices in Beloit, Lincoln, Mankato, Osborne or Smith Center. Hope to see your there!
Post Rock Extension District of K-State Research and Extension serves Jewell, Lincoln, Mitchell, Osborne, and Smith counties. Sandra may be contacted at swick@ksu. edu or by calling Smith Center, 282-6823, Beloit 7383597, Lincoln 524-4432, Mankato, 378-3174, or Osborne 346-2521. Join us on Facebook at “Post Rock Extension”. Our “Weekly Ag Roundup” is published every Friday on our website www.postrock.ksu.edu and my twitter account is @PRDcrops.
