Josh Bushong (column mug)ENE

With recent rainfall this past week and soon to be open wheat fields, I’ve had multiple discussions with farmers looking at options for this summer. Soybean, grain sorghum, feed and sesame usually get mentioned the most. Hopefully drought, heat and relentless winds will hold off until these crops can be established.

While driving throughout north central Oklahoma last week, I noticed significant acres of wheat that will not be taken to grain. I saw anywhere from 5 to 10% being grazed out closer to Enid, but as high as 30 or more percent going west to Woodward County. A few wheat fields were already laid down for hay and I assume more will soon be too. There also were a few wheat fields already chemically burned down in preparation of a summer crop.

Some soybean planting already has started, and once the ground dries out enough to hold a planter up many more acres will follow. Mid- to late-May planted soybeans have shown to be relatively consistent for many in the region the past five or so years. We received 2 to 4 inches in north central and half an inch to 2 inches a little further west. Soil temperatures were rising prior to the rains and should be back to 60 degrees after this next wave of heat.

With the blessing of a rain and warm temperatures, unfortunately also comes the weeds. Inadequate weed control is one of the most yield-limiting factors, as some research has shown losses as high as 79%. Certain herbicide programs may seem expensive, but still can be economical if yields are protected. From soybean emergence to the V3 growth stage (third trifoliate) is the most critical period to limit weed competition to protect yield potential.

Certain herbicides still are in short supply and hard to obtain. As always we recommend to rely on residual herbicides instead of solely relying on traits that allow the post-emergence applications of glyphosate, glufosinate, 2,4-D (Enlist) or dicamba (Xtend). ALS herbicides (such as Classic, FirstRate, and Pursuit) have good activity on many broadleaf weeds but can be weak on pigweeds and waterhemp. PPO herbicides (such as Cadet, Cobra, Reflex, Resource and UltraBlazer) have activity on many problem broadleaf weeds and also have been a good option if some weeds are suspected of ALS resistance. Assure II, Fusilade DX, Poast and Select are some good options if grass control is needed.

Recent field trials by Oklahoma State University have shown that pairing pre-emergent herbicides with post-emergent herbicides resulted in higher yields (about 10-15 more bushels) and fewer weeds. These trials looked at planting date and post-emerge application timings with and without a pre-emerge. Later planted soybeans generally benefited more from the pairing of a pre-emerge and post-emerge.

To save yield potential, it is best to start clean and stay weed-free for the first few weeks of crop growth. Soybean producers must first decide which herbicide traits is best for their operation, develop a herbicide pla, and also make a backup plan if herbicide applications are delayed or fail satisfactory control. Weed control strategies need to consider future crop rotations and also should be a long-term investment in managing herbicide resistant weeds. Going cheap now may become much more expensive later.

To find out more information, contact your local OSU County Extension Office to visit with your ag extension educator and review the Oklahoma Cooperative Extension Service factsheet PSS-2794, “Meshing Soybean Weed Management with Agronomic Practices in Oklahoma” and CR-2781, “Components and Ratios of Pre-mix Herbicides for Use in Soybean.”

Bushong is Oklahoma Cooperative Extension Service northwest area agronomy specialist.

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