Spring considerations – wheat pests, herbicide carryover and stored grain – Brookings Register


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As temperatures slowly begin to rise, wheat producers should watch for the army cutworm and pale western cutworm; both species can cause economic injury to wheat if populations become large. 
The army cutworm feeds at night and hides during the daylight hours just below the soil surface. Scouting for these caterpillars is typically determined by plant injury. Evidence is characterized by a clipping appearance near the base of the plant (as if someone snipped it off with a scissors). 
Often in winter wheat fields, caterpillars will feed on tender blades and avoid the stem and crown (which allow plant regrowth). If large patches of a field appear to be defoliated by these pests, or if two to four  army cutworms appear per square foot, management is recommended.
Pale western cutworms feed on plants just below the soil surface. They are typically observed later in the spring than the army cutworm and can occasionally be found in winter wheat, but are more common in spring wheat. 
If one or two pale western cutworms are observed per square foot, management is recommended. If management is deemed necessary, see the "South Dakota Pest Management Guide for Wheat" to determine what course of action is best suited for your operation. For more details on cutworm defoliation and management visit extension.sdstate.edu and search ‘cutworm’.
While we’re talking spring management, I should mention herbicide carryover. Due to dry conditions across much of the state, herbicide carryover could prove to be more of an issue this year than we typically see. Low moisture, low organic matter, extreme pH, and erodible soils are all contributing factors in herbicide carryover. Carryover is typically worse in areas where sprayer overlapping occurs (headlands) and intensified if spraying occurred late last year. To see a comprehensive list of common herbicides and their rotation restrictions visit extension.sdstate.edu and search "herbicide rotation restriction."
Lastly, I wanted to remind you to check grain bins this spring. This is a crazy time for many crop and livestock producers and it’s easy to forget about your stored grains. As temperatures warm up, so does the bin. We want to keep bins as cool as we can as long as possible. Dry grain should be kept at or below 40°F as long as possible. As summer temps hit, the goal is to keep bins at 60°F or below to limit insect activity and mold growth.
Here are a few tips to help keep your stored grain in condition if you plan to store it into the summer:
• Cover bin aeration fans when not in use. Fans essentially go through the ‘chimney effect’ where wind moves wet, warm air into the fan, and it travels upwards, affecting the grain inside.
• Provide an inlet for air near the roof eave and outlet exhaust near the roof peak to allow warm air to exit the bin (much like the principles of an attic). Several vents at the same elevation can still allow heat to remain at the top of the bin without exhaust at the peak or roof exhaust fans.
• Add a temperature sensor near the south wall of the bin to collect readings, or be sure to take some grain samples from this area, which is likely the warmest part of the bin.
• Periodically run bin fans throughout the spring to help keep grain cool and slow warm-up.
• During summer months, choose cool mornings every two-to-three weeks to run the aeration fan to keep grain cool and push cool air up through warm grain near the top of the bin.
• Run the fan only long enough to cool the grain at the top of the bin; this may mean running fans for a couple hours on more than one cool, dry morning. Running fans more than necessary could result in grain warming near the bottom of the bin.
• Unload some grain. By unloading grain in bins with center sumps, warm grain from the top of the bin is unloaded first, leaving a funnel shape in the center of the stored grain. This can help to reduce grain temperature near the top of the bin and eliminate cone-shaped peaks (which lead to excess grain warming).
• Check your bin airflow rates. Visit the University of Minnesota Extension’s ‘online fan selection tool’ for more information on fan selection (bbefans.cfans.umn.edu).
I wish you a safe and productive spring! 

Here are some upcoming events and announcements:
• Soybean On-Farm Research- Are you interested in comparing soybean seed treatments, foliar product applications, row spacing, or more? SDSU Extension is seeking producers that are interested in hosting on-farm soybean research trials on their operations. There is no cost to producers, and any reasonable soybean-related research topic will be considered for implementation by SDSU Extension staff. If you’re interested in learning more please email Connie Strunk at [email protected] or call 605-782-3290.
• Drought Hour Webinar: Free webinar focusing on drought issues May 17, and 24 at 11 a.m. CST. For details about each date and to sign up visit extension.sdstate.edu/events
• 2021 Garden Hour: Free webinar focusing on the latest gardening and landscaping questions in SD. Every Tuesday from 7-8 p.m. CST running May 4 - Sept. 28. Visit extension.sdstate.edu/events for details and registration.
• 2021 Ag Economic Dialogues: Free webinar May 21 at 10 a.m. CST focusing on Ag Economics. Register by May 20 at extension.sdstate.edu/events.

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