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Showing posts from June, 2018

As June transitions into July what soybean weed management options are still available?

Jeffrey L. Gunsolus Extension Agronomist-Weed Science

Waterhemp in soybeans. Photo: Liz Stahl
The combination of a long duration of wet weather and advanced growing degree days has created serious weed management challenges for many corn and soybean growers. Due to the impending June 20th cutoff date for approved dicamba formulations on Xtend soybean and weeds moving into their rapid growth phase, most of the questions I am receiving, and I hope to address, are focused on soybean.
Fields without a preemergence herbicide are the most challenging
Giant ragweed escapes in soybean. Photo: Dave Nicolai The most serious situations are in fields where no preemergence residual herbicide was applied. This often results in multiple weed species with a broad range of weed heights. In such situations please realize that there are no perfect solutions.

Due to their early emergence period, common lambsquarters and common and giant ragweed control will be especially challenging. The good news is t…

How does ponded water affect corn and soybean and soybean growth and development?

June 1 through 15 saw above normal rainfall. Frequent and significant rainfalls can remind crop producers of several things: 1) which fields are good candidates for tiling, 2) where grassed waterways need to be established or repaired, 3) that it might be time to chat with the crop insurance agent.

The ponded areas in some fields should have come as no surprise given the rain that has accumulated so far in June 2018 (Figure).

Since June 1 the University of Minnesota’s Northwestern Research and Outreach Center in Crookston has accumulated 4.07 inches of rain and much of the region has accumulated between 1 and 1.5 inches more rain than the 30-year normal (Figure, MRCC, 2018).


What flooded soils does to developing plants. 

No change in dicamba application cutoff date for Xtend soybeans

Jeffrey L. Gunsolus, Extension Agronomist - Weed scienceOn June 8, 2018 the Minnesota Commissioner of Agriculture released a letter to stakeholders indicating that the MDA will be keeping the 24(c) restrictions for XtendiMax, Engenia and FeXapan in place for 2018. The Commissioner’s letter also explains the rational for holding to the 24(c) restrictions, despite the challenges presented by late planting dates for soybean in many parts of the state.

Rationale for keeping the 24(c) restrictions Please keep in mind that if the 24(c) restrictions were removed then the default growth stage would be through the R1 growth stage but before the R2 growth stage. Due to the wide range of soybean planting dates, it is likely that many soybeans will not enter the R2 growth stage until July. In 2017, 50% of the dicamba-related injuries reported to the MDA occurred at or after July 2nd and 75% of the dicamba-related injuries occurred after June 21st. The sheer volume of dicamba-related injuries repo…

Refocusing attention on the most yield limiting pathogen of soybean

What causes an estimated 90,000,000 bushel yield loss of soybean in the North Central U.S. each year? What can cause an eye-popping 30% yield loss without above-ground symptoms? What can move any way that soil moves? What can invade a soybean plant and worsen brown stem rot and sudden death syndrome symptoms?

The answer to each question is the same: the soybean cyst nematode (SCN). SCN is a microscopic roundworm that was first found in the U.S. in North Carolina in 1954. SCN has since moved north and west, reaching southern Minnesota in 1978. Little by little SCN continues to spread, marching north in the state along with soybean production, cutting soybean yield-potential along the way (Figure 1).