Excessive precipitation and persistently wet conditions have prevented the planting of corn and soybeans in some fields and led to ponding and drown-out areas in others.  On acres where “prevent plant” is claimed for insurance, the U.S. Department of Agriculture’s Risk Management Agency requires protection from erosion and control of noxious weeds.  Planting a cover crop to these areas can help control weeds and prevent erosion, while enhancing soil structure and preventing fallow syndrome.

Fallow syndrome, which can hurt crop yield the following year, can occur when there is not enough living root material for beneficial soil mycorrhizal fungi to survive.  These good fungi facilitate the uptake of nutrients that are less mobile in the soil, such as phosphorus and zinc.  Planting a cover crop that is a host to these good fungi can help prevent fallow syndrome.

When planting a cover crop, check the herbicide history of the affected area. Cereal rye and oats tend to be among the most tolerant cover crops to previously-applied herbicides. This will vary depending on the herbicide applied, application rate, soil type, environmental conditions, and time of application.  In general, herbicides with longer residual activity have greater potential to hinder cover crop establishment.  Also, there tends to be more risk to grass cover crops if a residual grass herbicide was applied, and more risk to a broadleaf cover crop if a residual broadleaf herbicide was applied. 

 Think ahead to next spring.  Cover crops that winterkill, such as oats, sudangrass, sorghum-sudangrass, radish, turnip, barley, and crimson or berseem clover, eliminate the need to plan a spring termination.  Meanwhile, cover crops such as cereal rye and winter wheat will overwinter, so they need a spring termination plan.

Select a cover crop. Cost, availability of seed, and when you can plant the cover crop are key factors when deciding what cover crops to plant.  Consult with your local NRCS to determine approved cover crops and practices on prevent plant acres.

 Seed a cover as early as possible to compete with weeds.  Winter cereals (e.g. rye, winter wheat, and winter triticale) and warm season grasses like sorghum, sudangrass, or sorghum-sudangrass hybrids are favored by planting dates in mid-June through July.  Keep in mind spring cereals seeded during this time, such as oat, barley, and spring wheat, will likely develop a seed head, and brassicas (e.g. radish, turnip, rapeseed) may bolt and produce seed if planted before August.      

 If it gets late, adapt. Control weeds with an herbicide or tillage before planting a cover crop.  If you use an herbicide, keep in mind the potential for herbicides to impact cover crop establishment.  

Use a reliable seed source.Use good quality seed that has been cleaned, tested for germination and weed seed contamination.  Utilize local sources of seed as much as possible to help prevent the introduction of invasive noxious weeds such as Palmer amaranth.  Note that if you are considering using bin run seed as a cover crop, most of the seed purchased today is protected by the Plant Variety Protection Act and other seed laws and regulations.  This means that at a minimum most bin run seed cannot be sold or given to another person to plant, and depending on the protections of the seed originally purchased, any planting of the bin run seed may be illegal.  Also note that FSA does not allow straight seeding of corn or soybean on prevent plant acres. Check http://z.umn.edu/cover-crops and consult with your local NRCS to ensure you have an approved cover crop plan.   

Follow insurance dates and restrictions.  To be eligible for the full prevent plant payment, you cannot hay or graze the cover crop before Nov. 1 or harvest the cover crop at any time.  Consult with your crop insurance representative for further details regarding potential options and impacts on insurance payments and APH. 

More details on prevent plant can be found on the University of Minnesota Extension Crops website at http://z.umn.edu/crops. Click on the “Current Issues and Highlighted Resources” link.

This article was submitted by Lizabeth Stahl, Anna Cates and Phyllis Bongard of University of Minnesota Extension.