By Lizabeth Stahl and David Nicolai, Extension Educators

The growing season of 2016 has gotten off to a challenging start for farmers in areas hit with significant rainfall or hail events.

In southwestern Minnesota, for example, some fields planted up to three times with corn or two times with soybeans have drowned out again, while other areas have not been able to be planted at all. If you have drowned-out spots in fields, have crops that were hailed out, or you were not able to plant some areas yet, the following are some key considerations at this point in the season:

1) Planting corn at this late date is not recommended. The last recommended date for planting corn for grain in southern MN is June 15th for grain and June 25th for silage. Late-planted corn, even if the hybrid used is a much earlier maturity than normal for the area, is at high risk of not reaching maturity before a killing freeze, and any grain produced would likely be of high moisture at harvest time, which can lead to harvest and storage issues. Late-planted corn may also be at higher risk of pollinating during a hotter time of the season, which can further reduce yield potential.

2) Planting soybeans may be an option if planting can be completed soon and there are no restrictions due to previously-applied herbicides. If you are considering re-planting soybeans we recommend planting a soybean variety 1.0 RM earlier than normal at this time of the growing season. As a guideline, soybeans planted in late June but before July 1 should produce more than 50% of the expected yield at an optimal planting date. 

Farmers have reported success with planting soybeans after July 1, although research on such late planting dates is limited. In U of MN trials conducted at Rochester from 2007-2010, Behnken, et.al. evaluated soybeans ranging in maturity from a group 1.2 to a 0.2 relative maturity. Averaged across years and varieties, soybean yield decreased an average of 6.3 to 7.9 bu/ac each week planting was delayed from June 25th through July 16th.

No measurable yield was produced at the last planting date one year during the four-year trial. Soybeans planted after July 1 are at significant risk of not reaching maturity before a killing frost, and significant yield reductions should be expected. 

Other factors such as the costs involved in replanting (including seed, labor, and machinery costs), impacts on insurance, limitations due to a lack of timely rainfall (delayed soybean emergence due to dry soil), herbicide history, viability of other options and impacts on crop rotation should be weighed if you are considering planting soybeans after July 1. 

3) Consider planting a cover crop. Planting a cover crop may be the most viable option for areas where the original cash crop failed or for prevented plant acres. 

If herbicides have already been applied to the affected area, check the herbicide label to ensure that the products applied will not hinder cover crop growth and development. Check out the following publication for further details: “Managing risk when using herbicides and cover crops in corn and soybean”. 

Also when selecting a cover crop to plant, be sure to check recommended seeding dates. In most cases, you will not want the cover crop to reach its reproductive stages or to produce viable seed. For example, brassicas (e.g. turnips, kale, rape, mustards, and radishes) planted in June in MN will likely ‘bolt”, resulting in more stemmy growth and tougher, more fibrous roots, and they will likely produce viable seed. Planting brassicas after July 25th should help avoid these issues. 

The following resources discuss in more detail a variety of cover crop options for areas where the cash crop failed or for prevented plant acres: 

• “Prevented Plant Cover Crop Options” 

• “Prevented Plant: Cover Crop Forage Options” 

• “Minnesota Cover Crop Business Directory” lists cover crop seed suppliers and custom seeding operations in MN. 

4) Be sure to contact your local FSA office if you have areas where your originally-planned crop failed, if you intend to plant a different crop than originally planned, and/or you have prevented planting acres. Make sure you are in compliance with the latest Farm Bill or NRCS requirements to prevent soil erosion in these areas. 

5) Be sure to contact your crop insurance representative if you have areas where your originally-planned crop failed or was hailed to the point of total loss, if you intend to plant a different crop than originally planned, and/or you have prevented planting acres. Be sure to contact them before working up any ground or planting something in the affected area as check strips may need to be left in the field with the original crop for insurance purposes. 

6) Control weeds in affected areas. Letting unplanted areas go to weeds that ultimately go to seed can result in tremendous increases in the weed seedbank, leading to weed control headaches for years to come. For example weeds such as waterhemp can be a significant problem due the weed’s extended emergence pattern later into the cropping season. Waterhemp plants on average produce around 250,000 seeds per plant, but they have the potential to produce over 1 million seeds per plant under ideal conditions. Mowing weed infested areas when feasible can help decrease contributions to the weed seedbank. 

7) Prevent fallow syndrome. Besides the risk of being out of compliance with the latest Farm Bill, if large areas of a field are left unplanted and nothing is allowed to grow in the area for the season, you run the risk of having issues with fallow syndrome next cropping season. For further details about fallow syndrome, check out the article “Reduce Risk of Fallow or Flooded Soil Syndrome with Cover Crops”.