Crop & Pest Report


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South-Central/Southeast ND (09/24/20)

Information from the South Central/Southeast region of North Dakota.

The region’s rainfall from May 1 to September 21 ranges from 5.2 inches (Robinson) to 18.5 inches (Oakes), with the Carrington Research Extension Center (CREC) receiving 8.5 inches (source: NDAWN). The low rainfall in September (<1 inch) has been welcome for continuing dry bean harvest and initial soybean harvest.

The CREC’s and the region’s farm harvest efforts are primarily with soybean. We have discovered with harvest of soybean trials that seed moisture is low (commonly 12% or less). Farmers should be monitoring seed moisture closely during soybean harvest to avoid yield loss due to reduced weight with low moisture seed, as well as field and handling losses.

The low temperatures on Sept. 8-9 caused variable frost damage to our row crops. Sunflower likely had the least injury among row crops (besides the root crops) due to the plant’s tolerance to temperatures down to the mid-20s (plants beyond flowering stage [R5]) and most of the crop was at the late-seed development or physiologically mature stages. Late-planted or late-established dry bean likely suffered the greatest frost damage.


The following is an overview of frost impact and management of dry bean:

Dry beans are very susceptible to frost (30- to 32-degree F range). Frost will not reduce seed yield or quality at physiological maturity - at least 80% of pods have turned yellow and are mostly mature (R9 stage). Green pods and seeds present with immature plants are easily damaged by frost. Green seeds will shrivel and darken, resulting in an unmarketable portion of the harvested crop.

Frost-damaged seeds should be left in the field until dry if possible to allow separation from quality beans during combining. But this needs to be balanced with harvesting the marketable seed at the maximum moisture permissible. This will be around 17-18% moisture for navy bean and 14-16% for pinto bean. When beans are drier, loss occurs from less weight harvested/acre, during combining, and damage during seed transport. 

If possible, keep field areas of frost-damaged (e.g. low areas) or late-maturing beans separate from areas containing quality beans.

Another problem, primarily with pinto bean, is they will attempt to regrow and initiate new vines, flowers and pods if only partially damaged by frost. Of course it is too late in the season for the vegetative and reproductive structures to result in viable seed. The regrowth also will take away plant energy that is needed to finish marketable seeds, and becomes another harvest challenge.

ats.frost damaged pinto bean plants and seed


Greg Endres

Extension Cropping Systems Specialist

NDSU Carrington Research Extension Center

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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