Memorial Day storms hit us again this year, this time with the EF2 tornado in Edgar.  I checked NE Rain, and for the month, Clay County received between 5.9-9.7″ of rain with nearly 3/4 of that coming in the last 6 days !

Even with the saturated soils and localized flooding, there is still potential for drought.  It was this way last year at the end of May before the rains shut off in early June.

I’ve received questions regarding potential storm damage to crops.  Normally I’ve found that waiting a week helps with determining regrowth and decisions.  Overall, we’re fortunate that crops were so small.  Much of the corn was V1-V3 and the soybeans were anywhere from not planted to cotyledon stage.  The majority of damage occurred where emerged plants were silted over with soil and/or residue, standing in water for periods of time, of left with stems due to high wind and/or hail.

Corn Decisions

According to Purdue University Agronomist, Bob Nielsen, it takes around 48 hours for oxygen to be completely depleted from saturated soils.  Plants that are emerged above the water have a better chance of survival than those below it; however, it’s hard to tell exactly how long plants can survive in those conditions.  We also have several areas where plants were standing in water for a few days, the water receded, and now they’re standing in water again.   Only time will tell how those plants will fare.

Because the growing point of affected corn plants is below ground, in many situations, plants should recover if the growing point remained healthy.  Hopefully only small areas will need to be replanted.  For crop insurance decisions and options, please check out the following CropWatch article.

Soybean Decisions

Some emerged soybeans that were at cotyledon stage have been reduced to stems leaving gaps between healthy plants.  Soybean plants can compensate for reduced populations; however length of gaps and final stands do need to be assessed for replant decisions.  UNL on-farm research has shown less than 1.4-2.0 bu/ac yield difference between planting 90,000 and 180,000 seeds/acre. (See report.)  In our research, 90% of the planted stand was achieved at both seeding rates in irrigated 30-inch rows in no-till and ridge-till fields.

Consider what was found in 2006 in one dryland field in Nuckolls County where seeding rates of 100,000, 130,000, and 160,000 seeds/acre were planted. This field was at the cotyledon stage when it was hailed. Some plant stands dropped to 67,000 plants/ac. Yield was 4 bu/ac less than in the 160,000 seed/acre planting that had a final stand of nearly 98,000 plants/ac. The average yield in the field was 40 bu/ac. While this is only one field and one year of research, it is an example of how soybean plants can compensate for reduced populations by branching and how August rains in dryland can still allow reasonable yields to be produced.  Based on our on-farm research, leaving dryland stands of at least 65,000 plants/acre and irrigated stands of 90,000 plants/acre is likely a better choice than replanting, in the event that the gaps between plants are not large and are fairly even.

Many of the soybeans worst affected were reduced to stems.  Last year we watched as soybeans continued to develop plumules after the hail events and soil crusting in our area.  The plumule, which is the seedling stem tip and its undeveloped leaves above the cotyledonary node, may remain, but without the cotyledons to serve as a carbon and nitrogen source, development of new seedlings with small leaflets will be slow. These plants may not become competitive with surrounding plants in terms of pod and seed production. Therefore, when counting seedlings to determine plant stand, count only the seedlings that have at least one cotyledon. You can count seedlings missing cotyledons if they have large unifoliolate leaves that will soon unroll as in this picture.  

In summary,

we will monitor damage early next week to help with replant decisions.  Overall, I feel we are fortunate that the crops were so small and crop damage does not appear to be severe other than all the pivots that need to be replaced.  We will also need to watch for potential disease damage in weakened plants.  For crop insurance decisions and options, please check out the following CropWatch article.