Skip to Main navigation Skip to Left navigation Skip to Main content Skip to Footer

University of Minnesota Extension

Extension > Extension in your Community > Benton > County Agriculture Educator > Articles > Weather Weighs Heavy on Crops

print icon email icon share icon

Weather Weighs Heavy on Crops

University of Minnesota Extension, Stearns County News
September 17, 2014         
Source:  Dan Martens, Extension Educator
University of Minnesota Extension
Stearns, Benton & Morrison Counties


Weather Weighs Heavy on Crops
By Dan Martens, University of Minnesota Extension

FOLEY, Minn. (09/04/2014) —It usually does. Heavy rain, hail and wind raised havoc in some parts of central Minnesota during the past week. Planting dates for corn and other crops from early May to early July because of a late and wet spring had already set the stage for widely variable crop conditions.

Hail damage evaluation is based on leaf loss and broken plants where ears and pods are lost. Shredded leaf material that hangs on the plant and stays green still contributes to yield. Damage to pods for soybeans and ears of corn can be added to this. Yield loss due to leaf loss might be estimated from the following table based on corn stage and % leaf loss.

Hail % grain loss based on leaf loss
                       % Leaf Loss
Corn Stage  25  50   75   100

Silking          8   28   57     95
Milk             5   18   37     59
Dough          2   12   26     41
Dent          0     7   16     24

These figures are based on a corn crop being at these stages at a normal time of the year. We have some corn around the area that was planted in early July that is just now in the silking and tasselling stage. The loss figure in this table would be applied to what we already guess as a reduced yield because of late planting. Because this late crop is already assumed to be for corn silage, we’re thinking about tonnage loss also. For corn planted early in July, we’re maybe already limited to half the tonnage we’d normally expect – less perhaps with a normal frost date.

Hail damage to immature ears raises questions about the potential for mold to set in and cause further damage. Physical damage to ears can result in more corn smut. Corn smut does not cause health issues for cattle. Other kinds of molds can be a problem. The extent of mold issues is largely driven by weather conditions moving forward from this point.

In most cases where silage feed is needed, damaged corn will be chopped. Farmers will deal with mold and quality issues by blending with other feed material. For grain corn, we hope some damaged kernels will be sifted out of the grain during harvest, screening and drying. Farmers usually gain by setting harvest equipment to do an aggressive job of cleaning grain. This makes for safer storage and better acceptability in the market. There certainly could be situations that are bad enough so the crop would be left in the field. That’s pretty unusual.

Many farmers in our area will be working closely with crop insurance reps and adjusters to evaluate crops based on their specific insurance coverage.

For all corn silage crops, harvest decisions are determined by whole plant moisture that is right for the storage system used. Farmers, who are short of feed, often chop for day to day feed needs. For best livestock performance we recommend chopping daily rather than chopping more and feeding from it for 2-3 days. If it’s heating, it’s losing nutrients and palatability, and gaining spoilage. We wouldn’t care for a salad that was left on the table for 2 or 3 days. 

For late planted crops, it’s likely the crop will not dry down enough for storage of silage until after a killing frost and some time to dry.

For earlier planted corn, the crop might stay green longer with plentiful moisture. Remember the corn crop can be fully green and still mature and dry enough to chop for storage. At full dent, whole plant moisture can be down to 71% moisture; and then a milk line will start to show up on the kernel. At half milk line, the whole plant moisture might be 65%. At 1/4 milk line, the whole plant moisture might be 63%. Testing moisture is a good practice, but will be challenging with varied conditions across fields.

Some references suggest harvesting snaplage when the whole ear moisture is around 40%, maybe from 35 to 45%. High moisture shell corn is recommended with kernel moisture is 28 to 32%. It might ferment well under good conditions down to 26%. The black layer on the tip of the kernel usually appears when corn kernels are around 32% moisture. Testing moisture is a good practice.

It’s continues to be a challenging growing season. It’s a good year for people to be working and learning together in neighborhoods to find ways to make the best of things. It’s usually better that way.


Daniel Martens
Extension Educator, Ag Production Systems
(320) 968-5077
  • © Regents of the University of Minnesota. All rights reserved.
  • The University of Minnesota is an equal opportunity educator and employer. Privacy