Wind and Hail Damage Reported Across Iowa

The storms that moved across Iowa late last week and over the weekend brought rainfall, but they also brought some strong winds and hail. For those folks dealing with wind or hail damage, the first step should be to communicate with your crop insurance agent. Additionally, below are some resources that may be useful in evaluating the impact of the damage.

Hail Resources
 

• Corn: Many corn fields were tasseling or were just starting to tassel (VT), which unfortunately is when hail can be the most injurious to corn. When evaluating the hail damage, consider the amount of defoliation as well as stalk bruising and breakage. The ISU publication IPM 78 Hail on Corn in Iowa shows how to obtain an estimate of the potential yield loss from hail injury to corn.
  • Additional resource: Corn Loss Adjustment Standards Handbook (Crop Insurance Adjusters Handbook) (see pages 80 – 84)
     
• Soybean: Most soybeans ranged from R1 to R3. Even when hail damage occurs at this point in the season, it is still best to wait 7 to 10 days to assess injury. The extent of the injury is based on stand loss, broken and cut stems, and defoliation. The ISU publication IPM 79 Hail on Soybean in Iowa walks through how to estimate the potential yield loss from hail injury to soybeans.
  • Additional resource: Soybean Loss Adjustment Standards Handbook (Crop Insurance Adjusters Handbook) (see pages 62 – 67 and 71-73)
     
• Small grains (oats, wheat, rye, etc.): For those with small grains, Joe Lauer at the University of Wisconsin put together a good resource for evaluating hail damage
   
• Forages: For those with hail damage to forage crops like alfalfa or red clover, Dan Undersander and Dan Wiersma at the University of Wisconsin explain how to evaluate the damage in this resource here: https://fyi.uwex.edu/forage/how-to-manage-hail-damaged-alfalfa-and-red-clover/.
   
• Fungicides for hail damaged crops: One of the big questions we often get with hail damage is whether to apply a fungicide as already planned, because of hail, or whether to forego the application completely. A common misconception is that hail-damaged crops will be at a higher risk for disease infection. Note that our fungal diseases like gray leaf spot in corn or frogeye leaf spot in soybeans do not require wounding to infect the plant whereas bacterial diseases will more commonly infect the plant through open wounds.
  • Nathan Kleczewski, plant pathologist at the University of Illinois, did a nice job summarizing the research from various universities looking at the impact a foliar fungicide application has on hail damaged crops in this article here: http://cropdisease.cropsciences.illinois.edu/?p=1174.
     
  • Another good resource summarizing the research ISU has conducted looking at fungicide use on hail damaged crops can be found in the ICM Blog post "Fungicide Use on Hail Damaged Corn and Soybeans".

Wind Damage Resources:
 

Wind damage in corn varies from field to field, and it can be related to hybrid, corn growth stage, and other environmental conditions. Wind damage may have caused leaning, root lodging, or greensnap/brittlesnap. Like with evaluating hail damage, it’s best to wait a few days to fully evaluate how the plants are recovering. Plants that have leaning or root lodging should stand back up within a few days from the wind event if still in the vegetative stages. After tasseling and silking, the ability to stand back up is diminished. Wind damage to corn can also result in poor pollination due to additional plant stress and silks being covered by leaves.

For greensnap/brittlesnap, if the plants snapped off above the ear or where that ear would be, they could potentially still produce an ear from either the primary or secondary ear node; however, plants snapped off lower clearly represent a direct loss of yield potential. It is typically assumed that for each percent of plants snapped off equals a percent yield loss. This rule of thumb is slightly aggressive since neighboring plants can compensate with slightly higher kernel weights.

Additional resources:

• Damage to Corn Plants by Strong Winds (Bob Nielson, Purdue University)
• Lodging: mid to late season (ISU Integrated Crop Management Article)
• Greensnap – storm induced stalk breakage (ISU Integrated Crop Management Article)