Back
August 19, 2020

Damage to U.S. Corn from Derecho Storm still being Evaluated

Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.

Unfortunately, we will not know the full extent of the storm damage to the corn in Iowa for several more weeks or probably not until the corn is harvested. The damage from the storm is unprecedented in its scope and severity, so it has added a tremendous amount of uncertainty to the 2020 U.S. corn crop.

The condition of the U.S. corn crop declined 2% to 69% rated good to excellent. The corn is 76% dough compared to 50% last year and 69% average. The corn is 23% dented compared to 13% last year and 24% average.

Some of that decline can be attributed to the storm and some can be attributed to the continued dryness in much of western Iowa as well as northern Illinois, northern Indiana, and northern Ohio. The storm brought a lot of wind, but not much rainfall.

The forecast for this week is for more dry weather across much of the central Corn Belt. The temperatures are going to be more seasonal, but there is not much rain in the forecast.

In the August Crop Report, the USDA estimated the 2020 U.S. corn yield at a new record high of 181.8 bu/ac, but the big question is how many bushels of corn were lost due to the storm last Monday. Loss estimates from the storm range from 100 million to 500 million bushels.

A loss of 100 million bushels would equate to 1.2 bu/ac nationwide and a loss of 200 million bushels would equate to 2.4 bu/ac nationwide loss. The total extent of the loss from the storm is yet to be determined, but for now, I am going to estimate that 200 million bushels of corn were lost, but that is just a preliminary guess and if anything, it could be much higher than that.

If the corn was in the dough stage or dent stage when it was blown down, maybe 60% to 70% of the maximum dry matter had already accumulated. It will still try to fill the kernels, provided that the stalk is not broken, but the grain filling process is going to be disrupted. As a result, there could be more tip back of the ears, light kernels, and inadequate fill. There will be additional harvest losses due to the tremendous difficulty in harvesting tangled and down corn. The harvest loss alone might be as high as 25% to 30% in the hardest hit fields, or more.

There is also going to be some grain quality issues for the down corn. If the ear is close to the ground, soil could splash up on the ear resulting in potential mold issues especially if the ear had been damaged and there is a period of wet weather before harvest.

The Farm Services Administration (FSA) reported last Wednesday that 5.4 million acres of corn had been claimed as prevent plant. Even though they will not report the final certified corn acreage until October, I think the FSA number goes a long way to justify the corn planted acreage of 92.0 million acres. In fact, the planted acreage may end up slightly below 92.0 million acres.

Additionally, as a result of the storm, there will probably now be some additional abandoned acres that can't or won't be harvested. Therefore, I am going to reduce the corn harvested acreage for grain by 500,000 acres to 83.52 million acres or 90.7% of what was planted. The amount of abandoned corn acres could also increase as the damage assessment continues.

The storm added a layer of uncertainly to a corn crop that looked to be on track for a record yield. The weather is now more uncertain as well. The storm had a lot of wind, but it did not produce all that much rain. In fact, last Thursday's U.S. Drought Monitor indicated that the situation in Iowa was essentially unchanged from the prior week with 79% of the state abnormally dry and 6% in extreme drought.

The forecast is calling for below normal rainfall and seasonal temperatures for the last half of August, which could increase moisture stress especially in the dryer areas. The bottom line is that the 181.8 bu/ac yield estimate in the August Crop Report might end up being the highest yield estimate of the 2020 growing season.