Weather Impacts

Various weather events, including frost, drought, hail, and wind, in Pennsylvania affect corn. For specific information on dealing with crops affected by these events, visit cornandsoybeans.psu.edu.

Frosted Corn

Corn is occasionally damaged or killed by frost before it reaches the desired maturity for ensiling. If the frost is early and green leaves remain on the plant, the crop will continue to accumulate dry matter and should be left in the field until it reaches the appropriate moisture content. Plants that are killed and still immature will likely contain too much moisture for immediate ensiling. These plants will dry slowly, and dry matter losses will increase as the dead plants drop their leaves in the field and sugars leach from the frosted leaves. The best option is to leave the crop in the field to dry to an acceptable level (at least 72 percent moisture for a horizontal silo, 68 percent for an upright silo), unless it appears that dry matter losses are becoming too high or harvesting losses will increase dramatically.

Drought-Stressed Corn

When corn is so drought stressed that it may not resume growth, it should be ensiled. Corn in this condition usually has few ears and has leaves that have turned brown and are falling off. Be careful not to harvest prematurely because corn with ears and some green leaves may still have the potential to resume growth and accumulate dry matter later in the season. Often, corn in this stage will be higher in moisture than it appears. If this is the case, delay harvest. The net energy content of drought-damaged corn often is 85–100 percent of normal, and it sometimes contains slightly more crude protein. Drought-stunted silage often contains high fiber digestibility, so when it is supplemented with additional grain, it can be an excellent forage and sustain high milk production.

One concern with drought-stressed corn is the potential for high nitrate levels in the silage. High nitrate levels are found most frequently where excessive nitrogen rates were applied and when a drought- stressed crop was chopped within three days following a rain. Ensiling crops that are suspected to have high nitrate levels is preferred to green chopping because the fermentation process will decrease nitrate levels by about 50 percent. When in doubt, obtain a forage analysis with nitrate determination before feeding the questionable forage. Then take appropriate precautions in feeding this silage.