By Pierce Paul, OSU Extension
Causes of Stalk Rot: Several factors may contribute to stalk rot, including extreme weather conditions, inadequate fertilization, problems with nutrient uptake, insects, and diseases. This year, the combined effects of prevalent diseases such as northern corn leaf blight, southern rust, tar spot, and gray leaf spot may negatively affect stalk quality. However, the extent of the problem will depend on when these diseases develop and how badly the upper leaves of the plant are damaged. When leaves above the ear are severely damaged well before grain-fill is complete, the plants often translocate sugars from the stalk to fill grain, causing them to become weak and predisposed to fungal infection. A number of fungal pathogens cause stalk rot, but the three most important in Ohio are Gibberella, Collectotrichum (anthracnose), and Fusarium.
Checking for Stalk Rot: Symptom common to all stalk rots are deterioration and discoloration of the inner stalk tissues. Consequently, you can use the “squeeze test” or the “pinch test” to assess stalk rot and the potential for lodging without having to remove plants and split the stalks. Bend down and squeeze or pinch the internode of the stalk about 6-8 inches above the ground between the thumb and forefinger. If the inner node is easily compressed or collapses under pressure, you will likely have some type of stalk rot. The “push” test is another way to assess stalk rot and the risk for lodging. Gently push the stalks at the ear level, 6 to 8 inches from the vertical. If the stalk breaks between the ear and the lowest node, stalk rot is usually present. Stalk rot severity may vary from field to field and from one hybrid to another.
Consequences of Stalk Rot: Stalk rots may cause lodging, especially if the affected crop is not harvested promptly. On lodged plants, the ear on or close to the ground may develop ear rots and become contaminated with mycotoxins. In addition, lodging may lead to grain yield losses and slowdown the harvest operation. However, it is not uncommon to walk corn fields where nearly every plant is upright yet nearly every plant is also showing stalk rot symptoms. Many hybrids have excellent rind strength, which contributes to plant standability even when the internal plant tissue is rotted or beginning to rot. However, strong rinds will not prevent lodging, especially if harvest is delayed and the crop is subjected to strong winds and heavy rains. To minimize these problems, harvest promptly after physiological maturity, even if you have to do so at a slightly higher moisture content (moisture in the lower 20s).
R.L. (Bob) Nielsen
Agronomy Dept., Purdue Univ.
West Lafayette, IN 47907-2054
Email address: rnielsen at purdue.edu
Among the top 10 most discussed (and cussed) topics at the Chat ‘n Chew Cafe during corn harvest season is the grain test weight being reported from cornfields in the neighborhood. Test weight is measured in the U.S. in terms of pounds of grain per volumetric “Winchester” bushel. In practice, test weight measurements are based on the weight of grain that fills a quart container (37.24 qts. to a bushel) that meets the specifications of the USDA-AMS (FGIS) for official inspection (Fig. 1). Certain electronic moisture meters, like the Dickey-John GAC, estimate test weight based on a smaller-volume cup. These test weight estimates are reasonably accurate but are not accepted for official grain trading purposes.
The official minimum allowable test weight in the U.S. for No. 1 yellow corn is 56 lbs/bu and for No. 2 yellow corn is 54 lbs/bu (USDA-AMS (FGIS), 1996). Corn grain in the U.S. is marketed on the basis of a 56-lb “bushel” regardless of test weight. Even though grain moisture is not part of the U.S. standards for corn, grain buyers pay on the basis of “dry” bushels (15 to 15.5% grain moisture content) or discount the market price to account for the drying expenses they expect to incur handling wetter corn grain.
Growers worry about low test weight because local grain buyers often discount their market bids for low test weight grain. In addition, growers are naturally disappointed when they deliver a 1000 bushel (volumetric bushels, that is) semi-load of grain that averages 52-lb test weight because they only get paid for 929 56-lb “market” bushels (52,000 lbs ÷ 56 lbs/bu) PLUS they receive a discounted price for the low test weight grain. On the other hand, high test weight grain makes growers feel good when they deliver a 1000 bushel semi-load of grain that averages 60 lb test weight because they will get paid for 1071 56-lb “market” bushels (60,000 lbs ÷ 56 lbs/bu). Continue reading
By Clint Schroeder, OSU Extension, Allen County
The 2020 Ohio wheat harvest is rapidly approaching. Now is the time to prepare for a successful harvest. Before the combine goes to the field, a key component will be to have grain handling and storage facilities adequately sanitized. Taking the proper steps now should help eliminate insect infestations that can significantly reduce grain quality or salability.
The majority of insect infestations that occur in stored grains are a result of migration into the bin. These insect populations will be present in piles of spilled grain from the previous year, livestock feed in the area, litter, and weed growth. Newly harvested wheat can also be contaminated when it comes in contact with infested grain that was not cleaned from the combine, trucks, wagons, augers, dump pits, or grain leg buckets. Another source of contamination can be carryover grain in a bin that was not correctly emptied. Continue reading