COLUMBUS, Ohio - Though welcomed by corn growers across the state, the recent rainfall throughout Ohio will probably provide little relief for many cornfields.
Peter Thomison, an Ohio State University Extension agronomist, said the scattered showers might not be enough to lift the plants out of their drought-stressed conditions. Due to the continued dry weather, some corn plants may be prime candidates for lodging, or fallen stalks, in the coming weeks.
"One of the issues we are concerned about this year is stalk quality. Some of the corn did get moisture during critical stages of development, but it may not be enough to keep the plant alive through maturity," said Thomison. "Those plants may have obtained enough moisture to produce some pretty good ears. But with their limited root systems from early-season stresses, they are most likely to express lodging problems." Drought-stressed conditions increase the potential for stalk quality problems because not enough carbohydrates, or sugars, are being produced to keep the stalk alive and meet the demands for grain fill. The corn plant "cannibalizes" the sugars in the leaves, stalks and roots to develop the ears, and as a result, premature death occurs in the stalk, which paves the way for fungal infections.
Though some areas of the state have received rainfall, the limited root systems on the corn plants have resulted in nutrient deficiencies because the plants are unable to take up sufficient nutrients despite the presence of soil moisture.
"A lot of the corn crop has reached the point where it'll derive little benefit from any moisture," said Thomison, adding that symptoms of stalk lodging may begin to show up when the plants reach maturity in about two to three weeks. "As plants near maturity, the lower portion of corn plants in drought stressed fields may appear as nitrogen stressed, brown, and/or dead." Growers are urged to scout their fields for stalk quality problems and mark any lodging potential fields for first harvest. "Get out and see if the stalk tissue is disintegrating," said Thomison. "A grower can do this two ways: by pushing the stalk away to see if it snaps, or to pinch the stalk near the soil line to see if it easily collapses." Pat Lipps, an Ohio State plant pathologist with the Ohio Agricultural Research and Development Center, recommends growers check stalk quality as soon as the plants start losing their green color.
"As the crop matures, continue to check fields and squeeze about 100 stalks randomly throughout the field to get an idea of the level of stalk quality problems. Stalks that are easily crushed with your thumb and fingers are likely to lodge given wind or stormy weather," said Lipps. "The name of the game this year will be harvest before the crop falls down." Thomison suggested that growers keep the appropriate percent moisture content in mind when harvesting fields with lodging potential. "Ideally, we are looking at 24 to 25 percent moisture content which is higher than the moisture levels below 20 percent we've grown accustomed to in recent years," he said. "We ran into this same problem last year and growers let their corn stand in the field to dry down as late as October to save on drying costs, and heavy rains and winds came in and knocked a lot of that corn down. Some fields had lodging levels of over 50 percent." While stalk lodging may not directly affect yields, it does slow down harvest as lodged plants tend to drop their ears and plants lying on the ground are subject to additional diseases.
"Even if a grower can get still obtain yields, the grower has to harvest more slowly, and other fields get harvested later than normal," said Thomison. "Stalk lodging can have such an impact on harvest losses that many plant pathologists consider stalk rots to be the most significant yield-limiting disease of corn."