Monitor fields for flooding and ponding Crop producers who have had abundant rains in recent days should monitor their fields for problems with general flooding and ponding in low-lying areas, a South Dakota State University specialist said.
SDSU Extension Crops Specialist Bob Hall said too much water in low areas of fields may be causing problems with various physiological processes in plants, making it difficult for seedlings to survive in water-saturated fields. In addition, rains may have caused crusting that makes it difficult for seedlings to emerge.
Generally, small grain, corn, and soybean will tolerate about two to four days of flooding depending on air and water temperatures and developmental growth stage.
For example during early corn development � from germination to the V6 stage, when the leaf collar on the sixth leaf sheath becomes visible � corn can survive if underwater for no more than 48 hours, Hall said.
If weather is cool so that the plant's physiological processes slow down, it may survive longer. However, if air temperatures warm to about 75 to 78 degrees F or higher, 24 hours of flooding may cause the plants to die.
After the V6 stage, Hall said, flooded corn plants can survive four to five days � again, cool temperatures will help plants tolerate the flooding better.
"The bottom line is that growers need to dig up some of their plants and take a look at them," Hall said.
If the growing point of a corn plant is yellow to white in color, Hall said, the plant is alive. If it's brownish to black in color, it's dying.
"If 75 percent of your seeding corn population emerges, it doesn't pay to replant," Hall said, but added that farmers may choose to replant portions of a field where few or no plants survive. In soybeans, inspect the plants for new growth.
If new regrowth from axillary buds hasn't appeared after about three to five days of warm weather the soybean seedlings are likely dead.
If producers have 80,000 or more soybean survivors don't replant; if they have less than 80,000 survivors it's a replant or planting to another crop situation. In small grains, the spring-seeded small grains will likely afford a better opportunity for recovery compared to winter wheat.
Flooded spring grains may recover and in some cases be harvested as grain or as forage. In contrast, winter wheat, even if it survives, may be in such a condition once the water subsides that it way be difficult to harvest as grain and unfit as a forage crop. It depends on how fast the water subsides and howfast the above ground vegetation dries out.
In some cases this year, crops were seeded later than normal due to the cool spring. In these cases, the seed may not have germinated and developed into a seedling. In any case growers should go down the seed row and dig up some seeds or seedlings and see if they are still living or if it has started to rot.
Look for tissue in seeds or young seedlings that is bright in color. If the tissue is starting to darken in color it is likely dying.
Hall cautioned that producers should talk to their local crop insurance agents before they do anything if they think they've got a problem developing so as not to jeopardize their coverage.