Spring showers have turned into summer thunderstorms, strong winds and high temperatures. This combination could be very good or very bad for Iowa's soybean and corn producers, says David Wright, research program specialist for the Iowa Soybean Association. The good news is the soil moisture conditions for most of Iowa will be sufficient to supply the needs of both crops for the next few weeks. Coupled with warm temperatures, soybeans will really take advantage of the heat and grow quite rapidly accumulating approximately three nodes per week on a healthy plant. Nighttime temperatures in the 70s are perfect for allowing the plant to recover from the evaporative demand brought on by the warm daytime temperatures.
Keep an eye out for soybean aphids in your fields
"If Mother Nature continues to provide us with adequate, but not surplus, rain and continued warm temperatures, farmers will likely harvest a bountiful crop," says Wright. "However, don't forget that aphids could arrive as early as July 4 in some areas of Iowa. You need to scout fields and monitor aphid populations in each field and treat only when the population exceeds 250 aphids per plant." Research has shown that a one-time application of insecticide after the aphid population exceeds 250 aphids per plant is more economical than a prophylactic treatment that is poorly matched to aphid population growth. Warm temperatures are also good for corn growth and development. However, some farmers have already found a fair amount green snap in their fields. Green snap is the condition where rapidly growing stalks are broken by strong, sudden winds associated with thunderstorm downbursts and windy conditions that have been abundant this spring.
Greensnap problems can occur when corn is growing rapidly
Iowa State University Extension corn specialists remind us that the 5- to 8-leaf stages (10 to 24 inches in height) and the 12-leaf through tasseling stages are the most vulnerable growth stages of corn for greensnap to occur. These are two periods of very rapid growth in the corn plant. Several factors affect green snap. The timing and velocity of the wind are the most important, coupled with the particular corn hybrid involved. Monitor each field closely for green snap. "Although our abundant rainfall is good for soybean growth and development, it will likely cause an increase in bacterial diseases in soybean fields this summer," says Wright. "Watch your fields closely and consult ISU Extension to get more information on specific soybean diseases if they start showing up."