On July 27, Hardin County experienced hail that damaged soybean at the R3 growth stage (beginning pod). The R1 (beginning bloom) to R5 (beginning seed fill) stages are the most sensitive to defoliation. At 50% defoliation when soybeans are at the R3 growth stage, we expect a 9-18% reduction in yield.
Last year, we conducted a hail simulation trial at the Western Agricultural Research Station in South Charleston. Hail was simulated (via weed whacker) on July 18, 2013 when soybeans were at the R3 growth stage. Defoliation was 40-45%. Soybean yield was 74 bu/ac without hail simulation and 62 bu/ac with hail simulation. (Yes, this was a statistically significant yield reduction.)
Despite cool temperatures this year, soybeans are adding a 1-2 new trifoliates per week which should help the plant recover. In last year’s trial, there was very limited evidence of defoliation 12 days after the simulated hail.
-Laura Lindsey, Grace Bluck, Harold Watters, and Mark Badertscher