Volume 63 Number 9 Date 06/28/2018
SOYBEAN APHID - Densities have not increased noticeably since aphids were first observed on June 4. Counts averaged less than one aphid per plant in 29% of the fields surveyed this week, and the other 71% had no detectable aphid population. Routine monitoring should begin by the second week of July or once fields reach the R1 (first flower) development stage.
DEFOLIATORS - Leaf feeding by rose chafers, bean leaf beetles, Japanese beetles, sand chafers, slugs and various caterpillars is common in soybeans, though defoliation is light, ranging from 5-10% on no more than 10% of plants in most fields. The distinctive silver-spotted skipper caterpillar, recognizable for its two large orange eyespots on a dark purple head, were observed in Dane and Jefferson County fields this week. Defoliation rates have not exceeded the 30% economic threshold for soybeans in the vegetative stages as of June 28 and control has not been warranted for any field surveyed by DATCP.
-- Krista Hamilton, DATCP Entomologist