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Soybeans
Volume 62 Number 13 Date 07/27/2017 SOYBEAN APHID - Surveys continue to find very low aphid densities across the southern and central areas. All R1-R3 fields sampled in the past week had extremely low averages of less than 10 aphids per plant. Higher counts of 100-200 aphids per plant can be found on individual plants in the margins of some fields, but field-wide populations remain far below the 250 aphid-per-plant economic threshold, emphasizing the need for thorough scouting before control decisions are made. AMERICAN PAINTED LADY - Larvae of the American painted lady butterfly, also known as thistle caterpillars, have been observed at low levels in soybean fields this month. Large populations develop in some years, but treatment is discouraged since the mortality rates generally are high and the solitary caterpillars, which construct a messy silken web between the leaves, seldom cause significant defoliation. The larvae observed in the past week were full-grown and likely to pupate soon. Adult butterflies should begin emerging by early August. JAPANESE BEETLE - Light to moderate defoliation is widespread in soybeans, though surveys have found only two fields above threshold during the three-week period from July 6-26. The economic threshold for Japanese beetle and other leaf feeding soybean pests is 20% defoliation between bloom and pod fill. -- Krista Hamilton, DATCP Entomologist 
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