|
|
|
Soybeans
Volume 57 Number 15 Date 07/26/2012 SOYBEAN APHID - Densities are still abnormally low for late July. The average count in 65 fields surveyed from July 19-25 was only 3.2 aphids per 20 plants. The highest count documented this week was 26 aphids per 20 plants, or 1.3 per plant. Foliar insecticide treatments directed against this pest have not been justified for any Wisconsin soybean field sampled by DATCP this season. JAPANESE BEETLE - This insect continues to cause light to moderate (5-15%) defoliation of soybeans, particularly along field margins. Infestations were noted in Dane, Eau Claire, Grant, Green, Jefferson, Monroe and Sauk counties this week. The economic threshold for Japanese beetle and other leaf feeding soybean pests is 20% defoliation between bloom and pod fill. Spot treatment is an acceptable form of control for fields with the heaviest injury occurring in the peripheral areas. TWO-SPOTTED SPIDER MITE - Leaf bronzing, stippling and other symptoms associated with the mite have become more pronounced in soybeans in the last 2-3 weeks, and numerous fields have been treated. Nearly all of the 65 fields examined this week were infested to some degree, with the most severe symptoms appearing on plants along the field edges. Although recent rainfall may have temporarily slowed their build-up, scouting and spray schedules should be maintained. --Krista Hamilton, DATCP Entomologist 
|
|