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Soybeans
Volume 57 Number 14 Date 07/19/2012 SOYBEAN APHID - Densities remain extraordinarily low for this time of year. A very small proportion of soybean fields have populations of 20-100 aphids per 20 plants, but most sites contain fewer than 10 aphids per 20 plants or none at all. Insecticidal controls against this pest should not be considered for any field until the established threshold of 250 aphids per plant on 80% of the plants has been exceeded. TWO-SPOTTED SPIDER MITE - Damage to soybeans, corn and many other plants continues to be reported. This mite has become the leading threat to drought-stressed soybeans in the state. Infestations affecting 5-40% of leaves were noted in the past 2-3 weeks in Columbia, Dane, Richland, Iowa and Monroe counties and the problem is unlikely to subside unless there is meaningful rainfall soon. Reports from Fond du Lac, Grant, Lafayette, Manitowoc, Rock, Sauk, Vernon and Washington counties indicate that the mites are numerous enough in soybeans to require treatment. Scouting and control measures are in order for all susceptible crops. FALSE CHINCH BUG - These insects are appearing in soybeans in the south-central area. According to UW-Madison Entomologist Dave Hogg, infestations were noted this week in fields and on the sides of buildings at the Arlington Research Station in Columbia County. False chinch bugs are generalist feeders that prefer plants in the mustard and beet families, but migrate in large numbers to nearby no-till corn and soybeans as their weed hosts are killed by herbicide in the field. Outbreaks are associated with hot, dry weather, and have not been observed in Wisconsin since the last serious drought in 1988-89. --Krista Hamilton, DATCP Entomologist 
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