FROM AROUND THE STATE
ISSUE 15 August 9, 2001
GRASSHOPPERS STARTING TO MOVE INTO CROPS
Grasshoppers are becoming more active and moving out of cut hay and harvested small grains. Damaging levels of grasshoppers have been reported on the edge of fields in crops like lentils, flax. Watch the late season crops for increasing grasshopper numbers. If you see 8 grasshoppers per square yard (or 4 sweep with 15 inch sweep net) in the field or >20 grasshoppers per square yard in the field margin, an insecticide treatment would be necessary. Grasshoppers move around a lot, so they may move into and then out of a field. So, re-scout fields often.
WHAT ARE THE WHITE-COLORED BUTTERFLIES FLYING AROUND?
WILL THEY FEED ON MY CROPS? The beautiful white butterflies flying around are the Cabbage Butterfly, Clouded Sulphur, and Alfalfa Butterfly (more yellowish than white)! The Cabbage Butterfly prefers to feed on cabbage, broccoli, kale and other Brassicae plants. So, one could find it in canola. Fortunately, most of the canola is being swathed within the next few weeks. Clouded Sulphurs feed on clovers, sweet clovers, and alfalfa; where as the Alfalfa Butterfly prefers alfalfa, but can feed on clovers and other legumes. Normally, these butterflies are not pests in forage-legume crops grown in this area. The larvae or caterpillars of the Clouded Sulphur and Alfalfa Butterfly are velvety green caterpillars with a double lateral strip (white on top of red). The caterpillar of the Cabbage butterfly is green with a white lateral strip. These butterflies will NOT FEED on most of the our later crops – flax, sunflower, and small grains. Check out the "Atlas of North Dakota Butterflies" web site:
FLEA BEETLE ACTIVE IN CANOLA FIELDS AGAIN AND HOME GARDENS!
The Crucifer flea beetle is causing problems for home
owners with cruciferous plants in their gardens like cabbage, broccoli,
cauliflower, kale. These flea beetles are moving off swathed canola
fields into gardens. There is little a home owner can do except spray with a
general insecticide like sevin (carbaryl). If you prefer a non-chemical
approach, a physical screen barrier can help protect the garden plants as well.
Flea beetle pod-feeding on canola have also been reported. If the canola field
is going to be swathed soon and flea beetles are feeding mainly on the upper
pods, no spray is justified. If the pod-feeding continues to the mid-lower pods
and the field will not be harvest soon (within a few days), spray with Capture
(1.3 fl. oz./A) immediately.
Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center