Volume
4 Issue 5
June 19, 2007
Whoa! Major Armyworm Flight Detected
with Blacklight Trap Captures
Very high light trap captures have occurred over the
past few days at Lamberton and in NW MN. Migrating moths have moved
northward along the front that has been parked along the Minnesota,
North and South Dakota borders last week.
In SW MN at Fulda, a trap had been active for the past couple of
days and captured 147 moths the night of 6/13. The Lamberton trap
captured over 70 moths the same night. Where rainfall events
occurred in the Red River Valley, captures have been higher - the
Crookston trap recorded 109 on 6/11, 120 on 6/12 and 153 on 6/13.
High trap captures may not necessarily mean a region-wide
infestation, but individual fields are very likely at risk; it's
certainly a warning you don't want to ignore.
 Armyworm
infestations can be detected about two to three weeks after a peak
moth flight is recorded by a blacklight trap (Table
1). Three weeks after peak moth capture is approximately
the 5th instar based on the life table information (Table
2). This is the stage when larvae dramatically increase their
consumption of foliage and begin to cause noticeable leaf loss in
small grains.
 Starting
next week, check for armyworms in field margins, low areas with rank
plant growth, and areas where plants have lodged. Look for leaf
feeding, worm frass (droppings) around the base of plants, and
severed leaf material that has fallen to the ground. Larvae hide
beneath plant debris around the base of plants and in heads of wheat
and barley. All this can be done while checking for aphids and
making those final fungicide-insecticide tank mix decisions.
Table 3 provides current insecticide options for controlling
true armyworm in small grains.
To stay current with pest surveys in
Minnesota:
http://www.mda.state.mn.us/plants/pestmanagement/pestreports.htm
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