In Walsh County , Brad Brummond, Extension Agent, is reporting low levels of adults in fields. Evening monitoring of fields is critical in these regions. Degree days are accumulating at about 24 per day around the region. The Spotted stem weevil population has been small in North Dakota for the past several seasons. Spotted stem weevil larvae have been found to cause serious stalk breakage when 25 to 30 larvae are present in a stalk, weakening it when larvae make their overwintering cells in the stalk's base.
Breakage is most likely to occur during drought stress or high winds.
The weevils emerge in mid to late June. Eggs are deposited in epidermal tissue of the stem. If controls are directed at the adults in order to minimize egg laying, treatments should be initiated during the first few days in July. Treatment for sunflower stem weevils is recommended when scouting determines that an average of 1 adult per three plants is found. Last weeks recommendations to not treat headed wheat just for aphids is still accurate.