Insect Control

Bertha Armyworm (Mamestra configurata) may be a significant pest to industrial hemp. Bertha armyworm is a cyclical pest of canola and other crops in Manitoba, and caused significant defoliation of hemp in some 1995 crops.

Cutworms have been found to be a spring pest during a number of years in hemp fields. Scouting of fields in the spring is recommended. Generally cutworms are found in patches in the field.

Grasshoppers have been found to be a pest especially when hemp is grown in areas where there are a lot of pasture and hayfields. Grasshoppers have been observed to move into the hemp field in the spring but also later in the season and feed on the seed heads. Economic thresholds are currently unknown.

Lygus Plant Bugs have been found in high numbers in hemp but damage and economic thresholds are unknown.

European Corn Borer have been found on occasion in hemp stands. No economic numbers or thresholds have been observed. The Corn Borer weakens the stem and later in the season the stalk will break off at the point of entry.

For more information on these insects, and on Scouting for Insect Pests" go to the MAFRI website.