Carrington Research Extension Center
North Dakota State University
NDSU Extension Service
North Dakota Agricultural Experiment Station

Ag Alert

August 26, 1999


NDSU recently conducted a disease survey of commercial canola fields in North Dakota and northwest Minnesota. The survey included several counties in south-central ND including Stutsman, Foster, and Wells during August 3-11. About 10 fields were surveyed in each of these counties. In each swathed field, 40 lower stems were examined for incidence of sclerotinia (white mold) and blackleg.

Sclerotinia incidence ranged from 0-23% and averaged 7% in Stutsman County, ranged 0-30% and averaged 9% in Foster County, and ranged 7.5-45% and averaged 19% in Wells County. For each % of sclerotinia incidence, about 0.5-0.75% yield loss may occur. As an example, the 19% average sclerotinia incidence in Wells County represents a yield loss of 10-14%. Blackleg incidence generally was low in the 3-county area with a range of 0-12.5% and average of 3% in Stutsman County, 0-2.5% range and 1% average in Foster County, and 0-5% range and 1% average in Wells County.

Canola growers may want to check their swathed fields for incidence and potential yield loss of these diseases. Another consideration is impact of these diseases as future crop rotations are planned.


Some area flax fields have been swathed and others are near harvest. Flax harvest maturity is determined by visually estimating percent of brown bolls. Flax may be direct combined when about 90 percent of the bolls have turned brown. Keep in mind that flax may continue to bloom until frost especially if planted late or if weather conditions are cool and wet. Seeds from these late flowers seldom mature and are lost during threshing and cleaning. Delays in timely harvest can hamper the harvest operation or result in yield loss due to plant lodging, continued weed growth, or boll loss from grasshopper feeding or severe weather. If swathing is necessary, due to the presence of excessive weeds or lack of uniform crop development, the operation should occur when about 75 percent of the bolls have turned brown. Flax swathes are susceptible to movement by wind so cut stubble high and consider using a swath roller. Use sharp, well-adjusted cutter bars because flax stems are challenging to cut! Details on flax harvest timing and techniques may be obtained in the NDSU Extension Service circular A-1038 'Flax production in North Dakota'.

Greg Endres, Area Extension Specialist/Cropping Systems, Email:
1999 Ag Alert Archive * Carrington R&E Center Home Page * NDSU Agriculture