ISSUE 10 July 15, 2010
North Central ND
Wheat scab (Fusarium head blight) has been observed in commercial fields and at the North Central Research Extension Center. Although most scouted fields in the area have had low levels of scab, a wheat field in the Kenmare area had 12% incidence with one-third of the kernels damaged by scab on infected heads. The risk for scab infections ranged from low risk in the Minot, Watford City, and Williston areas, moderate risk in susceptible and /or very susceptible varieties in the Bowbells, Crosby, Mohall, Plaza, and Rugby areas, and high risk in the susceptible/very susceptible varieties in the Berthold and Bottineau areas. There was low risk for scab infection in the moderately resistant varieties across the region from July 10th through the 13th. For more information please go to the NDAWN website (Applications, Wheat, Disease Forecaster) and select the closest location and stage of wheat development (flowering is the best timing for scab control). Please refer to the 2010 North Dakota Field Crop Fungicide Guide for scab fungicides.
Wheat streak mosaic virus symptoms on wheat.
The leaf at the top has the mosaic pattern more
characteristic of a recent infection on younger leaves.
The leaf at the bottom has the streaking pattern more
characteristic of an older infection (photo by D. Waldstein).
Field Peas and Lentils:
Pea aphid populations have recently increased dramatically to above threshold numbers. Our sweep net samples averaged 40 aphids per sweep compared to a threshold of 12 aphids per sweep. Research from Manitoba has shown a 10% yield loss at 20 aphids per sweep. The best timing for pea aphids is when approximately 50% of the peas are at early pod. Pea aphids also feed on alfalfa and can move into field peas at especially high rates after alfalfa is cut. Lygus bug numbers have been low on field peas but above threshold on lentils.
The number of banded and
Arthurís sunflower moths have increased to more than 100 in our traps in
western Bottineau County. Trap
catches are not reliable for determining when insecticides should be
applied. Egg counts or
examining individual plants for adult moths will help producers determine if
an insecticide is warranted.
See Janet Knodelís article on pages 2-3 in this issue for more information.
Crop Protection Specialist
North Central Res. Ext. Center