 |
|
|
|||||
|
|
June 30, 2005 Scout for Diamondback Moth Larvae in Canola Fields Reports of diamondback moth larvae causing feeding injury to bud-flowering canola are common in the north-central region of North Dakota (Minot west to Tioga and north to Kenmare and Mohall and then east to Bottineau). Different diamondback moth life stages (adults, eggs, larvae, pupae) can be found in the field, according to Janet Knodel, North Dakota State University North Central Research Extension Center, area crop protection specialist in Minot. The larvae are about a half-inch long, light green and have a forked posterior. They have a habit of spinning down a strand of silk when disturbed. Larvae feed on the leaves, buds, flowers, seedpods, the green outer layer of the stems and occasionally, the developing seeds. “The amount of damage will depend on the crop stage and the larvae density and size,” Knodel says. “Extensive feeding on the flowers will delay plant maturity, cause uneven crop development and significantly reduce yield.” Producers can scout for larvae by beating plants and dislodging the larvae into buckets or onto the roof of a vehicle. Early monitoring and judicious use of insecticides when fields are above larvae thresholds are the best pest management practices for preventing losses. Economic thresholds are 10 to 15 larvae per square foot (one to two larvae per plant) during flowering or 20 larvae per square foot (two to three larvae per plant) during podding. “Many fields are close to the proper spray time for sclerotinia control (early-mid flowering), so if you are planning to spray for sclerotinia, a spray application of an insecticide-fungicide is recommended,” Knodel says. The pyrethroid insecticides, such as Capture, Decis, Warrior and Proaxis, are compatible with canola fungicides, such as Ronilan. Late-planted canola (June) also will need to be scouted for second-generation diamondback moths that will be emerging soon. There are usually three generations (32 days for each generation) born each year in North Dakota. ### Source:
Janet J. Knodel, (701) 857-7682, jknodel@ndsuext.nodak.edu
|
Market Advisor: |
|
North Dakota State University |
