North Central ND (6/16/11)
Flea beetle activity has increased since last week. We are catching both crucifer and striped flea beetles in our traps. Damage in area fields has ranged from 10-40% defoliation. Much of the canola in the area was planted later than normal with some seeding occurring into the first week of June. The majority of the canola is in the two to four leaf stage. Canola is susceptible to flea beetle damage until the six leaf stage. The insecticide residue from seed treatments is effective for about 21-26 days (Jan Knodel, Extension Entomologist). Producers who planted canola prior to May 27 should be checking their fields for flea beetle activity. If the 25% defoliation threshold has been reached a foliar insecticide application is recommended.
Small Grains- First Case of Rust in Wheat for 2011:
We observed the first case of rust for the 2011 season in a commercial winter wheat field south of Minot. Symptoms of stripe rust and leaf rust were observed on winter wheat plants in the boot stage. Fungicides that are used to control tan spot and Fusarium head blight (scab) are also effective against the rust diseases. Tan spot has been found in every wheat field surveyed. On average, 61% of plants in fields are infected with an average severity of 8%. Bacterial blight has been found in about 70% of fields with 50% of plants in infected fields showing symptoms of this disease. In barley, spot blotch and net blotch are common throughout the area. Small grain aphids are present in low numbers in some fields and thrips larvae have also been found in a number of fields. We continue to remain vigilant for barley yellow dwarf virus. If this virus is found in wheat or barley fields, aphids should be controlled much sooner than the current threshold (85% of stems with at least one aphid).
Daniel Waldstein - Crop Protection Specialist
North Central Research Extension Center, Minot