FROM AROUND THE STATE
ISSUE 13 July 30, 1998
Aphids have been observed on late planted canola in the area.
Aphids can damage canola by disrupting the terminal growth and thus reducing plant size and seed yield. Infestations are usually NOT economically important especially after pod formation. Control may be warranted only if the crop is planted late (still setting pods) and if natural enemies like lady beetles are not present.
"Good Bugs" (natural enemies) attacking sunflower beetles!
It is easy to observe many other insects besides the pests when scouting a sunflower field. Some of these insects are predators or parasites of the eggs, larvae, or adults of the sunflower beetle. Some predators that are commonly observed now are: lacewings, lady beetles, nabids or damsel bugs, flower bugs or minute pirate bugs, stink bugs, Syrphid or hover flies, ambush bugs, ground beetles, bee flies, to name a few. To determine what native parasitoids are present, larvae of sunflower beetle were collected from the sunflower planting date study at Minot, Carrington, and Fargo and sent to Dr. Larry Charlet, USDA ARS entomologist, for rearing. Examples of parasites of the sunflower beetle include two species of a Tachnid fly and a Pteromalid wasp. Learning how to recognize the good bugs can be difficult, so please consult a general insect book or NDSU extension factsheet entitled "Beneficial Insects of North Dakota."
Seed weevils (mainly red) are still being found in sunflower fields.
Infestation ratings are generally low (below economic levels) in the area.
Incidence of Sclerotinia wilt is increasing.
The univoltine flight of the European corn borer is over.
Several fields of sweet corn were above economic thresholds and had to be sprayed twice. The second bivoltine flight should occur in mid-August depending on the weather.
Mycosphaerella blight was observed on field peas in the area.
This disease can attack leaves, stems, flowers, and pods, and symptoms are a purplish-brown spots or lesions. The fungus is seed, stubble, and soil-borne. Losses can be reduced by crop rotation and using disease-free seed. No fungicides are registered in ND. However, Canadian research indicates that control by foliar application of fungicides is currently uneconomically.
Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center
Soil moisture levels are generally deficit in south_central North Dakota. For example, at the Carrington RE Center (CREC), a rainfall total of 5.75 inches has been received during April through July while the long_term average is 10 inches.
The dry conditions have been beneficial for haying and small grain harvest. Barley harvest is rapidly progressing and spring wheat harvest is underway. Preliminary reports indicate average barley yield and quality. Most of the region's canola has been or soon will be swathed. Field pea harvest has begun with limited reports indicating yields of up to 45 bushels per acre.
The current dry and warm weather is stressing warm_season crops including corn, dry bean, and soybean. Most corn is in the silking to blister stages and soybean in the pod to early_seed formation stages (R3_R5). For optimum yield, moisture stress must be minimal during these periods and beyond. On July 27 at the CREC, daily water use for corn and dry bean was 0.3 inches. From July 1 to 27, water use for corn and dry bean was just under 7 inches of water while rainfall at the CREC was 1.4 inches. Rainfall is needed now to reach average grain yield for dryland corn and beans!
In this region, current estimates are that scab generally appears less of a problem this year than in the recent past. While scab levels may be less, root rot and leaf diseases likely will substitute as significant contributors to yield and quality decline. Corn growers should continue monitoring for the European corn borer. Dry bean should be scouted for rust infections. Downy mildew appears more common this year in sunflower. Most sunflower are nearing the flowering stage so growers should be monitoring for insect pests of sunflower heads. Sunflower midge have expanded west and north from last year's problem areas. Midge are being found westward and near Highway 281. Growers should be scouting fields for this pest and the associated damage to start management plans for the future.
Area Extension Specialist/Cropping Systems
Carrington Research and Extension Center