AgAlerts 2001 From Griggs County
By John Swenson, Griggs County Extension Agent

Issue # 7, July 4, 2001

Small Grains Disease Forecasting System
Anthrax in Cattle
Leafy Spurge Flea Beetle Collection is Peaking
Thistle Caterpillars
Downy Mildew Found in Sunflower

Small Grains Disease Forecasting System

Small Grains Disease Forecasting System. Forecasts for tan spot, Stagonospora nodorum blotch, leaf rust, and Fusarium head blight (scab) are available for 32 locations in MN and ND. To use this forecasting system requires the station location and the stage of the small grain crop. Click on the following link to use the system. http://www.ag.ndsu.nodak.edu/cropdisease/

Anthrax in Cattle

Conditions are again favorable for anthrax. The wet spring combined with the current dry conditions could result in possible anthrax infections. Cattle producers are urged to monitor herds that have had a history of anthrax related deaths in the past few years. These herds are candidates for vaccinations to the adult animals. For more information on anthrax, contact the Cooperstown Veterinarian Clinic at 701-797-2216 or Extension publication A-561 Anthrax.

Leafy Spurge Flea Beetle Collection is Peaking

Now is the time to collect leafy spurge flea beetles. Collections on Tuesday, July 5th were very good. Beetle emergence is starting to peak, making collections easy. Landowners are urged to check their release sites for beetles and collect and spread them to new locations. The Griggs County Weed Board is still planning to hold more collection days. For times and places contact the Extension Office at 701-797-3312. If you are unable to attend, try and find someone who would collect for you. There is a large demand for these insects and we do not have enough labor to collect for everyone. Any help is greatly appreciated. This program success will be determined by everyone spreading the bugs.

Leafy spurge beetles feeding on leafy spurge (click on photo's to enlarge)

Captured beetles in a sweep net.

Thistle Caterpillar

(click on photo to enlarge)

    Reports of thistle caterpillars feeding on Canada thistle have been received from several areas in North Dakota. The caterpillar is known as the thistle caterpillar (but we may have two species feeding, Painted Lady and Red Admiral). The caterpillar is easily recognized by the prominent, stout spines on the body. Thistle caterpillar has been quite active in the region since late May, feeding on a number of crops. We are entering the second generation, and some different crops are being affected. Most reports have been caterpillar feeding on soybeans. In general, treatment of soybean is recommended when there is 25 to 30% defoliation prior to bloom; 20% after bloom or pod set. This requires 4-8 caterpillars per foot of row. On small soybeans a judgment call is required.   One reference suggests a treatment guideline of 3 larvae per foot of row, another is when damage is severe and plants are being killed.
    A big concern is when Canada thistle is being controlled with herbicides the caterpillars will move to a new food source, which most likely will be the crop. Be sure to monitor Canada thistle patches to observe the amount of caterpillars present when spraying or monitoring these areas. This might determine whether controls might be needed.
    Insecticides for thistle caterpillar control in soybeans include: carbaryl (Sevin XLR), Pounce, Warrior. Other insecticides that are effective against caterpillars in soybean are: Asana, Lorsban, Penncap-M and Scout X-tra.

Downy Mildew Found in Sunflower

Downy mildew is a seedling disease that affects sunflower. For more information on this disease, goto AgAlert Issue #6, June 21, 2001 or AgAlert Issue # 8, August 2, 2000.