ISSUE 5   June 10, 2010

North Central ND

Barley thrips: Early this week I was in a barley field in southwest Bottineau County with a healthy population of barley thrips. Female barley thrips overwinter in sod, especially in shelter belts with a preference for brome and Kentucky blue grass. Thrips are weak fliers but can move short distances in a field by flying. They can also be spread by wind. To determine the need for an insecticide application, the top two sheaths of a barley plant should be examined in at least nine separate areas of a field prior to heading. After heading it is not economical to spray for this particular pest. Barley thrips can be concentrated along field edges so it is important to sample from interior field locations as well as edges. A sampling plan from work done in North Dakota and Alberta is listed below. Only methyl parathion is registered for control of barley thrips in barley. However, pyrethroid insecticides (e.g., Baythroid, Grizzly, and Warrior) used to control other barley insects should give good control of barley thrips (Jan Knodel, NDSU Entomology).

Sources: http://www.ag.ndsu.edu/procrop/bar/bythrp06.htm http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm2477?opendocument

Canola: We have seen some flea beetle feeding in canola fields in the area but none above the 25% damage threshold that warrants an insecticide application. Striped flea beetles have been caught in our traps in McHenry, Ward, and Towner counties. The crucifer flea beetle has been the exclusive canola flea beetle species caught in traps in McKenzie, Renville, Bottineau, McLean, and Burleigh counties. In the areas where we’ve caught striped flea beetles, they comprise less than 10% of the total flea beetles caught. At this point, we have not observed the dramatic population shift from crucifer to the more insecticide tolerant striped flea beetles that areas of Canada have experienced.

Daniel Waldstein
Crop Protection Specialist
North Central Res. Ext. Center
daniel.waldstein@ndsu.edu

According to NDAWN (North Dakota Ag Weather Network) data, the region received 0.1 inch (Robinson) to 1.4 inch (Edgeley) of rain during May 26 to June 8. The region’s soil moisture continues to be at adequate to excess levels. Hail damaged crop in Ransom County (Englevale area) last weekend.

Alfalfa harvest continues between rainfall events. Pastures are in good condition. Winter wheat is in the heading to flowering stages. Fungicide use should be considered in winter wheat to prevent flag leaf damage from leaf spot disease and to reduce risk from scab (Fusarium head blight). April-seeded small grain fields are in the 4-leaf to jointing growth stages. The cool weather in late May and June has helped preserve yield potential in small grain. Timely-planted corn is in the 3- to 5-leaf stage. Weed spraying is nearing completion in small grain, continues in corn, and is starting in soybean. Soybean growth stages range from emerging to first trifoliate leaf. Bean and sunflower planting is nearly complete. Tan spot is commonly found in small grain but at low severity levels. Small grain aphids and barley thrips are appearing in small grain.

Greg Endres
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center
gregory.endres@ndsu.edu

Precipitation in southwest North Dakota has been highly variable this past week with NDAWN sites reporting from 0.17 inches at Beach to 0.86 inches at Dickinson. The majority of the NDAWN sites in the southwest though reported a third to a half inch. The greatest amount of precipitation for the week that has been reported was at Dutch Henry Butte with 1.15 inches. Growing Degree Days continue to lag compared to average with the coolest areas reported Beach, Bowman, and Dunn Center. As a result of cool conditions crop emergence and development has been slower than normal. This is probably beneficial for spring wheat but a drag on corn and sunflower. In comparison to 2009 the western half of the district is cooler while the eastern half of the district is on par with last year’s cool growing season. Alfalfa at Dickinson is about 30 inches tall and flower buds beginning to develop. We expect alfalfa harvest to begin shortly. Tan spot on wheat grown on land that was in wheat the previous year (2009) is exhibiting high incidence of tan spot but low severity. With moist conditions severity is expected to increase. If producers are growing wheat on wheat, yield expectations are over 35 bushel per acre, and incidence is greater than 10% (more than 1 plant in 10 exhibiting tan spot lesions) producers should consider an application of a foliar fungicide for the control of tan spot at the 4- to 5-leaf stage. Dixie Dennis IPM Scout for southwest North Dakota found Strip Rust in a wheat field in Adams County at the beginning of this week. Optimum temperatures for strip rust infection is 48 to 55^oF and sporulation is inhibited by temperatures above 68uper oF. Normally disease development is inhibited by our summer temperatures. Producers should scout and only after finding this disease determine if a fungicide application is necessary.

Roger Ashley
Area Extension Specialist/Cropping Systems
Dickinson Research Extension Center
roger.ashley@ndsu.edu