ISSUE 12 July 21, 2005
During July 1-18, the south-central regionís rainfall ranged from 0.4 inches at Carrington to 1.8 inches at McHenry as recorded at NDAWN (North Dakota Agricultural Weather Network) sites. Rain would be welcome in much of the region to maintain yield potential of corn, soybean, dry bean and sunflower. The next 6 weeks are especially critical to have adequate moisture and minimal stress for corn and beans. Winter wheat harvest is beginning in southern counties along the South Dakota border. The majority of the regionís spring wheat crop is in the dough stage. Fusarium head blight (scab) field severity is very high in winter wheat in southern counties.
In the Carrington area, foliar disease including tan spot, Septoria, leaf rust, and scab are prominent in spring wheat not treated with foliar fungicide. During the period of May 1 to July 18 at Carrington, corn growing degree day units total 1050, which is about 230 units ahead the same period in 2004. Soybean are in the full-flower stage (R2).
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center
Alternaria blight, a disease of safflower, was detected this past week on upper leaves and bracts of plants in many of the safflower fields in southwestern ND. This disease will often reduce yield by 15 to 30% as well as reduce seed test weight and oil content. Lesions on the leaf are characterized by small brown spots, about Ĺ inch in diameter, that may coalesce to destroy major portions of the leaf to the entire leaf of the plant. Lesions often have a characteristic pattern of concentric rings. When the disease moves into the head during flowering, infections will appear to discolor the end of seed and infected seed will shrivel and empty. If raised for bird feed or oil, the brown end seed will be discounted or rejected. Quadris received a Section 18 for use on safflower earlier this month. The product is applied at the rate of 6.2 to 9.3 fluid ounces per acre at the onset of the first flower ray on the primary head on the first plant in the field. Many fields are within a few days of this occurring in the area. Time of application is extremely important, so safflower producers should be scouting fields on a daily basis to determine both the presence of the disease as well as the stage of crop development. Quadris may be applied by air or ground. A copy of the Section 18 label for Quadris can be obtained at the following NDSU web site, http://www.ag.ndsu.nodak.edu/aginfo/pesticid/sec18_2003.htm#fungicide . With heavy dew occurring every morning, the likelihood of this disease spreading from lower leaves to upper leaves, bracts, and heads is high.
The above normal rainfall received over much of the area in June and heavy dew in the mornings in July is leading to additional disease problems in wheat and barley this year. Much of the crop has developed beyond the stage where fungicides could have been used for the control of rust and scab. In some areas of southwest North Dakota, scab has been found at low levels in 40% of the fields scouted. The first scab reported to us here at the Dickinson Research Extension Center was on wheat grown in fields where the previous crop was corn. However, the disease has also been recently reported in fields where the previous crop was wheat or some other crop. Rust is found in most fields and in some cases has completely killed all of the leaves on the plant. Fields treated with foliar fungicide appear to have had fewer problems with these diseases.
Wheat stem maggot is wide spread throughout the area and at levels, we have not seen for a few years. Barley thrips are present in large numbers but the crop is far enough along that these insects will cause little if any damage to the crop.
Area Extension Specialist/Cropping Systems
Dickinson Research Extension Center
Parts of Towner, Rolette and Cavalier counties received up to 2 inches of rainfall lake last week. Most of the region has not had significant rainfall the past ten days. Barley swathing begin this week in Benson county, with pre-harvest spraying of winter wheat also underway. Extensive crop losses from flooding have become evident throughout the region. Small grain leaf and head disease is heavier than normal. Most barley fields have some Fusarium head blight and wheat fields have reached the stage where Fusarium is detectable. Infection levels of up to 10 percent has been measured, but levels vary throughout the region. Flooding and disease damage will reduce average yields from previous years. Most canola is done blooming. Wild mold is a threat to untreated canola fields. Earliest planted sunflower will begin bloom late this week and many fields will be in bloom next week. Corn is beginning to tassel and is benefiting nicely from the warmer than average temperature. Soybeans are in bloom. A few fields in Nelson counties had soybean aphid detected in them last week. Drybean growth varies throughout the region, due to saturated fields. Most are in bloom with some having set the first pods. Many drybean fields have been sprayed for wild mold control. Field peas have suffered from the wet weather with, many fields showing leaf and pod disease. Flax growth is mostly good and most fields are still flowering.
Area Extension Specialist
Devils Lake Area Office