Cercospora leaf spot (CLS) (Figure 1 A, B) is the most damaging leaf disease of sugarbeet in North Dakota and Minnesota.
A majority of the state received rainfall during the last week. Specifically, areas south of I-94 have endured frequent rain events that have contributed to an elevated scab risk.
The IPM survey scouts visited 83 wheat fields and 38 barley fields during the week of June 15-19.
Timing. Application timing is often more important than fungicide selection. Targeting the early bloom stages is ideal (commonly 20%)
Flowering canola in some of the state is currently in moderate to high risk for sclerotinia infection. If daytime highs remain are cool to moderate (60’s – 70’s) and canopy moisture is high, a fungicide application could be warranted.
On June 19th the Sclerotinia risk map and calculator (www.ag.ndsu.edu/sclerotinia) became active for the 2015 season.
Sugarbeet Crop Update
The IPM survey scouts visited 112 wheat fields last week and found tan spot in approximately 35% of the fields.
Using the NDSU and National scab forecasting models, the greatest risk of scab remains in south central to southwest ND and a few pockets on the eastern side of the state.
Winter wheat has started to flower in parts of the state and early-planted spring wheat and barley are not far behind.
In the May 14th Crop and Pest Report issue, the NDSU Potato Blightline was advertised. This is sponsored by Syngenta Crop Protection, who notified us that they will not be using the twitter or text alerts mentioned in the article. You can still access the hotline recommendations by phone or website.
There have been several cases of yellowing wheat this year and most have been attributed to nutrient deficiencies and/or the cold wet weather experienced in May.
Samples of field peas with moderate to severe symptoms of bacterial blight have been received by the NDSU Plant Pathology Department.
On Monday, we received a wheat leaf sample collected by Dr. Janet Knodel and Sam Haugen (Plant Pathology graduate student) that was confirmed as stripe rust.
Soybeans are sensitive to multiple pathogens (see previous article), but I am concerned about Pythium infections in the earliest planted soybeans. Pythium is favored by cool soils, generally less than 60o F and lots of water. Soybeans that were planted three weeks ago had lots of both.
Fields that were planted before the heavy rains began and the cool temperatures set in a couple weeks ago are at high risk for root rot development.
After several days of precipitation and with cool weather in the forecast, this is a good time to start scouting winter wheat and spring wheat for fungal leaf spots.
Researchers at North Dakota State University and the University of Minnesota have demonstrated that a wide range of plant population with uniformly spaced plants resulted in high recoverable sucrose, but plant populations of 175 to 200 plants per 100 foot of 22-inch wide rows consistently resulted in the maximum recoverable sucrose per acre. It is important that the plants be evenly spaced within the rows.
During the last two growing seasons, Soybean Cyst Nematode (SCN) has been confirmed in seven additional North Dakota counties.
The Plant Pathology Department at North Dakota State University will again be providing the potato Blightline service at no charge to the potato industry of North Dakota and western Minnesota in 2015.