ISSUE 7 June 25, 2009
NDSU IPM FIELD SURVEY UPDATE
NDSU IPM field scouts surveyed 124 wheat fields and 37 barley fields across the state for the week ending June 19. The average growth stage for wheat fields was the tillering stage, and ranged from 1.5 leaf to flowering. The average growth stage for barley also was at tillering, and ranged from 1.5 leaf to boot.
Tan spot was found in 65% of the wheat fields surveyed, with an average severity in infected fields of 4.3%, and a high severity of 40% in one winter wheat field in a southeast county.
Five wheat fields were observed with wheat streak mosaic symptoms and two fields showed barley yellow dwarf virus symptoms. Only one field was observed to have a few grain aphids present. In barley, 65% of the surveyed fields had symptoms of either spot blotch or net blotch fungal leaf spot. As observed the previous week, severities of these two barley leaf spots remained low.
The NDSU IPM web page is now posting maps of field survey observations, at:
These maps will be updated on Wednesdays or Thursdays of each week.
WHEAT LEAF RUST
Wheat leaf rust was found by Greg Endres, Carrington REC Extension Agronomist, on June 23 in Jagalene winter wheat at the Ellendale winter wheat plot site. This is the first report of wheat leaf rust in ND this year. Jeff Stein, SDSU plant pathologist, reported that he observed wheat leaf rust on winter wheat on June 15th at Brookings, SD.
NDSU DISEASE FORECASTING SITE SHOWS INCREASED WHEAT DISEASE RISK
Rainy weather this past week has increased the risk of leaf disease and head scab infections in some areas of the state, especially in those areas with repeated rains and recurrent high dew points. The NDSU Small Grain Disease Forecasting site at:
predicts risk of infection for tan spot, Septoria blotch, leaf rust and Fusarium head blight (scab).
With the wide range of crop growth stages and the unpredictable weather this year, it is critical to keep on top of disease risk forecasts, disease development, and crop growth stages, to be sure that any needed fungicide is applied, and is applied at the appropriate timing. A blanket statement about disease risk and need for fungicide isnít going to work at all this year, because of the high variability in crop growth stages, crop condition, and spottiness of showers.
ND DATA COMPARING PRODUCTS FOR FUSARIUM HEAD BLIGHT (SCAB) SUPPRESSION
Several new products have been registered for scab suppression in wheat and barley this past year that generally have better activity against Fusarium head blight (scab) than Folicur (tebuconazole), the product that was traditionally used for this purpose for many years, available then as a Sec. 18 Emergency Exemption product.
The two newest products available are Prosaro (tebuconazole + prothioconazole), manufactured by Bayer Cropscience, and Caramba (metconazole), manufactured by BASF. The following table provides comparisons of these products to Folicur for reduction of scab severity and DON (vomitoxin). The data is a summary over uniform fungicide trials that were conducted on wheat and durum across ND from 2005-2007.
CORRECTION TO LAST WEEK'S REPORT ON FUNGICIDES FOR SCAB MANAGEMENT
In last week's edition of the NDSU Crop and Pest Report, I provided a table listing the recommended fungicide products for Fusarium head blight (scab) suppression in wheat and barley. I indicated that Caramba (metconazole) was registered for scab suppression from 10 to 13.5 fl oz/acre, with the higher rate giving better scab suppression.
In fact, the Caramba label from BASF states that the rate used for scab suppression should be 13.5 to 17 fl oz. The 10 fl oz rate is for leaf disease control only. Therefore, application of a 10 fl oz rate/acre of Caramba for Fusarium head blight (scab) suppression is not supported by the Caramba label.
Extension Plant Pathologist