ISSUE 6 June 19, 2008
WHEAT LEAF RUST DETECTED
NDSU IPM field scout, Andrew Friskop, detected trace levels of wheat leaf rust in two spring wheat fields in Richland County, on June 16. These fields were in the jointing stage, and only one or two pustules were found. This detection is about 10 days later than when wheat leaf rust was first reported in 2007. Leaf rust levels have been reported to be high on susceptible cultivars of winter wheat in states to our south this year.
NDSU OAT BREEDER REPORTS OAT CROWN RUST ON BUCKTHORN
Mike McMullen, NDSU Oat Breeder, recently reported to the Cereal Disease Lab that oat crown rust aecia are just beginning to appear on buckthorn, as of June 15 in Fargo. This seems much later than usual, but due to cool weather, oat development also is later than normal. The bright orange aecial cups on buckthorn hold an alternate spore form of the oat crown rust fungus, and their appearance generally indicates that the urediospore stage occurring on oat leaves will be showing up fairly soon in the region.
Aecial stage of oat crown rust on buckthorn.
(Photo courtesy Carl Bradley)
FUNGAL LEAF SPOTS MOST COMMON IN LAST WEEK’S NDSU IPM SURVEY
During the week of June 9-14, the NDSU IPM field scouts surveyed 99 wheat fields and 26 barley fields across the state, with some days unsuitable for scouting, because of heavy rain. During that week, spring wheat was generally in the tillering stage, with a few fields jointing. Winter wheat was jointing to early heading, and barley was predominately tillering, but about a third also were already in the jointing stage. This week’s sunnier and warmer weather should see crops rapidly developing beyond these growth stages.
Tan spot was the only wheat disease observed last week, with 1/3 of all wheat fields surveyed showing infection. The highest incidence and severity occurred in fields planted into wheat stubble. Some fungal leaf spotting also was observed in barley fields in the northwest region.
Other wheat or barley diseases were not observed last week, and neither were insects, except for a very few grasshoppers in field margins. Field scouts in the southwest did report seeing leafhoppers in the fields.
NDSU EXTENSION PLANT PATHOLOGY WEB SITE
The NDSU Extension Plant Pathology web site has recently been updated to include a link to the compilation of NDSU sponsored 2007 small grain fungicide trials. The site also has links to 3 new plant pathology publications, one on Ascochyta in chickpea, one on Black leg in canola, and one on rust diseases of wheat. The NDSU Extension Plant Pathology web site is found at:
RECENT CHANGES IN THE WHEAT AND BARLEY FUNGICIDE WORLD - A GOOD SUMMARY
Don Hershman, Extension Plant Pathologist from the University of Kentucky, recently wrote an excellent summary of recent changes in small grain fungicide registrations. His paper, titled "Recent Changes in the Wheat and Barley Foliar Fungicide Status Quo" outlines the struggles and milestones achieved with some recent registrations for wheat and barley fungicides. His paper can be found at a link on the following US Wheat and Barley Scab Initiative web site:
This paper is a concise synopsis of the history of recent registration events. Following the May 8, 2008 posting of his paper, EPA also granted an additional registration, to Prosaro fungicide, a premix of prothioconaozle and tebuconazole, manufactured by Bayer.
NDSU Extension Plant Pathologist
COOL SOILS/RECENT RAINS MAY ENCOURAGE ROOT ROT OF SOME ROW CROPS
Despite being very dry earlier this spring, we may begin seeing the effect of root rots in some row crops. Cooler than average soil temperatures often mean seeds stay in the ground longer, increasing their exposure to root rotting pathogens present in the soil. Last week’s rain, although much needed in most of the state, may give some root rot pathogens a foothold on some broadleaf crops, particularly those recently planted (edible beans and soybeans for example). Although there is not much that can be done to manage root rots after planting, the observation of suspected root rot in a field (poor stand, young plants yellowing/wilting/dying) may influence management decisions for the rest of the season, as well as for future crops in the field.
If you see some suspicious patches in the field, take note for the future, it may be root rot diseases.
Extension Plant Pathologist