April 10, 2015: Wheat Pest and Disease Update

From Ned Tisserat, Retired Plant Pathologist, Bioagricultural Sciences and Pest Management

Wheat rusts

 There is still nothing to report about rust diseases in Colorado.   Stripe rust was apparently fairly heavy in southcentral Oklahoma warranting fungicide sprays, but only light and scattered outbreaks have been reported in central Oklahoma and southwestern Oklahoma is very dry.   I suspect that stripe rust will eventually wind up here in Colorado, but if the present weather patterns persist, it may not cause significant damage.   But, of course, a lot can happen between now and flowering.  I will keep you posted.

Wheat streak mosaic

There are reports of some moderate wheat streak mosaic in states south of us.   I am a little concerned that we may see a higher incidence of this disease this year.   To refresh your memory, wheat curl mites vector the virus, primarily in the fall.   Early planting  and good fall growth, coupled with a late freezing date, may have extended the virus transmission period and increased severity.  I would begin to scout fields that look off color and may not be greening up and growing properly.   Look for flecking on the leaves and splayed plants.  If you suspect WSMV or one of the other mite vectored viruses, I would strongly urge you to submit a sample to the diagnostic lab here in Fort Collins http://plantclinic.agsci.colostate.edu/ for confirmation.   I’ll even offer you a deal – you send in the sample and I will pay for it!  It doesn’t get better than that.

Insect and mite problems

Insect and mite problems are apparently taking top billing this year.  Last week I mentioned problems with brown wheat mite in parts of the state.  Cutworms and wireworms may also be an issue.  Dr. Frank Peairs has  provided links http://webdoc.agsci.colostate.edu/bspm/Cutworms%20in%20wheat.pdf and http://webdoc.agsci.colostate.edu/bspm/False%20wireworms%20in%20winter%20wheat.pdf  for management options.


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