Disease Happenings - 2008

Archive of Disease Happenings 2007

May 21, 2008

April and May have been quite dry in most of the state. Disease pressure has been low for foliar fungal diseases such as dollar spot, but root diseases influenced by stress have been coming into the clinic. Symptoms of diseases such as Pythium root rot, take all root rot, leaf and sheath spot, and others show up more when turf is under stresses associated with drought and salt buildup due to excessive reliance on irrigation.

Fairy ring and ring symptoms associated with R. zeae and a new Rhizoctonia sp. have also been sent in recently. These disease tend to be very difficult to control, especially curatively. Rhizoctonia diseases are the subject of several research projects here at UF in Plant Pathology.

March 12, 2008

Rhizoctonia large patch, Bipolaris leaf spot and melting out, and Pythium root rot have been common diagnoses from the service so far this year. Central and south Florida tend to have warm-enough winters for us to see large patch whenever moist periods extend more than a couple days. North central and panhandle areas typcially don't see warm-enough temps in winter but typically see large patch in spring and fall. Seashore paspalum is diagnosed with large patch far more frequently than bermudagrass. See image for typical LP symptoms on the shorter mown grasses. When active the expanding edge of the patch is yellow to orange in many cases. Affected turf in the patch is wilty and thin.

Also note the smaller dollar spot symptoms in the fungicide-treated plot without large patch. Take into account all potential diseases when considering fungicides to apply.

Bipolaris leaf spot and melting out diseases are still apparent in south Florida on Bermudagrass greens. Crowns rot and the older leaves turn yellow and sometimes have purple spots on blades and sheaths (See image). Overall symptom is a thin unthrifty turf.

IFAS DDIS folks (thanks Xin) have developed a mapping website for our turf sample data. It shows what diseases occur on what grasses in what FL counties, during time periods the user specifies. Download the plug-in and try it.

http://ddis.ifas.ufl.edu/ddisx/jsp/mapreport/rpt4/index.jsp

 

• Rapid Turfgrass Diagnostic Service