Kentucky Turf Grass Diseases Evaluation

Turf Grass Diseases Evaluation

These models attempt to provide weather-based forecasts of several important turfgrass diseases in Kentucky. All are based on research published in scientific journals and are thus considered to be based on sound science. However, use the predictions of these models with a certain degree of caution because the effect of the models is limited on local condition and none of models has yet received adequate validation under Kentucky conditions.

Brown Patch Model #1: Forecasts brown patch on perennial ryegrass. Limited evaluations suggest that this model (as modified slightly from the original publication) is the accurate for predicting brown patch activity on perennial ryegrass for conditions in Central Kentucky.

Pythium Model #1: Forecasts Pythium cottony blight on cool-season grasses. In Kentucky, typically this disease is of greatest concern on high-maintenance creeping bentgrass and perennial ryegrass. The criteria of This model: the maximum air temperature > 82o F, the minimum air temperature > 68o F and. and at least 9 hours hours of relative humidity.
Pythium Model #2: Forecasts Pythium cottony blight on cool-season grasses. The criteria of This model: maximum temperature > 86 F is followed by at least 14 h of relative humidity exceeding 90% with a minimum temperature > 68 F.

Click here for more details of forecast models and more information for Brown patch, Pythium blight, Anthracnose, Fungicide control options for Kentucky.

Conditions in the turfgrass canopy are usually more conducive to dew formation than conditions at eye level (the height of standard weather monitoring equipment), because temperatures are usually cooler at ground level. Thus, these forecasting models may become more accurate if one selects a lower "threshold value" for relative humidity than called for by the models themselves. For most cases, we suggest using the value called for by the original model. However, we have provided the option for users to adjust the threshold to a lower value, should a particular model issue too many “false negatives” (a forecast of no disease when the disease is visually active on your golf course). If you conduct such comparisons, we welcome your feedback. Send your comments to Paul Vincelli (

Simply fill out the desired parameters then press the "Submit Choices" button. These data are based on the 24 hour period 7PM to 7PM. And should NOT BE USED FOR LEGAL PURPOSES.

Select date:

Model Criteria
Default(defined by models)
Set Relative Humidity Threshold for Brown Patch Model #2 or Pythium Cottony Blight :
Note: Enter relative humidity threshold criteria as whole numbers, e.g. 50% as 50

Output Preference
Infection table only All including raw data

Forecasts for Brown Patch Disease
Model #1

Forecasts for Pythium Cottony Blight on cool-season Grasses
Pythium Model #1
Pythium Model #2

Forecasts for Foliar Anthracnose on Poa Annua
Anthracnose Model

Ag Weather Center, Department of Biosystems & Agricultural Engineering, University of Kentucky