Pest Management BMP March 2022

35

1st Fungicide Application Made

2nd Fungicide Application Made

30

25

20

28 Day Spray Interval: Ignore Model Output

15

20% spray threshold

10

Dollar Spot Model Probability

5

Smith-Kerns Model Output

0

5/1

5/8 5/15 5/22 5/29 6/5 6/12 6/19 6/26 7/13

Image 1. Depiction of Smith-Kerns model use (University of Wisconsin Madison Turfgrass Diagnostic Lab)

Model-based + Resistant Varieties Applications to resistant varieties were triggered on a 28-day interval when the Smith-Kerns threshold of 40% is exceeded. Figure 1 shows the forecasted risk in 2020 for Ithaca, NY. Using the data-driven model approach extends the application intervals when disease pressure is below the verified threshold, and three fewer applications are made when compared to the preventative program for the 2020 season. However, combining resistant varieties with a data driven model-based approach required only two applications, or a 50-75 percent reduction from susceptible varieties and preventative strategies. It’s possible only one application was needed in 2020 considering the second application was triggered when the Smith-Kerns model rose above 40% for only one day.

The risk models can be used to look at historical weather data as a means of planning for future pesticide needs. As an example, simulations were run for two locations in New York (Ithaca and Millbrook) over a 5-year period. This simulation assumes management of 20 acres of fairways and fungicide applications costing $125 per acre for each scenario. Three different scenarios were simulated below: Preventative Applications to susceptible varieties begin when Dollar Spot is first observed in late May. The Smith-Kerns model was used as a proxy for the first application when the model output exceeded 20%. Applications were then made every 21 days until October. Model-based Applications to susceptible varieties were triggered on a 28-day interval when the Smith-Kerns threshold of 20% is exceeded. If model outputs exceed 40%, intervals shift to 21 days to account for high disease pressure situations.

Pest Management BMP Reducing Risk with Data Driven Fairway Pest Management

3