This summer at Des Moines Golf and Country Club, Director of Grounds, Rick Tegtmeier, CGCS and two ISU Interns conducted a fungicide study that compared name brand versus generic products for dollar spot control. The two interns from Iowa State University were, Tyler Boley and Tayler Riggen. They worked closely with Luke Dant from Syngenta Professional Products to set up a replicated study on the golf course.
How they did it
Plots were arranged on fairways at two different locations on the course in order to account for spatial variability. The fairways contain ‘Penneagle’ creeping bentgrass maintained at 0.5 inches. One set of plots were located on the north course and the other on the south course. Each set of plots was replicated three times. Treatments included an untreated control, Daconil WeatherStik, Manicure 6FL, and Echo 6F ETQ fungicides. All products were applied at a rate of 2 oz/1000 ft2, to deliver the same amount of active ingredient, using a backpack sprayer with #8002 flat fan nozzles. Carrier volume was 44 gallons/acre. Spray applications began on May 14 and concluded August 13. Applications were made on 14-day intervals for a total of 7 applications. Percentage of turf affected by dollar spot was visually estimated on July 1 and August 14.
What they found
Each plot in the study succumbed to some dollar spot, but it was clear there were differences between the products in our study (Table 1).
Similar trends were evident on each of the test plots between the north and south courses but the disease pressure on the north course was far more severe. An application of Bayleton was made to the plots on the north course on June 22 to help reduce disease pressure. The main findings from the study are summarized below.
- Control plots sustained significant damage and possibly needed reestablishment.
- All chemicals succumbed to some breakthrough if applied on 14-day intervals. At the rate used in our study, shorter intervals are needed with all products.
- Manicure 6FL seemed to have good control until approximately 10 days after each application. After that, there was significant breakthrough.
- Echo ETQ had less than desired control through the 14-day period between applications. Echo ETQ fungicide is green in color which is designed to help cool the turf and in turn help prevent disease. In our opinion, the green colorant has little effect and was barely noticeable after being sprayed.
- Daconil WeatherStik had acceptable control until 13 and 14 days after application, and then some small breakthrough was evident. Recovery was not exceptional, but due to better initial control of dollar spot, Daconil provided the best control of dollar spot.
- One option would be to compare prices of products to see if Manicure 6FL or Echo ETQ could be applied on 10 day intervals for lesser overall price, however; this would increase labor costs and wear and tear on spray equipment, possibly negating any cost savings by purchasing these generic products. In our study, Manicure and Echo provided nearly the same level of dollar spot control.