Adding a late fall application of Proxy (ethephon) before two traditional spring applications improves seedhead control of annual bluegrass

Annual bluegrass (ABG) (Poa annua L.) is a prolific seed producer in the spring on golf courses that in turn decreases aesthetic quality and trueness of ball roll on coolseason putting greens. Proxy (ethephon) applied twice in the spring after green-up is the current industry standard after the loss of Embark (mefluidide) from the turf and ornamental market. However, plant growth regulators including Proxy have been used for years to help suppressABGseedheads with inconsistent success. The primary objective of this study was to determine if ABG seedhead suppression is improved by adding a late fall application of Proxy to the two traditional spring applications of plant growth regulators at nine locations with diverse environments.Asecond objectivewas to determine the importance of including Primo Maxx (trinexapac-ethyl) in fall and spring applications. Adding a late fall application of Proxy prior to the two spring applications (F+S+S) improved control of ABG seedheads over the traditional two spring applications (S+S), but themagnitude of improvement varied among locations. When treatments were applied F+S+S, the industry standard tank mixture of Proxy + Primo Maxx provided consistent ABG seedhead control and turf quality, similar to Proxy + Fiata (phosphonate + proprietary pigment) and equal to or better than Proxy alone

Development and validation of a weather-based warning system to advise fungicide applications to control dollar spot on turfgrass.

Dollar spot is one of the most common diseases of golf course turfgrass and numerous fungicide applications are often required to provide adequate control. Weather-based disease warning systems have been developed to more accurately time fungicide applications; however, they tend to be ineffective and are not currently in widespread use. The primary objective of this research was to develop a new weather-based disease warning system to more accurately advise fungicide applications to control dollar spot activity across a broad geographic and climactic range. The new dollar spot warning system was developed from data collected at field sites in Madison, WI and Stillwater, OK in 2008 and warning system validation sites were established in Madison, WI, Stillwater, OK, Knoxville, TN, State College, PA, Starkville, MS, and Storrs, CT between 2011 and 2016. A meta-analysis of all site-years was conducted and the most effective warning system for dollar spot development consisted of a five-day moving average of relative humidity and average daily temperature. Using this model the highest effective probability that provided dollar spot control similar to that of a calendar-based program across the numerous sites and years was 20%. Additional analysis found that the 20% spray threshold provided comparable control to the calendar-based program while reducing fungicide usage by up to 30%, though further refinement may be needed as practitioners implement this warning system in a range of environments not tested here. The weather-based dollar spot warning system presented here will likely become an important tool for implementing precision disease management strategies for future turfgrass managers, especially as financial and regulatory pressures increase the need to reduce pesticide usage on golf course turfgrass

Analysis of 16 (k = 16) replicated studies comparing dollar spot control using the mean daily relative humidity (RH) logistic dollar spot model to a calendar-based approach at spray threshold probabilities of 10, 20, and 30%.

<p>Analysis of 16 (k = 16) replicated studies comparing dollar spot control using the mean daily relative humidity (RH) logistic dollar spot model to a calendar-based approach at spray threshold probabilities of 10, 20, and 30%.</p

Analysis of 62 (k = 62) replicated studies comparing dollar spot control using the mean daily air temperature and mean daily relative humidity (ATRH) logistic dollar spot model to a calendar-based approach at spray threshold probabilities of 10, 15, 20, 25, 30, 40, 50, and 75%.

<p>Analysis of 62 (k = 62) replicated studies comparing dollar spot control using the mean daily air temperature and mean daily relative humidity (ATRH) logistic dollar spot model to a calendar-based approach at spray threshold probabilities of 10, 15, 20, 25, 30, 40, 50, and 75%.</p

Research sites used in model validation and threshold refinement for deployment of dollar spot logistic regression models for use in advising fungicide applications.

<p>All sites were included in the meta-analysis comparing the efficacy of the logistic regression model to a calendar-based spray program. All sites were tested on creeping bentgrass.</p

Adding a late fall application of Proxy (ethephon) before two traditional spring applications improves seedhead control of annual bluegrass

Annual bluegrass (ABG) (Poa annua L.) is a prolific seed producer in the spring on golf courses that in turn decreases aesthetic quality and trueness of ball roll on coolseason putting greens. Proxy (ethephon) applied twice in the spring after green-up is the current industry standard after the loss of Embark (mefluidide) from the turf and ornamental market. However, plant growth regulators including Proxy have been used for years to help suppressABGseedheads with inconsistent success. The primary objective of this study was to determine if ABG seedhead suppression is improved by adding a late fall application of Proxy to the two traditional spring applications of plant growth regulators at nine locations with diverse environments.Asecond objectivewas to determine the importance of including Primo Maxx (trinexapac-ethyl) in fall and spring applications. Adding a late fall application of Proxy prior to the two spring applications (F+S+S) improved control of ABG seedheads over the traditional two spring applications (S+S), but themagnitude of improvement varied among locations. When treatments were applied F+S+S, the industry standard tank mixture of Proxy + Primo Maxx provided consistent ABG seedhead control and turf quality, similar to Proxy + Fiata (phosphonate + proprietary pigment) and equal to or better than Proxy alone

Year, state, location, site, season, and number of observations when dollar spot severity data were collected for the development of logistic regression models.

<p>Year, state, location, site, season, and number of observations when dollar spot severity data were collected for the development of logistic regression models.</p

Dollar spot foci effect size in 34 (k = 34) replicated trials where fungicide was applied based on the ATRH model using a 20% threshold compared to the calendar-based approach.

<p>Dollar spot foci effect size in 34 (k = 34) replicated trials where fungicide was applied based on the ATRH model using a 20% threshold compared to the calendar-based approach.</p

Analysis of 89 (k = 89) replicated studies comparing dollar spot control using a logistic model-based approach to schedule fungicide applications with a calendar-based approach without accounting for spray decision threshold.

<p>Different environmental variables included in the logistic model-based approach were a combination of mean daily air temperature and relative humidity (ATRH) and mean daily relative humidity (RH).</p