PACE Turf - Turfgrass Information Center

Warm Fall 2003 Impacts Overseed in Southwest

The moans and groans started when September average air temperatures stayed stuck above 90F (with maximum temperatures hovering over 100F), and escalated to sobbing, kicking and screaming when they stayed high (rarely dipping below an average of 80F) through the first three weeks of October.  In short, all of the elements for a difficult overseed were in place during the Fall of 2003.  For while the objective of overseeding is to encourage the growth of cool-season turf types such as ryegrass and Poa trivialis, and to discourage the growth of bermudagrass, the weather this autumn conspired to create exactly the opposite effect.  The above-average weather this fall has been absolutely ideal for bermudagrass, which flourishes when air temperatures are between 75 and 100F.  These same warm temperatures have weakened the growth of ryegrass and Poa trivialis, both of which prefer lower air temperatures between 60 and 75F. When average temperatures climb to above 80F, ryegrass and Poa trivialis take a big dive. The survival of these cool-season turf types is further compromised by the fact that bermudagrass growth escalates rapidly at these temperatures, crowding out the weaker rye and Poa triv stands.

Letter describing the problem

PACE Clubhouse Edition prepared for HiLo GCSAA

Effect of Primer Applications on Nutrient Leaching in Turfgrass Greens

Summary: A replicated experiment was designed to evaluate the effect of Primer on the leaching of nutrients on a Poa annua golf course green. Following six monthly applications of Primer at 6 oz/1000 square feet, analyses conducted on soil samples from 1, 2 and 4 inches depths revealed no significant differences between treated and untreated plots in levels of over 20 nutrients including, sodium, magnesium, calcium, total salts, and even the highly leachable potassium. In addition, no phytotoxicity and no effects on turf quality were observed in areas treated with Primer. On the basis of these results, multiple applications of Primer to turfgrass do not increase leaching of nutrients in the soil.

Full print version of report (123 KB)

Investigators: Wendy Gelernter, Ph.D. and Larry J. Stowell, Ph.D., CPPP, CPAg

Cooperator: Mark Schaer, San Luis Rey Downs

Sponsor: Stan Kostka, Aquatrols

Effect of Primo on overseeding

As detailed in the Super Journal report, "Evaluation of Primo rates and application: timing strategies for improved transition and turf quality on common bermudagrass fairways" (476 KB pdf document), trinexepac-ethyl can have both positive and negative effects on turfgrass quality. Key findings included:

  • Of the 41 treatments tested (4 rates, 5 timing strategies and single vs. double applications), we found that Primo treatments made at the time of the first ryegrass mowing (on October 23, 1996, or 1 day after the first mowing) resulted in an improved Fall transition from bermudagrass to ryegrass and significantly higher quality ryegrass during the critical winter and spring months than other treatments tested.
  • The most economical of the highest ranked treatments was a single application of Primo Liquid at 0.5 oz/1000 sq feet, applied on 10/23/96.
  • In contrast, Primo applications made later in the Fall (October 30, 1996, or 8 days after the first mow), produced a negative effect on turf quality during the 1997 Spring transition.
  • These results confirm that the currently labeled rate of 0.5 oz/1000 square feet for use of Primo Liquid in overseeding programs is the optimal rate for use in overseeding programs in the Low Desert, but that the currently recommended application timing (1 - 5 days before overseeding) may need to be adjusted. To confirm the results of this study, a 1997/98 trial that re-tests the highest ranked treatments from this year's study is recommended for initiation in September, 1997.

Project title: CEvaluation of Primo rates and application: timing strategies for improved transition and turf quality on common bermudagrass fairways

Principal investigators: Wendy Gelernter, Ph.D. and Larry Stowell, Ph.D., CPAg, PACE Turfgrass Research Institute

Cooperators: Tom Baty, Indian Wells Country Club

Sponsors: Hi Lo Desert GCSA and Novartis


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