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.
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
Pre-emergent Herbicides for Control of Smooth Crabgrass
Summary: In a replicated field trial conducted on a hybrid Bermudagrass tee at La Jolla County Club, La Jolla, CA, residual activity, various formulations, rates and application timings for the herbicides Dimension, Barricade, Ronstar and Pendulum were evaluated for pre-emergent control of smooth crabgrass, Digitaria ischaemum. Key results included:
- In warm winter climates such as California, it is possible that applications of pre-emerge herbicides for control of crabgrass can be made later than the manufacturers currently recommend (current recommendations are to treat when soil temperatures reach 50 - 55° F), thus extending the activity of these products into the summer months. This is based on our observation that soil temperatures at La Jolla CC reached 50 - 55° F on 3/3/97, but crabgrass seedlings didn't emerge until 5/5/97--a full two months later.
- The best performance (100% control for 4 1/2 months) came from Dimension 1EC at either 1.5 oz/1000 (applied once on 3/3/97) or 0.75 oz/1000 (applied twice on 3/3/97 and 5/5/97), Pendulum 60 DG, at 1.8 oz/1000 (applied once on 3/3/97), a single application of Barricade 65 WG, applied at 0.55 oz/1000, and split applications of Barricade 65 WG (applied 3/3/97 and 5/5/97) at either 0.28 oz/1000 followed by 0.28 oz/1000, or 0.37 oz, followed by 0.18 oz/1000.
- Lower rates of Barricade did not perform as well as either the high rate of Barricade or the split applications of Barricade, and the granular formulation of Dimension did not perform as well as the Dimension 1EC formulation.
- For reasons that are not clear, the performance of Ronstar 2G was equivalent to that of the non-treated control throughout the trial.
- The most effective products had a residual activity of 140 days (4 1/2 months).
Investigators: Wendy Gelernter, Ph.D. and Larry J. Stowell, Ph.D., CPPP, CPAg
Cooperator: Bruce Duenow, La Jolla Country Club
Sponsors: Dennis Shepard, Novartis; Randy Smith, Rohm and Haas
