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
