PACE Turf - Turfgrass Information Center

Chemical and Cultural Controls for Moss, Bryum argenteum on Putting Greens

Summary: In two trials conducted at Friendly Hills Country Club, Whittier, CA, a variety of herbicides, fungicides, surfactants, algaecides and fertilizers were tested for their ability to decrease infestations of Bryum argenteum (silver thread moss) on a heavily moss infested poa/bent putting green. Key findings include:

  • Moss was positively identified as Bryum argenteum on the basis of leaf cell architecture (upper leaves with rhomboid-hexagonal cells) and the silvery-white color of the plants. A blue-green algae was consistently found in association with the moss.
  • The most effective treatments contained chlorothalonil (Daconil 2787 and Daconil Ultrex) or quaternary ammonia (RD-20), with up to 80% moss control achieved by the end of the 3 month trial. No phytotoxicity was observed with these treatments. The efficacy of these products may be related to their algaecidal activity.
  • Treatments which injured turfgrass (Lesco Iron Plus fertilizer, Ronstar 2G and Dimension) resulted in an overall increase in moss by the end of the study. Although these treatments initially injured the moss plants, lack of competition of from injured turf appeared to allow the moss to expand its invasion into areas of thinning and/or damaged turf.
  • Some treatments which were reported to control moss at other locations (Ferrous sulfate, Ultra Dawn, Subdue 2E mixtures) had no effect on moss populations in this trial. This may be due to the fact that all treatments were made using broadcast applications (2 - 4 gallons spray solution/1000 sq ft), rather than spot treatments. In a follow up trial investigating the use of Ultra Dawn applied as a spot treatment, drench-type applications (4 oz/gallon UltraDawn, applied in 80 gallons spray solution/1000 sq ft) were found to be extremely effective for control of moss.
  • If moss infestations are heavy, gradual removal of moss, as was observed using chlorothalonil or quaternary ammonia, is the most desirable strategy, since it avoids the appearance of large areas of dead or dying moss. However, if moss infestations are light, spot treatments with products that rapidly kill the moss may be the most effective strategy.

Printable version of full report

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

Cooperator: David Michael, Friendly Hills Country Club

Sponsor: Rohm and Haas, Zeneca, PACE Consulting


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).

Full print version of report

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

Efficacy of herbicides for Poa control on overseeded fairways

Summary: In replicated field trials conducted on common bermudagrass fairways that were overseeded with perennial ryegrass, rates and timing of various herbicides were evaluated for Poa annua control efficacy. Key results include:

  • Pre-emergence herbicides such as Dimension and Barricade continue to be most effective when applied prior to overseeding, as opposed to after overseeding.
  • Applications made post-overseeding required higher rates of Dimension (200 lbs/A of the 0.25G formulation) to achieve the same efficacy observed at lower rates (150 lb/A) applied before overseeding.
  • The efficacy and longevity of split applications was evaluated, but was difficult to assess, due to low populations of Poa annua.
  • None of the treatments tested caused damage to either ryegrass or bermudagrass.

Printable version of full report

Principal Investigators: Wendy Gelernter, Ph.D. and Larry J. Stowell, Ph.D., CPPP, CPAg Cooperators: Nancy Dickens, Mountain Vista Golf Course Sponsor: Rohm and Haas

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