Chemical growth retardants have been used on a limited scale to reduce mowing maintenance of turfgrasses. In recent years foam materials have served as carriers for pesticides and most recently for growth retardants. A foam carrier for retardants could offer the possible advantages of serving as an effective marker during application, reducing spray drift, and increasing growth retardant effectiveness. Four field studies were conducted in 1973 and 1974 at Carbondale, Ill. to compare foam application of growth retardants to conventional spray‐application on established turfgrasses. Three chemical growth retardants were tested on a ‘Park,’ Newport,' and ‘Delta’ blend of Kentucky bluegrass (Poa pratensis L.) and a pure stand of ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.) with three commercially available foaming agents.
Growth retardant treatments resulted in lower grass height and decreased dry matter yields. In general, N‐phosphono methylamino‐diacetic acid (MON‐820) gave the best results with 3‐trifluromethyl‐sulfonamido‐p‐acetotoluidide (Sustar) intermediate and diethanolamine salt of 6‐hydroxy‐3‐(2H)‐pyridazinone (maleic hydrazide) least effective. Considerable losses in green color occurred with retardant treatments that gave the best growth retardation. The foam materials Fomex and Foamspray used as growth retardant carriers were equally effective as retardants applied by conventional spray methods. Thermofoam was not effective as a growth retardant carrier.
Growth retardants in foam carriers proved effective in reducing growth of turfgrasses. These findings show that foam application of retardants to roadbank vegetation merits investigation. Feasibility studies should also be conducted on the possibility of marketing a selected growth retardant with foam in an aerosol spray can or garden hose attachment as a home lawn care product.