THE USE OF PROPANE BURNERS FOR CONTROL OF ANNUAL BLUEGRASS (POA ANNUA L.) IN SOD PRODUCTION

At present, there is no herbicide registered for use in Canada to control annual bluegrass in sod production. Under serious infestations, aesthetic qualities are reduced and sod harvest becomes more complicated. The efficiency of propane burners to control annual bluegrass was tested in a trial initiated in Spring 1993. Specific objectives were to determine the appropriate period for treatment application and the heat intensity required for optimal control. Twenty-one plots (13 × 3 m) were treated with a conventional burner; a similar group was treated with a pipe burner. In addition to an untreated check, the combination of two tractor-burner speeds (3.6 and 5 km·h-1) and three gas pressures (20, 30, and 40 psi) made up the seven treatments. Randomized complete blocks were used and each treatment was replicated three times. The sod recovered well from all heat treatments. After 3 weeks, the best heat treatment reduced the annual bluegrass population by 70%. Unfortunately, this reduction lasted for about 1 month, after which the annual bluegrass population recovered. At best, weed population was reduced by 40% when evaluated in mid-September. Another trial is planned to identify environmental and edaphic factors that may reduce the effectiveness of heat treatments in controlling annual bluegrass in sod production.