An Investigation Into Cultural Approaches for Weed Control in Pesticide-Free Home Lawns.

In Ontario traditional pesticides are not permitted on home lawns. Without the use of pesticides, a greater emphasis must be placed on cultural practices to maintain healthy turfgrass swards. This study is examining several methods of renovating a weedy home lawn without pesticides and how post-renovation maintenance programs impact weed pressure in simulated home lawn environments at the Guelph Turfgrass Institute, Guelph, ON, Canada. Renovation methods were performed both in the spring and fall and treatments included aeration, roto-tilling, scalping, and seeding directly into an existing lawn.  Post renovation practices include fall core aeration, spring power raking, fall core aeration + spring power raking, a positive herbicide control of 2,4-D / dicamba /mecoprop, and a negative control of no maintenance practices. The various lawn maintenance methods are being performed in conjunction with and without overseeding. Results indicate that renovation in the spring increases the number of annual weeds in the roto-tilled plots, while fall roto-tilling has no annual weeds present, but results in more perennial turf weeds being established. Overall weeds are initially reduced by 5-15% by the renovation practices.  Of the post renovation practices the spring disturbance of power raking has the potential to lower weed population levels to levels that are not statistically different from the positive herbicide control, however timing with the weather so that the disturbance occurs during the cool wet weather of the spring plays an important role in weed control and turfgrass recovery.  Overseeding does not have an affect on weed population levels, however it does promote a thicker stand of turf.