Abstract:
Weeds interfere with turfgrass growth lowering functional and aesthetic quality of lawns.
Conventional weed control using synthetic pesticides is hazardous to lawn users and to the environment while cultivation alone is not sufficient. A study was conducted with the aim of exploring the potential of biofumigation with African spider plant (Cleome gynandra) as an environmentally friendly alternative to use of synthetic herbicides for establishment of weed-free Paspalum notatum turfgrass. Chopped Cleome gynandra incorporated into the soil at 4, 6 or 8 kg m-2 was compared with Basamid® (97% Dazomet) at 0.029 kg m-2 (positive control) and untreated (negative control) in a randomized complete block design experiment with four replications. Population of various weed species in the experimental plots was recorded weekly. Total fresh and dry weight of the weeds was also determined after weeding the plots. Paspalum plug width and height were measured every 14 days and sprig internode length, leaf length, leaf width, fresh and dry weights were measured on monthly basis to determine treatment effect on the growth of the turfgrass. Treatment effect on aesthetic quality was visually determined monthly using a rating scale of 1 to 9 to evaluate uniformity, colour, density and overall quality. Rating was based on the differences observed, nine being the outstanding treatment and one the poorest. The data collected were subjected to analysis of variance. Biofumigation with Cleome gynandra at rates of 6 or 8 kg m-2 was as effective as Basamid® at 0.029 kg m-2 in significantly
suppressing Galinsoga parviflora, G. ciliata and Bidens pilosa weed populations. Highest plug growth was obtained with Cleome gynandra at rates of 8 kg m-2 and Basamid® at 0.029 kg m-2 and untreated plots had the lowest plug growth. Biofumigation with Cleome gynandra at all the three rates: 4, 6 and 8 kg m-2 resulted in faster sprig growth than the negative control and although not significantly different from the positive control, numerically the growth rate was higher. Overall visual quality of paspalum turfgrass grown on plots treated with Cleome gynandra at 8 kg m-2 or 6 kg m-2 was as good as that of Basamid® 0.029 kg m-2. Negative control displayed the lowest overall quality in both trials. These results suggest that biofumigation with Cleome gynandra is as effective as Basamid® in suppressing weeds during lawn establishment and enhancing growth and aesthetic quality of the turfgrass.
