Alternative methods of weed control in apple orchards

The efficacy and cost of three alternative methods of weed control were compared to the traditional chemical method. 1) Flaming method was performed in 7 day intervals, three times. The most resistant perennial weeds were Taraxacum officinale Weber and Leontodon autumnalis L.. From annual weeds the most vigorous species was Polygonum aviculare L.. Flame weeding with lower driving speed gave good reduction of annual species in early growth stages (cotyledons to 4 true leaves). To obtain a higher efficacy of vigorous weeds, perennials, weeds in later growth stages and weeds with higher intensity of germination, the repetition of treatments were required. 2) The treatments of the hot-steam method were performed at 1 km.h-1 driving speed, in 7 day intervals. The 1st weed counting was executed after the first hot-steam application. The 2nd and the 3rd weed counting were performed after the second treatment. This technology was less effective on perennial weeds. The efficiency in the 1st week was better than the 2nd week after the 2nd treatment. The most resistant species were Linaria vulgaris Mill. and Polygonum aviculare. For higher reduction of vigorous weeds and for the longer time effect, the repetition of treatments are necessary, maximum 2 weeks after previous treatment. 3) Mulching was a very good alternative method to herbicide use and the best results of weed control were obtained in the following order: saw dust-coarse bark-hay (weed reductions were as high as 99,4% with saw dust, 99,3% with coarse bark and 96,0% with hay). The most dominant weeds were : Rumex accetosella L., Sonchus arvensis L., Taraxacum officinale and Chenopodium album. Only one application of post-emergence chemical weed control was performed. 2.2 kg.ha-1 of Simazine, 1 kg.ha-1' of Paraquat and 1,000 L of water were used. Chemical application was effective method for weed control during 2 to 3 weeks after treatment. Very resistant species was Hypericum perforatum L. The effect of herbicide application was best during the 2nd and maximum the 3rd week after the application of the 2nd treatment due to its residual effect. Later on, more new weeds germinated and emerged to a greater extent and the repetition of treatment was inevitable.