engleski

Efficacy of reduced herbicide doses in winter wheat

The integrated systems of weed management tend to use a reduced quantity of herbicides. This paper describes previous results from Croatian trials in which effects of herbicide rates for winter wheat lower than recommended were examined. Field trials were carried out in 1996/97 and 1997/98 on lessive pseudogleyic soil. Experimental design was a split-plot with tillage as the main factor and weed control level as the sub-factor. The three continuous tillage treatments were: 1. conventional (ploughing, disk-harrowing) ; 2. chiselling, disk-harrowing ; 3. disk-harrowing. The herbicide mixture triasulfuron (7.5 g a. i. /kg) + chlorotoluron (792.5 g a. i. /kg) was applied at three dose rates: 600 g, 800 g and 1200 g a. i. /ha at the tillering stage of crop (Zadoks scale 25-29). The data express a reduction in dry weed biomass of dominant species compared to untreated plots 12 weeks after spraying (1997-1998). The dominant weed species were: Ambrosia artemisiifolia, Chenopodium album, C. polyspermum and Polygonum aviculare. Chemical weed control reduced the biomass of annual broad-leaved weeds efficiently at all three herbicide rates applied (94-100 persent control). The average yield level varied significantly (P 0.01) between years from 4372 kg in 1997 to 6305 kg/ha in 1998. In 1998 disk-harrowing tillage (3) reduced crop yields for 8 persent compared to the conventional tillage, but the differences were not significant. The half herbicide dose of triasulfuron+chlorotoluron (600 g a.i./ha) provided.

Winter wheat; Soil tillage; Herbicide doses; Grain yield

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