[Effect of weed control with residual herbicides on the establishment of an apple orchard]
1993
Papic A, Eduardo Jose
During 1991-1992 and 1992-1993 growing-seasons, the effect of weed control due to the use of residual herbicides in the establishment of an apple orchard (Malus comunis), c.v. Roval Gala over a seedling rootstock, was evaluated. The orchard was established on September, 1991, on a sandyloam soil, with 5% o.m. content. Prior to the application of herbicides, plants were topped to a height of 90 cm 15 days later, the following herbicides were applied: - napropamide, at a rate of 2, 3, 4 kg a.i./ha, - diuron, at a rate of 2.4, 3.2, 4 kg a.i./ha. The effects of herbicides and dosages were evaluated by measuring the trunk diameter at 30 cm above soil level, and the increase in length of branches. Data were taken at 15 day intervals, for a period of 150 days. Also, 0.25 m2 samples of ground cover were sampled for each treatment 3 times during both seasons. From each sample, weeds were separated by families and species, and their dry weight expressed in dry matter/m2. The efficiency of both herbicides was evaluated using Abbot's formula in both seasons. Best efficiency (percentage) was obtained with the highest dosage and with the total weed control. In order to improve the control of a wide range of perennial weeds, one application of a systemic herbicide is recommended during springtime. Control of narrow-leaf weeds was almost complete with both herbicides, at all dosage tested. Therefore it is appropriate to use either herbicides at the lowest rate
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