Ground-cover-management systems by limited use of herbicides in young apple orchards

Trees (as whips without feathering) of the apple cv Florina/M.26 were planted into a sandy soil with low (1 percent) humus content and pH value of 5,1 (in KCL), in the spring of 1994. Soil trios of 120 cm in width have been covered (just after planting) with various materials like straw, livestock manure, black polypropylene and pine bark mulch, respectively. Check plots were treated by clean cultivation, or herbicide (Finale). At the beginning of the 2nd season all these has been completed by plots of living mulch established with Festuca pseudovina "Puszta". Young trees in all plots of groundcover materials produced considerably more shoot growth and increment of trunk circumference during the first two seasons. It was true for trees in plots of black polypropylene and pine bark mulch in the 3rd season, too. The living mulch of Festuca pseudovina provided a drastic retardation in vegetative development of trees. Flowering and yield of these young tress - in spite of significant differences in some cases - were not convincing enough to judgement real treatment's effects. Covering the surface of soil strips in the rows of new-planted trees proved to be real useful to preserve the water in the soil. Amount of nutrients in the soil has been affected depending on ground-cover management applied. There was hardly any weed population in plots covered, during the first season. Beginning from the middle of the 2nd summer, however, weed development throrugh the straw and livestock manure mulch became more and more intensive. The weed suppressing effect of pine bark mulch was slightly but it was the nest in plots of black polypropylene. The number of bacteria belonging to different physiological groups (e.g. nitrifying, aerob cellulolytic) increased as a result of groundcover with livestock manure or straw. Spore of arbuscular vesicular mycorrhizal (AVM) fungi, however, were more in rizosphere of trees in plots of pine bark mulch and black polypropylene, respectively. These AVM-fungi were identified mainly as Glomus and Acaulospora. A real evalution and comparison of ground-cover management systems will possible during the 4th season in 1997, i. e. in the year of the first crop of economic importance