ISHS Acta Horticulturae 422: International Conference on Integrated Fruit Production
CRITICAL PERIOD FOR WEED COMPETITION IN APPLE ORCHARDS: PRELIMINARY RESULTS |
| Authors: | D. Gut, E. Barben, W. Riesen |
| Abstract:
The critical period for weed competition in apple orchards describes the period when the tree strip must be kept free of weeds so that tree performance, as measured in the permanently weed-free control, is not adversely affected. It is not yet known when exactly such a period starts in spring and how long it must last. To answer this question four experiments at sites with different climatic and pedological conditions were started in 1990. Five tree strip ground cover treatments were established: permanently weed-free (control), permanent weed cover, weed-free from April to July, April to September, and May to July. Preliminary results of the experiment in Waedenswil show that the critical period starts shortly before blossoming (cv. Jonagold on M9). The vegetative and generative performance was not reduced when winter weed cover was removed about three weeks before blossoming. If weeds were not removed before blossoming, the fruit set was reduced and there seemed to be a certain compensation of the weakened generative sink by increased vegetative development (trunk growth). The length of the weed-free period required was not so clear: Under the Waedenswil site conditions a regrowth of weeds from June/July reduced yield compared to the control. With regrowth of weeds in September/October, yield and trunk growth were at least of the same magnitudes as in the control, while in 1993 the fruit size and the coloration were better than in the control. The results indicate that in putting down a temporary ground cover with spontaneous vegetation it would appear that N-management can be made to correspond to the requirements of the trees at a particular site. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
