STRATEGIES FOR EFFECTIVE WEED CONTROL IN THE FUTURE

Abstract

At present weed control in flowerbulb crops in the Netherlands is carried out mainly with chemical herbicides. To reduce the use of and/or the dependency on these herbicides, a program was started to find new methods for effective weed control in the future. Three different strategies were pursued, viz. covering of the soil, low-dose applications of herbicides and mechanical weed control. Some experimental data will be presented on weed control by these techniques. In some experiments the soil was covered with old straw during the whole growing season. This thick and undisturbed straw layer prevented germination and growth of weeds well. In summer, between two successive bulbous crops, covering the soil with intercrops such as Raphanus, Sinapis or Phacelia, can be succesfully used. Effects of intercropping on yield, and on disease and pest incidence are under present investigation. The principle of low-dose application systems for herbicides is that one or more contact-herbicides are well-timed and are applied at very low dosages on tiny herbicide-sensitive weed plants. Such a low-dose application system, based on the herbicide metoxuron, was developed for gladiolus and iris. Progress was also made for dahlia, lily and narcissus. Tulip and hyacinth crops have proved to be very sensitive to contact-herbicides. Consequently, development of low-dose application systems for these crops is not yet possible. Some experience was gained with mechanical weed control within bulbous crops using harrow- and hoe-equipment. First results indicate that this technique may be effective if applied in combination with (a) herbicide treatment(s) in the planting row. To optimize the effect of mechanical weed control, a change of the planting system of bulbs may be necessary.