Phytosanitary function of crop rotation is a known fact, so one of the basic motives for this work was to investigate its influence on the population densities of plant-parasitic nematodes. Long-term experiments, which are still in progress, were set up on luvic semigley on multi-layered Pleistocene sands on the experimental field of the Tobacco Institute Zagreb at Pitomača. Along with tobacco monoculture, investigations also included seven different types of crop rotations. As key crop, tobacco is included in all crop rotations. Results obtained indicate that presence of the population of endoparasitic nematodes, genus Pratylenchus, was to some degree crop dependent. Tobacco does not seem to stimulate intensive occurrence of this nematode population. However, as soon as it is included into crop rotation, the number of nematodes increases particularly in crop rotations involving a larger number of rotation fields. Soybean and oil-seed rape favour the spread of Pratylenchus species. Still, no alarming incidence of nematodes belonging to this genus was recorded. Ectoparasitic nematodes involve genera Tylenchus, Tylenchorhynchus and, to some extent, Paratylenchus, while incidence of genera Helicotylenchus and Rotylenchus is negligible. Members of these genera are no dangerous pests for the crops studied, even more so as they mainly appeared in populations that are not noxious. The established opinion about the population of saprophagous nematodes being more dependent on the amount of soil organic matter than on the crop type was not convincingly confirmed in this research.

Crop rotations; plant-parasitic nematodes; tobacco monoculture

Published by University of Zagreb, Faculty of Agriculture, Zagreb, CROATIA
Sponsored by Ministry Science and Education of the Republic of Croatia