Abstract
Damage by Kanzawa spider mite to tea leaves is known to be exacerbated by nitrogen fertilization, but the relationship between the development of Kanzawa spider mite and the nitrogen content of tea leaves in response to fertilization is still not clear. In the present study, the effect of different amounts of poultry manure and chemical fertilizer applications on the nitrogen content of leaves and on development of the Kanzawa spider mite was investigated.
The total nitrogen content in new leaves from young tea plants grown in pod culture increased in response to the amount of chemical nitrogen fertilizer. Furthermore, the growth and oviposition rate of Kanzawa spider mite reared on leaf discs was enhanced in response to increasing total nitrogen content in leaves.
In a field experiment, young tea plants were grown without fertilizer or with poultry manure or chemical fertilizer containing equivalent amounts of nitrogen. Acidification of soil was most acute and EC was highest with chemical fertilizer, followed by poultry manure. However, although the total nitrogen content in new leaves was highest with poultry manure, the growth of Kanzawa spider mite on leaf discs was delayed.
These results suggest that increasing the nitrogen content in leaves by chemical nitrogen fertilizer stimulates development of Kanzawa spider mite; however, poultry manure inhibits mite growth even though it increases leaf nitrogen content.
