POPULATION DENSITY OF MITES IN SOYBEAN FIELDS AS AFFECTED BY NODULATION AND NITROGENOUS FERTILIZATION.

The experiment was conducted at Gemmeiza Agricultural Research
Station, Gharbia in 2003 season. The study aimed to find the effect of
nodulation (or not) of soybean seed with the microsymbiont Bradyrhizobium
japonicum as well as nitrogen fertilization applied as ground fertilization at 15
and 30 kg/fed, or as spray fertilization (three sprays) at 15 and 30 kg/fed.
Population density of the spider mite, Tetranychus cucurbitacearum (Sayed)
and soil mites were evaluated.
Results indicated that population density of the phytophagous mite,
T. cucurbitacearum on five leaflets increased significantly with nodulation, n-
fertilization applied as ground or spray fertilization at 15 and 30 kg/fed.
Ground fertilization (30 kg/f.) induced the highest increase in
population while the spray fertilization (15 kg/f.) caused the lowest number
when compared with untreated check.
Total population densities of soil mites : Gamasida, Actinedida,
Oribatida and Acaridida increased with nodulation and fertilization and this
was highly noticed with nodulation and 30 kg/f. ground fertilization. Soil mites
density increased according to plant growth stage all over the growing
season. Oribatida and Gamasida were dominant after third spray