EFFECT OF SOME AGRICULTURAL PRACTICES ON THE INFESTATION OF SOYBEAN (GLYCINE MAX L.) WITH TETRANYCHUS URTICAE (KOCH.) AND BEMISIA TABACI (GEN.) IN SOHAG GOVERNORATE

Document Type : Original Article

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Plant Protection Research Institute, Agricultural Research Center, Dokki, Giza, Egypt.

Abstract

This work was conducted in Shandweel Research Station, Sohag governorate, Upper Egypt during the two successive seasons, 2009 and 2010, to study the effect of some agricultural practices included sowing dates, irrigation intervals, nitrogen as well as phosphorus fertilization levels and row spacings on the infestation levels of soybean caused by sucking pests namely spider mite, Tetranychus urticae Koch. (Order: Acariformes Fam: Tranychidae) and whitefly, Bemisia tabaci Genn.(Order: Homoptera Fam: Aleyrodidae). The obtained results revealed that the population density of T. urticae was decreased significantly with delayed sowing date, whereas B. tabaci population was at their lower populations by earliness of sowing date numbers during the two seasons. Also, Soybean plants when irrigated every 14 and 21 days harboured the lowest numbers of both pests compared with irrigated at weekly intervals during the two seasons. On the other hand, combinede effect of sowing date (1st June) and irrigation intervals (every 14 and 21 days) showed the lowest infestation with T. urticae, while, sowing date (1st May) and irrigation intervals (every 14 and 21 days) showed the lowest infestation with B. tabaci during the two seasons. However, the population density of the two insects decreased significantly with the decreasing of both nitrogen and phosphorus fertilization levels. The combined effect of nitrogen levels (5 or 15 kg) N/fed and phosphorus levels (15 or 30 kg P2O5/fed) exhibited the lowest infestation with the two pests mentioned during the two seasons. Row spacing proved significant effect on both pests. The planting distance of 60, 70 and 80 cm between rows recorded the lowest average population density of the two pests during both seasons.

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