Effect ofPlanting date , Potassium fertilization and some chemical & biological treatments on population density ofThrips insect Thrips palmi Karny (Thripidae: Thysanoptera) on Cucumber plants (Cucumis sativus L.)

Abstract

This study was conducted in a field belongs to the faculty ofagriculture/ Baghdad University during autumn season 2012 to evaluate the complimentary effects ofsome agricultural, chemical and biological methods in reducing the population ofThrips (Thrips palmi Karny) on cucumber plants Cucumis sativus L. in middle ofIraq(Baghdad-Abugraib). Results showed that all chemical and biological treatments had similar negative effects on population oflarval and adult stages ofthrips. Means were 0.840, 0.470, 0.602 and 0.545 insect/leaf where plants were treated with fungus Beauevria bassiana, fungus Trichoderma harzianum, insecticide Talstar, Talstar+B. bassiana or Talstar + T. harzianum, respectively, compared to significant high population, 2.487 insect/leaf resulted from the control treatment. Fertilization levels interacted differently with different treatments and significantly reduced insects population especially when level ofpotassium (P) was increased, a 50 kg ofP /donum suppressed insects population to 0.664 insect/leaf compared to recommended P level, 25 kg/donum that resulted in 1.203 insect/leaf. Thrips population was also affected by the two P levels where interacted with two planting dates. A combination of50 kg/donum, doubled P rate applied at 1st sep. 2012 was more effective in reducing insects population than 25 kg/donum applied at 1st Aug. 2012, means were 0.544 and 1.437 insect/leaf, respectively.