الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Citrus trees are considered to be the most produced fruit trees in egypt and all over the world several plant parasitic nematodes are recorded to attack the root system of citrus plants. the citrus nematode, tylenchulus semipenetrans cobb. is the most important one. infestation by citrus nematode can result in the disease named ”slow decline”. the occurrence of high populations of this nematode caused the encrusted appearance of the root due to soil particles that adhere to egg matrix (dirty roots) infests a large proportion that ranged from 812% of the total world citrus growing area. the obtained results could be summarized as follow : 1 plant powders tested by the preplant application method, marigold, tagetes erecta at 10/pot gave the highest percentage of increase of plant growth parameters as well as the high of nematode reduction infecting sourorange, citrus aurantium l. seedling under greenhouse conditions at 25±5°c. 2 horse manure as soil amendments at 10/pot by the preplant application method on sourorange seedling infected with t. semipenetrans, appeared to be the most effective in increasing plant fresh weight and shoot dry weight as well as reducing nematode population under greenhouse conditions at 25±5°c. 3 protecto product (bacillus thuringiensis) as a biological agent at 0. 01g/pot as well as n, p, and k ; and total chlorophyll contents status of lemon plant citrus limon l. infected with t. semipenetrans, increasing plant growth parameters as well as reducing nematode population under greenhouse condition at 17±5 m°.