الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 99 |  |  |
| | | from | 99 | | |
Abstract
The present research work aimed to study the occurrence, distribution of plant parasitic nematodes in three governorates (Alexandria, El-Behera and Kafr El-Siekh), pathogencity and control of the citrus nematode Tylenchuulus semipenetrans study aimed to identificate plant-parasitic nematodes associated with citrus trees orchards, particularly specially and to eliminate the damages induced by this complex through applications of some bioagents, fungicides and nematicides. Summary of the present work showed the followings:
1. A survey study was conducted to determine the plant-parasitic nematodes associated with citrus trees in Alexandria, EL-Behera and Kafer-Elshiekh governorates. The results indicated that 9 nematode genera were present in the surveyed citrus trees orchards i.e., Tylenchuulus, Trichodorus, Rotylenchus, Helicotylenchus, Aphelenchoides, Tylenchus, Pratylenchus, Tylenchorhynchus and Meloidogyne.
In soil samples of the surveyed governorates, Tylenchuulus semipenetrans was the most common with 100% FO, and the highest population density (1105 – 7121 J2s /250g soil). The other nematode genera and their respective percentage of occurrence were; Trichodorus (16.4%), Pratylenchus (14.6%), Helicotylenchus (13.3%), Aphelenchoides (10.9%), Tylenchorhynchus (8.4%), Meloidogyne (3.6%), Rotylenchus (2%) and Tylenchus (0.23%).
2. The reaction of the citrus species sour orange rootstock (C. aurantium), mandarine (Citrus deliciosa) and lime (Citrus aurantifolia) to T. semipenetrans indicated that all the tested citrus species were susceptible to T. semipenetrans. Seedlings of the tested citrus species showed symptoms of slow decline disease such as smaller leaves, stunt growth and di-eback branchs.
3. The reaction of the grapevine cultivars Crimson and Thompson to the citrus nematode, T. semipenetrans indicated that the tested cultivars were susceptible to T. semipenetrans. Infection with T. semipenetrans reduced the shoot and root dry weights of the tested grape cvs Crimson and Thompson seedless.