الفهرس 
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Abstract
Wheat is one the major cereal crop for human in Egypt and world, and leaf rust of wheat caused by Puccinia recondita f.sp. tritici is the most important diseases in Egypt. This study was concerned with the epdidemioloy of leaf rust in Egypt in relation to ecological conditions. Results obtained in this study can be summarized in the following: 1- Correlation between meteorological factors and wheat leaf rust. 1. Cleat differences was observed in reaction of 6 wheat cultivars to leaf rust infection during the period from 1989-1993. The cultivar Giza 160 was highly susceptible followed by Giza 155 which was moderately susceptible. However, Sakha 92 was moderately resistant, whereas Giza 157 was resistant and the two cultivars Sakha 8 and 69 were highly resistant. A regression equation between different meteorological factors and rust reaction on different cultivars such correlation was adaptable with susceptible cultivar Giza 160 and Giza 155 and then Sakha 92. 3. The analysis of regression equation proved a correlation between disease intensity on Giza 155 and Sakha 92 and temperature degrees, meanwhile positive correlation was found on Giza 155 between disease intensity and amount of rainfall. On the other hand, the highly susceptible cultiver Giza 160 exhibited positive correlation between rust severity and relative humidity and negative correlation with minimum temperature. 4. High intensity of wheat leaf rust was detected in compatible cultivars at Sakha location than those on Giza. 5. Progress of leaf rust severity on wheat cultivars during March, April, 1993 at Sakha location recorded that no leaf rust obtained before the first of April, however at Giza location in the middle of the same month, at Sakha it reached to maximum values on the end of April, rust severity was more clear in the susceptible cultivars Giza 160 and Giza 155. 6. Area under disease progress curve was positively correlated to each others on Giza 160, Giza 155, Sakha 92 and 157 according to their susceptibility. 7. Etay-El-Barood showed the highest recorded infection on the susceptible cultivars, Noubaria and Gemmiza followed the high scale of leaf rust severity after that. 8. Giza 160 was the most susceptible cultivar to leaf infection of different locations. Giza 155 and Sakha 92 were much less infection values, on the other hand, highest resistance was detected for Sakha 8 followed by Sakha 69 and Giza 157. 9. Leaf rust reaction was at the lowest values in Sids which recorded higher range of temperature and lowest amount of rainfall. 2- Effect of temperature on slow-rust components of leaf rust on two wheat cultivars in relation to growth stage. 1. Latent period decreased by raising the temperature degree, a significant increase was observed in latent periods with Giza 155 than in Giza 160, and this was more clear at growth stage 30. 2. The latent period of leaf rust disease recorded significant increase with the advancement in plant age of Giza 160 and Giza 155, however the former more susceptible exhibited more response for such phenomenon. Number of pustule was greatly affected with temperature degree where high significant increase was detected as the temperature varied from 12-14oC to 24oC. 3- Effect of meteorological factors on leaf rust germination and appressorium formation. 1. Spore germination and appressorium formation were more greater under environmental conditions of temperature ranged 20-22oC and plant sprayed with water than under 16-18oC and non sprayed plant. 2. On all tested cultivars, spore germination and appressoria formation increased after 48 more than after 24 hours. No clear differences wee observed between the cultivars under the same conditions of temperature and humidity. 4- Effect of ethephon and cobalt against feat rust on wheat. 1. Ethephon treatment was more effective in all selected cultivars than cobalt treatment and the effective was greater on the resistant cultivars, and high levels of ethephon 1200 ppm and cobalt 1 ppm remarkably decreased number and size of pustule and achieved certain degree of resistance against leaf rust. 2. Ethephone treament changed the infection type of Giza 165 from type 2 to type 0 and from type 3 to type 2 with Sakha 92 and from type 4 to type 3 with Giza 155. Moreover, seed treatment with ethephone reduced the size and number of pustules and the reduction in the number of pustules was 100, 67.48 and 72.84% on Giza 165, Sakha 92 and Giza 155, respectively at 1200 ppm.