الفهرس | Only 14 pages are availabe for public view |
Abstract The present work is designed to find suitable cheep friendly environmental methods as alternative to fungicides and nematocides for controlling root rot disease and root knot nematode of cucumber plants grown under greenhouse conditions. Results could be summarized as follow :- 1-Survey was carried out in different commercial greenhouse i.e El- Dokki , El- Haram , El- Noubareia , and Gazerit El- Dahab . Results indicated the highest infections were recorded in winter growing season, as compared to autumn growing season. Root rot disease recorded the high infections in autumn and winter growing seasons. While, root-knot nematode showed the moderate infections . 2- Fusarium solani was the most frequent isolated fungus from diseased cucumber roots . It occupied the first order ( 36.3 % ), followed by P. ultimum which occupied the second order ( 27.4 % ). R. solani has moderate frequency . 3-All isolated fungi were able to attack cucumber plants causing root rot symptoms. The most aggressive fungi were S. Rolfsii ( h ) and P. ultimum (d ) , they caused disease infection as 80.7 and 75.0 %, respectively. Meanwhile, R. solani (h) and F. solani (d ) showed moderate aggressiveness against cucumber plants ., Laboratory experiments 4- The lethal temperatures to R. solani , F. solani , S. rolfsii and P. ultimum were 54.0 , 58.0 , 56 or 58.0 oC and 52.0 , 56.0 , 54.0 and 56.0 oC when were exposed to temperatures for one minutes as agar disks with mycelia or growth suspension respectively . 5- Chlamydospores are more resistant to hot water which they killed at 64 oC while Sclerotia were killed at 58.0 and 60.0 oC for R. solani and S. rolfsii respectively when exposed to hot water for one minutes Sublethal temperatures significantly reduced the linear growth , resting stage production and resting stage germination of all root rot fungi. 7- The lethal temperatures for M. incognita was 44, 46, 48, and 50 oC when the exposures time as 30, 20, 10 and 1 minutes respectively. Pot experiments 8- The highest increase in soil temperatures was obtained with boiling water at the rate of 0.4 to 1.0 L / kg soil, which increased soil temperatures ranged between 78.0 to 94.0 oC with sandy , loam and sandy- loam soil. 9- The highest increase in soil temperature was obtained with hot water temperature degrees at 80.0, 90.0 and 100.0 oC at rate 0.5 L / kg soil, which increased soil temperatures ranged between 67.0 to 84.0 oC with sandy , loam and sandy- loam soil. 10- Different volumes of hot water at 95- 100 o C i.e. 0.0, 0.2 ,0.3 , 0.4 and 0.5 L / kg soil applied as soil treatment were tested to study their effect on soil temperatures , total count of root rot fungi , soil microflora and J2 of nematode in soil in addition to root rot and root knot nematode incidence of cucumber plants under pot experiments. 10-1-Effect on soil temperatures Results indicated that the highest increase in soil temperatures was obtained with hot water at the rate of 0.4 and 0.5 L / kg soil, which increased soil temperatures to 74.0 and 82.0 % respectively . 10-2- Effect on total count of root rot fungi Results indicate that complete reduction in total count of all tested fungi was obtained with hot water at 0.4 and 0.5 L / kg soil. Hot water at 0.3 L / kg soil reduced the total count more than 74.0 % for all tested fungi.. |