M. H. A. Hassan

Salicylic acid induced systemic resistance on onion plants against Stemphylium vesicarium.

Abstract This study investigated the induced defense responses and protective effects against Stemphylium vesicarium by application of Salicylic Acid (SA). The effect of SA to induce resistance in onion plants against Stemphylium vesicarium was investigated in greenhouse conditions. Different doses of SA (1, 2 and 5 mM) were tested in vitro; growth of S. vesicarium was not affected by SA treatment, foliage sprays of 2 mM SA significantly suppressed disease development up to 40.39% by day 15 after inoculation under greenhouse conditions. Changes in the activities of peroxidase, polyphenoloxidase, SA and phenolic content on onion after application of SA and inoculation with S. vesicarium were studied. Onion plants treated by SA and inoculated with the pathogen showed significantly higher peroxidase, poly phenoloxidase, SA content and phenolic content than inoculated water-treated plants.

Powder formulations of Bacillus subtilis, Trichoderma spp and Coniothyrium minitans for biocontrol of Onion White Rot

Abstract In vitro, B. subtilis, T. harzianum, T. viride, T. spirale and C. minitans isolates showed different inhibitory effects against the growth of S. cepivorum. T. harzianu. While T. spirale showed the greatest antagonistic effect to the pathogen, followed by T. viride and B. subtilis isolates. However, isolates of C. minitans showed a slight antagonistic effect. In greenhouse experiments, the application of the tested powder formulations of bacteria and fungi to infested soil at the time of planting and two weeks before transplanting, significantly reduced the incidence of white rot on Giza 6 onion cultivars. The application of bacterial antagonists two weeks before transplanting resulted in the highest reduction of disease incidence. However, a similar reduction in disease severity was detected when the tested fungal antagonists were applied at the time of transplanting or two weeks later. The use of these bioagents in the form of powder formulations as soil treatment could be recommended for the control of white rot in onion.

Effect of mycorrhiza and biofertilisers on reducing the incidence of Fusarium root and pod rot diseases of peanut

Pathogenicity tests of twenty-six fungal isolates were tested on peanut plants (Giza 5 cv.) and the results revealed that, Fusarium oxysporum isolate (No. I) followed by F. solani (No. II) then F. moniliforme (No III) significantly caused highest incidence of root rot disease. Also, F. moniliforme (No III) followed by F. solani (No II) then F. oxysporum (No I) gave the highest incidence of pod rot disease. The effectiveness of vescular arbuscular-mycorrhiza (VAM) at different application rates on the incidence of root rot, pod rot diseases and plant growth parameters of peanut was studied. All soil treatments with each rate of VAM significantly reduced root and pod rot diseases compared with control (rate 0%). The best reduction in the severity of both diseases with VAM was found at the rate of 3%. Application of rhizobacterin, microbin and cerialin biofertilisers at the different concentrations decreased the severity of both root rot and pod rot severity diseases compared with non-treated seeds. The greatest reduction in both diseases was achieved at a concentration of 8/100 g seeds. The highest number of pods and fresh weight (g) was achieved in seed supplemented with each biofertiliser at concentration of 8/100 g seed.

Management of Charcoal Rot of Sesame by Seed Soaking in Medicinal Plant Extracts and Hot Water

Macrophomina phaseolina causing charcoal rot was isolated from sesame seeds (cvs. Giza 32 and Shandawel-3) collected from different localities of Assiut, Sohage and El-Minia Governorates. The fungus was found in the highest frequently in samples collected from Assiut Governorate followed by Sohag and finally EL Minia Governorate. The obtained isolates were different in their virulence on the tested sesame cvs. Also, they differed in their growth nature including colony color and sclerotial production. The color of colonies of the pathogen seem to be correlated with density of sclerotial formation. Aqueous extracts of Majorna, Wild chamomile, Geranium oil and Nees plants were highly toxic to tested isolates of M. phaseolina, in vitro. On the other hand the rest of the tested aqueous extracts had no effect. Under greenhouse conditions in 2005 and 2006 seasons, soaking seeds of sesame before sowing in aqueous extracts of Eucalyptus, Nerium, Ocimum and Roesmary plants decreased the disease incidence. Aqueous extracts of Eucalyptus and Ocimum were the most effective treatment. Dipping sesame seeds in hot water at 60 oC for 5 minutes increased seed germination of Giza 32 and Shandawel-3 cvs. followed by 55 oC, 50 oC and 45 oC, while 40 oC treatment resulted the lowest seed germination rate. Dipping sesame seeds in hot water at different temperature before planting decreased seed, seedling and charcoal rots. Soaking seeds in hot water at 60 oC increased greatly plant height and decreased seed, seedling rot and charcoal rot followed by 55 oC and 50 oC, under greenhouse condition.

Role of certain potato tubers constituents in their resistance to bacterial soft rot caused by Erwinia carotovora pv. carotovora.

Erwinia soft rot causes destructive and serious damages to many vegetable crops including potato, in the field, transit and storage periods. The role of certain potato tuber constituents in the physiology of disease resistance has been investigated. Pectin substances and calcium contents of potato tuber had a pronounced role in the physiology of disease resistance. Alpha and Santa (less susceptible cultivars) contained the higher amount of pectin and calcium compared by Mirkal, Diamant, Askort, Geganite and Nicola cultivars (more susceptible cultivars). Tubers extracts of all healthy tested potato tubers cultivars contained fructose except Santa cultivar and glucose except Alpha and Mirkal cultivars. Tuber extracts of the more susceptible cultivars (Nicola and Askort) contained a higher concentration of glucose and fructose than those of less susceptible cultivars (Geganite, Mirkal, Santa, Alpha and Diamant).

Effect of certain cultural practices on susceptibility of potato tubers to soft rot disease caused by Erwinia carotovora pv. carotovora.

Erwinia soft rot causes destructive and serious damage to many vegetable crops including potato in the field, transit and storage periods. The effect of certain cultural practices on the susceptibility of potato tubers to soft rot bacteria was studied and the results of this work can be summarised in the following: potato tubers harvested on 1 May first exhibited the highest disease incidence compared with those harvested on 15 May or 30 May. Harvesting on 15 June resulted in the lowest disease infection. The application of high levels of nitrogen fertiliser as urea (46.5%), ammonium nitrate (31%) and ammonium sulphate (20.5%) resulted in an increase of the susceptibility of potato tubers to bacterial soft rot disease. In contrast, the addition of phosphorous as superphosphate (15.5%) fertiliser caused the reverse effect. The addition of potassium as potassium sulphate (48%) alone at any of the tested levels showed no effect. The susceptibility of potato tubers to bacterial soft rotting disease was increased by increasing storage periods at 4°C for 1, 2, 3 and 4 months. Spraying copper sulphate exhibited the highest decrease in soft rot incidence disease followed by manganese, zinc and iron. However, spraying of boron increased susceptibility to the disease. Potato tubers obtained from plants sprayed with copper and stored for different periods showed the lowest susceptibility to disease incidence. Tuber sprayed with zinc, iron, manganese and finally boron came next.

Enhance Suppressive Effect of Compost on Soybean Rhizoctonia Root Rot by Soil Treatment with Trichoderma harzianum

Enhance Suppressive Effect of Compost on Soybean Rhizoctonia Root Rot by Soil Treatment with Trichoderma harzianum This study deals with in vitro, under greenhouse, and field efficacy of Trichoderma harzianum (Th1 and Th2), and two types of compost, plant compost (PC) and animal compost (AC) to control the soybean root rot disease caused by Rhizoctonia solani. In vitro study indicated that, Trichoderma spp. isolate Nos. 1 and 2 were the most effective on the pathogen growth, also both composts at 50% concentration were effective on the growth of the pathogen.

Molecular characterization of Rhizoctonia solani isolates the incitant of soybean root rot

Rhizoctonia solani isolates used in this investigation were identified as anastomosis-4 (AG-40), collected from different localities from Assiut governorate in Egypt. Pathogenicity test of seven isolates of R. solani was evaluated on soybean Giza 111 cultivar under greenhouse conditions. All tested isolates were able to infect soybean plants causing root rot with different degrees of severities, isolate No. 1, 2 and 3 showed significantly highest root rot severity, while isolate No. 5 gave the lowest percentage of root rot rating. The sodium dodecyl sulphate polyacrylamide gel electrophoresis patterns were used to compare three isolates of R. solani. There are no variations among R. solani isolates except a few exceptions according to their protein patterns. DNA markers obtained from all isolates showed genetic similarity among different isolates obtained from different geographical regions barring few exceptions. Correlation between DNA patterns of R. solani isolates and their virulence was detected, but no correlation with anastomosis groups (AG).

Integrated control of root rot and wilt disease of faba bean by soil amendment with suppressive compost in combination with seed coating with an antagonistic yeast

For this study, 21 isolates of fungi belonging to Rhizoctonia and Fusarium genera were isolated from the diseased faba bean plants, obtained from the different localities in Assiut governorate, showing root rot and wilt symptoms. The isolates proved to be pathogenic on Masr 1 faba bean cultivar under greenhouse conditions. F. oxysporum isolates caused wilt disease; however, the isolates of R. solani and other Fusarium species caused root rot. The virulence of isolates on the tested faba bean cultivar was different. The highly pathogenic isolates of these fungi were employed in this study. The effect of soil amendment with Planta Rich and Rich Composts (CMs) alone or in combination with seed coating by the antagonistic yeast Pichia guilliermondi before sowing on the severity of Rhizoctonia and Fusarium root rot and Fusarium wilt of faba bean was tested under greenhouse and field conditions. The tested isolates of yeast proved to be highly antagonistic to the pathogen in vitro. The test rates of CMs were equivalent to 2, 7, 10 and 14 ton/feddan in the greenhouse and 7 and 10 t/feddan in the field conditions. Uncomposted soil was used as a control. The results showed that the tested CMs have a suppressive effect on the severity of root rot and wilt diseases of faba bean under greenhouse and field conditions. The application of CMs (Planta Rich and Rich) alone at the rates equivalent to 2, 7, 10 and 14 t/feddan in greenhouse and 7 and 10 t/feddan in the field conditions to the soil infested with the tested pathogens reduced percentage of the tested diseases compared with uncomposted soil. Combined CMs treatments with yeast seed treatment increased the suppressive effect of CMs on the disease severity.

Efficacy of antioxidants on incidence of Fusarium root and pod rot diseases in peanut

Abstract Several antioxidants namely ascorbic acid, salicylic acid, sodium benzoates, thiouria and catechol were used as seed treatment and foliar spraying to reduce the incidence of root and pod rot diseases of peanut caused by (Fusarium oxysporum, Fusarium solani and Fusarium moniliforme) as well as to determine of phenolic compounds and oxidative enzymes in the treated plants. Each antioxidant was used at different concentrations (2, 4, 6 and 8 mM) against tested pathogenic fungi in vitro. All antioxidants at 8 mM showed the greatest reduction of mycelial growth of the pathogens. In greenhouse experiments, treated seeds (Giza 5 cv.) or foliar spraying of peanut plants after 30 and 60 days from planting date with each antioxidant at 8 mM reduced severity of both diseases. The treated plants with antioxidants increased accumulation of phenolic compounds and activity levels of oxidative enzymes (catalase, peroxidase and polyphenoloxidase) in infected plants compared to healthy plants. http://zoobank.org/urn:lsid:zoobank.org:pub:AF539C90-4B38-4BFE-B77B-5F2A5D764D7A