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Essential Oils andTrichoderma Harzianumas an Integrated Control Measure Against Faba Bean Root Rot PathogensCarnation, caraway, thyme, peppermint and geranium essential oils have been found to have inhibitory effects against the mycelial growth ofFusarium solani,Rhizoctonia solani,Sclerotium rolfsiiandMacrophomina phaseolinaunderin vitroconditions. Complete inhibition of fungal growth was observed with the use of 4% carnation and geranium oils. Mycelial growth of the tested fungi showed more sensitivity to high concentrations of thyme than to caraway and peppermint oils. Moreover, essential oils used to coat seeds resulted in a significant reduction of root rot incidence of bean, at both pre- and post-emergence stages under greenhouse conditions. Under field conditions seeds coated with essential oils at a concentration of 4% sown in soil treated with the bio-agentTrihoderma harzianum, gave pronounced protection to emerged bean seeds against the invasion of root rot pathogenic fungi. Compared to the control, the above treatment resulted in a reduction of disease incidence at the pre-emergence stage. This reduction was calculated to be between 47.3 and 55.4% compared with a 16.1% reduction with the use of the Rizolex-T treatment. At the post-emergence stage, all applied treatments were able to reduce the percentage of root-rot incidence. Reduction ranged between 41.4 and 47.1% over the untreated control. Reduction in disease incidence was reflected in a yield increase of 15.1-28.8% and 40.1-50%, in seeds coated with one of the different essential oils, or combined withT. harzianumsoil treatments, in the respective order. Seeds coated with the fungicide Rhizolex-T caused a yield increase estimated as 11.3% over the check treatment. These results show that application of essential oils in integration with the bio-agentT. harzianummay be considered as an applicable, safe and cost-effective method for controlling such soilborne diseases.

Abstract:The suppressive effect of sodium and calcium salts applied individually or combined with the yeast Saccharomyces cerevisiae against Alternaria solani the causal agent of early blight disease of potato was evaluated under laboratory, greenhouse and field conditions. In vitro test a complete inhibition in fungal growth was observed at concentration of 30 mg/ml of both sodium bicarbonate and calcium chloride. The commercial backing yeast S. cerevisiae (CBY) enhanced the inhibitory effect of tested salts reflected in increasing mycelial fungal growth reduction when combined at the rate of 1:1 at each concentration tested. In pot experiment, under artificial infestation with pathogenic fungus, application of sodium bicarbonate or calcium chloride significantly reduced the early blight incidence and severity by increasing their concentrations. Their most effective concentration were 30 mg/ml that reduced the disease incidence by 50 and 62.4%, respectively. Superior effect of sodium bicarbonate or calcium chloride in disease reduction was observed when they combined with CBY. Field trails for evaluating the most promising greenhouse treatments were preformed under natural infestations during two successive summer seasons. Calcium chloride proved higher efficacy for reducing both disease incidence and severity than that of sodium bicarbonate when applied either alone or combined with CBY. Also, it is observed that increasing concentrations of both sodium bicarbonate or calcium chloride showed parallel decrease in disease incidence and severity. Application of (CBY) enhanced the efficacy of salts spraying against early blight disease. Similar trend was also observed with the increase of potato tubers yield. On the light of the present study it could be suggested that the usage of combined application of the yeast S. cerevisiae with sodium bicarbonate or calcium chloride might be used as easily applied, safely and cost effective control methods against such plant diseases.

Evaluation the efficacy of bio-agents, resistance chemical inducers and/or thyme oil application as foliar spray against vegetables foliar diseases incidence was carried out in open greenhouse conditions. The tested bio-agents were Trichoderma harzianum, T. Viride, Bacillus subtilis, Pseudomonas flourescens and Saccharomyces serevisiae. Calcium chloride, Potassium monohydrogen phosphate, Potassium bicarbonate, Saccharin, Ascorbic acid, Chitosan and Humic & Folic acid (mixture) as resistance chemical inducers were evaluated. The recorded foliar diseases, i.e. Powdery, Downy mildews of Cucumber, Cantaloupe and Pepper as well as Early, Late blights of Tomato were significantly reduced at all treatments either alone or in combinations comparing with untreated plants. Application with either T. harzianum and B. subtilis showed significant reduction in diseases incidence comparing with the other applied bio-agents. Under artificial infestation the most significant reduction in diseases incidence of tested vegetables were recorded in combined treatments of chemical inducers and S. serevisiae, i.e. (Chitosan + Thyme oil); (Chitosan + Saccharin); (Chitosan + Calcium chloride + S. serevisiae); (Chitosan + Potassium monohydrogen phosphate); (Saccharin + Potassium monohydrogen phosphate) ; (Humic & folic + Thyme oil) and (Chitosan + S. serevisiae) comparing with other applied treatments as well as untreated control.On the light of the present study it could be suggested that the usage of combined application of the bio-agents with resistance plant chemicals might be used as easily applied, safely and cost effective control methods against such foliar plant diseases.

The effect of T. harzianum and some essential oils alone or in combination with compost on the peanut crown rot disease under field conditions was evaluated. Under laboratory conditions, results indicated that all concentrations of essential oils significantly reduced the growth of A. niger. Complete reduction was obtained with thyme and lemongrass oils at 0.5%. All T. harzianum isolates significantly reduced the growth of A. niger. The highest reduction was obtained with isolate no. 1 which reduced the growth by 81.1%. Under field conditions, results indicated that all treatments significantly reduced the peanut crown rot disease. The highest reduction was obtained with combined treatments (compost + T. harzianum + thyme and compost + T. harzianum + lemongrass) which reduced the disease incidence at both pre- and post-emergence growth stages, respectively. Similar trend corresponding to the previous treatments significantly increased the peanut yield which calculated as an increase in yield more than 75.0 and 80.0 during two growing seasons, respectively. It could be suggested that combined treatment between biocompost and essential oils might be used commercially for controlling peanut crown rot disease under field conditions.

Different approaches of some antagonistic fungal, bacterial and yeast agents applied as seed treatment or soil drench was evaluated against various soil-borne pathogens causing vegetables root rot disease under greenhouse conditions. The tested pathogenic fungi were Alternaria solani Fusarium solani, F. oxysporum, Rhizoctonia solani, Sclerotium rolfsii, Macrophomina phaseolina and Pythium sp., meanwhile the tested bio-agents were Trichoderma harzianum, T. Viride and Bacillus subtilis, Pseudomonas flourescens and Sacchromyces serivisae. Significant reduction in the disease incidence was observed in bio-agent treatments in comparison with untreated control. Root rot incidence, at pre-emergence stage, significant effect was observed in bio-agent treatments as seed soaking comparing with soil drench treatment. The treated seeds showed a protective effect for seeds germination against the invasion by soil-borne pathogenic fungi. Meanwhile, soil drenched with different bio-agents showed more efficacy for reducing root rot incidence at post-emergence growth stage of tested vegetables, Cucumber, Cantaloupe, Tomato and Pepper. The obtained results revealed that the antagonist T. harzianum showed significant superior effect to reduce diseases incidence followed by B. subtilis. Also, the antagonists T. viride and P. fluorescence occupied significantly the second degree for reducing root rot incidence. The treatment with S. serevisiae had the lowest effect on disease incidence, although it significantly lesser than check control treatment. The present study demonstrates that application of bio-agents as seed treatment and soil drench may be useful for controlling root rot disease in field.

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