Background
Wheat is the most consumed cereal crops in the world infected by several pathogens and pests causing significant losses. The most threatening pathogens are fungi which cause serious diseases on roots, leaves and heads as one of the most threatening pathogens in specific wheat-growing countries. This study aimed to identify and evaluate the prevalence of damping-off fungal pathogens in different wheat fields at Basra and Maysan provinces.
Results
Disease incidence determination and fungal isolation were carried out from two sites at Basra province (Al-Qurna and Al-Madinah) and three sites at Maysan province (Al-Amarah, Kumit, Ali Al Sharqi and Ali Al Gharbi). Al-Qurna fields had the highest disease incidence (32%), while Ali-Alsharqi fields had the lowest one (11%). Fourteen fungal genera were identified. Rhizoctonia solani had the highest appearance (21.6) and frequency (20.20%) percentages followed by Fusarium solani (16.11,14.01) percentages and Macrophomina phaseolina (12.2,11.1) percentages. Seed treatment with R. solani (Rs1 isolate) showed significant decrease in germination (56.6%) compared to F. solani and M. phaseolina treatments. Seed treatment with R. solani (Rs1 isolate) showed significant decrease in germination (56.6%) compared to F. solani and M. phaseolina treatments.
Conclusions
These results revealed the prevalence of wheat damping-off disease in all examined fields at both Basra and Maysan province; the highest disease incidence was seen in Basra wheat fields (Al-Qurna fields); the identification of fungal pathogens showed that the most isolated fungus was R. solani followed by F. solani and M. phaseolina. Laboratory experiments showed the pathogenicity of isolated fungi which varied according to the isolate type.
Strawberry (Fragaria ananassa Duch.) is an important and valuable fruit because of its unique flavor and economic, nutritional and health benefits. It is one of the most consumed berries worldwide. Grey mould of strawberry fruits, caused by the necrotrophic ascomycete Botrytis cinerea Pers.: Fr., is one of the most important diseases. This airborne pathogen has the ability to kill strawberry cells through the production of reactive oxygen species and toxins causing massive production losses at all development stages and even post-harvest. The intensive production of strawberries has created a favorable environment for this disease. Strawberry grey mould management is typically very input-intensive, in particular with respect to chemical fungicides. As a result, the integrated pest management is required to control strawberry grey mould. A thorough understanding of B. cinerea epidemiology and infection processes is needed to guide future efforts in the development of innovative integrated management practices. This review summarizes the current knowledge of taxonomy and morphology, signs and symptoms, disease development, infection process, and control of B. cinerea using integrated disease management.
Due to the various negative impacts of chemical fungicides, the reduction of its applications in agricultural production process is widely recommended. Thus, the need and application of bio-agents in disease control has increased tremendously. The current study aimed at investigating the role of both bio-agents Glomus mosseae (mycorrhizal fungi) and Trichoderma harzianum in protection of Cucumis sativus (cucumber plants) against the fungal pathogen Alternaria alternata which is an opportunistic pathogen and the causal agent of cucumber wilt disease. Results obtained from this work revealed the positive influence of using bio-agents treatments in the reduction of pathogenic effects of A. alternata. The results also showed that G. mosseae and T. harzianum combination had a positive synergistic influence in reducing the detrimental effects of A. alternata ny improving the biomass yield (e.g. fresh and dry weight of root); as well as, on disease severity on C. sativus. Bio-agents (G. mosseae and T. harzianum) increased resistance in C. sativus by raising the production of enzymes catalase and peroxidase. Conclusively, this research revealed that using a multifarious combination of bio-agents significantly (P =.05) increased the efficiency of biological control of A. alternata than using each of them exclusively. Thus, it is recommended that to get an effective result in the control of the pathogen A. alternata in crops as highlighted by the results of this work; a combination of two bio-agents should be used.
Eggplant (Solanum melongena L.) production has gone through increasing difficulties due to relatively low yields in the last few years in Iraq. Alternaria solani, the causal agent of eggplant early blight; attacks hybrid and local varieties either in open field or in the greenhouse, causing a serious damage that led to decrease in crop yield. The strategies employed to manage this disease by Iraqi farmers were the synthetic fungicides application. In this study, several assays were conducted such as poisoned food technique (in vitro assay) and greenhouse experiment (in vivo assay); to evaluate the inhibitory efficacy of 3 three synthetic fungicides including; Topas® 100 (penconazole), Tilt 250 (propiconazole) and Leimay® (amisulbrom) on A. solani mycelial growth and disease intensity. In laboratory assays, Topas® 100 and Tilt 250 exhibited high inhibitory activities against A. solani as an airborne pathogen; recording mycelial inhibition rate above 94 % at a concentration of 1000 mg\ l. Furthermore, these two fungicides when applied preventively in greenhouse assays reduced significantly the disease severity index (DSI) by 18.83 % and 26.16 %, respectively. Current results revealed that Topas® 100 and Tilt 250 caused the highest antifungal potential manifested through reduction rate of fresh weight (9.62 and 8.58 g, respectively), and dry weight (4.61 and 4.60 g, respectively). Moreover, both fungicides recorded the highest peroxidase activities of 4.128 units/g/ml/min. and 3.038 units/g/ml/min., respectively. Current findings can be used to assist the eggplant growers to improve the control of early blight disease, and increase the marketable yields of this crop.
Eggplant, an important vegetable crop in Iraq, faces yield losses due to early blight disease caused by Alternaria solani. Two antagonistic fungi (Aspergillus niger and Purpureocillium lilacinum) isolated from eggplant rhizosphere were tested in vitro (dual confrontation technique) and in vivo (preventive treatments) as potential bioagents against the most virulent A. solani isolates. A. niger and P. lilacinum at 30% conidia/ml exhibited high inhibitory rate (55.11%) against A. solani mycelial growth. Furthermore, these two antagonistic species when applied preventively at 30% of the stock conidial suspension in vivo, reduced significantly disease severity index (<28.41%). Moreover, A. niger (11.98 units/g of soluble protein) and P. lilacinum (8.11 units/g of soluble protein) enhanced the polyphenol oxidase activity. Based on the results obtained by this study, it appears that A. niger and P. lilacinum could be employed as foliar treatments against A. solani to promote eggplant growth and development and induce plant systemic resistance. To control A. solani, it is encouraged to use natural enemies as components in integrated disease management. Keywords: Alternaria solani, biological control, polyphenol oxidase, Solanum melongena, antagonistic fungi
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