Control of root rot and wilt disease complex of some evergreen fruit transplants by using plant growth promoting rhizobacteria in the New Valley Governorate, Egypt

Root rot and wilt disease complex were detected in several guava, lemon and olive transplant nurseries and new orchards at El-Kharga, Baris, ballet, El-Dakhla and El-Farafrah districts, the New Valley Governorate, Egypt. The average percentage of root rot/wilt incidence and severity in surveying districts were 37.7, 26.5%in guava; 41.7, 34.0%;in lemon and 41.2, 29.5% in olive transplants, respectively. The most frequently isolated fungi from rotted roots of the guava, lemon and olive transplants were Fusarium oxysporum, F. solani, Macrophomina phaseolina and Rhizoctonia solani. In pathogenicity tests, all the tested fungi were pathogenic to guava, lemon and olive transplants. The effect of plant growth promoting rhizobacteria (PGPR) individually and/or mixed when used as a soil drench treatment were varied in reducing root rot/ wilt incidence and severity under greenhouse conditions compared with control. The mixed of PGPR gave the highest protection against root rot/wilt diseases compared with the use of PGPR individually. All treatments significantly increased plant height (cm), number of leaves transplanting-1, leaf area (cm2), fresh and dry weights transplanting-1 (gm) compared with control treatment

Management of root rot and wilt diseases of date palm offshoots using certain biological control agents and its effect on growth parameters in the New Valley Governorate, Egypt

Root Rot and wilt diseases were observed on different date palm offshoots in nurseries and new orchards in New Valley Governorate, Egypt. Pathogenicity tests showed that Fusarium oxysporum, F. solani and F. moniliforme were the causal agents of root rot and wilt diseases on date palm offshoots (cv. Saidy). In addition, the isolates of the three Fusarium spp. differed in their pathogenic capabilities. The effect of Bacillus subtilis (BSM1), B. megaterium (BMM5), B. cereus (BCM8), Trichoderma viride (TVM2), T. harzianum (THM4) as bioagents against root rot/wilt disease complex of date palm offshoots under natural infection in nursery cultivated in two location (Al-Kharga and El-Dakhla) and also, on growth of the tested pathogenic fungi under laboratory were evaluated. Under laboratory conditions, all the tested bioagents inhibited the growth of the pathogenic fungi with different percentages. Bacillus megaterium and B. subtilis showed the highest percentage of fungal growth inhibition, while T. harzianum gave the lowest ones. At the field level, the application of bioagents significantly reduced the disease severity compared with untreated offshoots (control) in both locations. Bacillus megaterium and T. viride showed the highest protection against fungal causal agents, while B. cereus and T. harzianum gave the lowest ones in this respect. Moreover, the bioagents significantly improved the growth parameters of offshoots viz. plant height, number of leaves plant-1, leaflet number leaf-1, and leaf thickness. Bacillus megaterium and T. viride recorded the highest values of all growth parameters in El-Kharga and El-Dakhla locations, while B. cereus and T. harzianum gave the lowest ones.

Application of date palm leaves compost and plant growth promoting rhizobacteria for controlling faba bean root rot disease in New Valley, Egypt

This study was designed to investigate the effect of date palm leaves compost (DPLC) individually and/or in combined with plant growth promoting rhizobacteria (PGPR) for controlling faba bean root rot disease caused by Rhizoctonia solani and Fusarium solani under greenhouse and field conditions. The obtained data indicate that DPLC at different concentrations significantly decreased root rot incidence either under artificial infection in pot or natural infection in field as well as increased growth and yield parameters during growing season 2013-2014. Date palm leaves compost at 8 ton/ feddan (feddan = 1.038 acres) recorded the highest protection against root rot disease and gave the highest increased of plant growth and yield parameters. On the other hand, PGPR viz. Bacillus megaterium, B. cereus and Pseudomonas fluorescens individually or mixed significantly decreased root rot incidence under greenhouse and field conditions. The mixed of PGPR strains significantly suppressed the diseases more than used alone of them. Plant growth promoting rhizobacteria increased efficacy of DPLC for controlling root rot disease in faba bean more than the applied of DPLC or PGPR alone under greenhouse and field conditions during both tested seasons as well as increased of nodulations, growth and yield parameters. The application mixed of PGPR strains and DPLC at 8 ton/feddan recorded the highest reduction of root rot incidence and increase of nodulations, growth and yield parameters during both growing seasons. 

Biocontrol and Plant Growth Promotion Characterization of Bacillus Species Isolated from Calendula officinalis Rhizosphere

The phenotypic and genotypic diversity of the plant growth promoting Bacillus genus have been widely investigated in the rhizosphere of various agricultural crops. However, to our knowledge this is the first report on the Bacillus species isolated from the rhizosphere of Calendula officinalis. 15 % of the isolated bacteria were screened for their important antifungal activity against Fusarium oxysporum, Botrytis cinerea, Aspergillus niger, Cladosporium cucumerinium and Alternaria alternata. The bacteria identification based on 16S r-RNA and gyrase-A genes analysis, revealed strains closely related to Bacillus amyloliquefaciens, B. velezensis, B. subtilis sub sp spizezenii and Paenibacillus polymyxa species. The electro-spray mass spectrometry coupled to liquid chromatography (ESI-LC MS) analysis showed that most of the Bacillus isolates produced the three lipopeptides families. However, the P. polymyxa (18SRTS) didn't produce any type of lipopeptides. All the tested Bacillus isolates produced cellulase but the protease activity was observed only in the B. amyloliquefaciens species (9SRTS). The Salkowsky colorimetric test showed that the screened bacteria synthesized 6-52 μg/ml of indole 3 acetic acid. These bacteria produced siderophores with more than 10 mm wide orange zones on chromazurol S. The greenhouse experiment using a naturally infested soil with Sclerotonia sclerotiorum showed that the B. amyloliquefaciens (9SRTS) had no significant (P > 0.05) effect on the pre-germination of the chickpea seeds. However, it increased the size of the chickpea plants and reduced the stem rot disease (P < 0.05).These results suggested that the Bacillus strains isolated in this work may be further used as bioinoculants to improve the production of C. officinalis and other crop systems. © 2013 Association of Microbiologists of India