Evaluation of Geranium Cultivars and Biorational Products to Control Botrytis Blight in the Greenhouse

Botrytis blight caused by the fungus Botrytis cinerea is an important disease of geranium, affecting leaves, stems, and flowers, and decreasing the crop’s marketability. Our objectives were to evaluate (i) susceptibility of geranium cultivars to B. cinerea and (ii) efficacy of biorational products for control of Botrytis blight on geranium. Disease assessment included the number of blighted leaves, foliar lesions, and leaves with B. cinerea sporulation. The area under the disease progress curve (AUDPC) was calculated. Among the ten geranium cultivars evaluated, ‘Pinto Premium Orange’, ‘Horizon Coral Spice’ and ‘Ivy Tornado White’ had significantly less disease than ‘Ringo 2000 Violet’, and ‘Maverick Scarlet Picotee’ for all measured parameters. When eleven treatments were compared in the efficacy trial of biorational products, Botector (Aureobasidium pullulans) and Prestop (Gliocladium catenulatum) effectively controlled the disease according to AUDPC for blighted leaves and leaves with sporulating B. cinerea in both ‘Ringo 2000 Violet’ and ‘Pinto Premium Orange’. Zio (Pseudomonas chlororaphis), Serifel (Bacillus amyloliquefaciens), Serenade Opti (B. subtilis) and LifeGard (B. mycoides) were also effective when combined with the geranium cultivar Pinto Premium Orange, one of the least susceptible cultivars in our study based on AUDPC values for all measured parameters. AUDPC for leaves with sporulating B. cinerea showed that all biorational products included in the study effectively limited B. cinerea except Actinovate (Streptomyces lydicus) in ‘Pinto Premium Orange’ geranium. A sustainable management approach could combine one of the least Botrytis susceptible geranium cultivars identified with biorational controls for effective Botrytis blight control.

Study of the Modulating Interactions of Multitrait Rhizobacteria Using Zea Mays L. as the Host Plant

Background: Rhizosphere is a soil region closest to roots of the plants inhabiting different types of microorganisms including rhizobacteria. Chemical fertilizers which are conventionally used for increasing crop production are dangerous in terms of minimizing the nutritional value of crops and may also be hazardous for biological agents. Therefore, the use of Plant Growth Promoting Rhizobacteria (PGPR) are favorable for improved crop production over chemical fertilizers. Objectives: The current study highlights the growth promoting traits of bacterial isolates through isolation of rhizospheric bacterial strains from different plants. Methodology: In this study, ten rhizospheric bacterial isolates were used, which were morpho-physiologically characterized and then tested for plant growth-promoting traits i.e., HCN production, ammonification and auxin production. Most of the bacterial strains gave positive results for these plant growth-promoting traits. To study the beneficial effects of these bacteria on plants, plant-microbial interaction assay was conducted using Zea mays. Results: Results revealed that these bacteria enhanced the growth as compared to control plants. Bacterial isolates Streptomyces lydicus (Cn6), Staphylococcus aureus (Cn7) and Bacillus pumilus (PP3) showed strong ammonia producing effects. The isolates Bacillus subtilis (Cn2), PP2 and PP5 exhibited strong potential of HCN production whereas only Streptomyces lydicus (Cn6) and Bacillus pumilus (PP3) were observed to be auxin producers. A maximum increase in fresh weight of the plants was observed in treatment with PP2 showing 94.36% increase over controls. Cn1 showed an increase (26.12%) in shoot length while Cn5 revealed a prominent increase (64.95%) in root length compared to the control plant. The isolates Cn5 and Cn4 showed improvement in the total chlorophyll content of the treated plants with a percentage increase of 100% and 99.82%, respectively compared to the control. Conclusion: In conclusion, these PGPR may be further used in agriculture research for growth improvement.

Susceptibilidad de aislados de Xanthomonas campestris pv. vesicatoria a Streptomyces y extractos bioactivos de Ganoderma

En el presente estudio, 10 aislados bacterianos de chile (Capsicum annuum L.) fueron identificados como Xanthomonas campestris pv. vesicatoria; se determinó su patogenicidad en invernadero y se evaluó su susceptibilidad a Streptomyces lydicus y extractos bioactivos de Ganoderma lucidum en condiciones in vitro y de invernadero, utilizando en cada caso un diseño completamente al azar. Todos los aislados causaron infección con una incidencia del 100% y variaciones en su severidad. Aunque todos los aislados fueron susceptibles a los tratamientos biológicos, los extractos bioactivos fueron superiores con un 100% de inhibición in vitro, así como en la reducción de infección foliar y población bacteriana en invernadero. Destacó una correlación fuerte entre población bacteriana e infección foliar (r = 0.9139**) en plantas inoculadas únicamente con el patógeno; en plantas tratadas adicionalmente con los biológicos, solo hubo una correlación débil en cada caso, sugiriendo su efecto benéfico en la supresión de X. campestris pv. vesicatoria.