Inactivation of isolated fungi on Erythrina velutina Willd. seeds through atmospheric plasma

This study aimed to evaluate the effect of atmospheric plasma application on the inactivation of fungi on the surface of Erythrina velutina seeds and on isolated fungal colonies. Two experiments were conducted using a completely randomized design. First, plasma was applied to the surface of the seeds using helium gas and atmospheric plasma for 3, 6, and 9 min in addition to the control (untreated seeds), constituting seven treatments with five repetitions each. In the second experiment, Petri dishes containing the inoculum of different fungi were treated with atmospheric air plasma for 3, 6, and 9 min (Air-3, Air-6, and Air-9) and were compared with untreated fungi in Petri dishes without treatment (control), totaling four treatments and five repetitions each. We found that the application of atmospheric air plasma to E. velutina seeds for 9 min had an antimicrobial effect on the fungi Aspergillus niger, Aspergillus flavus, Fusarium sp., Brachysporium sp., and Rhizopus sp. The formation of fungal colonies isolated from E. velutina seeds was also inhibited by 3 min of exposure to atmospheric air plasma, except for A. niger, whose inhibition occurred after 6 min of exposure to atmospheric plasma.

IDENTIFICACIÓN DE MICROORGANISMOS PATÓGENOS EN EL CULTIVO DE (Stevia Rebaudiana Bertoni)

En campos comerciales de Stevia rebaudiana localizados en los centro poblados Las Palmas y Esperanza la se determinó la incidencia y severidad de enfermedades ocasionales por microorganismos patógenos. La investigación se desarrolló en fases de reconocimiento de la sintomatología, identificación de agentes causales y determinación de pruebas de patogenicidad. Se encontraron 8 hongos, como agentes causales de los marchitamientos, necrosis de la raíz, manchas foliares y necróticas. 8 hongos, Fusarium sp., Rhizoctonia sp., Sclerotinia sclerotiorum, Sclerotium rolfsii. Cuyos daños ocasionan en los tallos y raíces, Septoria sp., Cercospora sp., Alternaria sp., Oidium. La Esperanza se ha encontrado más plantas infestadas por una mayor diversidad de microorganismos. Los microorganismos no mostraron preferencias entre hojas y tallos y raíz. Para ambas zonas los microorganismos con mayor presencia fueron. Fusarium, Septoria y Sclerotinia sclerotiorum, Sclerotium rolfsii.

Physiological and sanitary quality of ryegrass seeds submitted to different defoliation frequencies

ABSTRACT: This study determined the effect of different defoliation frequencies in a long-cycle ryegrass cultivar on yield components and the physiological and sanitary quality of seeds. Four defoliation frequencies were applied (without, one, two, and three defoliations). The time between defoliations was 350 degree-days. At the first, second, and third defoliation time, the plants were 15 cm, 20 cm, and 35 cm, respectively, and were lowered to half their height. The yield components and plant structure were evaluated through the tillers, along with the physiological quality of the seeds, which was verified by germination tests, first germination count, accelerated aging, tetrazolium test, field emergence, and weight of a thousand seeds. For the sanitary quality analysis, the percentage (%) of fungi incidence in the seeds was verified. The second defoliation determined the seeds’ high physiological and sanitary quality due to the higher amount of primary and secondary tillers produced concerning the other treatments. However, there was no significant difference for the third defoliation since the aerial tillers issued the same quality of seeds originated from primary and secondary tillers. The average incidence of fungi such as Colletotrichum sp., Fusarium sp., Phoma sp., and Dreshslera spp. was lower in ryegrass plants subjected to three defoliations.

Fusarium Wilt of Korean Blackberry Caused by Fusarium cugenangense

Wilt symptoms were frequently observed in Korean blackberry (Rubus coreanus) plants grown in farmers’ fields located in Gochang and Jeongeup, Jeonbuk Province, Korea during disease surveys in July 2020. The disease occurred in 10 of the 13 fields surveyed in the two locations. The incidence of diseased plants in the fields was 5-80%. Seven isolates of Fusarium sp. were obtained from the diseased plants and examined for their morphological and molecular characteristics. All the isolates belonged to Fusarium oxysporum species complex based on the morphological characteristics but were identified as F. cugenangense based on the molecular characteristics. Two isolates of F. cugenangense were tested for pathogenicity on Korean blackberry plants by artificial inoculation. Pathogenicity of the two isolates on the plants was confirmed with the inoculation tests, which showed wilt symptoms similar to those observed in the diseased plants in the fields investigated. This is the first report of F. cugenangense causing Fusarium wilt in Korean blackberry.

An Invitro Study: Antioxidant, Phytochemical Analysis and Antimicrobial Activities of Achranthes aspera

Medicaments, plants and plant-based are the basis of many of the modern pharmaceuticals we use today for our various purposes. The aim of the present study was to evaluate the antioxidant, phytochemical and antibacterial and antifungal activities of the Achyranthes aspera plant extract in different organic solvents. The radical scavenging activity of the different extracts of root, stem, leaf, and seed were evaluated by DPPH assay and the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, and antifungal activity against Fusarium sp. and Aspergillus niger was studied by Agar well cut diffusion method. All of the extracts exhibited different antioxidant and antibacterial activities and the activities varied from solvent to solvent, and the activities are concentrated. The antioxidant and antimicrobial activities were compared with the positive control Ascorbic acid and Cefuroxime. A qualitative phytochemical analysis was carried out and found to possess bioactive compounds like alkaloids, glycosides, terpenoids, steroids, flavonoids, tannins.

In vitro effect of salinity and pH on Fusarium sp., the causal agent of sweet-potato root rot

Fusarium root rot in a common pathogen of sweet potato, with a wide range of host plants. In the current study six new isolates of Fusarium sp., collected from infected sweet potato plants, along with a reference strain of Fusarium oxysporum, had their growth behavior studied in various pH and saline conditions. In vitro studies showed that salinity higher than 6% NaCl in the PDA substrate significantly reduces the fungal growth. At 12% NaCl, four of seven strains revealed complete mycelia inhibition. However, for the other two isolates, and for the reference strain, 12% salinity only reduced the growth with 77.4%. Regarding the fungal growth at different pH values, it was noticed that tested fusaria were not perturbed at up to 8.5 alkalinity. However, at a pH of 4.5, the growth rate was reduced, although the growth differences were diminished during prolonged incubation time. Considering the in vitro results, saline water should be tested as preventive immersion treatment on the sweet potato sprouts, before their planting, in order to reduce the incidence of Fusarium infection.