Nanofungicides with Selenium and Silicon Can Boost the Growth and Yield of Common Bean (Phaseolus vulgaris L.) and Control Alternaria Leaf Spot Disease.

There is an urgent need to reduce the intensive use of chemical fungicides due to their potential damage to human health and the environment. The current study investigated whether nano-selenium (nano-Se) and nano-silica (nano-SiO2) could be used against the leaf spot disease caused by Alternaria alternata in a common bean (Phaseolus vulgaris L.). The engineered Se and SiO2 nanoparticles were compared to a traditional fungicide and a negative control with no treatment, and experiments were repeated during two successive seasons in fields and in vitro. The in vitro study showed that 100 ppm nano-Se had an efficacy rate of 85.1% on A. alternata mycelial growth, followed by the combined applications (Se + SiO2 at half doses) with an efficacy rate of 77.8%. The field study showed that nano-Se and the combined application of nano-Se and nano-SiO2 significantly decreased the disease severity of A. alternata. There were no significant differences among nano-Se, the combined application, and the fungicide treatment (positive control). As compared to the negative control (no treatment), leaf weight increased by 38.3%, the number of leaves per plant by 25.7%, chlorophyll A by 24%, chlorophyll B by 17.5%, and total dry seed yield by 30%. In addition, nano-Se significantly increased the enzymatic capacity (i.e., CAT, POX, PPO) and antioxidant activity in the leaves. Our current study is the first to report that the selected nano-minerals are real alternatives to chemical fungicides for controlling A. alternata in common beans. This work suggests the potential of nanoparticles as alternatives to fungicides. Further studies are needed to better understand the mechanisms and how different nano-materials could be used against phytopathogens.

Evaluation of the Impacts of Potassium Bicarbonate, Moringa oleifera Seed Extract, and Bacillus subtilis on Sugar Beet Powdery Mildew.

Powdery mildew disease, caused by Erysiphe betae, is one of the most threatening diseases on sugar beet plants worldwide. It causes a great loss in the root yield, sugar percentage, and quality of produced sugar. In the current study, we aimed to evaluate the susceptibility of 25 sugar beet cultivars to infection with powdery mildew disease under Egyptian conditions. Moreover, we evaluated the impacts of three eco-friendly materials, including potassium bicarbonate (KHCO3; at 5 and 10 g L-1), Moringa oleifera seed extract (25 and 50 g L-1), and the biocontrol agent, Bacillus subtilis (108 cell suspension) against E. betae in two successive seasons 2020 and 2021. Our findings showed that there were significant differences between these 25 cultivars in their susceptibility to the disease under study. Using the detached leaves technique in vitro, B. subtilis showed strong antifungal activity against E. betae. Moreover, both concentrations of KHCO3 and moringa seed extract significantly reduced the disease severity. Under field conditions, tested treatments significantly reduced the severity of powdery mildew disease and prevented E. betae from producing its conidiophores and conidia. Scanning electron microscope examination of treated leaves demonstrated the presence of the decomposition of fungal hyphae, conidiophores, conidia, and the occurrence of plasmolysis to fungal cells and spores on the surface of the leaves. Furthermore, these treatments greatly improved the percent of sucrose and soluble solids content, as well as the enzymatic activity of peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase. It is noteworthy that treatment with moringa seed extract gave the best results, followed by potassium bicarbonate, then B. subtilis cell suspension. Generally, it is recommended to use the substances used in this research to combat powdery mildew to minimize or prevent the use of chemical fungicides harmful to public health and the environment.

The effect of using fresh farmyard manure (animal manure) on the severity of Fusarium verticilioides in soil, root, stem, and kernels as well as lodging and borer incidence of maize plants.

Fusarium verticillioides, an important maize pathogen, produce fumonisins, causes stalk rot and consequentially reduce crop growth and yield. Therefore, herein we aimed to evaluate the potential use of two farmyard soil organic manures, i.e., fresh (5-6 days old) and stored (5-6 months old) organic manure, to manage F. verticillioides infections as well as borer incidence and lodging in maize plants. After 30, 60, and 90 days of sowing, samples of soil, roots, and stems were collected to isolate F. verticillioides. Moreover, we estimated ear and kernel rot induced by F. verticillioides at the final harvest. Fresh organic manure treatment increased infection rates of F. verticillioides in soil, roots, stem and kernels compared to the control treatment. In contrast, stored organic manure plots treatments decrease F. verticillioides frequency. At 90 days after sowing, stored organic manure suppressed the survival of F. verticillioides, which reduced the F. verticillioides incidence percent. These results were similar to the effect of herbicides-and insecticide-treated plots demonstrated, which show a significant decrease in F. verticillioides incidence rates. Mycological analysis on symptomless kernels revealed a higher % of pathogen infection in opened husks variety (Balady) than closed husks variety (SC10). Compared with stored organic manure, the stem borer incidence and lodging percentage were the highest in fresh organic manure plots. Finally, these results demonstrated that storing organic manure within five to six months as farmyard manure led to high-temperature centigrade within organic manure, thereby destroying spores of F. verticillioides, whereas fresh organic manure did not.