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In the past decade, due to straw incorporation and soil salinization, wheat crown rot (FCR) mainly caused by Fusarium pseudograminearum has become widespread in the Huang-Huai wheat-growing region of China. It poses a serious threat to the high and stable yield of wheat and has brought potential toxin pollution to animal feed made from wheat straw. The phenylpyrrole fungicide fludioxonil is widely used in seed dressing or coating. Previous studies of our research group have shown that fludioxonil has a strong inhibitory effect on the mycelial growth of F. pseudograminearum, but the mechanism of inhibition has remained unclear. In this paper, the inhibitory mechanism of fludioxonil on the mycelial growth of F. pseudograminearum was studied, and the inhibitory effect of fludioxonil on spore germination, germ tube elongation and sporulation were evaluated, and the field control efficacy of fludioxonil on FCR was determined. The results showed that fludioxonil made the mycelium of F. pseudograminearum malformed as follows: the top mycelium branches increased, the mycelium became dense, the mycelium spacing became shorter; mycelial cells in the colony became irregularly enlarged, branches increased but were short and uneven in thickness, had blunt round top or were enlarged. Compared with mycelial growth, the inhibitory effect of fludioxonil on conidial germination was weaker, and the EC50 value to conidial germination was 7.2358–55.3856 μg/mL. However, fludioxonil delayed the germination time of conidia and increased the probability of conidia germination from intermediate cells. Fludioxonil also recorded a strong inhibitory effect on germ tube elongation, and the EC50 to germ tube elongation was only 0.0078 μg/mL. Fludioxonil caused conidial cells enlargement, but the teratogenic effect on the germ tube was not obvious. Fludioxonil could also delay the formation time of conidia. In the mung bean soup liquid medium containing fludioxonil, it took 72 h to form conidia, while 0.8 μg/mL completely inhibited conidia formation. The EC50 values of fludioxonil to sporulation ranged from 0.1439–0.2739 μg/mL. The control efficacies of fludioxonil against FCR at the jointing and filling stages of wheat were better than that of carbendazim, and it reduced the whiteheads rate at the milk stage, but decreased the control efficacy at the filling stage. Fludioxonil could be used as a seed dressing agent in the prevention and control of FCR. [ABSTRACT FROM AUTHOR]

Quinoa panicle rot (QPR) is a novel disease that poses a significant threat to quinoa production in China. Typical symptoms on panicles include a film of pale pink, grey‐white, or dark brown mould on the grains during the grain‐filling stage. Furthermore, QPR causes quinoa grain discolouration, unfilling, and malformation. In total, 37 isolates were identified as belonging to three species: Trichothecium roseum (nine isolates), Alternaria alternata (12), and Fusarium citri (16) based on morphology, and phylogenetic and pathogenicity characterization. The present study shows for the first time that T. roseum, A. alternata, and F. citri are the pathogens responsible for QPR. An evaluation of the growth and germination rates revealed a significant difference among the three species, with T. roseum and F. citri isolates having higher fitness in warmer (25–30℃) and humid conditions (water activity ≥0.98). However, A. alternata preferred cooler (20–25℃) and more arid conditions, and germinated in a wide range of water activities (water activity of 0.90–1.00). Among the three species, T. roseum and F. citri are probably responsible for the pink and grey diseased grains in humid regions, and A. alternata for the black‐brown diseased grains in arid regions. Pathogenicity tests showed that all three species could infect the quinoa panicles. The results of this study provide a basis for the recognition and management of QPR. [ABSTRACT FROM AUTHOR]

This research reported the in vitro pathogenicity of Verticillium lecanii strains, L2 and L5, and Beauveria bassiana strains, B76 and B252, against Megoura japonica using leaf-dip method. The virulence potential of these four entomopathogenic fungal strains of V. lecanii and of B. bassiana were compared between fungi conidia (concentrations 1 × 106, 1 × 107, and 1 × 108 conidia mL−1) and culture filtrate. Moreover, binary combination of four different fungal strains (L2 + B76, B76 + L5, L2 + B252, and L2 + B76 + B252 + L5) were evaluated against M. japonica under control condition. Aphid mortality was recorded after two, four, six, and eight days of post-treatment. In the conidial concentration bioassay, strain B76 showed maximal mortality (85.3%) against bean aphid, and strain L5 showed the lowest effect (60.0%) at the highest concentration (1 × 108 conidia mL−1) at eight days post-treatment. Whereas, binary combinations of B76 and L2 strains showed the highest effect against M. japonica (90.5%) than other combinations. Moreover, in comparison with the effect of filtrate and conidia bioassay, 91.4% and 84.1% were achieved in strain B76, and the lowest effect (63.8% and 55.1%) was recorded in strain L5.

The importance of having a technique that allows an efficient expression of symptoms of anthracnose is based on the early differentiation of cultivars and the optimization of genetic, material and financial resources. The objective of this research was to generate an alternative inoculation technique for Colletotrichum gloeosporioides on mango for early anthracnose tolerance screening. On this technique was optimized some of the most relevant components such as isolate virulence, conidial density, the inoculum deposition on leaves and using of surfactants. The study was carried in Iguala, Mexico, during the production cycles 2015-2016. C. gloeosporioides was biologically and culturally characterized. Gro and Sin monosporic strains were isolated from leaves, flowers, fruits and branches with anthracnose symptoms from commercial mango orchards located in Guerrero and Sinaloa states, Mexico. These strains show mycelial growth at 2.2 and 2.1 cm of diameter per day, spore density of 4.3×106, 3.9×106 conidia/ml, germination of 27 and 26%, virulence, with incubation period 4.5 and 4.1 days after inoculation, incidence of 90 and 92% and severity of 3.2 and 3.5 cm of diameter. The highest incidence and severity values with the lowest incubation period, was obtained using Gro isolate (1×105 conidia/ml) and polyoxyethylene-20-sorbitan monolaurate as spreader-sticker inoculated on the abaxial surface on detached young leaves, 15-20 days old, with a soft brush and incubated under dark condition. This inoculation technique allowed the optimal expression of C. gloeosporioides virulence in mango leaves and could be incorporated as a tool in the early differentiation of tolerance and susceptibility among cultivars. [ABSTRACT FROM AUTHOR]

This paper addresses the hypothesis that the spray application system used will affect the retention of spray deposits of microbial herbicides on different plant structures. There was greater spray retention on the hypocotyl of 4 to 6-true leaf Amaranthus retroflexus plants (20-31%) sprayed with an aerosol-producing laboratory sprayer than with a hydraulic nozzle (3-5%). Spray deposition and retention from the hydraulic nozzle was increased by 28-42% when the nozzle was used horizontally. Spray droplets generally contained the expected conidial number for the conidial concentration but this was affected by increased inoculum density (size, concentration and mycelial contamination), causing a reduction in the actual number of conidia present, compared to the expected. Up to 40-50% of the conidia in the sprayed suspension could not be accounted for when conidium deposition was on a target. This loss could increase to 90-92% when the weed was sprayed under a crop canopy. [ABSTRACT FROM AUTHOR]

This research reported the in vitro pathogenicity of Verticillium lecanii strains, L2 and L5, and Beauveria bassiana strains, B76 and B252, against Megoura japonica using leaf-dip method. The virulence potential of these four entomopathogenic fungal strains of V. lecanii and of B. bassiana were compared between fungi conidia (concentrations 1 × 106, 1 × 107, and 1 × 108 conidia mL−1) and culture filtrate. Moreover, binary combination of four different fungal strains (L2 + B76, B76 + L5, L2 + B252, and L2 + B76 + B252 + L5) were evaluated against M. japonica under control condition. Aphid mortality was recorded after two, four, six, and eight days of post-treatment. In the conidial concentration bioassay, strain B76 showed maximal mortality (85.3%) against bean aphid, and strain L5 showed the lowest effect (60.0%) at the highest concentration (1 × 108 conidia mL−1) at eight days post-treatment. Whereas, binary combinations of B76 and L2 strains showed the highest effect against M. japonica (90.5%) than other combinations. Moreover, in comparison with the effect of filtrate and conidia bioassay, 91.4% and 84.1% were achieved in strain B76, and the lowest effect (63.8% and 55.1%) was recorded in strain L5. [ABSTRACT FROM AUTHOR]

Using transmission electron microscopy, we studied the presence of melanin and cell wall thickness of clinical isolates of Sporothrix schenckii obtained from cats, dogs and humans as compared to reference strains. We detected differences regarding presence of the melanin among the clinical isolates of S. schenckii and a correlation between presence of melanin and cell wall thickness.