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  • Lauridsen posted an update 9 months ago

    Field observations suggest that reduced fungicide sensitivity exists in field populations of Podosphaera aphanis, the causal agent of strawberry powdery mildew (SPM). SPM is one of the most common diseases in strawberry production and is controlled using foliar fungicide applications. This study characterizes the sensitivity of 19 P. aphanis isolates to the most common fungicides used against SPM in California. Isolates were collected from commercial fruit production fields in Oxnard, Ventura, Santa Maria, Salinas, and Watsonville, and from a plant nursery in Balico, California. Healthy, unfurled strawberry leaves (cv. Monterey) free of any visual disease symptoms were removed from actively growing plants and treated with one of six commercially formulated fungicides using the minimum labeled rate and inoculated with conidia of P. aphanis. Inoculated leaves were incubated at 20°C under 16/8 hours of day/night lighting and assessed for disease incidence (%) after 14 days. Pathogen growth on the treated leaflets constituted a measure of insensitivity to the fungicide. The six fungicide treatments and their average disease incidence on treated leaves for the 19 isolates are penthiopyrad (51.4%), quinoxyfen (41.5%), myclobutanil (39.8%), trifloxystrobin (19.8%), cyflufenamid (19.3%), and fluopyram + trifloxystrobin (3.5%). The average disease incidence for the trifloxystrobin treatment was raised significantly by two isolates considered to be resistant to the product (disease incidence > 66.6%). Two isolates collected from organic production systems were sensitive to all fungicides. We document compromised fungicide efficacy due to resistance to most of the fungicides currently used for control of SPM in California. This is the first report of resistance in P. aphanis to any fungicide in California and the first report of resistance in P. aphanis to penthiopyrad and quinoxyfen worldwide.On the North China Plain, one of the most water-deficient regions in China, bare fallow has been implemented over a large-scale area to conserve water during the growth season of water-intensive winter wheat since 2015. However, the effects of this bare fallow on fungal community and the occurrence of crop diseases are poorly understood. Here we measured soil chemical properties, fungal community composition and the occurrence of crop diseases after 15 years of long-term fallow (continuous maize or soybean) and non-fallow (maize-wheat rotation; soybean-wheat rotation) cropping systems. Bare fallow during the winter-wheat growth season significantly decreased soil organic matter, available nitrogen and phosphorus. It also changed the composition of soil fungal communities, i.e., increased relative abundances of some potentially pathogenic species of Lectera, Fusarium and Volutella but decreased beneficial Cladorrhium and Schizothecium. Meanwhile, the epidemic tendency of maize diseases changed correspondingly the disease index of southern corn leaf blight and maize brown spot increased, but the incidence of stalk rot decreased compared with the non-fallow system. Soybean diseases were very mild regardless of the cropping system during the total experimental period. Network analysis demonstrated that the soil fungal diversity associated with maize diseases was affected by the decreased soil organic matter and available nitrogen and phosphorus. Our results suggest that bare fallow in winter-wheat season affected the soil chemical properties, fungal community and the occurrence of maize fungal diseases.Soft rot bacteria classified in the Pectobacteriaceae (SRP), including Pectobacterium and Dickeya spp., are responsible for soft rot and blackleg diseases of potato. Since 2014, blackleg outbreaks caused by D. dianthicola have increased in the US and Canada. Our previous study found that the most abundant causal organisms of blackleg disease in New York State were P. parmentieri and D. dianthicola, with the latter being the only Dickeya species reported. In the present study, we identified and characterized pathogenic SRP bacteria from 19 potato samples collected in New York State during the 2017 growing season. We used genome sequence comparison to determine the pathogens’ species. We found eight P. versatile, one P. atrosepticum, two P. AS1517499 carotovorum, two P. parmentieri, and six D. dianthicola isolates in our 2017 sample SRP collection. This is the first time that P. versatile is reported to cause potato blackleg disease in New York State. We determined the phylogenetic relationships between the SRP strains using 151 single copy orthologous gene sequences shared among the set of bacteria in our analysis, which provided better resolution than phylogenies constructed using the dnaX gene.Browntop millet (Brachiaria ramosa (L.) Stapf), which is native to the United States, was recently introduced into India as one of the small millet crop. In September 2018, leaf blight symptoms were observed on cv. Dundu Korale on the adaxial side of the leaves in a field at Bangalore, India (13.0784oN, 77.5793oE). Initial lesions were brown with small yellow halo that ranged from 1 to 5 mm and eventually enlarged exhibiting light brown centers. Afterwards, spots coalesced and leaves were blighted. About 75% of the plants were infected in the field of 0.5 ha. Samples of symptomatic and asymptomatic leaves were collected, and nine isolates were recovered from culture on potato dextrose agar (PDA). Single conidial isolation was performed. Colonies were grey to olive green with regular margins at 7 days when cultured on PDA at 27 ± 1oC and 16 h light and 8 h dark cycles. Conidiophores were single or in clusters from 4.92 to 6.04 μm in width. Conidia were fusoid, cylindrical to slightly curved ranging from 38.50 rale is susceptible to B. setariae.Accommodative esotropia is a condition commonly encountered by pediatric ophthalmologists. Patient with accommodative esotropia wear hyperopic glasses to decrease accommodation which occasionally provide them with good vision without glasses. Children are known to have limited compliance with glasses and patching. Their limited cooperation can also lead to variability in angle measurement across visits and defer surgery. To cope with these challenges, our team offered botulinum toxin injection to the medial rectus as an optional treatment while waiting for compliance and deferring the surgery. This is retrospective study including data from 114 accommodative esotropia patients who were injected with botulinum toxin into the medial rectus between 2010 and 2017. Of these, 102 patients met the inclusion criteria. Almost half of the patients were boys (47.06%). The average angle deviation before injection was 40 prism diopters (PD). The post-injection angle averaged at 11 PD at 2 weeks, 19 PD at 3 months, and 25 PD at 6 months.

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