Sporulation rate in culture and mycoparasitic activity, but not mycohost specificity, are the key factors for selecting Ampelomyces strains for biocontrol of grapevine powdery mildew (Erysiphe necator)

To develop a new biofungicide product against grapevine powdery mildew, caused by Erysiphe necator, cultural characteristics and mycoparasitic activities of pre-selected strains of Ampelomyces spp. were compared in laboratory tests to the commercial strain AQ10. Then, a 2-year experiment was performed in five vineyards with a selected strain, RS1-a, and the AQ10 strain. This consisted of autumn sprays in vineyards as the goal was to reduce the number of chasmothecia of E. necator, and, thus, the amount of overwintering inocula, instead of targeting the conidial stage of the pathogen during spring and summer. This is a yet little explored strategy to manage E. necator in vineyards. Laboratory tests compared the growth and sporulation of colonies of a total of 33 strains in culture; among these, eight strains with superior characteristics were compared to the commercial product AQ10 Biofungicide® in terms of their intrahyphal spread, pycnidial production, and reduction of both asexual and sexual reproduction in E. necator colonies. Mycoparasitic activities of the eight strains isolated from six different powdery mildew species, including E. necator, did not depend on their mycohost species of origin. Strain RS1-a, isolated from rose powdery mildew, showed, togetherwith three strains from E. necator, the highest rate of parasitism of E. necator chasmothecia. In field experiments, each strain, AQ10 and RS1-a, applied twice in autumn, significantly delayed and reduced early-season development of grapevine powdery mildew in the next year. Therefore, instead of mycohost specificity of Ampelomyces presumed in some works, but not confirmed by this study, the high sporulation rate in culture and the mycoparasitic patterns became the key factors for proposing strain RS1-a for further development as a biocontrol agent of E. necator

Improving the Management of Powdery Mildew of Cucurbits

NYS IPM Type: Project ReportThe primary goals of this project were to evaluate powdery mildew resistant (PMR) pumpkins and to determine if there is a benefit of applying fungicides to PMR pumpkins. Through this project, resistant varieties of pumpkin were shown to be an effective way to manage powdery mildew; however, challenges were also revealed. Two powdery mildew resistant (PMR) varieties were commercially available when this study was conducted. Magic Lantern was shown to be less resistant than an experimental pumpkin line being developed by Harris Moran (HMX 6687) or a Cornell line (98-714). There was a benefit to applying fungicides to Magic Lantern. An integrated program was highly effective: there was significantly less powdery mildew on PMR Magic Lantern receiving a 14-day fungicide program than on susceptible Wizard receiving a 7-day fungicide program. The other PMR variety, Merlin, was found to be very susceptible to bacterial wilt. A range in susceptibility was also detected among PMR muskmelons. Both race 1 and 2, but not race 3, were present based on powdery mildew occurrence on differential genotypes. Some PMR muskmelons with resistance to both race 1 and 2 (Starfire and HMX 7607) had significantly less powdery mildew than PMR muskmelons with resistance only to race 1 (Eclipse and HMX 7606). Apollo, which has resistance to both races, had a similar amount of mildew as Eclipse. Applying fungicides to Eclipse and to Apollo improved control. The 7-day program was more effective than the 14-day program when compared using Eclipse. Other diseases, which are controlled by fungicides used for powdery mildew, can become a problem when resistant varieties are used alone to control powdery mildew. Anthracnose was a much greater problem in nontreated than fungicide-treated plots in the muskmelon experiment. Also, PMR varieties may be more susceptible to other diseases than other varieties. PMR pumpkin Merlin had a higher incidence of bacterial wilt than susceptible pumpkin Harvest Moon (90% vs 3% on 25 Aug) in another IPM-funded project. It was not possible to investigate the possibility that PMR pumpkins and squashes, like PMR muskmelons, respond differentially to the races of the powdery mildew fungus. Phytophthora blight developed in this research field

The growth strategies, pollination, and dispersal of Moneses uniflora, with mycological notes.

http://deepblue.lib.umich.edu/bitstream/2027.42/53463/1/1897.pdfDescription of 1897.pdf : Access restricted to on-site users at the U-M Biological Station

Collema indet

Lichen

Lepraria indet

Lichen

Management of Powdery Mildew and Phytophthora Fruit Rot, Two Important Cucurbit Disease

NYS IPM Type: Project ReportPowdery mildew is the primary foliar disease of cucurbits: it occurs every year throughout New York. Ways growers can reduce the amount of fungicide used and/or the cost of their fungicide program without a reduction in disease control were identified through research conducted in 1997