There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

Research in the effects of climate change on plant disease continues to be limited, but some striking progress has been made. At the genomic level, advances in technologies for the high-throughput analysis of gene expression have made it possible to begin discriminating responses to different biotic and abiotic stressors and potential trade-offs in responses. At the scale of the individual plant, enough experiments have been performed to begin synthesizing the effects of climate variables on infection rates, though pathosystemspecific characteristics make synthesis challenging. Models of plant disease have now been developed to incorporate more sophisticated climate predictions. At the population level, the adaptive potential of plant and pathogen populations may prove to be one of the most important predictors of the magnitude of climate change effects. Ecosystem ecologists are now addressing the role of plant disease in ecosystem processes and the challenge of scaling up from individual infection probabilities to epidemics and broader impacts.

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Climate Change Effects on Plant Disease: Genomes to Ecosystems

Differentiation and secondary metabolism are correlated processes in fungi that respond to light. In
Aspergillus nidulans
, light inhibits sexual reproduction as well as secondary metabolism. We identified
the heterotrimeric
velvet
complex VelB/VeA/LaeA connecting light-responding developmental
regulation and control of secondary metabolism. VeA, which is primarily expressed in the dark,
physically interacts with VelB, which is expressed during sexual development. VeA bridges VelB to the
nuclear master regulator of secondary metabolism, LaeA. Deletion of either
velB
or
veA
results in
defects in both sexual fruiting-body formation and the production of secondary metabolites.

VelB/VeA/LaeA Complex CoordinatesLight Signal with Fungal Developmentand Secondary Metabolism

The usefulness of mixtures (multiline cultivars and cultivar mixtures) for disease management has been well demonstrated for rusts and powdery mildews of small grain crops. Such mixtures are more useful under some epidemiological conditions than under others, and experimental methodology, especially problems of scale, may be crucial in evaluating the potential efficacy of mixtures on disease. There are now examples of mixtures providing both low and high degrees of disease control for a wide range of pathosystems, including crops with large plants, and pathogens that demonstrate low host specificity, or are splash dispersed, soilborne, or insect vectored. Though most analyses of pathogen evolution in mixtures consider static costs of virulence to be the main mechanism countering selection for pathogen complexity, many other potential mechanisms need to be investigated. Agronomic and marketing considerations must be carefully evaluated when implementing mixture approaches to crop management. Practical difficulties associated with mixtures have often been overestimated, however, and mixtures will likely play an increasingly important role as we develop more sustainable agricultural systems.

Use of multiline cultivars and cultivar mixtures for disease management

The controlled environment of greenhouses, the high value of the crops, and the limited number of registered fungicides offer a unique niche for the biological control of plant diseases. During the past ten years, over 80 biocontrol products have been marketed worldwide. A large percentage of these have been developed for greenhouse crops. Products to control soilborne pathogens such as Sclerotinia, Pythium, Rhizoctonia and Fusarium include Coniothyrium minitans, species of Gliocladium, Trichoderma, Streptomyces, and Bacillus, and nonpathogenic Fusarium. Products containing Trichoderma, Ampelomyces quisqualis, Bacillus, and Ulocladium are being developed to control the primary foliar diseases, Botrytis and powdery mildew. The development of Pseudomonas for the control of Pythium diseases in hydroponics and Pseudozyma flocculosa for the control of powdery mildew by two Canadian research programs is presented. In the future, biological control of diseases in greenhouses could predominate over chemical pesticides, in the same way that biological control of greenhouse insects predominates in the United Kingdom. The limitations in formulation, registration, and commercialization are discussed, along with suggested future research priorities.

Biological control in greenhouse systems

SUMMARY Few plant pathogens have had a more profound effect on the evolution of disease management than Erysiphe necator, which causes grapevine powdery mildew. When the pathogen first spread from North America to England in 1845, and onwards to France in 1847, ‘germ theory’ was neither understood among the general populace nor even generally accepted within the scientific community. Louis Pasteur had only recently reported the microbial nature of fermentation, and it would be another 30 years before Robert Koch would publish his proofs of the microbial nature of certain animal diseases. However, within 6 years after the arrival of the pathogen, nearly 6 million grape growers in France were routinely applying sulphur to suppress powdery mildew on nearly 2.5 million hectares of vineyards (Campbell, 2006).The pathogen has remained a focus for disease management efforts ever since. Because of the worldwide importance of the crop and its susceptibility to the disease, and because conventional management with modern, organic fungicides has been compromised on several occasions since 1980 by the evolution of fungicide resistance, there has also been a renewed effort worldwide to explore the pathogen’s biology and ecology, its genetics and molecular interactions with host plants, and to refine current and suggest new management strategies. These latter aspects are the subject of our review. Taxonomy: The most widely accepted classification follows. Family Erysiphaceae, Erysiphe necator Schw. [syn. Uncinula necator (Schw.) Burr., E. tuckeri Berk., U. americana Howe and U. spiralis Berk. & Curt; anamorph Oidium tuckeri Berk.]. Erysiphe necator var. ampelopsidis was found on Parthenocissus spp. in North America according to Braun (1987), although later studies revealed isolates whose host range spanned genera, making the application of this taxon somewhat imprecise (Gadoury and Pearson, 1991). The classification of the genera before 1980 was based on features of the mature ascocarp: (i) numbers of asci; and (ii) morphology of the appendages, in particular the appendage tips. The foregoing has been supplanted by phylogeny inferred from the internal transcribed spacer (ITS) of ribosomal DNA

/pdf/grapevine-powdery-mildew-erysiphe-necator-a-fascinating-yp9ywj14zs.pdf

Grapevine powdery mildew (Erysiphe necator): a fascinating system for the study of the biology, ecology and epidemiology of an obligate biotroph.

Berries of Vitis vinifera are reported to be susceptible to infection by Uncinula necator until soluble solids levels (brix) reach 8%, and established colonies are reported to sporulate until brix reach 15%. However, our analysis of disease progress on fruit of selected V. vinifera cultivars indicated that severity became asymptotic several weeks earlier in fruit development. When mildew-free fruit clusters of V. vinifera ‘Chardonnay’, ‘Riesling’, ‘Gewurztraminer’, and ‘Pinot Noir’ were inoculated at stages ranging from prebloom to 6 weeks postbloom, only fruit inoculated within 2 weeks of bloom developed severe powdery mildew. Substantial ontogenic resistance to infection was expressed in fruit nearly 6 weeks before fruit brix reached 8% and over 2 months before they reached 15%. Rachises of ‘Chardonnay’ and ‘Riesling’ fruit clusters developed severe powdery mildew when inoculated at bloom, and disease increased steadily over the next 60 days. The rachis of fruit clusters inoculated 31 days afte...

https://apsjournals.apsnet.org/doi/pdfplus/10.1094/PHYTO.2003.93.5.547

Ontogenic resistance to powdery mildew in grape berries.

Ampelomyces quisqualis normally infects senescent colonies of Uncinula necator in late summer. Our objective was to introduce the mycoparasite at the start of an epidemic, and thereby reduce the rate of disease increase. Prior to establishing field trials, isolates of A. quisqualis were evaluated for pathogenicity, virulence, and host range in greenhouse and laboratory assays. Infection of powdery mildew colonies only occurred when plants were kept wet and resulted in sporulation of A. quisqualis within 10 days. Two isolates of A. quisqualis (G5 and G273) were evaluated for pathogenicity and virulence against 18 monoconidial isolates of U. necator on grape seedlings and showed little evidence of pathogenic specialization. Three isolates (G273, SF419, and SF423) were equally pathogenic to Sphaerotheca fuliginea on cucurbit, S. macularis on strawberry, and U. necator on grape seedlings. All A. quisqualis isolates appear to have a broad host range and cause significant damage to powdery mildew colonies. Pycnidia of A. quisqualis G273 were produced on cotton wicks saturated with malt extract agar or wheat bran malt extract agar. Wicks were suspended above grapevines of Vitis vinifera «Riesling» and Vitis interspecific hybrid Aurore. Conidia were dispersed during rain to infect powdery mildew colonies while leaf surfaces were wet. Conidia were released for 3 months in 1990 from a single deployment of wicks. Higher numbers of conidia were released during the entire growing season in 1992 and 1993 due to replenishment of colonized wicks at monthly intervals. Wicks released conidia for 1 to 2 months in 1992 and 1993 before becoming depleted. Powdery mildew development was reduced on Riesling vines in 1990 following deployment of colonized wicks at 15 cm of shoot growth. Disease severity but not incidence was reduced on Aurore vines in 1992 under A. quisqualis-colonized wicks. High rainfall in 1992 provided ample opportunities for dispersal of inoculum of the mycoparasite and the wet conditions were conducive to parasitism. Disease development was late and much reduced in 1993, which was a drier season than 1992. Consequently, no differences were observed in A. quisqualis-treated and untreated plots in the same vineyard that year

Partial control of grape powdery mildew by the mycoparasite Ampelomyces quisqualis.

Comparison of Coat Protein-Mediated and Genetically-Derived Resistance in Cucumbers to Infection by Cucumber Mosaic Virus Under Field Conditions with Natural Challenge Inoculations by Vectors

Comparison of coat protein-mediated and genetically-derived resistance in cucumbers to infection by cucumber mosaic virus under field conditions with natural challenge inoculations by vectors

Vitis labruscana 'Concord' is a widely planted grape cultivar grown in the United States for processing into juice and other products. Concord fruit are sporadically but sometimes severely damaged by the grape powdery mildew pathogen, Uncinula necator. The effects of powdery mildew on vine growth, yield, and quality of Concord grapes at three levels of cropping intensity commonly found in commercial grape production were determined in vineyard studies. Top-wire cordon-trained Concord vines were balance pruned, pruned to retain 80 nodes, or minimally pruned. Replicated plots of the foregoing were then either protected from powdery mildew by regular fungicide applications, or were inoculated and left unsprayed. Over a 4-year period, the effects of foliar infection on vine growth, yield, and juice quality of unsprayed vines were compared with vines that received a conventional protection program of four fungicide applications. Failure to control powdery mildew resulted in a chronic reduction in wood maturity measured as the number of nodes on canes that developed periderm. The reduction in nodes did not reduce yield, possibly due to compensation in shoots produced from the remaining nodes. Powdery mildew did not affect bud survival or vigor, measured as the number of shoots produced per node on retained canes. The most significant effects of powdery mildew were on berry sugar levels and juice color and acidity, which on the unsprayed vines were sometimes reduced below minimally acceptable thresholds for processed grapes. Significant reductions due to powdery mildew in these parameters occurred in all three pruning treatments, but were most pronounced at higher cropping levels.

https://apsjournals.apsnet.org/doi/pdfplus/10.1094/PDIS.2001.85.2.137

Robert C. Seem

Papers

Grapevine powdery mildew (Erysiphe necator): a fascinating system for the study of the biology, ecology and epidemiology of an obligate biotroph.

Ontogenic resistance to powdery mildew in grape berries.

Partial control of grape powdery mildew by the mycoparasite Ampelomyces quisqualis.

Comparison of coat protein-mediated and genetically-derived resistance in cucumbers to infection by cucumber mosaic virus under field conditions with natural challenge inoculations by vectors

Effects of Powdery Mildew on Vine Growth, Yield, and Quality of Concord Grapes.