Botrytis infection

There are several reports of the use of ozone with biotic pathogens, and the responses noted were independent of each other. These reports include Lophodermium pinastri infection of white pine, Fusarium. infection of cabbage, Botrytis infection of poinsettia bracts, rust on bean, and brown root rot of tomato. These results could reflect the conditions used. 

The aroma of botrytized wines has been studied more extensively than that of the grapes. Mashuda et ah (1984) identified the lactone sotolon (4,5-dimethyl-3-hydroxy-2,(5)-furanone) as a principal compound in a botrytized aroma. Sotolon is also a key aroma compound in flor wines, for example, vin jaune, sherry (Dubois et ah, 1976 Martin and Etievant, 1991 Moreno et ah, 2005). However, Sponholz and Hiihn (1993) found no correlation between the degree of Botrytis infection and sotolon... 

Botrytis Effect on Fermentation. Peynaud et al. (28) suggest that Botrytis cinerea ( noble rot ) produces a substance that inhibits yeast activity. While this substance has not been isolated in the United States, it has been the author s observation that botrytis-infected grapes ferment at a slower rate and have more difficulty completing fermentation. This fermentation inhibition also may be attributable to the higher initial °Brix and, later, to the ethanol and higher residual sugar content of the botrytized wines. 

When this parasite invades the grape-berry, it leaves a characteristic metabolic footprint which has been shown to be closely correlated with the degree of infection and the associated technological problems. Although the correlation is not linear it may nonetheless be modelled using neural networks and thus it is quite possible to express the degree of Botrytis infection in the form of an index. 

Nisiotou, A. A., Nychas, G.-J. E. (2007). Yeast popnlations residing on healthy Botrytis-infected grapes from a vineyard in Attica, Greece. Applied and Environmental Microbiology, 73, 2765-2768. 

Canopy management may also mitigate or make worse the potential for Botrytis infection. Generally, dense canopies which minimize air circulation and light incursion favor a relatively humid environment which increases the potential for mold growth. Open canopies not only favor air circulation but spray penetration as well (English et al., 1990). 

Margalit (2004) proposed that optimal harvest sugar concentrations be 19°Brix to 23°Brix (white cultivars) and 21°Brix to 24°Brix (red cultivars). However, winemakers in the United States will frequently require more mature fruit optimal to maximize flavor development associated with physiological maturity (i.e., desired tannin structure). In the case of late harvest or Botrytis-infected fruit, the concentration of fermentable sugars can be much higher, ranging upward to 40% w/w. 

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