Wisconsin tobacco varieties are moderately resistant 
to the fungus causing black root rot (Thielaviopsis 
basicola) (30). A susceptible variety planted in soil 
that previously produced tobacco is very markedly 
stunted. The fungus is nearly ubiquitous in Wisconsin 
soils, so that susceptible tobacco varieties are self- 
eliminating. Havana 42 5 has this resistance; whether 
it is retained in the experimental tobacco is 
undetermined. 
Tobacco anthracnose, caused by Colletotrichum 
destructivum, occurs occasionally on plants in the seed 
bed. Commercial varieties, including Havana 42 5 , are 
susceptible, but infection is rare. 
Blue mold, caused by Peronospora tabacina, has 
recently been a devastating disease in the Eastern 
United States and Canada. The fungus does not remain 
viable over winter in Wisconsin or many parts of the 
United States. Although the disease occurred once in 
Wisconsin, (14) the state has remained free of it since, 
presumably because the winds during the growing 
season are predominantly western and southwestern. 
Spores produced by the perennating fungus in the 
Caribbean region are extremely unlikely to reach 
Wisconsin. 
Environmental Assessment 
Page 38 
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