Image Number: 1440047

Uneven growth of tobacco in the field is indicative of black root rot. Affected plants often become yellowed and are smaller than neighboring healthy plants. Stunting is more evident during the early part of the growing season and during cool, wet seasons. On hot days, leaves of the diseased plants wilt more rapidly than those of healthy plants, but recover during the night. Plants usually grow out of the problem as soil temperatures rise, unless the variety is highly susceptible to the fungus and cool, wet soil conditions prevail. the most distinctive symptoms of black root rot occur on the roots. The entire root system is greatly reduced with smaller roots exhibiting a typical brown to black discoloration of their tips, and larger roots having brown or black spots on their surface. The outer root tissue may slough easily.
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Image location:
United States


Kingdom: Fungi
Phylum: Ascomycota
Subphylum: Pezizomycotina
Class: Sordariomycetes
Subclass: Hypocreomycetidae
Order: Microascales
Family: Ceratocystidaceae
Genus: Thielaviopsis
Subject: Thielaviopsis basicola (Berk. & Broome) Ferraris


Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Subclass: Asteridae
Order: Solanales
Family: Solanaceae
Genus: Nicotiana
Subject: Nicotiana tabacum (burley type) L.
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Image uploaded:
Monday, January 1, 1990
Image last updated:
Tuesday, August 2, 2011