Verticillium

Verticillium is a genus of fungi in the division Ascomycota. Within the genus, diverse groups are formed comprising saprophytes and parasites of higher plants, insects, nematodes, mollusc eggs and other fungi thus it can be seen that the genus is a wide ranging group of taxa characterised by simple but ill-defined characters. The genus may be broadly divided into three ecologically based groups 1) mycopathogens 2) entomopathogens (Zare and Gams, 2001) and 3) plant pathogens and related saprophytes (Barbara and Clewes, 2003). The better known species of Verticillium fall within the plant pathogenic ecotype, Vertcillium dahliae and Verticillium albo-atrum that cause wilt diseases in economically important plant species such as cotton, tomatoes, potatoes, eggplants, peppers, ornamental woody plants, as well as plants in natural vegetation communities.

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Symptoms are superficially similar to Fusarium wilts. Crop rotation, the use of resistant crop varieties and deep plowing, may be useful in controlling Verticillium wilt.

Selected species

• Verticillium dahliae Kleb.

• Verticillium lecanii Viegas - This fungus species was first described in 1861. It has a worldwide distribution found on insects. In horticulture and agriculture it is sometimes used as an entomopathogen (infects insects) for controlling insect pests like mealybugs and mites and aphids. It's a bio-pesticide/Bio-Insecticide that is sprayed on insects while they are feeding off of desirable plants. The insects are infected when they come into contact with the sticky fungal spores which then grow and invade the body, thus pathogenesized, the insects internal organs are consumed, leading to the insects death.

• Verticillium albo-atrum Reinke & Berthold - Causes Verticillium Wilt or Maple Wilt. First identified from potatoes in Germany in 1870. This species attacks over 300 different cultivated plants and can persist as a saprophytic soil organism for more than 15 years. When infecting ornamental trees like Maples, Elms, Aspen, Ash, Beech, Catalpa Oak plus many more the first symptoms are midsummer wilting on one side of a tree or branch. The sapwood has greenish or brownish streaks, and the infection can take a few years to progress to the rest of the tree or move rapidly. The fungi universally move up the xylem vessels. In fruit trees the infection is know as 'Black Heart' and is common in apricots and sometimes effects almonds, peaches, plums and avocado. This Fungus also effects herbaceous ornamentals and vegetables like Chrysanthemum, mints, Lychnis, tomatoes, eggplants, okra, rhubarb. Causing wilting and death. Identification can be made by looking for one-celled conidia, hyaline round to ellipsoid which are formed at the tips of whorled branches. They are easily separated from the tips.

References and external links

• Barbara, D.J. & Clewes, E. (2003). "Plant pathogenic Verticillium species: how many of them are there?" Molecular Plant Pathology 4(4).297-305. Blackwell Publishing.
• Phillips, D. H. & Burdekin, D. A. (1992). Diseases of Forest and Ornamental Trees. Macmillan. ISBN 0-333-49493-8.
• Zare,R. and Gams, W. (2001). A revision of Verticillium sect. Prostrata. III. Generic classification. Nova Hedwigia. 72. 329-337.
• Fact sheet from Ohio State University Extension on verticillium and fusarium