Fusarium wilt of tobacco

Fusarium wilt of tobacco is widespread in tobacco growing regions of the world and can cause significant losses in yield and quality. The pathogen is quite variable, with different pathogenicity and host ranges associated with forma speciales and lineages from tobacco and sweet potato or cotton. At least 4 groups have been described, including F. o. f. sp. vasittfectum from cotton, one that includes all isolates originally recovered from tobacco (F o. f. sp. nicotianae), and two E o. f. sp. batatas groups with different pathogenicity to flue-cured tobacco or wilt-resistant sweet potato. In addition, a new species has recently been described causing wilt of flue-cured tobacco in China. The Fusarium wilt pathogen has the potential to spread quickly, and can be associated with tobacco seed. In experiments conducted in Connecticut, the fungus was present both inside and on the exterior of the seed and can account for the rapid spread of the pathogen between farms, states and even between countries. The wilt pathogen can interact with plant parasitic root-knot and cyst nematodes to increase disease, and can persist in soils for years in the absence of a host crop. Fusarium wilt may best be managed in tobacco by integrating different tactics, including plant resistance, sanitation, rotation, nutrition, nematode management, and fumigation or biofumigation. Wilt resistance has been, and continues to be, the most effective and economical means of reducing disease. However, wilt resistance does not eliminate the pathogen from soils, so breeders and pathologists must work together to develop and deploy wilt-resistant tobacco cultivars indefinitely. (C) 2015 Elsevier Ltd. All rights reserved.