Protection Methods

- During cultivation

No control methods for Fusarium wilt are currently available in France.

After harvest, it is a common practice to bury crop residues in the soil. Numerous chlamydospores are produced in buried plant tissues colonised by Fusarium oxysporum f. sp. nicotianae. Elimination of crop residues limits this source of inoculum and thus reduces the amount of inoculum in a field.

- Next crop
 

Farm equipment, including tractor wheels, used in fields where the disease is present must be thoroughly cleaned before use in other fields where the disease is not present. Thorough rinsing with water is often sufficient to remove the infested soil.

Crop rotation can help reduce the occurrence of the disease. Rotation, in order to be be effective, must be long enough and should not include crops that are hosts of Fusarium spp. such as sweet potato, cotton, etc.

In Zimbabwe, where Fusarium wilt has been observed in Burley tobacco, it is recommended to soak the nursery soil with a solution of benomyl to limit the damage.

The most effective method for control of this disease is the use of resistant varieties. Partial resistance has been observed in Nicotiana tabacum. This type of resistance involves multiple genes with additive effects. These genes have been introduced into several American cultivars that demonstrate varying levels of resistance to the disease.

As part of Fusarium wilt management, control of root-knot or cyst nematodes is recommended when the latter are present even where a variety resistant to Fusarium wilt is used. Nematodes damage the roots, and reduce the effectiveness of resistant varieties. Occasionally, the use of varieties resistant to root-knot nematodes is recommended (see also the fact sheets on Meloidogyne spp. and Pratylenchus spp.).
 

*In order to give a "universal" character for the proposed protection methods, we have produced a fairly comprehensive inventory of these and have included  the fungicides reported in the various tobacco producing countries. For some diseases, we have even suggested alternative phytosanitary methods. It is obvious that the adaptation of these recommendations varies depending on the country and the pesticide legislation prevailing in the given country.

U.S. situation

Fusarium wilt is not as aggressive as some other diseases, such as Granville wilt or black shank, but it might also be considered an “opportunistic” disease. If tobacco plants are stressed in certain ways, such as by root wounding or nematode infection, significant fusarium wilt may develop. Although crop rotation and stalk and root destruction are beneficial to some extent, these practices do not drastically reduce fusarium wilt development because of the fungus’s ability to live on organic matter and form resistant spores. Nematode management is the most effective management practice for reducing incidence of fusarium wilt.

(Mina Mila - North Carolina State University)