Pathogenicity in Verticillium on strawberry plants

Summary

In the most common strawberry cv. ’Elsanta’, Verticillium infection can lead to rapid wilt
and even death of plants. It is known, that a dead plant can be located directly beside vital
ones. In a survey of 8 fields in Brandenburg, Mecklenburg- Vorpommern, Sachsen-Anhalt
and Sachsen, 432 genotypes of Verticillium dahliae Kleb. were isolated from wilted and
even vital plants from 8 fields and classified by PCR-fingerprints. For strawberries, the
genotypes can be classified as apathogenic, weakly and highly pathogenic according to
the results of climate chamber experiments on strawberry transplants.
At landscape scale, similarity analysis of the PCR fingerprints of 432 genotypes resulted in
13 genetic subtypes. Several of these subtypes occurred at all fields, whereas 1 subtype
was found in one location only. At field scale, 2 to 11 different subtypes per field were
observed. Vital plants were colonised by up to 9 subtypes, wilted plants by up to 11
subtypes. Population structure of Verticillium subtypes is different between vital and wilted
plants, the same subtypes can occur in either plant group. In our plot experiments, wilt
symptoms could be reduced by changing the Verticillium population structure in the plant.
Inoculation of plants with a mixture of three Verticillium genotypes sustained plant vitality
over a period of 15 months (WO 2007/051654).