Meloidogyne chitwoodi, M. fallax and M. hapla – resistance of plants relevant in Swedish cropping systems
The genus Meloidogyne, i.e. the root-knot nematodes, is widespread and has an extremely broad host range. This report focus on three Meloidogyne spp.; M. chitwoodi and M. fallax, which are both regulated in the EU, and M. hapla, which is widely distributed in the EU. Both M. chitwoodi and M. fallax has recently been found for the first time in Sweden.
These three nematode species are very difficult to control. Preventing introduction and further spread is the most efficient measures. Bare fallow, when the fields are kept clear of all susceptible plants, can efficiently reduce the nematode populations. Due to the very broad host range it is a challenge to manage the nematodes with crop rotation. Nevertheless, this report includes a review of the available information associated with the host status of different plant species relevant for Swedish agriculture. Some crops and cultivars are either immune (i.e. show no nematode feeding or reproduction) or resistant (i.e. severely suppress the reproduction) against certain Meloidogyne spp. Further, this report also includes information about the level of damage sustained by the nematodes on different crops and cultivars, i.e. their level of tolerance against the different nematode species.
To briefly summarize; although some crop species were reported as immune or resistant, the response was, to a very high degree, cultivar specific. Relatively few cultivars were immune whereas many were resistant. Immune plants, which does not support any nematode reproduction will be the most efficient in decreasing nematode populations and the effect should theoretically be comparable with bare fallow. In cultivars classified as ”resistant” some reproduction occurs but they do not support a population increase.
Almost all tested weed species were found to be susceptible. Thus it is important to remove all weeds to prevent population growth of the nematodes.
This report provides a first screening of the available information for a very large number crops/cultivars. Therefore, further analysis may change the assessment for some cultivars.