Breeding of lucerne for increased resistance to animal and plant pests
Paru en 1975 dans Fourrages n°64 (page 19 à 34)
Auteurs : Guy P.
The intensification of Lucerne production has increased the importance of its predatory insects and parasites. Pathologists and zoologists have endeavoured to establish the list of the main predators and parasites in France, with their relative importance, the most infested regions, and the levels attained by insect populations at the moment of notable attacks.
1) Distribution of the main Lucerne pathogenic agents :
The main losses in the North of France are due to Verticillium albo-atrum, Colletotrichum trifolii and Ditylenchus dipsaci cause also important damages. Viruses are mainly present in the Mediterranean area.
2) Relationships between Lucerne and its insect predators :
The main predators during the vegetative phase are : Sitona humeralis, which leads on nodules, larvae of Phytonomus variabilis, abundant on second growths, Apion pisum, present on first growths, Acyrthosiphon pisi, found in numbers which vary much with the method of management.
3) Genetical aspects of resistance :
There exist in Medicago sativa various genetical mechanisms of resistance to a high number of parasites, e.g. polygenic resistance to Verticillium alboatrum, monogenic resistance to Colletotrichum trilolii...There are in France varieties resistant to Verticillium, to Nematodes and, to a lesser extent, to Colletotrichum.
A regional adaptation of the varieties is necessary, certainly as regards forage production, but also, occasionally, for seed production.