Resumen de Disease and pest control in the bioenergy crops poplar and willow
An understanding of the population ecology, genetics and epidemiology of pests and pathogens is necessary for the development of reliable and effective pest and disease management systems in energy crops. Rust diseases are among the most devastating on poplars and willows. Analysis of forms of the Melampsora rust pathogens has revealed a complex array of species, form species, races and pathotypes. The important rusts on poplars all appear to be leaf-infecting with life-cycles involving alternate hosts and the full complement of rust spore stages. Most of the rusts on willows are similar, except that there are forms which infect stems and young shoots and which complete their life-cycles vegetatively, as a single spore stage and without the intervention of an alternate host. Rust/clone interaction trials, begun in 1993, have been established at four sites in N. America to determine the regional occurrence of species and races of poplar rust and to assess selected clones for resistance. Until now, only M. medusae has been recorded and was most severe at a site which was in close proximity to a planting of the alternate host, Larix laricina. Trials on willows, begun in 1991 and involving 6 sites, have shown that the Melampsora species and pathotypes occurring in rust populations in the UK and Sweden are similar, but markedly different from those occurring in Canada. New pathotypes have arisen recently in the UK apparently in response to selection pressure from long-term plantings of certain clones. Insect pests occurred at all sites but usually without causing significant damage.
Until recently, Septoria musiva and S. populicola, which are responsible for leaf spots, cankers and probably also plant death in poplar, were confined to the northeastern United States and Canada. Probably due to movement of propagating material, S. populicola now occurs also in the Pacific Northwest. Extensive genetic variation has been encountered among Septoria isolates, using pathogenicity tests and DNA-RAPD profiling. The use of resistant clones is probably the only practical means of controlling S. musiva. Research is attempting to establish linkage between DNA markers and genes for disease resistance.
