Faba bean rust and pea powdery mildew management by intercropping with cereals and by cultivar mixtures

Trabajo presentado en la International Conference Advances in grain legume breeding, cultivations and uses for a more competitive value-chain, celebrada en Novi Sad (Serbia) el 27 y 28 de septiembre de 2017.Limited biodiversity is a problem of modern agriculture. The generalization of intensive monocrops has entailed a loss of biological richness in agricultural ecosystems, which has originated several problems, such as reduced soil fertility or a higher incidence of pests and diseases. Two strategies to introduce diversification in our agricultural systems are intercropping, by mixing different crops in the same field, or varietal mixtures, i.e., growing together different varieties of the same crop. In the frame of LEGATO project we have tested during three field seasons both strategies to control two important diseases of grain legumes: rust in faba bean and powdery mildew in pea. In the case of intercropping, the main crop (faba bean or pea) was mixed with either one of two cereals (wheat and barley) or another legume (pea or faba bean). As for varietal mixtures, the experimental design consisted of mixing different proportions of a resistant monogenic variety with a susceptible one Alternate-row mixing was the system employed in both experiments. Results point to a significant reduction of the incidence of both diseases in the intercropped treatments compared to that of the monocrop. Both in the case of rust in faba bean and powdery mildew in pea the best results are obtained when the legume is combined with barley. Varietal mixtures also achieve an important reduction in the levels of both diseases in the susceptible variety. A proportion of 50/50 (resistant/susceptible) appears to be the most efficient combination, balancing adequately disease suppression and increase of genetic variability.N