[Using of the threshold of control at leek and onion]

allium cepa alternaria alternaria porri calidad crop yield cultivation cultivo cultivo de hortalizas diagnosis diagnostic enfermedades fungosas feuille fongicide fungal diseases fungicidas fungicides hojas insecte nuisible insecticidas insecticide insecticides leaves leeks maladie fongique meteorological elements peronospora peronospora destructor pest insects plant protection poireau pratique culturale protection des plantes puccinia allii puerro quality rendement des cultures rendimiento de cultivos thrips tabaci vegetable growing