Leaf anthracnose (Colletotrichum gloesporioides) is one of the most important diseases of onion in southern Brazil, manifesting as syndrome dependent upon plant growth stage and genotype. In order to better understand the symptomatological patterns and to screen resistant varieties, it was evaluated the reaction to anthracnose and the disease progress rate in 21 onion varieties under greenhouse conditions during 2004/05. Plants were inoculated at growth stage H (all true leaves emitted) and inoculated by spraying a suspension of 1.2 x 10(6) conidia. Inoculated plants never died, but did show different levels of disease severity. No variety was completely resistant to the isolate Cg 103. However, about half of them, i.e. the varieties Alfa Tropical, Alfa Tropical II, Belém IPA 9, Crioula Hortec, Crioula Roxa, Epagri 304, IPA 6, Régia, Rosada Empasc 358, Roxa IPA 3 and Super Precoce, exhibit lower disease progress rates, suggesting the existence of several sources for partial resistance.
Allium cepa L.; resistência parcial; mal-das-sete-voltas
