Tropical Plant Pathology
On-line version ISSN 1983-2052
FURTADO, Edson Luiz; MENTEN, José O.M. and PASSOS, José Raimundo. Intensidade do mal das folhas em plantas jovens e adultas de seis clones de seringueira na região do Vale do Ribeira: South American leaf blight intensity evaluated in six clones of young and adult rubber trees in the Vale do Ribeira region, São Paulo state, Brazil. Trop. plant pathol. [online]. 2008, vol.33, n.2, pp. 130-137. ISSN 1983-2052. http://dx.doi.org/10.1590/S1982-56762008000200007.
Rubber tree clones present different intensity of symptoms, depending on their age. This is mostly clearly seen inthe presence or absence of old leaves with ascopores, corresponding to flows of new and susceptible leaves. The objective of this work was to evaluate the intensity of symptoms of South American leaf blight (SALB) in six rubber tree clones, one and eight years old, in the Vale do Ribeira region, São Paulo state. The results showed that clones FX 3864, RRIM 600, IAN 873 and IAN 717 suffered more attacks when young, and RRIM 600, IAN 717 and FX 3864 when adult. The clone IAN 873 showed the smallest amounts of disease in the adult phase, due to uniform change in the leaves and a compact flow of new leaves, which happened during a season that was unfavorable to pathogen infection, presenting the phenomenon of avoidance or evasion in time.
Keywords : Microcyclus ulei; incidence; avoidance; evasion.