Efficacy of control of copper for citrus canker on lemon and its relationship with rainfall.

FOGLIATA, G.M.; MARTINEZ, C.V.; ROJAS, A.A.; MUÑOZ, M.L.; PLOPER, L.D.

Foz do Iguacu

Congreso; International Citrus Congress 2016; 2016

IAC - IAPAR

Citrus canker, an important quarantine citrus disease, is controlled by applying cupric fungicide-bactericides. Field tests were conducted for nine years to evaluate the efficacy of cuprous oxide, copper oxychloride and cupric hydroxide on citrus canker control. Different climate variables were analyzed to determine which ones were correlated with the incidence of canker in the untreated control in these field trials. Variables were analyzed at different times within the period of infection (October to March). The average efficacy of the different fungicide-bactericides was: 93% in years with low incidence of disease (less than 21% of fruits with symptoms of citrus canker in the untreated control), 87% in years with medium incidence (30%-40% in the untreated control), and 83% in years with high incidence (about 70% in the untreated control). The results showed a strong positive correlation between rainfall in the period December-January (summer months) and citrus canker incidence in the untreated control. Incidence also showed a positive correlation (although weaker) with the number of rainy days in that period, but not with duration of leaf wetness. Although it is important to protect the fruit during the whole period of susceptibility to infection, the most critical months are December-January in the lemon production area of Tucumán, Argentina.