Removal of Symptomatic Cassava Leaves as Cultural Practice to Control Cassava Bacterial Blight

Abstract

The cassava landrace BEN 86052, susceptible to cassava bacterial blight (CBB), was chosen for the field experiments conducted in the forest savannah transition zone at Abomey-Calavi, Benin Republic. One month old plants were spray-inoculated with Xanthomona axonopodiss pv. manihotis (Xam) strain GSPB 2506 to achieve a homogenous infection across all plots. Disease development and cassava growth parameters were monitored over 12 months. Diseased leaves were removed four times at an interval of three weeks. A detailed symptom evaluation of percentage of spots, blight, wilt and dieback revealed significant reduction of blight and wilt symptoms in removed leaves plots. Disease severity was reduced by 71% in plots with leaf removal compared to non-removed leaves plots. Growth parameters leaf, stem and root weight at 6 and 12 months after planting were not significantly different between removed leaves and non-removed leaves plots. In fact, removal of infected leaves had no significant effect on root yield and reduced the epidemic potential of cassava bacterial blight in the field in the same season and the transfer of the infection by contaminated cuttings to the next season. Removal of diseased leaves should be highly effective in cassava fields with low disease incidence and specifically recommended for moderately resistant or resistant cultivars as part of an integrated management to control the cassava bacterial blight.