Necrotic leaf removal, a key component of integrated management of Mycospaerella leaf spot diseases to improve the quality of banana: the case of Sigatoka disease

摘要

Bananas are harvested at the green preclimacteric stage prior to sale. The time between harvest and the initiation of the natural ripening process is called green life. Black Leaf Streak Disease and Sigatoka Disease are the main foliar diseases affecting banana production. Sigatoka Disease (SD) is due to Mycospbaerella musicola, which frequently causes early ripening in commercial banana plantations, considered as an important source of damage. Our work aimed at determining the effectiveness of the removal of necrotic leaves, one month before harvest, on recovering banana quality arising from SD-infested plants. Materials and methods. Banana plants (totaling 80) at the flowering stage were selected in an experimental plot. These plants were dividedinto two groups of SD infestation levels: level 1 (Severity Index at flowering < 10%) and level 2 (Severity Index at flowering > 25%). We divided each group into two treatments: a treatment with no necrotic leaf removal and a treatment with necrotic leafremoval. Fruits were harvested at the same physiological age, at 900 degree-days. Fruit quality was characterized by weight, diameter, % of ripe fruit in the field and fruit green life. Results. Our results showed that the removal of necrotic leaves causes a reduction in size parameters but leads to a strong reduction in SD effects on the fruit maturity, thereby preventing premature ripening. Banana plants whose necrotic leaves were removed produced fruit with a very long green life. Discussion. Removal of necrotic leaves allows thwarting the negative effect of SD on fruit physiology. This shows that the presence of necrosis during the last month of fruit, growth is responsible for this fruit physiological modification characterized by early ripening.Conclusion. Removal of necrotic leaves one month before the date of harvest may be a technique that can limit production losses when the infestation level by SD is high.