Necrotic leaf removal, a key component of integrated management of

Introduction. 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 Mycosphaerella 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 divided into two groups of SD infestation levels: level 1 (Severity Index at flowering  25%). We divided each group into two treatments: a treatment with no necrotic leaf removal and a treatment with necrotic leaf removal. 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

Impacto de las enfermedades foliares de Sigatoka sobre la calidad del banano

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Effect of different levels of Sigatoka disease severity on banana pulp colour and early ripening

International audienceLes bananes sont généralement récoltées vertes, en phase pré-climactérique, avant la mise en marché et la commercialisation. Le temps de transport nécessaire entre la zone de production et les chambres où sont mûris des fruits est appelé durée de vie verte ou green life (GL), qui est défini par le nombre de jours entre la récolte et l'initiation naturelle des processus de maturation. Il a été montré que la Sigatoka Disease (SD) a une influence sur le comportement post récolte des fruits. Ce travail a pour objectif de déterminer s'il existe une relation entre le niveau de sévérité de la SD et des paramètres de qualité de la banane caractérisés par des caractéristiques pomologiques, notamment la couleur de la pulpe. Dans une expérimentation conduite avec des fruits récoltés à âge physiologique constant, nos résultats montrent que la SD a un effet très marqué sur le pourcentage de fruits mûrs au champ et sur le poids des fruits à la récolte, mais pas sur le calibre. Nous avons également montré que la couleur de la pulpe était fortement affectée par la SD ; quand l'intensité de la maladie augmente, les paramètres définissant la couleur de la pulpe sont modifiés - la valeur de L* (clarté) décroit ; les valeurs de a* (axe rouge - vert) et b* (axe jaune-bleu) augmentent, donnant un teint grisâtre à la couleur de la pulpe, avec un peu moins de teinte verte et plus de jaune et de rouge. Ces résultats nous permettent de proposer une méthode de contrôle de la qualité des fruits, par mesure au champ de la couleur de la pulpe, dans le but de réduire les pertes après-récoltes. (Résumé d'auteur

Natural Ecosystem Surrounding a Conventional Banana Crop Improves Plant Health and Fruit Quality

Natural ecosystems near agricultural landscapes may provide rich environments for growing crops. However, the effect of a natural ecosystem on crop health and fruit quality is poorly understood. In the present study, it was investigated whether the presence of a natural ecosystem surrounding a crop area influences banana plant health and fruit postharvest behavior. Plants from two conventional banana crop areas with identical planting time and cultural practices were used; the only difference between banana crop areas is that one area was surrounded by a natural forest (Atlantic forest) fragment (Near-NF), while the other area was inserted at the center of a conventional banana crop (Distant-NF). Results showed that bananas harvested from Near-NF showed higher greenlife and a more homogeneous profile during ripening compared to fruits harvested from Distant-NF. Differences in quality parameters including greenlife, carbohydrate profile, and pulp firmness between fruits harvested from Near-NF and Distant-NF are explained, at least partly, by differences in the balance of plant growth regulators (indole-3-acetic acid and abscisic acid) in bananas during ripening. Furthermore, plants from Near-NF showed a lower severity index of black leaf streak disease (BLSD) and higher levels of phenolic compounds in leaves compared to plants from Distant-NF. Together, the results provide additional evidence on how the maintenance of natural ecosystems near conventional crop areas could be a promising tool to improve plant health and fruit quality

Relation between the severity of Sigatoka disease and banana quality characterized by pomological traits and fruit green life

International audienceBanana fruit are typically harvested at a green preclimacteric stage prior to sale. The green life (GL), which is defined as the number of days between harvesting and initiation of the natural ripening process, is important for harvesting, shipping and marketing. Sigatoka disease (SD) has previously been shown to influence the postharvest quality of banana fruit. The present study was conducted to determine (1) whether there is a relationship between the level of SD severity and the banana quality as characterized by several pomological traits and fruit green life, and (2) whether there is a level of SD severity that is acceptable for fruit exporting. In an experiment conducted with fruit harvested at a constant physiological age, our results showed that the disease decreases fruit GL. Based on the relationship established between SD severity and GL, it is possible to define an acceptable disease level threshold corresponding to a specified GL. Additionally, we found that high SD infections caused a reduction in fruit weight but did not affect fruit size. Possible explanations are discussed. (Résumé d'auteur

Black leaf streak disease affects starch metabolism in banana fruit

International audienceBlack leaf streak disease (BLSD), also known as black sigatoka, represents the main foliar disease in Brazilian banana plantations. In addition to photosynthetic leaf area losses and yield losses, this disease causes an alteration in the pre- and postharvest behavior of the fruit. The aim of this work was to investigate the starch metabolism of fruits during fruit ripening from plants infected with BLSD by evaluating carbohydrate content (i.e., starch, soluble sugars, oligosaccharides, amylose), phenolic compound content, phytohormones, enzymatic activities (i.e., starch phosphorylases, alpha- and beta-amylase), and starch granules. The results indicated that the starch metabolism in banana fruit ripening is affected by BLSD infection. Fruit from infested plots contained unusual amounts of soluble sugars in the green stage and smaller starch granules and showed a different pattern of superficial degradation. Enzymatic activities linked to starch degradation were also altered by the disease. Moreover, the levels of indole-acetic acid and phenolic compounds indicated an advanced fruit physiological age for fruits from infested plots. (Résumé d'auteur

Presentation_1_Natural Ecosystem Surrounding a Conventional Banana Crop Improves Plant Health and Fruit Quality.pdf

<p>Natural ecosystems near agricultural landscapes may provide rich environments for growing crops. However, the effect of a natural ecosystem on crop health and fruit quality is poorly understood. In the present study, it was investigated whether the presence of a natural ecosystem surrounding a crop area influences banana plant health and fruit postharvest behavior. Plants from two conventional banana crop areas with identical planting time and cultural practices were used; the only difference between banana crop areas is that one area was surrounded by a natural forest (Atlantic forest) fragment (Near-NF), while the other area was inserted at the center of a conventional banana crop (Distant-NF). Results showed that bananas harvested from Near-NF showed higher greenlife and a more homogeneous profile during ripening compared to fruits harvested from Distant-NF. Differences in quality parameters including greenlife, carbohydrate profile, and pulp firmness between fruits harvested from Near-NF and Distant-NF are explained, at least partly, by differences in the balance of plant growth regulators (indole-3-acetic acid and abscisic acid) in bananas during ripening. Furthermore, plants from Near-NF showed a lower severity index of black leaf streak disease (BLSD) and higher levels of phenolic compounds in leaves compared to plants from Distant-NF. Together, the results provide additional evidence on how the maintenance of natural ecosystems near conventional crop areas could be a promising tool to improve plant health and fruit quality.</p