Annual pruning of cactus pear cladodes provides an opportunity for adding value to this crop by extracting mucilage from which to create edible films and coatings for perishable fruits such as guavas (Psidium guajava L.). The objective of this research was to create mucilage films and assess their effects on quality and shelf life of guava cultivar 'Media China'. Cactus pear cladodes were peeled, cubed, and homogenized in distilled water. Mucilage was precipitated using ethanol, then dried and ground. The experimental films tested were: no films as control (C), mucilage plus glycerol (T 1), and mucilage plus glycerol and polyethylene glycol (T 2). Two experiments were conducted with two different concentrations of mucilage, glycerol, and polyethylene glycol. Guavas were harvested from local farmers and treated with a fungicide before coating. The treated fruit was stored for eight or six days at room temperature (28°C and 20% RH or 27°C and 20% RH, respectively). In the first trial, the T 2 film increased fruit weight loss more than C and TI film. Both films delayed fruit skin colour and maintained higher firmness (F), total soluble solids concentration (TSSC), and dry matter concentration (DMC) than C fruit. In the second trial, T 1 and T 2 films reduced fruit weight loss and delayed fruit skin colour more than C fruit. Firmness, TSSC, and DMC of fruit were similar among treatments. Overall, the experimental mucilage films showed a tendency to prolong shelf life and maintain some quality attributes of guava. Further research is needed to understand the mucilage potential as an edible film at cold room conditions.
In fall 2014, 5 to 75% percent of chili and bell pepper (Capsicum annuum L.) in commercial fields located in the Mexican states of Durango, Zacatecas, and Michoacán had symptoms of deformed, small, mosaic, curled, and chlorotic leaves; shortened internodes; plant dwarfing; or phyllody and rosetting leaf tips. At the same time, leafhoppers and psyllids were observed in the fields, and more than 50 beet leafhoppers (Circulifer tenellus) and nearly 300 potato psyllids (Bactericera cockerelli) were collected from the pepper plants and adjacent weeds. Based on the insect pressure and observed symptoms, nearly 400 pepper samples were collected across this region of Mexico and tested for the presence of leafhopper- and psyllid-associated pathogens. In all, 76% of the pepper samples were found to be infected with ‘Candidatus Liberibacter solanacearum’, beet leafhopper-transmitted virescence agent (BLTVA) phytoplasma, a strain of a curtovirus, or a combination of any two or three of these pathogens. Additionally, 77% of the collected leafhoppers and 40% of the psyllids were infected with one or more of these pathogens, in addition to Spiroplasma citri. Specifically, the leafhoppers were infected with BLTVA phytoplasma, S. citri, or a strain of curtovirus. Of particular interest, potato psyllids were not only infected with ‘Ca. L. solanacearum’ but also with phytoplasmas that belong to the groups 16SrVI subgroup A and 16SrI subgroup A. The presence of mixed infections in pepper plants and the insect vectors highlights the need for growers to effectively control both leafhoppers and potato psyllids from solanaceous crops in this region of Mexico in order to prevent the spread of these bacterial and viral pathogens.
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