Tea (Camellia sinensis (L) O. Kuntze) is a plantation crop, grown commercially in Asia, Africa and South America. Among biotic threats to tea production, diseases caused by fungal pathogens are most significant. Worldwide, tea plants are challenged by several root, stem, and foliar diseases. Foliar diseases, blister blight, grey blight, and brown blight are particularly important as they adversely affect the bud and the two youngest leaves, causing loss of harvestable shoots. Over the past several decades, climate change and field management practices have influenced the risk of crop damage by several fungal pathogens, as well as the development and spread of diseases. Management interventions, such as the adoption of good cultural/agronomic practices, use of fungicides and microbial biocontrol agents, plant defense elicitors, and deployment of resistant cultivars, have mitigated damage to tea plants caused by fungal diseases. A clearer understanding of knowledge gaps and the benefits of plant disease management strategies available is needed. The present article reviews the prevailing knowledge of major fungal pathogens of the tea crop, their genetic variability, the damage they cause and its economic impact, the need for new disease management strategies as climate change intensifies. We will also emphasize important knowledge gaps that are priority targets for future research.
Unripe mangoes contain a network of minute latex canals in its exocarp, outer mesocarp and the pedicel. Latex, when retrieved, separates into an upper oily layer containing antifungal resorcinols and a lower aqueous layer with chitinase activity. Latex disappears in coincidence with ripening and decline of fruit resistance to fungal pathogens. The present study investigated if retention of latex at harvest enhances fruit resistance and reduces anthracnose and the stem-end rot (SER) development during ripening. Latex was retained by harvesting fruit with a portion (approximately 1 cm) of pedicel while in the controls, latex was drained off by removing the pedicel. Anthracnose and SER development from natural infections or following artificial inoculation was assessed at ripe stage. The results showed a significant reduction in the incidence and severity of anthracnose in the cultivar 'Willard' susceptible to anthracnose when latex was retained at harvest. There was delayed SER development when latex was retained in the susceptible cultivar 'Karutha Colomban'. A negative trend was observed between the pedicel length and anthracnose or SER level in cultivars susceptible to the two respective diseases. The fruit peel in which latex was retained had greater chitinase activity. The reduction of anthracnose and SER could be due to the greater resorcinols and chitinase activity respectively in latex-retained fruit. The results indicate a direct involvement of latex in fruit resistance and the possibility of its manipulation to protect ripe fruit from fungal rotting.
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