Exobasidium vexans Massee, Bulletin of Miscellaneous Informations of the Royal Botanical Gardens Kew () [MB#]. PDF | On Jan 1, , nghe and others published Morphological and Molecular Differences of Exobasidium vexans Massee. Blister blight (causal agent, Exobasidium vexans) is an economically devastating disease of tea (Camellia sinensis). To determine what.
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Close Find out more. Knowledge Bank home Change location. Go to distribution map The first indication of blister blight disease is exobasidiun small, pale-green, pale-yellow, or pinkish, translucent spot on the tea leaf which is readily seen against the darker green colour when the leaf is held against the light.
Reitsma and van Emden refer to these tiny infection spots as stages in the disease.
blister blight of tea (Exobasidium vexans)
The circular spots enlarge until they reach exobaasidium diameter ranging from 3 to On the upper side of the leaf, the spots slowly become sunken into a shallow depression; at the same time on the under-side they become correspondingly convex, forming the typical blister lesion.
The upper concave surface of the lesion is smooth and shiny, whereas the lower convex surface is at first dull, then grey and finally pure white, due to a dense, velvety growth on which the spores are produced.
Affected tea expbasidium can often be distorted, folded or irregularly rolled, owing to the development of the blister lesions on the mid-rib and the margin. The disease also affects the tender and young green stems. On the stem a pale yellow spot appears; this gradually elongates and encircles the whole stem which becomes slightly swollen at this point.
Basidiomycota >> Ustilaginomycetes >> Exobasidiales >> Exobasidium vexans
When the spores are ripe the patch on the stem turns grey. The fungus penetrates the tender stem and consequently the leaves and buds above the diseased part wither and necrotize.
Finally the stem bends over and breaks off at the affected spot Petch, Chemical Control Due to the variable regulations around de- registration of pesticides, we are for the moment not including any specific chemical control recommendations.
For further information, we recommend you visit the following resources: EU pesticides database www.
Removal of shade also helped to control the disease in Taiwan Liau, However, in southern India, regulation of the existing shade by pollarding the branches of shade trees has been found to be useful Venkataramani, Other measures include adequate weed control, plucking and pruning regimes, lane cutting and the choice of planting material Hudson and Muraleedharan, Some phylloplane organisms may have potential for biological control Balasuriya and Kalaichelvan, Because the fungus infects the tender foliage that forms the harvest, direct crop losses can occur.
The tea industry in southern India suffered enormous crop losses in the early years of blight Subba Rao, Between and the annual loss amounted to 18 kilotonnes of tea, before control measures were fully implemented on an extensive scale Venkata Ram, Diseased leaves also affect the quality of finished tea if included in processing as several biochemical characteristics are changed resulting in reduced quality Baby et al.
However, others suggest that some infection can actually lead to an increase in quality Rajalakshmi and Ramarethinam,