Wood rot (<i>Hypoxylon serpens</i>)
Wood rot in tea has been reported from several countries including India, Kenya, Malawi, Zimbabwe and Sri Lanka. The pathogen implicated is Hypoxylon serpens. Significantly, all affected areas lie at or above 1500 m.
The characteristic symptoms normally appear when the bushes are about 15 to 20 years old. Suddenly, the foliage of a branch will show wilting followed by scorching. Such branches snap off easily near the base. Sometimes intact lower branches with green foliage in these bushes could snap off similarly, especially when workers walk through during field operations. The bases of such branches have characteristic black encrustations (stroma - fungal fruiting bodies containing spores). The pathogen appears to be disseminated mainly through pruning knives and the infection progresses from pruning cuts during wet weather. Under natural field conditions, infection at 60-90% and over 90% could bring about 27 and 36% yield reductions, respectively, showing that the disease can cause significant damage.
- Plant resistant clones, if available.
- Avoid pruning of tea bushes and rejuvenation pruning during dry weather.