Some spatial, temporal and spatio-temporal considerations of wood decay of tea ( Camellia sinensis), caused by Nemania diffusa (Syn. Hypoxylon vestitum)

Abstract

Tea stem wood decay caused by N. diffusa is confirmed here to be a soft rot. The activity of periodic pruning of tea bushes contributed to dissemination of disease through the contaminated pruning knife. Once contaminated, the infection can spread linearly in either direction at approximately 1.2 cm per annum. This compared well with the rates experienced under ex situ inoculation tests, which worked out to be 1.7 cm per annum. Field resistant tea cultivars recorded a relatively lower number of fibre cells than the field susceptible cultivars. The natural susceptibility (decay potential) of tea stem wood due to N. diffusa infection was around 69 g cm −3 yr −1, with the capacity to cause in vitro wood loss/decay in the range of 62–75%. Under natural field conditions, long-term infections accounted for an increase in disease score of about 0.3 for every 1 m rise in altitude starting from a base level of 1500 m, commensurate with a rate of increase of disease of approximately 0.01% m −1 rise per year.