MSc

The study was conducted to find out the extent of incidence of TPD and related parameters in the rubber growing small holdings of Meenachil taluk. Fifty four small holders who sell their produce as latex and representing different parts of the taluk were selected for the study. Holdings with trees tapped either on BO 1 or Bo 2 panel only were included in the study.
The study revealed that the small holders have high preference for the clone RRII 105 due to its inherent capacity for faster growth, higher yield and disease resistance. Rainguarded tapping is not being practiced on a large scale, as only 35.19 per cent of the holdings resorted to this practice. Tapping intensity in the surveyed holdings was invariably 1/2S d/2, without any rest on Sundays.
Planting density varied from 460 ha-1 to 550 ha-1 and density of trees under tapping varied from 300 ha-1 to 500 ha-1. Planting density upto 550ha-1 was found not to have any effect on bark thickness or incidence of TPD.
The mean incidence of TPD, in terms of complete dry cuts, was 7.56 per cent for the clone RRII 105. During the initial four years of tapping, the incidence was below five per cent in the holdings surveyed.
In the present study, positive correlation was observed between dry rubber yield per unit area and incidence of TPD. Mean bark thickness showed highly negative correlation with incidence of TPD. Also, bark thickness was found to have highly significant positive correlation with annual mean drc. But no correlation was observed between annual mean drc and TPD incidence. Bark consumption showed highly significant correlation with TPD incidence, and non significant correlation with yield. This indicates induction of TPD by recovery tapping without concomitant increase in yield. Thus comparable incidence of TPD was encountered in rainguarded and nonrainguarded holdings, without realizing comparable yield.
Low incidence of TPD was observed in plantations with slower growth. High incidence of TPD was generally observed near house holds and cattle sheds, in low lying areas, banks of rivers and canals etc.