The response of bellyache bush (Jatropha gossypiifolia) plants cut off at different heights and seasonal times

Abstract

A study was undertaken to quantify the susceptibility of bellyache bush plants cut off using a brush-cutter at different heights above ground (0, 10, 20 and 40 cm), during either summer or winter. Uncut plants acted as controls. At the time of cutting in summer, plants were fully foliated, flowering and producing seed. In contrast, winter-treated plants were fully defoliated and dormant. The sugar concentration in sap of plants differed significantly between seasons, averaging 23 and 18% sucrose for winter and summer cutting times, respectively.
A significant interaction occurred between the season and height of cutting on plant survival. No plants survived if cut off at ground level, irrespective of season. With cutting at 10 cm, 100% mortality was still achieved during summer, but 40% of winter-cut plants survived. Thereafter, survival increased with increasing height of cutting, with plants more susceptible when actively growing in summer. Winter off-cuts that were stacked in piles were viable 12 months after cutting and a few at the bottom of the piles grew adventitious roots, despite being disconnected from any direct supply of water or nutrients. The susceptibility of bellyache bush to cutting near ground level in summer suggests that the use of tractor-mounted slashers should be investigated as a control option for treating infestations where the terrain is suitable. However, one should not ignore the possible use of brush-cutters and similar equipment for clearing small infestations or 'rougher' sites.