Phenology of bellyache bush (Jatropha gossypiifolia L.) in northern Queensland

F.F. BebawiA,B, R.J. MayerC and S.D. CampbellA,B

A Tropical Weeds Research Centre, Department of Natural Resources and Mines, PO Box 187, Charters Towers, Queensland 4820, Australia.

B CRC for Australian Weed Management, PMB 1, Waite Campus, Glen Osmond, South Australia 5064, Australia.

C Agency for Food and Fibre Sciences, Department of Primary Industries, PO Box 1085, Townsville, Queensland 4810, Australia.


Abstract

An understanding of the seasonal patterns of leaf, flower and seed production of weeds is valuable when determining the most appropriate timing of control activities. This 12 month study determined the seasonal changes in leaf density and the timing of flowering and capsule production of the exotic weed bellyache bush (Jatropha gossypiifolia L.) located within both riparian and sub-riparian zones of northern Queensland. Monthly measurements of sugar concentrations were also undertaken to determine if seasonal variations in the level of sucrose fraction occurs. Prevailing environmental conditions (ambient temperature, soil temperature, soil moisture content, light density and rainfall) were monitored, with correlation analysis identifying any significant relationships with the ecological parameters measured.

Maximum leaf density of bellyache bush plants occurred during the wet season (November-April), with up to 17 (January) and 20 (January) leaves per stem present on plants within sub-riparian and riparian zones, respectively. Leaf density then declined during the dry season and remained at one leaf or fewer per stem for the cooler months in the dry season (June-August). Flowering occurred from June to April (11 months) in riparian zones and from September to April (8 months) in sub-riparian zones. Capsule production commenced in September and October within riparian and sub riparian infestations, respectively. Capsules were present on plants for 10 months within both zones. A low sugar concentration phase (14-17%) lasted for seven months from November to May and a high one (19-23%) lasted for five months from June to October. These results suggest that in northern Queensland, the wet season may be the optimum time to implement control techniques dependent on plants having high leaf cover and/or low energy reserves.

Keywords: Jatropha gossypiifolia, bellyache bush, phenology, riparian zone, sub-riparian zone, deciduous, chemical control.

 

Plant Protection Quarterly (2005) 20 (2) 46-51.