Patterns of infestation by invasive parasitic plants of the genus Cuscuta in selected districts of Uganda

Abstract

Invasive parasitic plants of the genus Cuscuta threaten plant ecosystems, due to their rapid spread and attack on various host plant species. The parasites attach to the host and deprive it of water and nutrients from the hosts thereby weakening or killing it. Despite their rapid spread in Africa, parasitic plants of the genus Cuscuta have attracted limited research attention, although information on their taxonomy, biology and host range is required for their management. This study was conducted to generate information on Cuscuta spp. occurring in Uganda and their hosts, awareness of the population, and control strategies to manage the invasive species. The main objective was to assess the patterns of infestation of plants by parasitic plants of the genus Cuscuta in the rural and urban areas of Uganda. The specific objectives were: (i) to identify species of the genus Cuscuta occurring in Uganda; (ii) to characterize the hosts of the parasites; (iii) to determine the level of awareness of the human population on Cuscuta spp.as invasive parasitic plants; and (iv) to design control strategies for these invasive parasitic plants. The Study was carried out in an Urban district (Kampala) and two Rural districts (Arua and Maracha). I conducted inventories of hosts and potential hosts (affected and not affected individuals) in 20 circular plots of 0.1964ha giving a total of 40 plots. Socio-economic surveys were conducted among 30 respondents in each site, comprising60 questionnaires in total. The results show that two Cuscuta species (Cuscuta campestris Yuncker and Cuscuta reflexaRoxb) occur in Uganda.The two species generally infested different sets of hosts (C. campestris mostly infested F. benjamina whereas for C. reflexa, it was T. peruviana). Regarding the level of awareness of the population on the Cuscuta spp. as invasive parasitic plants, the population was generally ignorant of the biology and control of these species. Control in the rural Districts was by a single approach of mechanical removal, whereas an integrated approach of prevention, mechanical removal and chemical control was used in the urban district. An integrated approach combining sensitization, prevention, mechanical removal and chemical control with selective herbicides is recommended for the control of the invasion. It is therefore necessary to map out the invasion, raise awareness of the population on the invasive parasitic plants, and implement of an integrated approach towards control.