Diversity and distribution of aerial parasitic plants on woody plants in home gardens of selected districts of Western Uganda.

Abstract

Parasitic plants, through a range of infestation strategies, attack and destroy crop plants and therefore require management. In Uganda, the vulnerability of crop plants as hosts to parasitic plants has not been much studied. The present study was aimed at documenting the parasitic plants and establishing the factors influencing their distribution on host plants. The district and sub County Agricultural Extension Service workers in the study area were consulted and these provided a link to farmers. From each selected homestead, gardens present were surveyed for parasitic plants. A total of 176 home gardens were studied in the districts of Mbarara and Bushenyi. A total of 214 number individuals of all shrubs and 954 numbers of individuals of all trees belonging to 21 families were recorded and observed for presence of parasitic plants; 89.47% were domesticated while 10.53% were wild. Four parasitic plant species were encountered in the whole study area with incidence of Agelanthus sp (43.41%), Tapinanthus buvumae (33.09%), Viscum capense (16.10%) and Tapinanthus constrictus (6.59%). There was higher incidence of parasitic plants on domesticated (crop) compared to wild (non crop) Parasitic plants were mainly restricted to the crown and rare on the stem. Most of the host plants 33 (45.21%) had parasites located on the top branches. Only one host plant had parasite located in the upper stem (1.37%) and this was Coffea robusta. No parasite was found on the lower stem. Top branches had the most number of parasitic plants for T. costrictus, Agelanthus sp and T. buvumae. This was followed by mid branches and base branches respectively The DBH of the host plant shows that there are more parasitic plants on host plants with smaller DBH compared to host plants with a higher DBH. There is no statistically significant effect of branching pattern to the presence of parasites on host plants (p>0.05). Parasitic plants were more found on host plants that had closed crown than host plants which had open crown. About 84.67% of the host plants had rough bark characteristics while 15.33% were found on smooth bark characteristics. Parasitic plants were all found on host plants with rough bark characteristic. Nearly 50.86% of the host plants had stem branching pattern between 31 o and 60 o ; 43.41% had stem branching pattern between 61 o and 90 o while 5.74% had stem branching pattern between less than 30 o. There is no statistically significant effect of branching pattern and the presence of parasitic plants on host plants. The findings indicate that there was a negative significant correlation between the level of education and the knowledge/perception of the parasitic plant species. The findings further indicate that there is a positive significant correlation between age of the respondents and the knowledge of existence of parasitic plants and their potential hosts. The respondents were composed of 89 (51.15%) females and 85 (48.85%) males. Overall, 63 (25 females; 38 males) had knowledge of parasitic plants; 22 (34.9%) had knowledge of the host plants, while 95.5% had experienced them in their own gardens. 72% of the females who had knowledge on parasitic plants were aware of the host plants, as compared to 39.5% of males who were aware of the host plants. 33.3% of the females who had knowledge of parasitic and host plants had experienced them on their own gardens; all the males who had knowledge of parasitic and host plants had experienced them on their own gardens. It was found out that 4 (67%) of the females who had knowledge of parasitic and host plants had experienced them on their own gardens were 36 years and above; 8 (53%) of the males who had knowledge of parasitic plants, knew host plants and had experienced them on their own gardens and were 36 years and above. This study provides a baseline on presence of parasitic plants in home gardens highlighting the most likely affected of domesticated and wild crops for appropriate management.