The Potential of Rust as a Biological Control of Parthenium in Ethiopia

Abstract

Parthenium is an invasive annual weed that is widely spread in Ethiopia. Parthenium rust caused by the rust fungus Puccinia abrupta var. partheniicola, has been used as a biological of the weed. The rust was found to be effective and was introduced to Australia from Mexico as bio-control agent. The current study was done to determine the rust's incidence and distribution, virulence and host-specificity, and its effects on the morphological and seed production capacity of parthenium during 1998-2002. The rust was found in mid-altitude (1500-2400 m) regions of Ethiopia with over 50% incidence. As a result of rust infection, reductions were observed in mean plant height was 11.1%, number of leaves per plant 21.5%, leaf area 27.5%, number of branches 13.4%, dry matter yield at maturity 24.8% and number of seeds produced 42.7%. Comparison of P. abrupta isolates showed that Ambo and Debre Zeit isolates
were comparatively the most virulent based on the number of pustules per leaf and number of leaves infected. Host specificity study on weed and related crop plants revealed no apparent infection except on parthenium. Microscopic examination using leaf clearing and staining technique showed host reaction with poor development of uredospores on Guizotia abyssinica varieties. The rust shows
significant potential as a classical biological control of parthenium in mid altitude areas of Ethiopia