Observations on the gall rust fungus Prospodium transformans, a potential biocontrol agent of Tecoma stans var. stans (Bignoniaceae) in South Africa

Abstract

Tecoma stans var. stans, a tree originating from the Americas, is emerging as an invasive weed in South Africa. A microcyclic gall inducing rust fungus, Prospodium transformans, has been investigated as a biological control agent against this plant. Development of germinating teliospores and symptoms on host plants are described, and the optimum temperature for teliospore germination was found to be 18-22°C. Inoculations of plants grown from seed originating from South Africa and various localities in Mexico and Texas (USA) indicate that there are likely races specific to morphological variants of this widespread and highly variable plant species. Despite readily inducing galls on plants grown under quarantine glasshouse conditions in South Africa, this rust fungus failed to establish in the field upon release. It is suggested that the origin of the form of this plant, which has become invasive in South Africa, needs to be identified to source the correct race of P. transformans for release in South Africa.

A comprehensive review on ecology, life cycle and use of Tecoma stans (bignoneaceae)

“…An attempt was made to control the spread of T. stans through gall-forming rust fungus Prospodium transformans Ellis and Everh. Cummins (Pucciniales: Uropyxidaceae) and Clydonopteron sacculana Bosc, (Lepidoptera: Pyralidae) as a biological control agent (Wood 2014 ). Teliospores germination was found to occur at 18–22 °C.…”

A Global Overview of Diversity and Phylogeny of the Rust Genus Uromyces

“…glanduliferae on Impatiens glandulifera [ 30 ], and Prospodium transformans on Tecoma stans var. stans [ 31 ]. A number of studies on Uromyces species have been carried out by a number of researchers (see Table 1 ), but the assessment of species from other rust genera has not yet been well established.…”