Puccinia myrsiphylli is a rust fungus in the genus Puccinia, family Pucciniaceae, and is native to South Africa. It has been tested, introduced, and targeted in Australia and New Zealand as an effective biocontrol agent for Asparagus asparagoides, also known as bridal creeper.
Taxonomy Puccinia myrsiphylli was initially described by Felix von Thümen in 1877. Ethel M. Doidge noted Paul Sydow's 1884 monograph as a resource for this species. P. myrsiphylli was described further in 1926. Later, in 1932, Doidge made an entry describing each section starting with: "[Aecidia]," "Uredo-sori hypophyllous," and "Teleuto-sori". She ends this entry by writing, "I have not seen the aecidia." P. myrsiphylli is in the family Pucciniaceae, and the host-substratum are leaves that are alive from Myrsiphyllum falciforme.
Description Puccinia myrsiphylli is a rust fungus with the following characteristics: "Uredospores ellipsoid or sub-globose, pale yellow 30-40 x 26-30 μ; epispore hyaline, about 1.5 μ thick, closely and finely echinulate and with 4-5 scattered germ pores…Teleutospores oblong, cuneate or clavate, apex rounded, acuminate or truncate, usually attenuate at the base, usually gently constricted at the septum, light brown, darker at the apex, 43-70 x 17-28 μ; epispore smooth, about 1.5 μ thick, thickened at the apex (up to 7 μ); germ pores obscure, pedicel short, fragile, hyaline or tinged with brown." The rust fungus shows up in early to late autumn with little, orange structures on the top of the leaves of the A. Asparagoides, and looking like warts. This is the spermagonia and pycnia stage of the disease cycle. Next, there are aecia, which take the form of cup-shapes and are also orange, but they are on the under side of the leaves. The aecia produce aeciospores, and lead to uredinia. Uredinia and telia are on the under side of the leaves, but also on stems. The uredeina are also orange and in the shape of pustules, while the telia are a brown-black color, but also in the shape of pustules. The uredinia produce urediniospores, which are dispersed by the wind. Telia occur several weeks later. Then the telia produce thick-walled resting spores called teliospores. P. myrsiphylli is likely macrocyclic because it includes all five spores stages. It is also likely autoecious because field reports show that pycnia, aecia, uredinia, and telia of P. myrsiphylli were found on A. asparagoides. No other host plants outside of A. asparagoides are required for P. myrsiphylli to complete its life cycle. The researchers in this study found dormant teliospores on extremely diseased cladodes and stems around spring/early summer time in the winter/rainfall region. This suggests that the fungus survives the dry summer months on debris, when above-ground biomass of host plants have stopped growing. It is the thick-walled teliospores that make sure the rust can survive when bridal creeper deteriorates during the summer. P. myrsipjylli recycles each 3–4 weeks during the summer. P. myrsiphylli has two natural enemies: Cecidomyiidae larva and Eudarluca caricis. However, these two enemies do not look like they have a major impact on P. myrsiphylli.
Distribution and habitat Puccinia myrsiphylli is found in Eastern Cape Province in South Africa. P. myrsiphylli was present in South Africa in winter regions, aseasonal regions, and summer rainfall regions in all regions where there is widespread A. asparagoides. In southern Africa, the occurrence of P. myrsiphylli was dependent on the existence of living foliage of its host plant and season of rainfall. P. myrsiphylli is a very flexible pathogen, as shown by its ability to distribute widely throughout many different South African climate regions. It can also survive harsh, dry conditions without its host. P. myrsiphylli can be found in South Africa, Australia, and New Zealand.
… excerpt ends here. Continue reading the full article.
