Puccinia myrsiphylli
| Bridal creeper rust | |
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Basidiomycota |
| Class: | Pucciniomycetes |
| Order: | Pucciniales |
| Family: | Pucciniaceae |
| Genus: | Puccinia |
| Species: | P. myrsiphylli
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| Binomial name | |
| Puccinia myrsiphylli | |
| Synonyms[1] | |
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Puccinia myrsiphylli is a rust fungus in the genus Puccinia, family Pucciniaceae, and is native to South Africa.[2] 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
[edit]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.[3] P. myrsiphylli was described further in 1926.[4] 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.”[3] P. myrsiphylli is in the family Pucciniaceae, and the host-substratum are leaves that are alive from Myrsiphyllum falciforme.[5]
Description
[edit]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."[3]
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.[6] This is the spermagonia and pycnia stage of the disease cycle.[6] 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.[6] The aecia produce aeciospores, and lead to uredinia.[6] Uredinia and telia are on the under side of the leaves, but also on stems.[6] 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.[6] The uredinia produce urediniospores, which are dispersed by the wind.[6] Telia occur several weeks later.[6] Then the telia produce thick-walled resting spores called teliospores.[6]
P. myrsiphylli is likely macrocyclic because it includes all five spores stages.[6] It is also likely autoecious because field reports show that pycnia, aecia, uredinia, and telia of P. myrsiphylli were found on A. asparagoides.[7] No other host plants outside of A. asparagoides are required for P. myrsiphylli to complete its life cycle.[7] The researchers in this study found dormant teliospores on extremely diseased cladodes and stems around spring/early summer time in the winter/rainfall region.[7] This suggests that the fungus survives the dry summer months on debris, when above-ground biomass of host plants have stopped growing.[7] It is the thick-walled teliospores that make sure the rust can survive when bridal creeper deteriorates during the summer.[6] P. myrsipjylli recycles each 3–4 weeks during the summer.[6]
P. myrsiphylli has two natural enemies: Cecidomyiidae larva and Eudarluca caricis.[7] However, these two enemies do not look like they have a major impact on P. myrsiphylli.[7]
Distribution and habitat
[edit]Puccinia myrsiphylli is found in Eastern Cape Province in South Africa.[5] 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.[7] In southern Africa, the occurrence of P. myrsiphylli was dependent on the existence of living foliage of its host plant and season of rainfall.[7] P. myrsiphylli is a very flexible pathogen, as shown by its ability to distribute widely throughout many different South African climate regions.[7] It can also survive harsh, dry conditions without its host.[7] P. myrsiphylli can be found in South Africa, Australia, and New Zealand.[7][8]
Biological control agent
[edit]Surveys identified Puccinia myrsiphylli as a possible biological control agent for A. asparagoides, which is also called bridal creeper.[9] Bridal creeper is originally from southern Africa, and has been in Australia since 1871.[10] Surveys were conducted in South Africa to find out if P. myrsiphylli would be able to spread as a possible biological control for A. asparagoides.[7] Specificity information was also gathered because safety is a key criterion for introduction of a biological control agent into a different country.[7] A study showed that it had a limited host range, which supported the introduction of the rust into Australia.[7] In 2000, P. myrsiphylli was approved for introduction into Australia (Kleinjan et al., 2004).[7] Conservationists see bridal creeper in areas of native vegetation as a threat, and had approved it as a target of biological control.[10]
In New South Wales, Australia, P. myrsiphylli has been monitored, and there is reason for optimism that it is affecting the growth of A. asparagoides.[7] From July 2000 to November 2001, the rust was monitored at three places in New South Wales: Scheyville National Park near Windsor, Eurobodalla National Park near Moruya, and Bar Beach near Narooma.[4] The monitoring showed that the epidemic could have a heavy and detrimental impact on A. asparagoides.[4] However, the spread was up to 30 m in the first four months after the release, which is relatively slow.[4] A glasshouse experiment was also done.[4] The result was that in the infected plant, the number of tubers, rhizome length, and shoot mass decreased by 60%.[4] P. myrsiphylli builds up resistance and oversummering inoculum which allows it to survive the harsh, dry summer and to return for the next growing season.[4]
The rust fungus Puccinia myrsiphylli requires 8 hours or more of the leaf being wet in order to infect bridal creeper.[4] Between 16 and 20 degrees Celsius is the optimal infection temperature.[4] However, infection is totally stopped at 25 degrees Celsius.[4] In tests, P. myrsiphylli only develops successfully on A. asparagoides.[4] Every other species tested were unaffected or very resistant to the rust.[4] For P. myrsiphylli to be effective, it needs to attack the bridal creeper's root system because 90% of bridal creeper's biomass is below-ground rhizomes and tubers.[4] The way P. myrsiphylli works is by infecting leaves and stems, which cause heavy defoliation of bridal creeper plants.[4] It limits the nutrients and water available for the host plant's production of vegetation and reproduction.[4] P. myrsiphylli also reduces the photosynthetic surface, which destroys leaf tissue.[4] The rust destroys the capacities of A. asparagoides in 20 weeks.[4] Morin believes it will likely take several years for P. myrsiphylli to decrease the biomass below ground.[4]
P. myrsiphylli has gone above and beyond expectations, because it did not die and recolonized at specific places in between seasons.[6] The rust is particularly effective in coastal areas, where conditions are ripe for epidemic growth.[6] Those who use, develop, and manage land in Australia have excitedly used P. myrsiphylli at more than 2,500 locations around Australia.[6] Combining P. myrsiphylli with another biological control agent, a leafhopper, Zygina sp., acted together to lessen the growth of rhizome length and number and biomass of tubers in A. asparagoides.[11] In addition, a long-term 7-year study has shown decreases in seedling, shoot numbers, and above-ground biomass of A. asparagoides across all sites that were observed (using the biological control agents of the leafhopper and P. myrsiphylli).[12] Some sites recorded greater declines in A. asparagoides on trellises than others due to varying climate and leafhopper factors.[12] Due to the expansive nature of the study, scientists feel confident that the biocontrol agents of leafhopper and Puccinia myrsiphylli played a role in the decline of A. asparagoides.[12]
After P. myrsiphylli was introduced in Australia, it was also detected in New Zealand.[9] New Zealand is also trying to find ways to deal with undesirable weeds.[13] Invasive exotic weeds have a negative impact on production and biodiversity.[13] Puccinia myrsiphylli has spread across bridal creeper's range in northern New Zealand.[8] It as an effective biocontrol agent in New Zealand.[8] P. myrsiphylli is seen as a high quality example of effective biological control in New Zealand's 90-year history of weed biocontrol studies.[13] P. myrsiphylli is likely effective by itself, but it has also been tested with other fungal pathogens.[8] For example, it has been tested with Colletotrichum Gloeosporioides.[8] In that test C. Gloeosporioides was only mildly effective on its own.[8] This illustrates that P. myrsiphylli is seen as the most impactful biological control agent in this situation.[6] The Environmental Risk Management Authority of New Zealand was attempting to “de-new” the classification of Puccinia myrsiphylli, which would allow those who use, develop, and manage land in Australia to manipulate P. myrsiphylli for even greater biocontrol effectiveness.[8]
References
[edit]- ^ "GSD Species Synonymy: Puccinia myrsiphylli (Thüm.) G. Winter, Flora, Regensburg 67: 261 (1884)". Species Fungorum. Retrieved 6 May 2022.
- ^ "The Australian war on bridal creeper". Pesticide Outlook. 13 (2): 71–72. 2002-05-01. doi:10.1039/b203221j. ISSN 0956-1250.
- ^ a b c Doidge, Ethel (1932-12-04). "A Preliminary Study of the South African Rust Fungi". Bothalia. 2 (1): 1–170. doi:10.4102/abc.v2i1.1787. ISSN 2311-9284.
- ^ a b c d e f g h i j k l m n o p q r Morin, Louise; Willis, Anthony J.; Armstrong, Joel; Kriticos, Darren (2002). "Spread, epidemic development and impact of the bridal creeper rust in Australia: summary of results". Thirteenth Australian Weeds Conference Papers: 385–388. CiteSeerX 10.1.1.673.5974.
- ^ a b "Index Fungorum - Names Record". www.indexfungorum.org. Retrieved 2022-05-06.
- ^ a b c d e f g h i j k l m n o p Morin, Louise; Neave, Michael; Batchelor, Kathryn; Reid, Adele (2006). "Biological control: a promising tool for managing bridal creeper, Asparagus asparagoides (L.) Druce, in Australia". Plant Protection Quarterly. 21 (2).
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b c d e f g h i j k l m n o p Kleinjan, Catharina A.; Morin, Louise; Edwards, Penelope B.; Wood, Alan R. (2004). "Distribution, host range and phenology of the rust fungus Puccinia myrsiphylli in South Africa". Australasian Plant Pathology. 33 (2): 263. doi:10.1071/ap04006. ISSN 0815-3191. S2CID 22350029.
- ^ a b c d e f g Harman, H.M.; Waipara, N.W.; Winks, C.J.; Smith, L.A.; Peterson, P.G.; Wilkie, J.P. (2008-08-01). "Natural enemies of bridal creeper Asparagus asparagoides in New Zealand". New Zealand Plant Protection. 61: 362–367. doi:10.30843/nzpp.2008.61.6884. ISSN 1179-352X.
- ^ a b Waipara, N. W.; McKenzie, E.H.C.; Harman, H.M.; Winks, C.J.; Park, D. (2006). "First record of bridal creeper rust, Puccinia myrsiphylli, a classical biocontrol agent of the environmental weed bridal creeper, Asparagus asparagoides, in New Zealand". Australasian Plant Disease Notes. 1 (1): 23. doi:10.1071/DN06010. ISSN 1833-928X. S2CID 38951082.
- ^ a b Scott, John and Kleinjan, C.A. (1991). "Bridal creeper (Myrsiphyllum asparagoides) in Australia and developments towards its biological control". Plant Protection Quarterly. 6 (3).
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Turner, Peter J.; Morin, Louise; Williams, David G.; Kriticos, Darren J. (2010-09-01). "Interactions between a leafhopper and rust fungus on the invasive plant Asparagus asparagoides in Australia: A case of two agents being better than one for biological control". Biological Control. 54 (3): 322–330. doi:10.1016/j.biocontrol.2010.06.005. ISSN 1049-9644.
- ^ a b c Morin, Louise; Forrester, Robert I.; Batchelor, Kathryn; Holtkamp, Royce; Hosking, John R.; Lefoe, Greg; Virtue, John G.; Scott, John K. (November 24, 2021). "Decline of the invasive plant Asparagus asparagoides within the first seven years after release of biological control agents in Australia". Biological Control. 165: 104795. doi:10.1016/j.biocontrol.2021.104795. ISSN 1049-9644. S2CID 244650108.
- ^ a b c Hayes, Lynley; Fowler, Simon V.; Paynter, Quentin; Groenteman, Ronny; Peterson, Paul; Dodd, Sarah; Bellgard, Stanley (2013). "BioControl of Weeds: Achievements to Date and Future Outlook". BioControl of Weeds.
{{cite journal}}: CS1 maint: multiple names: authors list (link)