Melampsora euphorbiae on Euphorbia dendroides

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Timothy
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Melampsora euphorbiae on Euphorbia dendroides

Post by Timothy » Fri Apr 21, 2006 7:34 am

I have recently found Melampsora euphorbiae on tree spurge - Euphorbia dendroides in a rather concealed zone in Dwejra - Gozo. This fungal pathogen is known to give rise to typical rust diseases of Euphorbia species. This finding is rather alarming as M. euphorbiae is known to spread rapidly in vast areas killing its hosts as result. Infact in Turkey, China and the USA it has recently been evaluated as an effective Biological weed control agent for Euphorbia spp. What concerns me is, the pathogenicity of this fungus on E. melitensis - Maltese Spurge which is endemic to Malta as well as Euphorbia paralias - Sea Spurge and Euphorbia peplis - Purple Spurge which are both endagered species. Such a disease outbreak could lead to further depletion of these plants from the Maltese habitat. I am currently in the process of performing some short studies on the particular isolate of the fungus I have found locally to detrmine its pathogenicity to mentioned Euphorbia species. In context with recent postings - Yes Rust diseases are becoming very common in Malta particularly on spontaneous flora : Please inform me should you happen to come across more attacks particularly on Euphorbia species.
Timothy Pace-Lupi

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Post by MWP admin » Fri Apr 21, 2006 11:20 am

This is really a worrying event. We dont want to loose another nice endemic species. I am also afraid in that there might be no solution to it, becasue who / which budget is going to apply the 'cure' (eg a fungicide) to whole population spread over the Maltese islands ???

Nice topic Tim (I mean not the news itself)

Some links on this Fungual pathogen:

http://www.bspp.org.uk/ndr/july2004/2004-39.asp

http://www.invasive.org/weeds/asian/euphorbia.pdf
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Post by IL-PINE » Fri Apr 21, 2006 4:40 pm

Wow! This is a particularly disturbing topic! This would lead to the demise of many species of plants from our islands. And this is just talking about Euphorbia. I guess there are others affecting particular plants - imagine one infesting orchids......

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Post by robcar » Sat Apr 22, 2006 7:18 pm

It is not only we humans who are suffering from the -effects of globalisation - the spread of all sorts of invasive aliens, pests and pathogens is a major threat to biodiversity in many regions - of course in Malta we are not immune from such threats & with our warm, humid climate I can imagine that such fungi could be a major issue

- good luck with your work Timothy - Unfortunately in my case, I am afraid that I would not be able to recognise or diagnose rust disease on local spontaneous plants

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Diseases on Spontaneous Flora

Post by Timothy » Mon Apr 24, 2006 7:03 am

The incidence of disease in the natural environment is a normal Phenomenon that occurs within any natural environment and may not be prevented. However any alterations in natural habitat could faccilitate disease difusion, therefore introduction of new flora and fauna, introduction of cultivated plants, chemical imbalance as a result of polution and also changes in climatic conditions are all such examples. Chemical control such as fungicides is deffinately not a solution as this will have further implications on the natural biodiversity of the area, therefore one should rely upon biological control and integrated measures based soley on the natural elements occuring within the zone where the disease was found. More stringent mechanical measures may also be applied to prevent the spread of the disease in question should it be severe and virulent. Rest assured however that diseases in the natural environment rarely become virulent on indigenous/ endemic species and pose a greater threat to cultivated plants and crops. Furthermore wild plants are more hardy to thrauma caused by disease than cultivated plants and often coexist with the disease in question also acting as a source and reservoir of the pathogen to cultivated crops. Nevertheless diseases in the natural habitat must always be observed, surveyed and reported both to reduce their implications on agricultural practices as well as to reduce their negative effects on indigenous flora and foresee a severe outbreak. Regarding the case of Euphorbia rusts - one notes orange pustules which look like grains of sand all over the plant, on leaves, fruits, and stalks. I found the disease only in one location so far where it is isolated by the cliffs of Dwejra and distant from other euphorbia specimins however I am constantly viewing different zones throughout Malta.
Timothy Pace-Lupi

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Post by jackpot » Wed Apr 26, 2006 8:56 am

I have a pic for you about the orange pustules of the fungus- fortunately not from Malta but from Germany- it is the parasitic fungus Uromyces pisii growing on Euphorbia cyparissias. The compact Euphorbia plant (branched and about 30cm high) changes its habit beeing attacked (unbranched and up to 1m high), because the fungus leads to a superproduction of growth-hormones that the spores of the fungus can be much more better distributed.
Both organisms are native to Germany- therefore, it is a more or less stable balance (and in fact the fungus has no interest to kill its host because he would destroy his elevator :)
Hopefully, the Maltese fungus on Euphorbia is native, too, otherwise this could be really lead to problems.
So, what happens if you learn that this fungus is endemic to Malta???
Big problem- a fight between mycologists and plant lovers :lol: :lol:
Ok- serious- you should keep an eye on rusts, in general (and due to the specific situation of the Maltese Islands).

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Post by jackpot » Wed Apr 26, 2006 8:58 am

here is the pic
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Uromyces pisii at Euphorbia cyparissias.jpg
Uromyces pisii at Euphorbia cyparissias.jpg (10.79 KiB) Viewed 54398 times

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Melampsora euphorbiae on Euphorbia dendroides

Post by Timothy » Thu Apr 27, 2006 7:12 am

The last posting on the Incidence of Uromyces pisii was very intersting, I will deffinately search for data about this particular rust fungus to better understand the symbiotic relationship it establishes with its host. Unfortunately rusts including Melampsora euphorbiae are not endemic to Malta, and they are only classified as indigenous to a particular zone based on their occurance within the areas in question, thats why it is important to report new findings. However it is possible at research level to perform molecular studies in which one can compare DNA of the particular isolate of fungus found in one region to that of an other - yet this is very laborious and doesnt always render results which are beneficial to understanding the nature or virulence of the disease. I have done such a study on Verticillium dahliae mostly orginating from Olive in Malta and found that one Isolate originating from an Olive tree on Comino out of the 60 local isolates I studied gave a slightly different genetic make up and was slightly similar an isolate found on pepper plants in spain. This indicates that in an insegnificant manner (due to low statistical value) the isolate of V. dahliae I found on Comino may be a strain of the disease which is native to Malta, particularly considering the isolated and remote environment of Comino. Yet It took more than a year and much funding to reach this result and still it is not enough to lable the strain as endemic! Therefore you can see that Endemism is a vast subject regarding plant diseases and not all that important as it rarely renders results which are anything more than self satisfying. At the end of the day it is the control of the disease and epidemiology that are the most important rather than the disease origins.
Timothy Pace-Lupi

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Post by jackpot » Thu Apr 27, 2006 9:33 am

Interesting what you say, and I agree most of it, but :wink: .
Uromyces as other rust are parasites (no symbiotic interactions) -
"fortunately" your Melampsora is not endemic, so we can try to limitate them :)
(my comment about endemic rusts was only joking) :lol:

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Post by Lisa » Thu Apr 27, 2006 7:58 pm

hi
how would you describe this fungus in laymen terms? is it like black spots only on one side of leaf? As i noted this at wied il ghasel

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Post by jackpot » Tue May 02, 2006 5:06 pm

Hi Lisa: spots are yellowish when young, dark brownish with age, usually only at the undersides of leaves.

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Post by Lisa » Tue May 02, 2006 7:37 pm

thanks a lot . maybe it is the same thing then. unfortunately my camera is not working so i dont have photo

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Post by Timothy » Wed May 03, 2006 6:31 am

Sorry for not having replied sooner, yes it apears as orange to brown spots, normaly rusts tend to appear on the under-side of the leaves but this is not always the case. In fact M. euphorbiae which I noted in Dwejra was on all plant areal organs - leaves, fruits, flowers and branches, particularly on fruits it gave larger pustules which seemed like large grains of sand. At first I had my doubts on the disease as it was not localised and even appeared on upper-sides of leaves. I will ask Stephen to post a photo he took of it for me at the lab unfortunately the specimin was already desicated when the photo was taken. As regards to taking the necesary action to prevent the spread of the disease, our section/ department is handling the matter, yet we observed the area and the infected plant is well isolated and probably far from other hosts. At the moment we need the plant to be kept alive untill we have finished studying the disease, yet it is being monitorred reguraly by my self.
Timothy Pace-Lupi

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