• The Korean Journal of Pesticide Science
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• v.14 no.3
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• pp.261-265
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• 2010

Lichens, a symbiotic organism of fungi and algae, cause serious damage to national heritages of stone master piece and costly trees for gardening. The present study was conducted to screen effective fungicides against lichen-forming fungi to control the biological agents deteriorating stone heritages and trees. Five commercial fungicides (Fenarimol EC, Etridiazole EC, Iminoctadinetriacetate SL, Difenoconazole+lminocatadinetriacetate ME and Difenoconazole+Azoxystrobin SC) were tested against the lichen-forming fungi (LFF) isolated from seven saxicolous (Caloplaca sp., Ramalina sp., Xanthoparmelia sp., and Xanthoria sp.,) or corticolous (Parmelia sp.,) lichen species. Preliminary screening test showed that no LFF could grow on the MY (malt-yeast extract) agar medium amended with the recommended concentrations of each fungicide. Further screening was conducted at 1%, 10% and 20% of the recommended concentrations of the fungicides. After 7 week incubation at $15^{\circ}C$ in the dark, Difenoconazole+Iminocatadinetriacetate ME and Difenoconazole+Azoxystrobin SC completely inhibited the fungal growth of all the tested LFF, even at 1% of the concentration. Two fungicides of Fenarimol EC and Iminoctadinetriacetate SL exhibited a moderate inhibition activity at the lower concentrations. Etridiazole EC was less effective in the fungal growth inhibition than the other four fungicides. The results suggested that lichens colonizing on precious stone heritages and trees can be eradicated by applying Difenoconazole+Iminocatadinetriacetate ME and Difenoconazole+Azoxystrobin SC even 1% of the recommended concentrations. Selected fungicide application at such a low concentration will facilitate the chemical use to prevent and preserve stone heritages from biological deterioration induced by lichens and the allied microbes.

• Research in Plant Disease
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• v.13 no.1
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• pp.34-39
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• 2007

Lichen thalli of Dirinaria applanata heavily colonized on the twigs of dead or dying Rhododendron trees in Solok island, Jeonnam province in Korea. Pathogenesis of the lichen on the trees was investigated to find out the possibility of lichen as a causal agent. Histological examination of the lichen colonized twigs was attempted with differential staining technique. Lichen-forming fungus colonized only on the surface of bark and there was no direct penetration of fungal hyphae into the plant tissues. Symbiotic algae of the lichen was also examined. The isolated algal cells were inoculated on artificially induced wounds of the healthy trees. Histological examination of the inoculated tissues showed that some algal cells were successfully colonized inside the tissues without any pathogenic symptoms, even 2 months later, The extract of the lichen thalli was also examined using 10% of DMSO solution. Treated tissues showed no pathogenic symptoms, even 4 weeks later. The results suggested that the lichen was not directly involved in the death of the trees.

• Research in Plant Disease
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• v.13 no.3
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• pp.223-227
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• 2007

Lichen is a symbiotic association which lichen-forming fungi associate with green algae or cyanobacteria capable of producing food by photosynthesis. Lichen is one of the most widely distributed eukaryotic organisms on every kind of surface of soils, rocks and trees. Lichen-forming fungi commonly colonize on the surface of barks of dead or dying trees, which they use merely as a means of support without parasitizing. Lichen consortium of Parmotrema autrosinense and several crustose lichens heavily colonized on the surface of P. mume in Suncheon, Jeonnam province in Korea. The lichen consortium on the surface of P. mume gave the affected trees a dull gray appearance and suppressed their normal growths. Severely affected twigs or branches resulted in the death when the lichen thalli were not rubbed off the barks of P. mume. Twigs or branches of P. mume were recovered from blight syndrome when the lichen thalli were rubbed off, The recovered twigs or branches became healthy and clean when $Tween^{(R)}$ 20 or thiophanate-methyl paste were treated on the barks of P. mume. This is the first report of lichen diseases on P. mume caused by colonization of consortium of several crustose lichens including P. autrosinense.