Zbornik gozdarstva in lesarstva, 54, 1997, s. 109 - 124 
GDK 411.16: 172.8 (Cenangium ferruginosum Fr.) +181.22 +181.31 
Prispelo/ Received: 10.10.1997 
Sprejeto/ Accepted: 28. 1 O. 1997 
Izvirni znanstveni članek 
Original scientific paper 
INFLUENCE OF MOISTURE, TEMPERATURE AND GROWTH MEDIUM 
ON CENANGIUM DIEBACK OF PINE (CENANGIUM FERRUGINOSUM 
FR., ASCOMYCOT/NA) 
Dušan JURC., Maja JURc·· 
Abstract 
C. ferruginosum culture was grown in vitro on MEA medium at 1 O, 20, 25; 30 and 35° 
C, on media with water activity modified to 0,98, 0,96 and 0,94 and on MEA, PDA and 
OA media at 23° C. The fungus grows at temperatures between 1 o° C and 25° C and 
on media with available water between 0,98 and 0,96. The optimal temperature for 
growth is 25° C, while at 30° C it doesn't grow at all. The best growth occurs on PDA 
medium, the second best on MEA medium and the lowest growth on OA medium. 
Composition of growth medium is an important factor and influences growth rate 
considerably. These results explain the ability of the fungus to invade the tissues of its 
host during colder periods of year and when the substrate is highly moistened. High 
summer temperatures are unsuitable for its growth. 
Keywords: Cenangium dieback of pines, Cenangium ferruginosum Fr., 
temperature, moisture, growth medium. 
VPLIV VLAGE, TOPLOTE IN HRANILNE PODLAGE NA SUŠICO 
BOROVIH VEJ (CENANGIUM FERRUGINOSUM FR., ASCOMYCOTINA) 
Izvleček 
lzolat C. ferruginosum smo gojili na hranilni podlagi MEA pri 1 O, 20, 25, 30 in 35° C, na 
gojiščih z vodno aktivnostjo uravnano na 0,98, 0,96 in 0,94 in na hranilnih podlagah 
MEA, PDA in OA pri 23° C. Gliva uspeva na temperaturah od 10° C do 25° C in na 
hranilnih podlagah z vodno aktivnostjo med 0,98 in 0,96. Optimalna temperatura za 
rast je 25° C, vendar pri 30° C ne uspeva več. Najbolje raste na hranilni podlagi PDA, 
manj na MEA in najmanj na OA. Sestava hranilne podlage je pomemben dejavnik, ki 
močno vpliva na hitrost rasti glive. Ugotovitve pojasnjujejo sposobnost glive, da 
prerašča tkiva gostitelja v hladnejših letnih obdobjih in ob visoki vlažnosti substrata. 
Visoke poletne temperature so neustrezne za njeno rast. 
Ključne besede: sušica borovih vej, Cenangium ferruginosum Fr., toplota, vlaga, 
hranilna podlaga. 
Asist. mag., dipl. biol., Gozdarski inštitut Slovenije, Večna pot 2, 1000 Ljubljana, SLO 
•• Asist. dr., dipl. inž. gozd., Gozdarski inštitut Slovenije, Večna pot 2, 1000 Ljubljana, SLO 
110 
Zbornik gozdarstva in lesarstva, 54 
CONTENTS / KAZALO 
1 INTRODUCTION / UVOD ................................................................. 111 
2 MATERIAL AND METHODS / MATERIAL IN METODE ............ 112 
2.1 COLLECTING SITE/ MESTO VZORČENJA ................................ 112 
2.2 SAMPLING PROCEDURE ANO ISOLATION / NAČINI 
VZORČENJA IN IZOLACIJA ............................................................ 112 
2.3 MEASURMENT OF FUNGAL GROWTH IN VITRO I 
MERJENJE RASTI GLIVE IN VITRO ............................................. 113 
3 RESULTS / REZULTATI .................................................................. 113 
3.1 EFFECTS OF TEMPERATURE ANO AVAILABLE WATER 
ON GROWTH OF C. FERRUGINOSUM I VPLIV 
TEMPERA TURE IN DOSTOPNE VODE NA RAST C. 
FERRUGINOSUM ............................................................................. 115 
3.2 DIFFERENCE IN GROWTH ON MEA, PDA ANO OA / 
RAZLIKA V RASTI NA MEA, PDA ANO OA .................................. 118 
4 DISCUSSION / RAZPRAVA ............................................................ 119 
5 POVZETEK ......................................................................................... 121 
6 ACKNOWLEDGEMENTS / ZAHVALA .......................................... 122 
7 REFERENCE$/ VIRl ........................................................................ 122 
1 INTRODUCTION 
111 
Jurc D., Jurc M.: Vpliv vlage, toplote in hranilne podlage ... 
Austrian pine grows in very small scattered natura! stands in the Alpine regions 
and also in central and southern parts of Slovenia. It is widely distributed as an 
allochtone tree species in the Karst region near the Adriatic coast, where it has 
been planted on more than 20.000 ha of degraded land beginning more than 100 
years ago. 
The epidemic of Cenangium ferruginosum Fr. in 1986 affected the greater part 
of the region and caused the felling of approximately 10.000 m3 of Austrian pine 
(JURC 1987). Although only trees with more than 80 % of the crown dead were 
cut, numerous trees with dead branches in the crowns remained. Since that tirne 
the Cenangium dieback of pines has only appeared occasionally and locally. 
Analysis of climatic factors for 1985, in comparison with 1 O year averages, 
showed that the relative humidity had reached a 1 O year minimum in all months 
from July to October, registered precipitations reached a 1 O year minimum in 
September and October, while in August temperatures reached a 1 O year 
maximum. This unusually dry, hot weather was proceeded by an unusually wet 
period. The first signs of dying in Austrian pine branches were noticed in 
December 1985. The largest mortality occured in 1986 on the southern and 
south-western slopes and in areas with shallow soil. AII observations were in 
accordance with other well-described examples from the literature where drought 
stress is regarded asa decisive factor in C. ferruginosum dieback (JURC 1987). 
C. ferruginosum is usually regarded as ubiquitus and opportunistic fungus which 
kills the bark and cambium of twigs and branches weakened by environment, 
other pests and pathogens, or natural senescence (BUTIN 1996, SINCLAIR / 
LYON/ JOHNSON 1987). Outbreaks of Cenangium dieback occur only once in 
several years. The fungus is usually a competent saprobe on pine twigs killed by 
various agents. lts saprobic existence ensures a supply of spores and it seems 
likely that incipient infections begin each year in the summer and autumn and are 
held in check by host defenses unless these are overcome by environmental 
damage or by other pests (SINCLAIR/ LYON / JOHNSON 1987). This common 
view of repeated yearly infections was overturned by the results of JURC (1996) 
who revealed the constant endophytic existence of C. ferruginosum in the healthy 
needles of Austrian pine. 
112 
Zbornik gozdarstva in lesarstva, 54 
The objectives of our laboratory study were to determine the temperature and 
available water requirements for the growth of C. ferruginosum in culture and to 
test its growth on different artificial nutrient media. 
We hoped that these data would reveal the ecological factors which are decisive 
in fungal growth and are prerequisites for outbreaks of the disease. Such factors 
should enable the fungus to break its quiescent endophytic state and to spread 
quickly through weakened tissues of its host. 
2 MATERIAL ANO METHODS 
2.1 COLLECTING SITE 
A sampling of Austrian pine needles was performed in a natura! stanci of Austrian 
pine on Smolnik hill near the town of Jesenice (1075 m above sea level, y=54 
343000, x=51 42100; projection G.-K., UTM MV43) in January 1995. This forest 
belongs to plant association Pinetum subil/yricum Schmidt 1936 and grows on 
limestone. 
2.2 SAMPLING PROCEDURE ANO ISOLATIONS 
The tree from which the samples were taken was about 60 years old. A branch 
was cut from the lower whorl of the southern part of the crown using tree loppers. 
Needles were transported in cold boxes at 4°C in clean polyethylene bags and 
processed within 24 hours. Four needles of each age class, without any signs of 
damage, were washed in running tap water for one hour. From every needle 
three 0,3 cm long segments were taken - one from the base, one from the middle 
part and one from the tip of the needle. They were then surface-sterilised (1 min 
in 50 % ethanol v/v, 5 min in sodium hypochlorite with 2,6 % of active chlorine, 1 
min in 50 % ethanol v/v). The segments were blotted dry and plated onto 2 % 
malt extract agar (Malt Extract, Biolife S.r.l., 20 g r1, Agar Bios Special LL, Biolife 
S.r.l., 20 g r\ Twelve segments per plate and 2 replicate plates per age class 
were plated out. Petri dishes were then incubated at 23° C and examined weekly 
for six weeks. Mycelial outgrowths from the segments were subcultured and 
identified. 
113 
Jurc D., Jurc M.: Vpliv vlage, toplote in hranilne podlage ... 
The fungus used in all further experiments was isolated from the base segment of 
a four year old needle and it fit, in all details, to the description of C. ferruginosum 
anamorf (KUJALA 1950). 
2.3 MEASURMENT OF FUNGAL GROWTH IN VITRO 
1 % malt extract agar medium was used (MEA, Lab M Ltd, pH 4,5) to measure 
fungal growth. In all cases 25 ml of malten agar was poured into 9 cm diameter 
Petri dishes and inoculated with 4 mm diameter agar plugs of C. ferruginosum 
cultures taken from the growing margin of 14 day old colonies. The diameter of 
the colonies was measured in two directions at right angles to each other. AII 
experiments were carried out in triplicates. The effect of temperature was 
examined by placing inoculated MEA agar plates in darkness at 1 O, 20, 25, 30 
and 35° C. The effect of water availability (aw) was examined by modifying the 
media with glycerol to the values of 0,98, 0,96 and 0,94 aw (DALL YN / FOX 
1980, MAGAN / LACEY 1984). Plates with the same aw were enclosed in clean 
polyethylene bags and incubated at 1 O, 20, 25, 30 and 35° C for 29 days. 
To compare the growth rate on different growth media the fungus was incubated at 
23° C on 2 % MEA (Malt Extract, Biolife S.r.l., 20 g r1, Agar Bios Special LL, Biolife 
S.r.l., 20 g r\ 3,9 % PDA (Potato dextrose agar, bioMerieux 51411, 39 g r1) and 3 
% OA (oatmeal 30 g r1, Agar Bios Special LL, Biolife S.r.l., 20 g r1) 
3 RESULTS 
Colonies of C. ferruginosum in culture have characteristics which make the 
growth tests less comparable and reliable. The growth of the mycelial colony is 
irregular and outgrowths can develop from some parts while in other parts the 
growth can be slower or halted. This is the reason for the great variation seen 
among some of the experiments. Photo 1 shows the morphology of C. 
ferruginosum cultures on MEA, OA and PDA media, while photo 2 shows slimy 
conidial masses on mycelium. 
114 
Zbornik gozdarstva in lesarstva, 54 
Photo 1: Differences in growth of 41 days old C. ferruginosum cultures on 
OA, MEA and PDA media (from left to right). 
Fotografija 1: Razlike v rasti 41 dni starih kultur C. ferruginosum na gojišču OA, 
MEA in PDA (od leve proti desni). 
Photo 2: Slimy conidial masses on culture of C. ferruginosum (ali photos 
by D. Jurc). 
Fotografija 2: Sluzaste mase konidijev na kulturi C. ferruginosum (vse 
fotografije: D. Jurc). 
115 
Jurc D., Jurc M.: Vpliv vlage, toplote in hranilne podlage ... 
3.1 EFFECTS OF TEMPERATURE ANO AVAILABLE WATER ON 
GROWTH OF C. FERRUGINOSUM 
At 1 o° C and 20° C the growth of C. ferruginosum is similar, while the highest 
growth rate occurs at 25° C. High temperatures (30° C and 35° C) are not suitable 
far the growth of the fungus, in fact, at these temperatures, it doesn't grow at all 
(Graph 1). 
62 
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Graph 1: 
Grafikon 1: 
--------------------------------------··1~ 
r -ff;:f ::-.::-.::-. - - - - .-:-:::::::.-::-:::.-::-.::-.::-.7 
.-r··-_ _., 
z--,, ,,,~..::z.;. 
....... CF _10 
--- CF _20 
------ CF _25 
....... CF _30 
3 5 7 9 11 13 15 17 19 21 23 25 27 29 --- CF - 35 
Days of growth / Dnevi rasti 
Diameter (mean ± S.E.) of C. ferruginosum culture at 
temperatures 1 O, 20, 25, 30 and 35° C. 
Premer (srednja vrednost ± S.E.) kulture C. ferruginosum pri 
temperaturah 1 O, 20, 25, 30 in 35° C. 
116 
Zbornik gozdarstva in lesarstva, 54 
At 10° C C. ferruginosum grows well on relatively humid growth medium (aw1, 
aw2), it doesn't grow in relatively dry conditions (aw3) (Graph 2). 
60 
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Graph 2: 
Grafikon 2: 
--- AW2_10 
3 5 7 9 11 13 15 17 19 21 23 25 27 29 -··-·· AW3_10 
Days of growth / Dnevi rasti 
Diameter (mean ± S.E.) of C. ferruginosum culture on medium 
with different available water (aw1 = 0,98, aw2 = 0,96, aw3 = 
o 0,94), at 10 C. 
Premer (srednja vrednost ± S.E.) kulture C. ferruginosum na 
podlagi z različnimi količinami dostopne vlage (aw1 = 0,98, aw2 
= 0,96, aw3 = 0,94), pri 10° C. 
117 
Jurc D., Jurc M.: Vpliv vlage, toplote in hranilne podlage ... 
Growth rate of the fungus at 25° C and higher aw (aw1, aw2) is less than that at 
1 o° C. As at 1 o° C the fungus doesn't grow at aw3 (Graph 3). 
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Graph 3: 
Grafikon 3: 
Days of growth / Dnevi rasti 
Diameter (mean ± S.E.) of C. ferruginosum culture on the 
medium with different available water (aw1 = 0,98, aw2 = 0,96, 
aw3 = 0,94), at 25°C. 
Premer (srednja vrednost ± S.E.) kulture C. ferruginosum na 
podlagi z različnimi količinami dostopne vlage (aw1 = O, 98, aw2 
= 0,96, aw3 = 0,94), pri 25° C. 
At 30° C and 35° C there is no growth on any medium no matter what the aw. 
118 
Zbornik gozdarstva in lesarstva, 54 
3.2 DIFFERENCE IN GROWTH ON MEA, PDAAND OA 
The growth of C. ferruginosum cultures on different growth media is presented in 
Graph 4. The growth on MEA medium is irregular, often with rather quick 
outgrowths of parts of a colony, which leads to a high leve! of variability in the 
results. In culture, the fungus forms conidiomata which begin to appear on 
the14th day of subculturing on PDA and OA and on the 20th day on MEA. 
E 95 .s 
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Graph 4: 
Grafikon 4: 
4 7 10 13 16 19 22 25 28 --- OA_23 
Days of growth / Dnevi rasti 
Diameter (mean ± S.E.) of C. ferruginosum culture on the MEA, 
PDA and OA at 23° C. 
Premer (srednja vrednost ± S.E.) kulture C. ferruginosum na 
podlagi MEA, PDA and OA pri 23° C. 
The growth rate of the fungus is highest on PDA medium, while on MEA it is 
higher than on OA up to the end of the experiment, when the growth rate is 
equalised. 
4 DISCUSSION 
119 
Jurc D., Jurc M.: Vpliv vlage, toplote in hranilne podlage ... 
The biology and pathogenicity of C. ferruginosum has been thoroughly 
investigated in numerous works. It is defined as a facultative parasite of many 
pine species, although it rarely occurs in fir and spruce species (KUJALA 1950, 
LORENZ 1967, SMERLIS 1973). lts occurrence and ecological role is mostly 
regarded as saprobic and, as such, it cannot be harmful to its host if it grows 
under favourable climatic and site conditions (KOBAYASHI / MAMIVA 1963, 
LUKOMSKI 1968). The interpretation of its definition as a facultative parasite is 
based on numerous examples of its epidemic spreads after prolonged droughts, 
severe winters or other ecological disturbances in previous seasons, (LENGYEL 
1963, PETRAK 1961, DONAUBAUER 1974, TORRES 1972, CAPRETTI / 
PANCONESI / PARRINI 1987, JURC 1987, SINCLAIR / LYON / JOHNSON 
1987) such as epidemics of C. ferruginosum after attacks of harmful insects 
(DOMINIK 1976, LORENZ 1966, 1967). 
C. ferruginosum fructifications are found on pine branches. lf branches with 
immature ascomata are kept in moist conditions numerous conidiomata with 
masses of conidia can be found on the bark (JURC, D., unpublished 
observation). Stromatic tissues are formed in the bark and ascomata are formed 
on the scars of dropped needles, in bark cracks, or over entire branch surfaces. 
Millar (1981) supposed that infection occurs through, or in the vicinity of, the 
terminal bud in the succulent terminal region. Mechanical damage from insects 
as possible entrance points are also mentioned. Gremmen's (1959) statement 
that this fungus is a pioneer organism of branches stili attached to the tree and 
that it only seems to inhabit branches suffering from primary parasitic attack, e.g. 
after damage by Gremenie/la abietina or after insect damage ( Cecidomya 
brachyntera), is also well-accepted. 
C. ferruginosum is frequently isolated from Scots pine. lts endophytic occurrence 
in needles of P. sy/vestris in plantations was reported by Rack and Scheidemann 
(1987). In parallel research of healthy and diseased needles they established that 
the fungus is more frequently isolated from the top and bottom of the crown, 
although there was no difference in the frequencies of isolation between old and 
young trees, and none among different age classes of the needles. Helander et 
120 
Zbornik gozdarstva in lesarstva, 54 
al. (1994) faund that the highest number of C. ferruginosum infections occur in 
the base segments of needles of Scots pine. They suppose that the fungus either 
systematically colonizes the needles beginning with the twigs and moving through 
the petioles into the needle base or that colonisation starts from spores invading 
the needle base and proceeding systematically into the twigs. 
We presume that the relatively high C. ferruginosum infection rate of the needles 
enables this fungus to invade the twigs of drought stressed Austrian' pine trees 
and that its constant presence as an endophyte explains why the epidemics can 
occur suddenly over such large areas, as occured in Slovenia in 1986. Our 
results explain the ability of the fungus to invade the tissues of its host during 
colder periods of year and when the substrate is highly moistened. High summer 
temperatures are unsuitable far its growth. Suitable conditions for its spread from 
the needles to the twigs occurs more often in the wet and relatively warm winter 
conditions of a submediterranean climate than in Nordic countries where the 
epidemic dying of pines doesn't occur. The optimal humidity far growth of this 
fungus is high and even at 10° C it stili grows considerably. The symptoms of C. 
ferruginosum dieback of twigs occurs in Slovenia during the winter months 
(December through March) when the average monthly temperatures varies 
between 3° C to 7° C and when more than half of the yearly precipitation falls 
(1.643 mm). A prerequisite condition far the outbreak cf a Cenangium dieback of 
pines is a previous drought which modifies or damages the host. The nature of 
these damages are not defined but are inevitably connected with host defense 
mechanisms. 
There are no comparative literature data about the growth of C. ferruginosum on 
different nutrient sources. Based on our data it has been established that the 
substrate is an important factor and influences the growth rate of the fungus 
considerably. 
5 POVZETEK 
121 
Jurc D., Jurc M.: Vpliv vlage, toplote in hranilne podlage ... 
Namen laboratorijskih poskusov je bil določiti toplotne in vlažnostne razmere za 
rast C. ferruginosum v kulturi in ugotoviti rast glive na različnih hranilnih gojiščih. 
Predvidevali smo, da bodo ti podatki odkrili tiste ekološke dejavnike, ki so 
odločujoči za rast glive in so pogoj za izbruh bolezni. Ti dejavniki omogočajo glivi, 
da prekine svoje mirujoče endofitno stanje in hitro preraste oslabela tkiva 
gostitelja. 
Rast C. ferruginosum je pri 1 o° C in 20° C podobna, najhitrejša je pri 25° C. 
Visoke temperature (30° C in 35° C) niso ustrezne in pri teh temperaturah gliva 
ne raste (grafikon 1 ). 
Pri 1 o° C C. ferruginosum dobro raste na relativno vlažni hranilni podlagi (aw1, 
aw2), ne raste pa na relativno suhi podlagi (aw3) (grafikon 2) 
Pri 25° C in višji dostopni vlagi (aw1, aw2) je rast manjša kot pri 1 o° C. Gliva ne 
raste na aw3 (grafikon 3). 
Pri 30° C in 35° C gliva ne raste ne glede na količino dostopne vode. 
Najhitreje raste na gojišču PDA. Na gojišču MEA je rast večja kot na gojišču OA 
vse do konca poskusa, ko se izenači. 
Domnevamo, da relativno močna, stalna okuženost zdravih iglic s C. 
ferruginosum omogoča tej glivi razrast iz iglic v vejice črnih borov, ki so oslabljeni 
zaradi suše. Njena stalna endofitna prisotnost je razlog, da epidemije nastopijo 
nenadno na tako velikih območjih, kot v Sloveniji v letu 1986. Naši rezultati 
pojasnjujejo sposobnost glive, da okuži tkiva gostitelja med hladnimi letnimi 
obdobji in takrat, ko je podlaga dovolj vlažna. Visoke poletne temperature so 
neustrezne za njeno rast. Ustrezne razmere za njeno razraščanje iz iglic v vejice 
so pogostejše v vlažnem in relativno toplem zimskem obdobju 
submediteranskega podnebja kot pa v hladnem podnebju nordijskih držav, kjer 
se epidemije bolezni ne pojavljajo. Optimalna vlažnost za rast glive je visoka, pri 
njej znatno raste še pri 1 o° C. Simptomi sušice borovih vej se pojavljajo v 
122 
Zbornik gozdarstva in lesarstva, 54 
Sloveniji v zimskih mesecih (od decembra do marca), ko so poprečne mesečne 
temperature med 3° C in 7° C in ko pade več kot polovica letnih padavin (1.643 
mm). Pogoj za izbruh sušice borovih vej je predhodna suša, ki spremeni oziroma 
poškoduje gostitelja. Narava teh poškodb ni znana, vendar so neobhodno 
povezane z obrambnimi mehanizmi gostitelja. 
V literaturi niso opisani primerljivi podatki o rasti kulture C. ferruginosum na 
različnih hranilnih podlagah. Na osnovi naših podatkov ugotavljamo, da je 
hranilna podlaga pomemben dejavnik, ki močno vpliva na rast glive. 
6 ACKNOWLEDGEMENTS 
The work was funded by The Ministry of Agriculture and Forestry, The Ministry of 
Science and Technology of the Republic of Slovenia (No. V9-6913-040) and The 
British Council of Slovenia (ALIS link No.28 1996/99). 
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Bekampfung.- Georg Thieme Verlag, Stuttgart.New-York, 261 s. 
CAPRETTI, P. / PANCONESI, A. / PARRINI, C., 1987. Dieback of Aleppo and 
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DALLYN, H. / FOX, A., 1980. Spoilage of materials of reduced water activity by 
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DOMINIK, J., 1976. lnsect pests and fungus diseases in young plantations and 
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DONABAUER, E., 1974. Dieback of Pines in Austria caused by Scleroderris 
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123 
Jurc D., Jurc M.: Vpliv vlage, toplote in hranilne podlage ... 
GREMMEN, J., 1959. A Contribution to the Mycoflora of Pine Forests in the 
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HELANDER, M. L. / SIEBER, T. N. / PETRINI, O. / NEUVONEN, S., 1994. 
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of simulated acid rain.- Can. J. Bot. 72, s. 1108-1113. 
JURC, D., 1987. Zanimivosti naše mikoflore. 2 Povzročitelj sušice borovih vej.-· 
Proteus, Prorodoslovno društvo Slovenije, Ljubljana, s. 183-187. 
JURC, M., 1996. Endofitne glive in njihove značilnosti v iglicah črnega bora 
(Pinus nigra Arn.). (Endophytic fungi and their characteristics in the needles 
of Austrian pine (Pinus nigra Arn.)).- Dissertation thesis, University of 
Ljubljana, Department of biology, 198 s. 
KUJALA, V., 1950. Ober die Kleinpilze der Koniferen in Finland.-
Communicationes Instituti Forestalis Fenniae, Helsinki, 38, 121 s. 
KOBAYASHI, T./ MAMIYA, Y., 1963. A Cenangium causing dieback of Japanese 
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LENGYEL, G., 1963. Dieback of Pinus nigra var. austriaca in Hungary, 1960-
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