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ŠUMARSKI LIST 1-2/2012 str. 38     <-- 38 -->        PDF

D. Diminić, N. Potočić, I. Seletković: ULOGA STANIŠTAU PREDISPOZICIJI CRNOGABORA... Šumarski list br. 1–2, CXXXVI (2012), 19-36


Croatia revealed significant dieback symptoms in some areas as the consequence
ofSphaeropsis sapineaoccurrence.


Research carried out in November 2001 found the fungus presence with
different impact to P. nigrain Istria, healthy sites and also ones with various
disease symptoms were observed (Figure 1, Table 1). In plantations which revealed
good health statusS. sapineawas found only on cones, but in plantations
with dieback symptoms its presence was found in needles, shoots and
branches, causing in some cases dieback of trees. According to dieback symptoms
observed, research localities were categorised in four health categories
as shown in Figure 1.


It was revealed that along the drought (Figures 19 and 20, an example for
period 1961–1990 vs. 1999), the site conditions also played an important role
in pines’ predisposition to fungus attack during last years. This conclusion
was supported by analyses of nutrition status in pines and site conditions (soil
sub-types, soil types and depth, site rockiness, exposition and inclination,
Table 1). Analyses of nutrition status obtained clear difference among sites
comparing the nitrogen (N) and potassium (K) concentrations in pine needles
(Figures 6–11). In sites with lower N/K ratio the disease symptoms were not
observed, but in sites with increased N/K ratio the dieback symptoms were revealed,
following nitrogen and potassium relation in general (Figures 12 and
13). According to Brown (1999) fertilization only by nitrogen can increase the
susceptibility of broadleaved trees to pathogenic organisms due to the influence
of nitrogen on growth of aboveground plant biomass, and imbalance of
above- and belowground plant parts biomass can lead to the increased susceptibility
of trees to water stress. Higher nitrogen concentartions as pines’
predisposition to S. sapinea were confirmed by De Kam et al. (1991), Van Dijk
et al. (1992) and Stanosz et al. (2004). Opposite to nitrogen, potassium play
important role in plant resistance to drought and pathogenic organisms
(Bergmann 1992, Marschner 1995).


Inoculation experiment in Austrian pine seedlings confirmed the S. sapinea
pathogenicity and also the same capability of isolates obtained from healthy needles
(VIPAVA, IMI 368260) and ones with symptoms (DP 04-1 and DP 06-3,
described in Diminić et al. 2004) to cause bark necrosis. Previous fertilization
with ammonium sulphate caused increased seedlings growth according to treatments:
0, 20, 40 and 80 g/m2, and also increased length of bark necrosis in inoculated
pines (Tables 2 and 3, Figures 14–18), which supported the nitrogen
role in disease development.


According to up-to-day worldwide knowledge and results of our research,
it can be concluded thatS. sapineacan live (latent phase) in healthy looking
pines in Istria. And, in drought periods it can turn to serious pathogen, causing
dieback in predisposed trees. It this circumstances, site play an important
role in pines’ resistance to disease, indirectly influencing appearance (or not)
of various dieback symptoms.


Key words:Pinus nigra, plantations, health status, dieback,Sphaeropsis
sapinea, site conditions, drought