sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDÜ ORMAN FAKÜLTESİ DERGİSİ
Table 2: Characteristics and disease incidence of monitoring plots. Stands are given in
the order of descending disease incidence. (I: seedlings; II: saplings, III: young pole stage)
Stand
Number
n
A. alba
counted
Density of
young
stand
Density of
canopy
Age
Class
185
Alternate
host
recorded
Disease
Incidence
%*
Stem
cankers
%*
7 45 +++ 0 I ++ 100 100
13 33 ++ 0 I ++ 100 93
2 27 +++ 0 II + 100 76
11 25 + 0 II ++++ 100 67
1 14 ++ + II ++ 100 65
12 15 ++ + I - II ++ 94 60
5 7 ++ 0 III 0 83 28
9 n.r. 127 + ++ I - II ++ 70 52
3 46 +++ 0 I - II 0 39 2
6 14 +++ 0 II + 22 8
8 14 ++ 0 II 0 14 0
4 16 ++ 0 II + 5 0
10 n.r. 304 +++ +++ I + 2 0
Total
687
4. DISCUSSION
Mean
63,8
* mean of plots
Mean
42,4
The results show the potential of the rust fungi to infect young plantations of
silver fir up to 100 % and in rare cases up to 100 % incidence of stem canker. Thus,
M. caryophyllacearum may under certain circumstances still be a serious threat for
high quality timber growth of A. alba under modern silviculture. However, a
disease incidence up to 50% of the trees is mostly restricted to harmless branch
cankers. To provoke a certain amount of stem cankers, the infection pressure must
be higher. This occurs both in natural regeneration as well as in advance plantings,
if a close association with an alternate caryophyllaceous host is given.
Data shows that all age classes from seedling stage till pole stage can equally be
infected. Roth (1955) found stem cankers between 1.5 and 15.2 m tree height
(average 6.1 m) in Swiss fir forest. Heck (1894) found stem cankers between 0.5
and 18.5 m (average 5.0 m) in SW-Germany. Both give evidence that even late
pole stage firs can also be infected at the leaders or twigs in the upper crown.
Nicolotti et al. (1994) and Solla and Camarero (2006) stated a positive
correlation between disease incidence and shorter distance to rivers. This can be
due to air humidity in sites or regions where humidity is a limiting factor for the
infection process of the fungus. Furthermore, under German conditions, the main
alternate host S. nemorum is rather linked with plant associations in sites close to
ditches, rivers, or to other moist and nutrient rich sites (e.g. “Stellario-Alnetum”)