sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDÜ Faculty of Forestry Journal
portion of the middle density of perithecia was included in the high density. It was
suggested that about one-third of the total area covered with perithecia belonged to
low density class, one third to middle density, and one third to high density class.
20 out of 23 cankers were oval shaped, two cankers were triangular, and only
one was shaped irregularly. All triangular shaped cankers had the centre of the
canker close to the ground line. The irregular shape of the canker area has been
already observed and explained (Davidson and Lorenz, 1938). The annual
extension of the cankered areas is usually uniform and therefore the shape of
canker area is usually oval. However, this extension is occasionally stopped
suddenly by some unknown cause, around either the entire margin or only a portion
of it. Such sudden cessation of the extension gives the canker an irregular shape.
The extension of the canker is faster in the longitudinal direction than in the
transverse direction. This leads to the elongated oval shape of canker area. Cankers
could be from 1.32 to 2.62 longer than they are wide while the average
length/width proportion was 1.74 (± 0.18 at 95% confidence level).
Within the canker shape analysis it was observed that the trunk gradually grows
thicker up to canker centre and then the trunk thins down. The thickness of the
canker was measured for 14 specimens at 10 cm intervals. It was determined that
the thickness of the Eutypella canker was represented by a parabola very well.
Polynomial regression using a second order polynomial model was performed for
each of the 14 specimens. The R 2 was up to 97.8% and the average R 2 was 76.7%.
This shows again that the canker shape is a regular oval.
Table 2: Summary statistics for different kinds of areas of Eutypella cankers
Canker area
(dm 2 ) Whole Without bark low
density
156
Perithecia (averages)
middle
density
high
density
Minimum 12.3 0 0 0 0 0
Maximum 168.0 43.7 14.9 16.6 45.8 64.7
Mean 53.3 11.3 6.5 3.9 *
95% confidence
interval (±)
Total
10.9 20.5
20.6 6.3 2.2 1.8 7.3 9.2
* Middle density of perithecia could hardly be distinguished from high density.
Therefore, some portion of the middle density of perithecia was included in the
high density.
3.4. Isolates
Davidson and Lorenz (1938) stated that a single species of Eutypella has been
consistently isolated from discolored wood from under the centre and from near the
margins of the discoloration. Our study strongly supports this statement. From 9
dissected trees, 97 discs and 237 boring holes, 1896 samples were cultivated on