sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

3. RESULTS
SDÜ Faculty of Forestry Journal
3.1. Incidence of the disease in forest stands
Site 1 had the greatest number of diseased trees, altogether 70 trees. Eutypella
cankers usually form infection centers, while single occurrences are rarely found
(Kliejunas and Kuntz, 1974; Martinez, 2003) since ascospores are disseminated
only over short distances (Johnson and Kuntz, 1979). There were four infection
centers and six single trees distributed around the hill. A full inventory of one
infection centre at Site 1 was performed. All trees were identified and measured for
their diameter at breast height (DBH) within an area of 2.7 hectares. In the
searched area, 20 tree species were determined. The most common species was the
sycamore maple (41.7% of all trees), followed by the big leaf linden (Tilia
platyphyllos Scop.) with 15.3%, the common hornbeam (Carpinus betulus L.) with
10.6%, and the northern red oak (Quercus rubra L.) with 9.7%. Among 606
sycamore maples in the 2.7 hectare area, 3.3% were diseased by E. parasitica. This
is within the range of the usual incidence of Eutypella canker (Gross, 1984b).
At Site 6 on the area of 7.2 ha, frequency of Eutypella canker was determined.
28.6% of 192 field maples had canker.
3.2. Common measurable characteristics
Table 1 shows a summary of the statistics for four variables. The sample size was
different for each variable measured. Eutypella cankers were found over the entire
DBH range from thin to large, as previously reported by French (1969). The average
trunk diameter at breast height was 25 cm. The relative frequency of cankered trees
among 7 classes showed that 52% of diseased trees had a DBH between 11 and 22 cm.
65% of all trees with Eutypella canker occurred on first 220 cm of trunk above
the ground line, and 92% of all cankers occurred on the first 435 cm of trunk.
These results are comparable to French (1969), who noted that 60% of all cankers
occurred on the first 244 cm of trunk and 81.5% on the first 488 cm of trunk.
33 cankers were measured for canker length. 85% of cankers did not exceed a
length of 120 cm. Gross (1984a) measured 27 trees and the range of canker length
was from 10 cm to 170 cm with an average of 67 cm. Wide range of canker length
was directly related to the age of the canker and could be explained as such.
Table 1: Summary statistics for common measurable characteristics of Eutypella canker
Trunk DBH
(cm)
Vertical
distribution (cm)
154
Length of
canker (cm)
Width of
canker (cm)
Sample size 38 37 33 31
Minimum 11 35 30 23
Maximum 61 1150 233 115
Average 25 216 102 59
95% confidence
interval (±)
3.6 73.9 18.6 9.5