sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDÜ Faculty of Forestry Journal
Pathogenicity trial was carried out in the campus area of Süleyman Demirel
University, during October-November, 2007. The D. pinea isolates were grown on
PDA (Merck) at 24ºC in the dark, for one week. Four wounds of 2 x 2 mm were
made approximately 2 cm below the shoot apex, on one terminal and three lateral
shoots of each seedling, removing a needle fascicle by a scalpel and agar plugs
with D. pinea mycelia cut from the actively growing culture were placed myceliaside-down
on the wounds (Blodget and Stanosz, 1997). Wounds were then
wrapped with parafilm. Non-colonized agar plugs were placed on control
seedlings. Five seedlings were used for each species-isolate combination and a
randomized complete block design was used in the trial. Seedlings were incubated
under field conditions for 9 weeks. Average temperature in October was 14.4°C
(maximum up to 28.2 °C, minimum 0.8 °C) and in November 7.4 °C (maximum up
to 22.9 °C, minimum -10°C). Average relative humidity was 58 % in October and
76 % in November. The seedlings were regularly irrigated and controlled for
characteristic disease symptoms. Dead shoots were recorded.
At the end of the inoculation period, inoculated terminal and lateral shoots were
cut 15 cm below the inoculation point and brought to the laboratory. Based on the
color changes on the shoots and needles, lesion sizes were measured. Then the
needles on the shoots were removed and the shoots were cut into 1 cm long
segments, from the inoculation point to the cut end of the shoots. The segments
were surface sterilized by keeping them 10 seconds in 96 % ethyl alcohol and 4
minutes in 1 % NaOCl and dried between sterile paper towels. They were then
placed on petri plates with 2.5 % bacto agar and 0.05 % tannic acid, 5 segments per
plate, in a clockwise serial order.
The plates were incubated at room temperature for 4 weeks and examined under
stereomicroscope for the presence of D. pinea colonies growing from the segments.
Dead shoot rate, lesion length and fungal growth data obtained for each tree
species-isolate combination were statistically analyzed by using SPSS program.
3- RESULTS
Susceptibility of the tree species to D. pinea and the virulence of the D. pinea
isolates among those host species were different from each other. Dead shoots were
observed in all isolate-host combinations, except for P047 and P097 isolates on J.
excelsa. Considering the dead shoot rates, within host variation of the isolates was
low, while host species had high variation. The highest rate was on C. libani
(98.0%), followed by P. nigra (51.0%) and P. brutia (31.9%). Dead shoot rates
were low on Abies (16.0%), P. sylvestris (12.8%) and J. excelsa (4.0%) (Figure 1).
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