چكيده لاتين :
In October 2005, specimens of powdery mildew were collected on oak trees from West Azarbaijan and Kordestan provinces forests. There are three species of oak trees in these forests as follows, Quercus brantii Lindl. , Q. infectoria Oliv. and Q. libani Oliv. , but symptoms of disease had seen only on Q. infectoria leaves. During the survey, two species of fungi causing powdery mildew were identified as follows:
1- Erysiphe alphitoides var. alphitoides
Mycelium on leaves, amphigenous, mostly on upper surfaces, forming patches or effused, grayish white, conidia ellipsoid-ovoid to doliform, (24-) 27-33 (-36) × 12-22.5 μm, cleistothecia subgregarious to gregarious, dark brown, (72-) 88-132 (-152) μm, appendages (4-) 6-15 (-25) in number, (60-) 80-140 (-180) μm in diameter, equatorial, hyaline, aseptate, apex 3-6 times dichotomously branched, branches close and regular, tips of the ultimate branches recurved when mature, asci 3-9 (-12) in number, sessile or with short stalks, (45-) 56-64 (-72) × (32-) 36-48 μm, ascospores (2-) 3-7 (-8) in each ascus, ellipsoid to ovoid, (15-) 18-21 (-25.5) × 9-15 μm.
These characters with slight differences in number of asci and ascospores were the same as that Braun (1987) had said for Microsphaera alphitoides var. alphitoides, however, in the studied specimens, asci and ascospores number was 3-12 and 2-8 respectively, but the above mentioned number in the Braun key (1987) are 5-16 and (4-)6-8 . According to the recent changes-based on phylogenic surveys-on the taxonomy of some Erysiphaceae proposed by Braun and Takamatsu (2000), this species is accepted as Erysiphe alphitoides var. alphitoides.
Specimens examined: on Quercus infectoria, West Azarbaijan, between Piranshahr and Sardasht, Qabr Hossein, 1440m, 4 October, 2005, Tavanaei & Zargaran, (315F1001). Kordestan, between Baneh and Mahabad, Kanisoor village, 1550m, 3 October, 2005, Tavanaei, (315F1003). Kordestan, between Saqqez and Baneh, near the Gemareh leng village, 1480m, 2 October, 2005, Tavanaei & Fatehi, (315F1006).
2- Phyllactinia guttata (Wallr. : Fr.) Lev.
Mycelium forming on lower surfaces of leaves, spots yellowish white, conidia clavate to fusiform, 44-64 (-76) × (12-) 16-24 μm, cleistothecia subgregarious, mostly not mature, mature ascocarps (180-) 220-260 μm in diameter, peridium cells irregularly polygonal, appendages 4-9, equatorial, acicular, with basal swelling, bulbous base 36-60 μm in diameter, appendages lenth 140-360 μm, asci with short or long stalks, 13-19 in each ascocarps, 68-100 × 28-40 μm , 2 spored, ascospores ellipsoid to ovoid, 28-40 × 16-22 μm in diameter.
The mentioned attributes were according completely to characters of Phyllactinia guttata that described by Braun (1987).
Based on available literatures, the fungus Phyllactinia guttata don’t reported on Q. infectoria previously in all over the world, thus, Q. infectoria is reported as a Matrix novafor mentioned fungus.
Specimens examined: on Quercus infectoria, Kordestan, near the Baneh, 1450m, 3 October, 2005, Tavanaei, (315F1101).
