Tamietti G, Matta A
DIVAPRA-Patologia vegetale, Università di Torino, V. L. da Vinci 44, 10095 Grugliasco, Italy.
Plant Dis. 2003 Aug;87(8):1005. doi: 10.1094/PDIS.2003.87.8.1005B.
During the early summers of 2001 and 2002, in Forno Canavese in northwest Italy, a leaf disease was observed on the old apple cv. Furnas in a domestic orchard. Lesions on the upper side of the leaf were brownish, irregular in size and shape with somewhat dendritic margins, became black, and often coalesced with time. On the underside, lesions were smaller with more definite margins. Beginning in July, scattered acervuli (95 to 170 μm) were observed erupting through the epidermis on the upper side of leaves. Conidia were ampule shaped, 1-septate, constricted at the septum, hyaline, guttulate, and 6.1 to 8.4 × 14.6 to 22.0 μm. Severely diseased leaves abscised prematurely. The fungus was identified as Marssonina coronaria (Ellis & J.J. Davis) J.J. Davis, teleomorph Diplocarpon mali (1) although the conidia were slightly shorter than those originally described for this fungus. Monoconidial isolates were obtained by spreading mini-suspensions of conidia taken from acervuli on malt agar (MA) and transferring single-germinated conidia to MA, potato dextrose agar, V8 agar, or apple leaf agar (ALA). The fungus grew slowly, producing small colonies on V8 and ALA only. On ALA medium, after 3 months incubation at 20 to 22°C, the colonies were 5 to 7 mm in diameter with light brown, irregular margins and dark brown centers bearing acervuli. Conidia from pure cultures were collected, suspended in sterile, distilled water (250,000 ml), and sprayed on the leaves of three 'Golden Delicious' apple shoots maintained in a mist chamber at 20 to 25°C for 2 weeks. In two independent experiments, the fungus reproduced symptoms like those observed on 'Furnas' and was reisolated from acervuli. No symptoms were observed on water-treated controls. To our knowledge, apple leaf blotch has not previously been reported in Italy. Although now it is a minor disease, it could become more important in sustainable crops because of its relatively low sensitivity to copper fungicides (2), the only products that can be used under that program. References: (1) Y. Harada et al. Ann. Phytopathol. Soc. Jpn. 40:412, 1974. (2) J. Ruide et al. China Fruits 2:51, 1997.
2001年和2002年初夏，在意大利西北部的福尔诺卡纳韦塞，一个家庭果园里的老苹果品种“富尔纳斯”上观察到一种叶部病害。叶片上表面的病斑呈褐色，大小和形状不规则，边缘有点呈树枝状，随后变黑，且常常随着时间的推移而融合。叶片下表面的病斑较小，边缘更清晰。从7月开始，在叶片上表面观察到散生的分生孢子盘（95至170μm）突破表皮。分生孢子呈安瓿形，具1个隔膜，在隔膜处缢缩，无色透明，具油滴，大小为6.1至8.4×14.6至22.0μm。严重患病的叶片过早脱落。该真菌被鉴定为苹果盘二孢（Marssonina coronaria (Ellis & J.J. Davis) J.J. Davis），其有性型为苹果双壳菌（Diplocarpon mali）（1），尽管分生孢子比最初描述的该真菌的分生孢子略短。通过将取自分生孢子盘的分生孢子微悬浮液涂布在麦芽琼脂（MA）上，并将单个萌发的分生孢子转移到MA、马铃薯葡萄糖琼脂、V8琼脂或苹果叶琼脂（ALA）上，获得了单孢分离物。该真菌生长缓慢，仅在V8和ALA上形成小菌落。在ALA培养基上，于20至22°C下培养3个月后，菌落直径为5至7mm，边缘浅褐色、不规则，中心深褐色，带有分生孢子盘。收集纯培养物中的分生孢子，悬浮于无菌蒸馏水中（250,000个/ml），并喷洒在置于20至25°C的雾室中的3个“金冠”苹果嫩枝的叶片上，持续2周。在两项独立实验中，该真菌产生了与在“富尔纳斯”上观察到的症状相似的症状，并从分生孢子盘中再次分离得到。水处理对照未观察到症状。据我们所知，此前意大利尚未报道过苹果叶斑病。尽管目前它是一种次要病害，但由于其对铜杀菌剂相对不敏感（2），而铜杀菌剂是该种植方案下唯一可使用的产品，因此在可持续作物中可能会变得更加重要。参考文献：（1）Y. Harada等人，《日本植物病理学会年报》40:412，1974年。（2）J. Ruide等人，《中国果树》2:51，1997年。
