Sigatoka leaf diseases are a major constraint to banana production. A survey was conducted in Tanzania and Uganda to assess the distribution of Pseudocercospora species and severity of Sigatoka leaf diseases. Pseudocercospora species were identified using species-specific primers. Sigatoka-like leaf diseases were observed in all farms and on all cultivars, but disease severity varied significantly (P < 0.001) between countries, districts/regions within countries, altitudinal ranges and banana cultivars. In all regions except Kilimanjaro, P. fijiensis, the causal agent of black Sigatoka, was the only pathogen associated with Sigatoka disease. Mycosphaerella musae was associated with Sigatoka-like symptoms in Kilimanjaro region. Black Sigatoka disease was more severe in Uganda, with a mean disease severity index (DSI) of 37.5%, than in Tanzania (DSI = 19.9%). In Uganda, black Sigatoka disease was equally severe in Luwero district (mean DSI = 40.4%) and Mbarara district (mean DSI = 37.9%). In Tanzania, black Sigatoka was most severe in Kagera region (mean DSI = 29.2%) and least in Mbeya region (mean DSI = 11.5%). Pseudocercospora fijiensis, the most devastating sigatoka pathogen, was detected at altitudes of up to 1877 m a.s.l. This range expansion of P. fijiensis, previously confined to altitudes lower than 1350 m a.s.l. in East Africa, is of concern, especially for smallholder banana farmers growing the susceptible East African Highland bananas (EAHB). Among the banana varieties sampled, the EAHB, FHIA hybrids and Mchare were the most susceptible. Here, the loss of resistance in Yangambi KM5, a banana variety previously resistant to P. fijiensis, is reported for the first time.

中文翻译：

---

引起乌干达和坦桑尼亚香蕉叶病的假尾孢属物种分布

Sigatoka 叶病是香蕉生产的主要制约因素。在坦桑尼亚和乌干达进行了一项调查，以评估 Pseudocercospora 物种的分布和 Sigatoka 叶病的严重程度。使用物种特异性引物鉴定假尾孢属物种。在所有农场和所有品种上都观察到了叶斑病样叶病，但疾病严重程度在国家、国家内部地区/地区、海拔范围和香蕉品种之间存在显着差异（P < 0.001）。在除乞力马扎罗山之外的所有地区，黑斑斑病的病原体斐济紫菜是唯一与斑斑病相关的病原体。Mycosphaerella musae 与乞力马扎罗地区的 Sigatoka 样症状有关。乌干达的黑斑病更严重，平均疾病严重程度指数 (DSI) 为 37.5%，比坦桑尼亚 (DSI = 19.9%)。在乌干达，卢韦罗区（平均 DSI = 40.4%）和姆巴拉拉区（平均 DSI = 37.9%）的黑斑病同样严重。在坦桑尼亚，Kagera 地区的黑斑病最严重（平均 DSI = 29.2%），而 Mbeya 地区最轻（平均 DSI = 11.5%）。Pseudocercospora fijiensis 是最具破坏性的 sigatoka 病原体，在高达 1877 米的海拔高度被检测到易感的东非高地香蕉（EAHB）。在采样的香蕉品种中，EAHB、FHIA 杂种和 Mchare 最易感。在这里，Yangambi KM5 的抗性丧失，以前对 P. fijiensis 有抗性的香蕉品种，