识别与危害Identification & damage
甘蔗叶片出现细长斑点，翻到叶背，又能看到凸起的褐色锈疱。这提示褐锈病，但颜色只能提供线索，确诊还要看病原证据。
Elongated spots may appear on cane leaves, with raised brown pustules underneath. These signs suggest brown rust, but colour is only a clue: diagnosis needs pathogen evidence.
来源与传播Origins & spread
褐锈病由真菌引起；病叶产生的孢子，可以随气流扩散。雨滴也能帮助近距离传播；湿润叶面为后续侵染创造条件。
Brown rust is caused by a fungus; spores produced on diseased leaves can spread in air. Rain splash can move spores locally, while leaf wetness creates conditions for infection.
生活史与微观过程Life cycle & microscopic processes
微观画面里，孢子落在适宜的湿润叶面，萌发并建立侵染。真菌在叶组织中发展，之后形成新的孢子堆，继续释放孢子。褐锈和橙锈可能长得相似，甚至同时出现在一片叶上。需要时送检，结合孢子形态或分子检测，不靠手机滤镜判断。
A spore landing on a suitably wet leaf can germinate and establish infection. The fungus develops in leaf tissue, forms new pustules and releases another crop of spores. Brown and orange rust can look similar and may occur together on the same leaf. When needed, use laboratory spore examination or molecular testing, rather than image colour alone.
田间检查与确认Inspection & confirmation
巡田既看新近展开的叶，也看较老叶，记录品种、叶位和病斑范围。持续比较新病斑和新锈疱，比只拍一张最严重的叶片更有用。预防首先选当地表现可靠的抗病品种，并保留品种和田块记录。避免过量施肥；潮湿天气后加强检查，不把露水当作病原本身。
Scout recently expanded and older leaves; record cultivar, leaf position and affected area. Track new lesions and pustules over time, rather than relying on one severely affected leaf.
预防、治理与复查Prevention, management & follow-up
发现新病斑后，结合病情和当地预警，判断是否需要药剂保护。选当地登记的甘蔗用药，按标签实施；不要等大片叶片坏死再补救。已经坏死的叶组织不会因喷药立刻复原，复查要看新增病斑。把品种、天气、诊断和处理记录放在一起，调整下一轮管理。
Start prevention with locally reliable resistant cultivars and keep cultivar and field records. Avoid excessive fertilisation and intensify scouting after humid weather; dew itself is not the pathogen. After new lesions appear, combine disease observations with local warnings to assess treatment needs. Use locally registered sugarcane products as labelled; do not wait for widespread leaf death. Dead leaf tissue will not immediately recover after spraying; assess newly developing disease. Use cultivar, weather, diagnosis and treatment records together to guide the next management decision.