马铃薯晚疫病

Late blight is caused by the fungal-like oomycete pathogen Phytophthora 5种. 马铃薯是主要寄主，而马铃薯是主要寄主. 5种 also can infect other solanaceous plants, 包括西红柿, 牵牛花和毛龙葵. These infected species can act as source of inoculum to potato.

在北美, late blight survives between seasons in infected seed tubers, 清理垃圾堆和志愿者种植植物. 这种潜在的破坏性疾病可以在作物发育的任何阶段感染马铃薯的叶片和块茎. 了解这种快速破坏性疾病的症状和疾病周期对于实施管理方案是必要的.

图片来源:

Andy Robinson, NDSU/University of Minnesota

图1. Initial symptoms of late blight are small, 浅绿色到深绿色, circular to irregular-shaped water-soaked spots.

The first symptoms of late blight in the field are small, 浅绿色到深绿色, circular to irregular-shaped water-soaked spots (图1). These lesions usually appear first on the lower leaves. 病变通常在叶尖或边缘附近开始发展，那里的露水保留时间最长.

在酷, 潮湿的天气, 这些病变迅速扩大, 深褐色或黑色病灶, 经常出现油腻(图2). Leaf lesions also frequently are surrounded by a yellow chlorotic halo (图3).

图片来源:

Andy Robinson, NDSU/University of Minnesota

图2. Late blight lesions expand rapidly into large, 深褐色或黑色病灶, often
出现油腻.

图片来源:

Andy Robinson, NDSU/University of Minnesota

图3. Leaf lesions frequently are surrounded by a yellow chlorotic halo.

The lesions are not limited by leaflet veins, and as new infections occur and existing infections coalesce, entire leaves can become blighted and killed within just a few days. The lesions also may be present on petioles and stems of the plant (图4).

图片来源:

Andy Robinson, NDSU/University of Minnesota

图4. Late blight lesions may be present on petioles and stems of the plant, especially in new growth where moisture persists.

在活跃生长期间, 尤其是在凉爽的时候, 潮湿的天气, 在病灶边缘(图5)或沿叶柄(图6)可见白色霉变区。. This is the area where the late blight pathogen actively is producing spores. 随着天气变暖变干燥, 这些病变变得干燥, stop sporulating and become tan (图7).

图片来源:

Eugenia Banks, Ontario Ministry of 农业 and Food

图5. 在活跃的晚疫病生长期间, 尤其是在凉爽的时候, 潮湿的天气, a white mildew-appearing area is visible at the edge of the lesions.

图片来源:

尼尔·古德米斯塔德，NDSU

图6. 活跃生长的晚疫病会导致叶柄上出现白色的霉变区域.

图片来源:

尼尔·古德米斯塔德，NDSU

图7. Brown, 干 lesions can develop following warm and 干 weather.

A pale green to yellow border often surrounds the lesions. Severely infected fields often produce a distinct odor.

Late blight infection of tubers is characterized by irregularly shaped, 皮肤上轻微凹陷的区域，大小和颜色从棕色到紫色变化很大(图8)。. These symptoms may be less obvious on russet and red-skinned cultivars.

图片来源:

Eugenia Banks, Ontario Ministry of 农业 and Food

图8. Late blight infection of tubers is characterized by irregularly shaped, slightly
凹陷的区域可以变化很大，从棕色到紫色，大小不一
皮肤.

棕褐色到红棕色, 干, 在变色区域的皮肤下发现粒状腐烂，通常延伸到块茎不到1 / 2英寸(图9)。. The extent of the rotting in a tuber depends on the susceptibility of the cultivar, temperature and length of time after the initial infection.

图片来源:

Andy Robinson, NDSU/University of Minnesota

图9. Late blight causes a tan to reddish-brown, 干, 在变色区域的表皮下发现粒状腐烂，并延伸到块茎中.

The margin of the diseased tissue is not always distinct but can be, 特别是在冷藏温度下储存的马铃薯种子(图10). 然而, 晚疫病感染组织和健康组织之间的边缘常以延伸到块茎健康果肉的棕色指状标志.

图片来源:

弗朗西斯科·比塔拉·莫利纳，NDSU

图10. The margin of the diseased tissue is not always distinct but can be, particularly in seed potatoes that have been stored at cold storage temperatures

Infections of other tuber rot organisms such as soft rot bacteria, 粉红腐病或漏病经常利用晚疫病疫区作为感染场所，其进展往往比晚疫病更快. 使诊断变得困难.

可以通过显微镜检查受感染的叶片或块茎的孢子样来确定晚疫病的阳性鉴定. 非产孢样品的鉴定和晚疫病基因型的鉴定可以通过PCR来完成. 这项服务在NDSU提供.

一些晚疫病基因型已被证明对杀菌剂甲螨灵有抗性. 当晚疫病被证实时, 确定晚疫病基因型对于确保有效的化学处理至关重要. 联系您的本地分机 office for current information on fungicide-resistant late blight genotypes.

P. 5种, 引起晚疫病的原因, 是异苯类真菌样病原体吗, 这意味着有性生殖需要两种交配类型，即A1和A2. 病菌需要活的植物或块茎组织才能在没有卵孢子的野外生存.

然而, in some areas of the world where both mating types of the pathogen are present, a sexual spore that is capable of soil survival is produced. Although soil survival is not known to occur definitively in the U.S., anecdotal evidence indicates that sexual combination has occurred, 这表明土壤存活是可能的.

Infected potato tubers are the primary source of inoculum for P. 5种. 这包括储存中的土豆, 被感染的块茎在收获期间被遗漏，在冬天保持不冷冻(志愿者), 种子块茎和受感染的扑杀堆, 和P. 寄生在其他寄主植物上. 病原菌可从受感染的种块茎传播到新出的马铃薯植株上, where it produces airborne spores that can move to neighboring plants.

晚疫病病菌喜欢自由的水分和凉爽到适中的温度. 夜间温度为华氏50至60度，白天温度为华氏60至70度，最有利于疾病的发展. 雨水中的游离水, 露水灌溉和喷灌都为病原菌的感染和发展提供了必要的水分.

孢子在三到五天内发育，需要12小时的自由湿度才能发生感染. 在感染后的几天内，叶子和茎上的病变会以小斑点的形式出现.

病变扩大到水浸泡, gray-green areas on the leaf and sporulate if conditions are favorable. 孢子被风和雨带到健康的植物上，在那里疾病循环再次开始. A disease cycle can occur every five to seven days, resulting in rapid spread and movement of late blight.

Tubers are infected by spores washed from lesions to the soil. Spores germinate and swim to tubers in free water and infect primarily the eyes. 块茎感染的特征是马铃薯皮上出现褐色到紫色的斑点. Cutting just below 皮肤 reveals a dark, reddish-brown, 干, corky rot.

图片来源:

D. Inglis; Reprinted from Schumann and D’Arcy, 2000

图11. Late blight infected seed often decays, but can move up the seed piece into
阀杆.

有效控制这种疾病需要实施综合疾病管理方法. 晚疫病是一种社区疾病，有效管理需要社区管理. Here are methods to help control the disease:

• 销毁所有被淘汰的土豆和志愿者的土豆.
• 种植晚疫病无种子块茎.
• Do not mix seed lots because cutting can transmit late blight.
• 使用标记为控制晚疫病的种片杀菌剂处理(目前的杀菌剂清单可在北达科他州大田作物植物病害管理指南中找到), PP622). Recommended seed treatments include Revus, Reason and mancozeb.
• 避免种植可能长时间保持潮湿或可能难以喷洒的问题区域(靠近支点中心的田地), 沿着电力线和林木线).
• Avoid excessive and/or nighttime irrigation.
• 消除接种源，如毛茄类杂草和志愿者土豆.
• 定期侦察场地, 特别是在低, 潮湿的地区, 沿着树线, 在支点中心和其他长时间保持湿润的地区，晚疫病可能首先发生.
• Use foliar fungicides on a regular and continuing schedule. 一旦出现晚疫病，只有在田间施用叶面杀菌剂才能控制晚疫病. (A current list of fungicides can be found in the NDSU “Fungicide Guide,” PP622).
• 保持对晚疫病的最新预测. In our region, the NDSU Potato Blightline (http://ndawn.ndsu.nodak.edu/potato-late-blight.html)在生长季节运作，并提供每周晚疫病更新和预测.
• Quickly destroy hot spots of late blight.
• Kill vines completely two to three weeks before harvest. Consider adding a fungicide when vine killing if there is late blight pressure.
• 在马铃薯收获后和堆放前施用磷肥可以防止马铃薯在贮藏过程中感染和晚疫病的蔓延.
• Monitor home garden and market tomatoes near you for late blight. Late blight can move from these local sources to potato fields.

了解更多信息 on this and other topics, see www.ag.sh-fyz.com

NDSU推广服务处不认可商业产品或公司，即使参考商标, 商标或服务名称. NDSU encourages you to use and share this content, but please do so under the conditions of our Creative Commons license. 你可以复制, 分发, transmit and adapt this work as long as you give full attribution, don’t use the work for commercial purposes and share your resulting work similarly. 欲了解更多信息，请访问 www.ag.sh-fyz.com/agcomm/creative-commons.