Photo 1. Photo 2. Blisters of cabbage white rust, Albugo candida , on the outer leaves of Chinese cabbage especially top right and bottom left. Photo 3. The pustules have burst and are releasing the powdery spores. On the upper surface the spots are yellow-green.
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Photo 1. Photo 2. Blisters of cabbage white rust, Albugo candida , on the outer leaves of Chinese cabbage especially top right and bottom left. Photo 3. The pustules have burst and are releasing the powdery spores. On the upper surface the spots are yellow-green. Photo 4. The pustules are round at first, smooth, white and shiny. Later, they are powdery after they have burst to release the spores.
Severe infection causes leaves to become distorted and to die early. Albugo candida. There are different strains. Members of the brassica family, e. Albugo ipomoeae-aquatica Ipomoea aquatica and Albugo ipomoeae-panduratae on sweetpotato and many other Ipomoea species, as well as Convolvulus species. The disease starts as small white blisters on the leaves, stems and flower stalks.
The blisters are closed at first and then burst to release powdery spores, similar to the development of rust pustules, hence the name "white rust".
The spores in the pustules are called sporangia, and each sporangia produces several swimming spores called zoospores. After a short time, the zoospores stop swimming, germinate and infect. Another kind of spore forms in brassicas that produce flowers, e. Systemic infection occurs when Albugo grows inside the plant. The flowers are deformed: they swell and produce spiky growths that look like antlers, so they are called "stagheads".
Oospores, which are the result of different strains "mating", are produced inside these stagheads. The oospores are a survival stage, and remain alive in the soil for many years. Oospores are also found in leaf and stem blisters of broccoli and other brassicas.
Albugo survives in soil, plant debris and infected seed. It is spread short distances when spores in the pustules are splashed in water from infected to healthy plants, and also by insects. Albugo is spread over longer distances in infected plant material, including seeds; in addition, spores in the pustules on leaves, stems and flowers, are spread by wind.
Albugo is a water mould or oomycete; it is not a fungus. It is not a rust either, but it has similarities to rust diseases, for instance, those on peanut see Fact Sheet no. It is an important disease of brassicas, but one that does best in cool conditions, with heavy dews.
Leaves can become distorted. In Samoa, the disease is common on Chinese cabbage variety Pak Choy when plants are grown at cooler higher elevations. Look for the white blisters on the underside of the older leaves, leaf stalks, stems and flowers. The blisters are round to oval and smooth at first, and then when they burst they release masses of white powdery spores. Make sure imported seed is from a reputable source.
Note, there are no varieties of broccoli that are resistant to cabbage white rust. South Pacific Commission. This fact sheet is a part of the app Pacific Pests and Pathogens. Photo 5. Pustules of white blister rust, Albugo candida , on leaves of Indian mustard. All rights reserved.
Aecidium candidum Pers. Gray Cystopus candidus Pers. Albugo candida commonly known as white rust , is a species of oomycete in the family Albuginaceae. It is sometimes called a fungus, but in fact forms part of a distinct lineage of fungus-like microorganisms, Oomycetes, commonly known as water moulds.