What is albugo?



This fungus is quite common on Cruciferae, where the white "blisters" or "white rust," Albugo Candida, form quite conspicuous patches. Affected portions of leaves and stems should be fixed in chromo-acetic acid and cut in paraffin. Sections 5( or less in thickness will be found most satisfactory. Stain in iron-alum and counter-stain lightly with orange.

The white blisters cause little distortion, but are easily recognized by their color; the oogonia do not cause any change in color, but they cause great distortion in the pods or stems, so that these organs may reach several times their normal size. Parts only slightly distorted should be selected, as well as the extreme cases; otherwise, you will secure only old fertilized eggs, with very few of the younger stages. The oosporic phase of Albugo bliti is easily recognized on Amaranthus, especially on A. retroflexus, where the oospores may be seen with the naked eye by holding the leaf up to the light. The oospores usually occur in more or less circular patches upon the leaf. When they occur among the floral structures, there is often a slight reddish coloration. Unfortunately for the collector, it is very seldom that any red coloration in Amaranthus is due to the desired material.

The oosporic stage of Albugo Ipomeae, on the morning-glory, causes extreme distortion of the stem. For sections, it is well to cut out small pieces of the cortex, rather than to fix larger pieces of the stem.





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