The fungi differ one from another but the symptoms which they cause are very similar. The only reliable method for separating these diseases is laboratory culture and identification of the fungus isolated from diseased plants.
Plants first show a wilted appearance.
Individual branches or even single leaves may be affected at first. Leaves develop a yellow color, often in V-shaped sectors between the major veins. Leaves eventually die and fall. Discoloration or brown streaking is often found in vascular tissues. The fungus can be readily isolated from the diseased stems.