psudan said: Some of my plants look diseased. Could be a virus or something caused by the bugs. I took a bag of leaves showing different characteristics to the Ohio State county extension office yesterday. Some were yellow veined and others were crinkled or had black areas around the edges.
From what I have read, many of the dahlia tubers in circulation have some virus or another. On many plants the virus isn't evident unless the plant is otherwise stressed. I have pulled and tossed several plants that were obviously virused - yellow veining, crinkly leaves and stunted growth are all signs of various virus. The yellow veining one is tricky, as that can also be caused by nutritional issues, but with all of the insects moving from plant to plant, we can be sure the viruses are spreading. There is a concern in the dahlia community about dealers not trying to clean up their stock and selling on tubers from virused plants. But it is not always easy to know when a plant is virused. If the plant isn't showing signs, it doesn't mean it doesn't have a virus, and tubers from that plant may exhibit signs the following year. I have several that I have grown for a few years that always have some yellow veining on the leaves, but otherwise grow normally. I no longer trade on or sell those tubers, but I haven't has the heart to just toss them when they are otherwise looking healthy and making good blooms.
Black wilty edges are from fungus - I have one dahlia that seem really susceptible to it (Juuls Allstar) and get some of it every year. this year I saw it on a number of plants during June when we had so much rain - my experience with that has been to just snip off the offending leaves, and usually it just disappears.
