Plant Diseases/grapvine diseased?
Re the attached photo, I've had my Common Grapevine for three years, without problems. This spring, I re-potted it (in peat, and into a 25 gallon tub) and moved it to its final, intended position in a bright and warm, newly built conservatory where it gets more or less constant (if Irish) sun.
It was doing just fine there until about the beginning of August when it should be in its prime (Shouldn't it?) but since when it shows increasing and now serious discolouration. As you can see, the leaves are (from the bottom leaves up and from the leaf edges inwards) losing all their colour. (Actually, the leaves in the picture are some of the better ones, in the earlier stages of discolouration.)
I keep it well watered, and well fertilized with a slow release liquid fertilizer (Miracle Gro Pour & Feed, which all my other plantsseem to love) .
Dear Dan, I am a bit concerned about the soil you are growing this grape in. Perhaps it is TOO rich. I wouldn't grow anything in pure peat. While grapes will grow best with rich soil, it might be good to put a potting mix in with the peat. That being said, I DO know exactly what is wrong with your grape leaves and it should be a very easy fix. This type of leaf discoloration, where the veins remain green and the margins of the leaves turn light green to yellow is known as chlorosis and is caused by lack of iron in a form that the plant can use. This is common in acid loving plants such as gardenia and many others. All you have to do is get some Ironite and apply to the plant. This has chelated iron which is quickly taken up by the plant. It should green your grape up fast. That, and probably repotting it in a mix of the peat and a somewhat sandy potting soil will fix this plant up in no time. The other possible contributor to the chlorosis is waterlogged soil, which is why the soil may be too rich. Make sure that the grape has good drainage, and if you have a saucer under the plant to catch runoff water, NEVER leave the saucer with water in it. I hope this information helps, but please write back if you have further questions. Good luck, Melissa