Q. I am having a serious problem with my grape vine. It seems to have stopped growing and is losing leaves. I used a lot of bone meal on the plants and I am wondering if I have over fertilized it? The ground is never dry, the flower bed it's planted in is on the same drippers as prior years.
|Readers grape plant. Notice the leaf discoloration in the top|
center of the picture that might be a disease problem.
A. Thanks for sending a good detailed picture. I looked at the picture closely upon magnification which I could do on my computer. Here is what I could determine from the picture and your comments.
I saw some good strong growth from some of the vines, but there appeared to be a fair amount of unproductive wood in the canopy. I am wondering if there is quite a bit of dead wood in that vine.
You reported leaf drop and I could see some scorching in the leaves. This type of leaf damage is common to some grape diseases. The grape bunches looked very healthy so I am guessing that something happened rather quickly to the vine.
|This could be a problem to have grape clusters this exposed|
in our high light intensity desert climate. However, this
exposure faces east so it is not quite so bad.
It is possible it could be diseased if there is a lack of air movement in that location. If that microclimate is higher in humidity it might also cause some leaf problems (disease) that could cause defoliation. This is not the climate for disease problems to florish so I would not be treating for diseases unless humidity and cool temperature persisted or if I saw the chance for diseases to persist from year to year due to the microclimate. In our climate, this type of weather condition does not usually persist and there is enough stored energy in the plant for it to refoliate.
One problem might occur and that is defoliation of the vine and sunburn of the already semi mature bunches of grapes. If grape clusters are exposed to sunlight early when they are small they can accomodate higher light intensities but their is an increased chance of sunburn on the berries when the plant defoliates when the grape berries are this far along.