Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: kierae0608 on 21/12/2011 11:43:49
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When i was pruning my holly bush for a wreath, I noticed that about 60% of the leaves had black spots on them , Does anyone know what this is and how i can stop it spreading to whats left of my bush. ?
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Sounds like you have Holly Tar Spot.
This can be caused by a number of fungal infections. Leaves will become covered in brownish or black spots and will eventually drop off. The leaf drop usually begins at the bottom of the plant and works its way up.
If caught early, use of a fungicide will cure the problem, but it sounds like it is too late for this remedy in your case.
You will need to remove the infected leaves and clear away any dropped leaves. Infected leaves around the base of the plant will pass on the infection to the remainder of the plant.
If this is going to prove to be too much of a task, as it may well be, you could remove the infected lower branches. However, this is going to leave you with a very sorry looking bush and you may find it necessary to prune the whole bush back very hard. Don't do this when there is the risk of frost, wait until the risk is passed in the early spring, then prune hard. Depending on the size/age of your bush, you may be lucky and find fresh growth in late spring. A large older plant may not survive hard pruning.
Once Holly Tar Spot has taken hold, fungicides are of little or no use, so keep an eye on the new growth. Ensure you have cleared away any trace of infected leaf from around the ground and treat with a fungicide immediately if you see any signs of the return of the problem.
To avoid Holly Tar Spot, don't allow your bush to become too wet. Avoid watering in the early morning and late evening and ensure a good airflow around the whole plant.