English Laurel Rot

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Posted by Horticulture Guy - Peter Punzi | Posted in Outside U.S. Gardeners | Posted on 29-10-2006

Q. I have a 6-foot laurel hedge, which is about 35 years old. Over the past year, the leaves in various areas of the hedge have suffered from a fungal/mildew problem. On advice from a local gardening specialist, I sprayed the leaves with something they recommended. This temporarily alleviated the problem but over the weekend when I was clearing out the plants around the hedge, I noticed that there were a lot of leaves lying under and along the base of the hedge.  When these were all cleared out, it became apparent that some of the branches at the bottom were rotten through. They didn’t even need to be cut, they just snapped, despite being very thick. It now seems that the stems with this problem are the ones which have all the diseased leaves – hence the randomness of the leaf problem. All growth for about 2 foot from the bottom has now been cleared and the worst of the rotten wood removed. The majority of the hedge is healthy but it now has some gaps! Will the whole hedge die? Given that it is November and the onset of winter, it wasn’t a good time to prune it, but I thought it would be better than leaving it. The base is now clear and air can circulate. I live on a very busy, noisy road so can’t be without my hedge as it provides a vital sound and privacy barrier. Should I take it all out and replace it with the largest replacements I can buy or should I leave it and see if it survives and grows back? Your help/advice would be much appreciated as, due to the time of year, time is of the essence! Charmaine – United Kingdom Many thanks.

A. Although English Laurel (I assume it is English since you are from the UK and probably don’t call it English Laurel there) is quite disease resistant wet conditions can create conditions ripe for bacterial and fungal infections.  In this case it was probably one of the rotting pathogens like Fusarium, Rhizoctonia, or Pythium.  These can attack both roots and stems.  Your instincts were good, as cleaning diseased wood should be done as soon as you find it.  The key is to cut back into clean disease free wood if possible and clean your pruning equipment between each cut to prevent spreading the disease.  These Shrubs are very resilient but you will need to address the air circulation and also determine if the soil stays overly wet which will exacerbate the situation.  I would see how it fares over the winter.  You may see new growth from the root system.  In the future in addition to normal hedging (which concentrates the growth decreasing air circulation) you may also want to do some modest thinning. Let me know how things progress.