I have a number of Box 2 years old in large ceramic pots.The inside of the bushes are turning brown and the leaves dying slowly progressing to the outer leaves.Can anyone offer advice.
Nothing is wrong. Inner leaves die off because the outer ones are blocking all the light. That's fine and normal.
Oldest leaves only is normal, a whole bunch of leaves dying in sufficient quantity to make bushes look gaunt indicates a problem. First suspect is moisture, too much or too little. Both cause excessive shedding of older leaves. If leaf color has been poor (pale) for awhile there is probably a nutrient deficiency, this might also cause them to drop more leaves than usual. With common holly, for instance noticeable yellowing and dropping of inside leaves attributed to a nitrogen deficiency.
Are there spots on the leaves? There is an article in the September 2006 The Plantsman detailing the spread of box blight. Apparently it is spreading rapidly throughout Europe. As of the date of the article there were unconfirmed cases reported in Italy and France as well as confirmed cases in Germany, Belgium, Holland and Ireland. The recommendation is to remove and destroy any badly infected plants. Otherwise, control the blight by removing any diseased wood. Then use the standard measures to prevent fungal growth ---keep the foliage dry and ensure good air circulation.
More info on box blight: http://www.rhs.org.uk/learning/research/projects/cylindrocladium.asp http://www.rhs.org.uk/advice/profiles0801/box_blight.asp Apparently only found on clipped box plants, and particularly plants clipped at the wrong time of year, which weakens the plant: http://shopping.guardian.co.uk/household/story/0,1587,1562110,00.html
