July 30, 2014


RHS Names Top Garden Diseases of 2013

Box blight enquiries received by charity reach record high

The Royal Horticultural Society (RHS) has named the top 10 garden diseases of 2013, based on enquiries received by the RHS Gardening Advice team. For the 18th year running honey fungus is the number one disease, with its presence confirmed on 215 samples, covering 78 plant genera.

Honey fungus, which is considered the most destructive fungal disease in UK gardens, spreads underground, attacking and killing the roots of perennial plants and then decaying the dead wood. If its presence is confirmed, the only effective remedy is to excavate and destroy the infected root and stump, cutting off the food base on which the rhizomorphs feed.

While it was no shock that honey fungus was the number one problem disease in 2012, perhaps the biggest surprise was the influence the weather had on the list. The mild, wet autumn of 2013 is thought to be behind a record increase in Cylindrocladium (4th) and Volutella (5th) box blight cases, with enquiries for both diseases reaching their highest levels since the RHS began keeping detailed digital records in 1996. As in 2012, leaf spots and Pythium occupied the 2nd and 3rd spots in the list.

Rusts (8th) were less common in 2013, with enquiries falling more than 50% on the 2012 figure, which means it slipped four places down the list from a high of 4th in 2012. This was mainly because heuchera rust was less common in nurseries in 2013, while the dry summer restricted the spread of the damp-loving disease that thrived in the very wet summer of 2012.

RHS Chief Scientist Dr John David says: “The high rainfall levels we experienced in 2013 provided the perfect conditions for certain diseases to thrive, most notably Cylindrocladium and Volutella box blight. Should our weather continue to be marked by extreme events, whether that’s extreme wet or warmth, we could see an increase in these types of disease.

“Through our daily interaction with RHS members, via our Gardening Advice and diagnostic services, we are at the forefront of the fight both to identify and advise on the most effective way for gardeners to limit the impact of diseases.”



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