Root rot’s been a scourge this summer

A FEW years ago garden designer Carol Gallagher-McCulloch stood in her show garden at Gardening Scotland and explained to visitors that the beautiful pink-flowered rhododendrons she’d planted alongside hydrangeas, weren’t rhododendrons at all, but their close cousin Kalmia latifolia, otherwise known as the Calico bush.

Considering that these ultrahardy evergreens (left) are so easy to grow it seems incredible they aren’t better known.

They’re the ultimate low-maintenance plant — growing slowly, flowering reliably, suited to almost any position and free from most pests and diseases.

However this year I’ve heard that some kalmias have been dying off and, according to the European Kalmia Society, phytopthora root rot may be the problem.

This fungal disease flourishes in precisely the sort of wet conditions that we endured for most of last year and it is closely associated with potato blight, which was also prevalent.

There are no chemical controls to tackle the problem so the only solution is to remove not just affected plants but the soil they were growing in.

You must also watch closely for signs of other plants including cherry trees, acers and rhododendrons showing similar symptoms.

Improving soil drainage is also important as phytopthora spores love waterlogged conditions.