Pest and disease experts have released guidance on powdery mildew on hardy nursery plants and herbaceous perennials.
Tips from the Horticultural Development Company (HDC) include taking care not to confuse symptoms because the disease can lead to leaf purpling with no clear fungal growth.
Its fact sheet advises growers to minimise long spells of high humidity, avoid overhead watering at night and use wide spacing of plants in full sunlight.
ADAS consultant Tim O'Neill said successful control needed an "integrated strategy" combining varietal selection, good cultural management and selective fungicide use. For crops that are field-grown and then potted, observations in roses indicate a clear link between severe disease in the field and poor establishment after potting," he added.
"Good control of powdery mildew and other foliar diseases for as long as possible before lifting will help maintain plant vigour and reduce establishment failure during containerisation."
The fact sheet on the control of powdery mildew diseases on hardy nursery stock and herbaceous perennials is available from the HDC. To request a copy, please call 0247 669 2051.
TIM BRIERCLIFFE, BUSINESS DEVELOPMENT DIRECTOR, HTA
"Information such as this is critical especially now that growers have fewer pesticides, must use the ones we have more carefully and learn how to use the environment around the crop as well. Tim O'Neill is an expert for the ornamentals sector so the industry couldn't have better information."