RHS anticipates an increase in honey fungus and glasshouse thrips this autumn

This summer's extreme temperatures could see a rise in garden plant's vulnerability to common problems, the Royal Horticultural Society has said.

The RHS anticipates that there could be an increase in honey fungus and glasshouse thrips this autumn, as a result of susceptible plants experiencing heat and drought stress.

Honehy fungus, or Armillaria sp can be one of the more aggressive of plant problems, and gardeners are warned to look for symptoms that include clumps of honey-coloured fungus with white spores and white fungal sheets between bark and wood.

Glasshouse thrips, or Heliothrips haemorrhoidalis also thrived over the summer. The sap-sucking insects have previously been able to live only in heated glasshouses, but they increasingly survive outdoors in the south of the UK. The bugs cause silvering of the upper leaf surface of plants including Viburnum and Rhododendron. Thrips can reduce plant vigour and occasionally lead to plant viruses.

Sara Redstone, RHS Biosecurity Lead, said: “Rain may have revived the UK’s gardens in recent weeks but gardeners should be on the lookout for problems that will have been exacerbated by the shock temperatures in summer, increasing stress levels and leaving plants more susceptible.'

In order to avoid plants succumbing to pests and diseases such as these two, the RHS suggests focusing on plant health. Grow in suitable conditions, water young plants less often but more thoroughly during establishment.

Redstone said: “One of the best ways to maintain healthy plants year round is to let nature help in your garden. Try not to over-tidy your garden as we head into autumn – those seed heads, nodding flower heads and fallen leaves and twigs will support a wealth of wildlife including birds and predatory beetles over the next few months that will help keep populations in check before they become a nuisance.

"Avoiding over-crowding of plants and considering the right plant in the right place will also help keep your garden healthy. If you haven’t already got them in place and you have the space, consider installing water butts in preparation for next year to help keep plants replenished in drier spells, and add compost to soils to keep plants nourished and refreshed.”

Here's our piece on how to limit the spread of honey fungus with the help of plants.