Diseases & Disorders

Helpful advice on what to do when problems strike, whether they're diseases, disorders or otherwise - and how to prevent them occurring


Fungal infection

Phytophthora is our second most reported disease. Causing die-back and leaf damage on trees and shrubs and is often fatal.

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  • Quince leaf blight

    Quince leaf blight

    Quince leaf blight is caused by the fungus Diplocarpon mespili. In wet seasons it can cause severe leaf spotting and premature leaf fall, whilst fruit may also be spotted and distorted.

  • ©RHS SCN0004452

    Raspberry and blackberry aphids

    Several species of sap sucking aphids can suck sap from the leaves, shoot tips and flower stalks of raspberry, blackberry and other hybrid berries.

  • Raspberry cane blight. Image: RHS, Horticultural Science

    Raspberry cane blight

    Raspberry cane blight is a common and serious fungal disease of raspberries, causing extensive die-back of canes.

  • Raspberry rust

    Raspberry rust

    Rust disease on raspberries is a fairly common problem, and can cause concern when high levels of the disease are present. However, whilst it can be a very conspicuous disease, affected plants still usually give a satisfactory yield of fruit.

  • Raspberry spur blight. Image: RHS, Horticultural Science

    Raspberry spur blight

    Raspberry spur blight is a fungal disease of raspberries causing purple patches on canes. It rarely kills raspberries, but can reduce yield severely by weakening the canes and killing buds.

  • Raspberry viruses

    Raspberry viruses

    Maintaining a healthy bed of raspberry plants is often difficult due to their susceptibility to virus infection. Many different viruses can cause a decline in vigour and yield. The symptoms produced by virus infection can be very variable.

  • Red thread. Image: RHS, Horticultural Science

    Red thread

    Red thread is one of the most common fungal patch diseases found on lawns, particularly where the turf is deficient in nitrogen. It causes brown patches of turf, especially during a wet summer.

  • Reversion


    Reversion is the name given when a cultivar known for a particular leaf shape, colour, or other striking characteristic ‘reverts’ back to a different form found in the plant’s parentage. The term is often used to describe a variegated shrub or tree that produces non-variegated shoots.

  • Rhododendron diseases

    Rhododendron diseases

    Rhododendrons (including deciduous azaleas) may be attacked by several diseases, causing unsightly foliage or a lack of flowers. The most significant are powdery mildew and bud blast.

  • ©RHS SCN0006716


    Ring barking or girdling can cause dieback or death of a tree. Damage may result from careless use of machinery close to a tree, excessively tight wire or tree ties or mammals gnawing on the bark, often at the base of the main trunk. Occasionally, girdled trunks or limbs can be saved.

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