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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  • Strawberry viruses

    Strawberry viruses

    Several viruses and phytoplasmas (which have characteristics in common with both viruses and bacteria) infect strawberries to cause a wide range of symptoms which result in poor vigour and low yield.

  • Sweet pea leaf with virus. Image: RHS, Horticultural Science

    Sweet pea viruses

    Many viruses affect Lathyrus spp. (sweet peas) causing streaked flowers, mottled leaves, stunted growth and dead patches on leaves.

  • Take-all patch. Image: STRI

    Take-all patch

    Take-all is a fungal disease of lawns, particularly those with a high percentage of fine bentgrasses (Agrostis spp.). It causes brown patches of grass, most often in summer when the turf is under drought stress.

  • Tar spot of maple

    Tar spot of maple

    Tar spot is a very conspicuous fungal leaf spot disease of sycamore and some other maples. Whilst the large leaf spots sometimes cause gardeners concern, they actually do very little damage to the tree.

  • Fly agaric (Amanita muscaria). Credit: RHS/Herbarium.


    There is no standard definition for a toadstool, and no clear distinction between toadstools and mushrooms. Both terms refer to the fruiting bodies produced by fungi. Most of these fungi are harmless or even beneficial to plants, but there are a few that can cause disease problems, such as honey fungus and the fairy ring fungi.

  • Tomato leaf mould

    Tomato leaf mould

    Leaf mould can develop rapidly to cause significant yield loss in greenhouse-grown tomatoes. It is rarely seen on outdoor crops.

  • Tomato plants affected by virus show mosaic patterns on leaves. Image: RHS, Horticultural Science

    Tomato viruses

    Many viruses affect tomatoes causing mosaic patterns on leaves, leaf distortions, stunted growth, bronzing or marbling patterns on the fruit.

  • Blossom end rot of tomato fruit. Credit:RHS/Pathology.

    Tomatoes: fruit ripening problems

    Although easy to grow and very rewarding, tomatoes can suffer from a range of easily preventable problems at the time of ripening.

  • Cracking in tomatoes is caused by fluctuating moisture levels in compost. Image: ©Garden World Images

    Tomatoes: fruit splitting and cracking

    Although easy to grow, tomato fruits can suffer from splitting and cracking in late summer. This is difficult to prevent, as it is caused by fluctuating temperatures and water supply - which are often out of the control of the gardener.

  • Magnesium deficiency shown by the tomato leaves. Credit:RHS/Tim Sandall.

    Tomatoes: leaf problems

    Although easy to grow and very rewarding, tomatoes can suffer from a range of easily preventable leaf problems.

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