Dr. Phyto

forsythia / border forsythia

Forsythia × intermedia

Diseases & pests on this plant

• bacterial blight / canker (multi-host)Pseudomonas syringae pv. syringae

  Brown-black angular leaf spots with yellow halos, blackened buds + young shoots that fail to open, sunken brown cankers on stems with bacterial ooze in spring, blossom blight in cool wet bloom periods, branch dieback in heavy infections.

• grey mould (Botrytis)Botrytis cinerea

  Fuzzy grey mould on leaves and stems.

• Phytophthora root + crown rotPhytophthora cinnamomi

  Sudden wilting + collapse of mature trees during summer heat stress, dark sunken cankers at base of trunk often oozing dark sap, root system rotted away to small white feeder roots only, gradual general decline + sparse foliage 1-3 years before final collapse, characteristic V-shaped soil-line lesion when bark peeled back.

• honey fungus (Armillaria root rot)Armillaria mellea

  Plants decline, leaf out poorly, then whole branches or the whole shrub/tree dies — often suddenly in summer; under the bark at the base and on the roots there is a sheet of white fungal growth that smells strongly of mushroom; flat black "bootlace" rhizomorphs run through the soil; honey-coloured toadstools may appear in clusters at the base in autumn.