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Shrub Fungus

Holly shrub. image by LiteWave from

Shrubs are a common sight in many landscaping projects. Although most species are quite hardy, even the strongest shrubs have the potential of succumbing to fungal diseases. Fungus disease can damage the appearance of your shrub, and may be fatal if not handled properly.


Diagnosis of a fungal disease can be quite difficult as there are many different kinds of fungus. Common symptoms include spotting of the shrub's foliage or needles, discoloration such as a yellowing of the leaves and light mildewy powder on the foliage. Diagnosis from this point can be troublesome, as many fungal infections display similar, if not identical, symptoms.

Common Fungal Diseases

There are, however, common fungal diseases that strike shrubs more often. Root rot is common in some species of shrubs, such as the Lawnson's cypress, and is usually caused by overwatering, poorly draining soil or flooding. This fungus attacks the roots of the shrub, rotting them out and making the shrub unable to absorb nutrients. Vascular wilt also attacks the roots, but the fungus travels up through the vascular system of the shrub, causing the foliage to wilt and die off. Both these common fungal infections are fatal more often than not.


Fungal diseases can be difficult to control, as they spread easily. A fungus travels through the air as spores, which then land on healthy plants and are activated if they are hit with water or moisture. Fungus also travels through the dirt. The common mushroom is the fruit of an underground fungus. If a shrub is susceptible to fungal infection and is planted in soil containing a fungus, it will most likely be attacked.


Prevention is one of the most effective methods of fighting fungal infection. Planting in good, well draining soil will prevent the growth of fungus, which prefers moist environments. New shrubs should never be planted in soil where a serious fungal infection such as root root or vascular wilt was present, unless the new shrub is a resistant variety. Plant resistant shrubs whenever possible.


Spraying of fungicide can control infections and may prevent the spread of fungal infections to the soil. Fungicide use will vary according to the shrub variety and the type of fungal infection. Fungicides are usually sprayed in the Spring, around mid-May, and done again four to eight weeks after to prevent further fungal infection.


If there is any doubt as to the fungal infection variety, collect samples from the shrub and send them to your local University Extension. This service will identify the fungus and give control options.

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