August 25, 2014

Disease is an unfortunate fact of life for gardeners. Sadly, many botanical enthusiasts deal unwarranted damage to their plants trying to remove diseases improperly. In order to prevent this, we’ve compiled this helpful catalogue of common plant diseases and their treatments.

Diseases and Symptoms

Blights: One of the most common classes of plant diseases, Blights kill plants by withering leaves, branches, and fruit. Different types of blights need to be treated differently, some of the most common are listed below.

•Fire Blight (Bacterial): Causes wilted, blackened shoots. Common in fruit trees and roses of all varieties.Apples

•Early Blight (Fungal): Characterized by dark, sunken spots on roots, ring-like black spots on leaves. Found in tomatoes, peppers, tubers, and many trees.

•Late Blight (Fungal): Affected plants show watery spots, and white growths on the undersides of the leaves. Found in many decorative flowers, especially those in the Rhododendron family.

•Legume Blight (Bacterial): Common throughout the Southern United States, this deadly blight causes long, oval spots oozing infectious slime to form on the stems of many legume and potato species.

Cankers: Superficially similar to cold injury, cankers are characterized by cracked, oozing sores on shoots or trunks. Frightfully common in hardwoods, vines, and shrubs of all types.

Rots: Any disease which causes decay in roots, stems, or fruit without affecting leaves can be classified as a rot. Unfortunately, rots can affect any plant, but are particularly common in mushrooms and plants with woody stems.

Rusts: A rare, and very distinctive ailment, plant rusts are a specialized fungal infection that leave a strange, rust-like dusting on the plants they affect. They primarily affect cedars, apples, and pines.

Fusarium Wilt: The most common type of wilt, Fusarium can affect almost any species of garden plant in North America. It clogs the system whereby the plant circulates water, causing it to wilt as if dehydrated for no apparent reason.


Once you’ve identified the disease, you can set out treating it. While it might be necessary to use a chemical product to do so, always make sure you have the right disease beforehand, to avoid unnecessary danger to your plants.

•Bacterial Blights: Unfortunately, bacterial blights are difficult to treat. Use the right cultivars, and always remove infected plants from their healthy counterparts. A three year rotation will save your plants from most bacterial blights.

•Fungal Blights: Ensuring good air circulation, growing resistant cultivars, and in emergencies, using healthy transplants can annihilate fungal blights.

•Cankers: Simply cutting away affected branches, and keeping plants strong by limiting pruning can easily get rid of cankers, no chemicals required.

•Rots: Often persistent, rots are best dealt with by keeping the soil well-drained, and planting beneficial fungi where possible.

•Rusts: Most rusts need to grow on two different plant species to survive. To take them out, just move the effected plants further apart.

•Fusarium Wilt: Fusarium can stay in the soil for a long time after even one plant is affected. Never replant in problem areas, and make heavy use of resistant cultivars.