How to identify different plant diseases?

Elvis Elvis

There are several different fungal diseases but many have the similar symptoms of a fuzzy mold growth on stem or leaves of the plant. Sometimes the mold will be gray, white or purple, depending on the type. Botrytis mold is gray and you’ll notice that the stems seem to have ‘imploded’ or caved in on themselves, while downy mildew is a white or purple mold that turns black on the undersides of the leaves.

Damping off is a fungal disease that makes your young plants look like they’ve been pinched off at ground level, while rust leaves orange or white spots on leaves and stems, but rarely kills the plant. Powdery mildew causes a white/gray mold on the plant but is similar to rust in that it doesn’t usually kill the plant. It does, however cause poor growth and reduced yields.

How to identify different plant diseases?

Viruses in plants

Some plant diseases are caused by viruses. Mosaic is one such disease. You will notice light green/yellow mottled patches on leaves along with deformed flowers that also have unusual color variations. Ring spot will leave rounded yellow spots on the leaves, while leaf curl makes leaves blister and curl up in a distorted fashion. Viruses are mostly spread by chewing insects like aphids, but they can also be spread be the gardener’s hands or tools.

There is no successful treatment and the only thing is to dispose of the affected plants quickly and disinfect any tools that have come into contact with them. Using lime sulphur spray can contain leaf curl in peaches.

Bacterial disease in plants

If your plant has wilted in double quick time, has tissue that is mushy or slimy or you notice oozing growths on the stem or leaves, you will know that is has a bacterial disease. Discard all affected plants immediately by burning them and disinfect tools to prevent the spread. A good disinfectant can be made using one part bleach to 9 parts of water.