Dealing With Vegetable Diseases: Bacteria

| 9/10/2013 9:16:00 AM

Karen NewcombPlant pathologists consider a vegetable to be sick (diseased) when it doesn’t develop or produce normally because it is being attacked by some living organism.

A typical leaf or stem infection has the following appearance: a sunken, brown center is bordered by a tan or yellow area that is surrounded by a pale green border into which the disease is growing. Infected fruit also shows similar color zones. Although leaf and fruit discoloration may occur with insect damage, the discoloration does not appear in definite zones.


Bacteria are typically one-celled plants that swim through every inch of your soil. By estimate, 1 pound of garden soil contains over 2 million bacteria. Fortunately, most bacteria are harmless, and many are beneficial in helping to break down organic matter in the soil. Some, however, kill vegetables or make them inedible. The most visible characteristic of bacterial infections in vegetables is an oozing, gelatinous fluid flowing from the infected area.

You might find any of the following three kinds of bacterial damage in your garden: bacterial spots, soft rots and wilts.

Bacterial spots, or blight, may start as dark green spots or streaks on the leaves and stems, then later turn gray, brown, or reddish-brown, and ooze a gelatinous fluid. The spots may even drop out, leaving ragged holes, and the leaves may wither and die. Scabby or sunken brown spots or blotches caused by bacteria are generally called blights.