Gardeners must always be alert to any signs of disease in the landscape.  One sick plant can infect surrounding plants, spreading the disease and multiplying the amount of damage caused.  If you’re observant enough to catch a problem early, you can often minimize the harm and protect the rest of your plants from getting sick.  Bacterial leaf spot is a common disease that you may encounter while caring for your flowers and vegetables.  Here are some tips for diagnosing and controlling bacterial leaf spot.

Bacterial leaf spot can attack many different types of plants.  Flowers and vegetables such as geraniums, poinsettias, celery, cucumbers, and others are all susceptible to this disease.  Symptoms vary depending on the afflicted plant.  It may be characterized by flat or sunken spots that start small and increase in size, forming papery translucent areas that are confined by leaf veins.  Spots may also appear on fruit and vegetables.  The disease is caused by the Pseudomonas and Xanthomonas bacteria, which can be harbored in plant debris and survive for months as a potential danger.

Once a plant is infected, there is no effective remedy.  However, it’s important to take immediate steps to stop the bacteria from spreading through the garden.  This means removing and destroying the entire sick plant, including the root system.  Discard the infected material in the garbage.  If you want to compost the material, burn it and put the ashes into the pile.  Bacteria can live in the soil for a long time so it’s a good idea to remove and discard the soil around the sick plant as well.  Sometimes fruit trees and other woody plants can survive a bacterial infection if you prune the infected branches before the disease overtakes the plant.

There are many things you can do to prevent bacterial leaf spot from occurring.  Choose cultivars that are resistant to bacterial disease and make sure plants are healthy before you put them in the ground.  Allow enough space between plants for air to circulate freely.  If you’ve dealt with an outbreak this year, plant something different in that spot next year.

Keep the garden tidy and free of dead plant matter.  Clean up thoroughly at the end of the growing season to get rid of debris that can act as a bacterial breeding ground.

Bacteria will attack the plant through moisture on its leaves or outside surface.  For this reason, you should take special care to water plants without getting the foliage wet.  You may use any method that supplies water to the roots without dampening the stems and leaves.  For example, lay down soaker hoses or use a watering can with a long spout to get water directly to the soil.  Avoid watering from overhead because it can splash up bacteria from the ground.  You should also avoid working with wet plants because bacteria can be easily spread in the process.

Bacteria may also be transferred from one location to another on a dirty shovel.  To keep this from happening, clean your tools in soap and water and rinse with rubbing alcohol, at a minimum.  Soaking tools in a bleach solution for five minutes or using heat to sterilize tools will be even more effective in destroying bacteria.

Because plants that become infected usually can’t be saved, it’s crucial to take preventative measures against bacterial leaf spot.  Avoiding outbreaks of infection is better than trying to repair the situation after multiple plants exhibit sign of disease.  By following these simple tips, you can keep your entire garden healthy and beautiful.