Bacterial Leaf Spot

Bacterial Leaf Spot

Disease Description:

As the name implies Bacterial Leaf Spot is caused by a bacteria that finds its way inside a leaf and begins to multiply. It usually gains access through some damage, caused by insects, wind driven debris or physical damage, on the leaf surface.

Symptoms and Damage:

Dark green or brown spots that are sometimes ringed with a yellow halo will appear on health leaf surfaces. As the spots age they dry up and crack leaving tears and holes in the plants leaves. The bacteria sometimes enter from the edge of a damaged leaf which cause the edges to brown and dry up. The leaf will quickly be overtaken by these lesions causing it to yellow and eventually fall.


Plants that are growing in a high humidity location and are crowded together are prime suspects for bacterial infections. Poor air flow also contributes to bacteria growth by allow pathogens to settle on leaf surfaces. Low light levels for plants that like full sun can also encourage bacteria growth. Outdoors it is spread by wind, insects and rain.

Prevention and Control of Bacterial Leaf Spot

There are many benefits to avoiding chemicals when dealing with plant diseases. The harsh chemicals in some fungicides may cause more harm to an already injured plant not to mention the possible harmful effects to you or your loved ones.

First choices for attempting disease control.

Used when green don't solve the issue.

Only use when blue options have failed and the plant cannot be discarded.

Prevention- Preventative measures are the best defense against bacteria. Be sure that plants are receiving the recommended amount of light and moisture. Be sure that there is adequate airflow between plants and any new plants brought into the home are kept quarantined for at least 4 weeks. And remember to practice good plant hygiene by removing dead plant material from the compost near your plants.

Manual- Pruning back the infected areas if the infection is not to severe can eliminate leaf spot.

Organic- Copper based sprays are available but may become less effective with repeated applications.

Biological- A number of different microorganisms exist that increase a plants ability to ward off other diseases, though they may be difficult to obtain for the home gardener.

Chemical- Some commercial fungicides can prove effective though many are unavailable to the average house plant gardener.

More information on Bacterial Leaf Spot:

Defining Bacterial Leaf Spot - http://www.extension.umn.edu/distribution/horticulture/dg1170.html

Natural Leaf Spot Control - http://www.planetnatural.com/site/xdpy/kb/bacterial-leaf-spot.html

Symptoms of Bacterial Leaf Spot PDF- http://www.ent.uga.edu/peach/peachhbk/bacterial/bacterialspot.pdf