Plant Diseases

 

Plant diseases are caused by microscopic pathogens such fungus, oomycetes, bacteria and viruses.  They can spread through the air, through soil, on insects and on contaminated tools.  It is very hard to eradicate diseases once plants become infected.  Prevention is key to keeping your plants healthy.

Make sure your plants are planted high in well drained areas with ample sunlight and airflow.  Use good watering techniques that apply water directly to the soil around the plant keeping the stem and leaves dry.  Rotate plant locations each season.  Get rid of ants.  They protect insects that carry diseases.  Sterilize your pruning tools with bleach or alcohol.

When a plant becomes infected, decide whether it is better to pull it out or try to save it.  If the plant is still young, it is best to remove it and place a new one in another location.  If you plan to save it, try to identify the disease and treatment options.  Remove infected parts if possible. Do not try to save a diseased plant by overwatering or adding additional fertilizer.  This will only cause more problems.

Composting infected plants will likely spread the disease to other parts of the garden.  Compost piles need to maintain a temperature of 150 degrees for 5 days to effectively kill pathogens.

The University of California Integrated Pest Management has extensive information on diseases and ways to treat them.  An index based on plant type can be found at this site: http://ipm.ucanr.edu/PMG/diseases/diseases.vegies.html .

Below are some common diseases and treatment options:

• Powdery Mildew
• Blossom End Rot
• Late Blight
• Cucumber Mosaic Virus
• Fusarium wilt
• Verticillium wilt

Fungicides you may want to consider.

More information on preventing diseases:

https://extension.umn.edu/how/preventing-plant-diseases-garden