Tomato farmers often notice spots of various shapes and sizes on tomato fruits and leaves in the open field or inside greenhouses. These spots increase in size and number when the weather is humid and moderately warm. It is a sign that these plants need your help.
To find out how to keep tomatoes healthy, you need to identify the problem of the plant. Therefore, you need to scrutinize the spots on tomato leaves in your farm.
The first and most common possibility is that these spots are caused by increased exposure to sunlight (leaf scorch) and using pesticides or fertilizers at the wrong time. In this case, the spots will disappear on their own after a few days. If they don’t disappear or increase in number and size, it is time to take appropriate action and determine the cause so that we know how to treat it.
First, there’s no need to panic. Second, read the following text and start solving the problem.
The main cause of spots on tomato fruits and leaves is bacteria. There are at least seven types of bacteria that cause spotting, the most important of which are:
Bacterial canker of tomato (Clavibacter michiganensis subsp. michiganensis)
Pathogen: Bacteria responsible for bacterial canker which causes white spots on leaflets, with symptoms similar to a bird’s eye. This disease causes much larger damage of a different nature.
This bacterium enters through the stomata where the initial infection starts and then extends to the surrounding tissues.
Symptoms of the disease:
- Edges of leaf turn brown.
- Vascular discoloration, yellow and then brown, and the presence of a sticky fluid.
- White spots with brown centers on the fruit (bird-eye spot).
Family: Nightshades: Tomatoes, eggplant, capsicum, and potatoes.
Symptoms of the disease: Moderately warm temperature and high humidity, fast-growing tomatoes are infected more than slow-growing tomatoes.
This disease is widely spread in Turkey, Iran, and the United States.
Transmission conditions: Mainly seed-borne.
Economic importance: Losses range from 50% to 90% of the crop if the disease is not controlled early.
Disease management:
- The use of healthy seeds is the first and most important condition for disease control.
- It’s preferred to use seeds that have been soaked in an acid solution (such as sulfuric acid) or Novo Safe.
- Significant reduction in infection can be achieved by chemical seed treatment.
- Once the disease appears in the crop, stringent health measures, such as destroying infected plants and isolating infected rows, can reduce crop yield loss.
- Preventive measures (destruction of residues from the previous crop, sterilization and disinfection of greenhouses and equipment) are necessary to prevent protected crops from becoming infected.
Resistant varieties are available but have not yet been largely incorporated into commercial varieties.