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• Recognize Phytophthora
• Phytophthora in tomato
• Phytophthora in pepper

When tomatoes and peppers are affected, soft spots on the trusses of the first bunches occur. These spots turn grey-green to black. Sometimes irregular brown rings are also formed on the fruit. The leaf also discolours blue-green and shrinks. Stains are visible on the petiole and stem.

The species of Phytophthora found particularly in tomato is Phytophthora infestans and is also called potato blight. The fungus causes infestation in several ways. For example, superficial discoloration develops on the stem, cluster and petioles, which can eventually cause the affected parts to die off within just a few days. You can also see that the leaves become discolored and shrivel and that fruits also turn brown and shrivel. The latter is called dry rot.  

In sweet bell pepper the species Phytophthora capsici occurs. This causes a slightly different infestation. Here you mainly see that the stem base turns brown-black, followed by a mild wet rot. The roots of the plant also rot, causing the plants to wilt.

Fighting Phytophthora is difficult because only a small number of crop protection products are available. 

If you have found Phytophthora in the crop, take the following measures:

• Work hygienically to prevent further spread in the crop.
• Remove all affected plant parts and residues from the greenhouse.
• Disinfect the drain water and do not use water that may be contaminated. This is because Phytophthora can also spread through the feed water. 
• Disinfect the greenhouse thoroughly during the crop rotation to prevent the fungus from remaining in the greenhouse. You can use the disinfection protocol for your crop for this purpose.

By taking several measures, you can try to prevent Phytophthora as much as possible:

• If you receive new plants after the crop rotation, check them for Phytophthora. Make sure that you do not plant the infected plants.
• Keep the climate in the greenhouse as dry as possible. Try to avoid high humidity and guttation to minimize condensation.
• If you are spraying against other diseases or pests, make sure you do this as early in the day as possible. In this wat the crop will dry out in the evening, because at night the crop dries less quickly. 
  
  

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