Why do succulents easily suffer from diseases when they get rained on in the summer?

During the rainy season, if you haven’t taken preventive measures for your succulents, you may notice that they exhibit symptoms to varying degrees. These symptoms could include black spots, dark dots, and dark stripes, as well as issues like powdery mildew and water-related decay.

Why do succulents tend to develop diseases more easily during the rainy season? There are two main reasons: high temperatures and high humidity. Succulents, especially Echeveria, originate from climates that are generally not very hot and rather dry. They are not well-suited to environments with high temperatures and humidity. On the other hand, certain pathogens such as fungi and bacteria thrive in conditions of high temperature and humidity. This imbalance can lead to the occurrence of various diseases in succulents.

Taking the most commonly occurring fungal diseases due to rain as an example (bacterial or viral diseases are more often transmitted through insect bites that cause wounds, and rain is not their primary mode of transmission, though it can contribute to their spread).



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Fungal diseases are most prone to spreading in moist environments because fungi thrive and reproduce well under wet conditions. Rainwater provides the necessary moisture for the growth of fungal pathogens, which can then be spread to plant surfaces or soil through raindrop splashes. The spores or mycelium of fungal diseases can enter plant tissues through wet surfaces on leaves, leading to infections.

1. Increased Humidity: Rainfall increases the humidity in the air, creating a favorable environment for the reproduction of fungal diseases. Many fungi prefer humid conditions and grow and reproduce rapidly in high humidity environments.

2. Wet Leaves: Rainwater falling on the leaves of succulent plants causes the leaf surfaces to become wet. This moist environment promotes the growth and reproduction of fungal pathogens on the leaf surfaces. Fungal spores can be spread to other leaves or plant parts through rainwater splashes, triggering infections.

3. Pathogens in Rainwater: Rainwater can carry various pathogens such as fungal spores, bacteria, or viruses (especially when splashed from the soil surface or transmitted through other plants). When rainwater contacts leaf surfaces, these pathogens can make contact with or enter the plant’s interior, leading to the occurrence and spread of diseases.

4. Plant Damage: The impact and infiltration of rainwater can cause physical damage to the leaves and stems of plants. These damaged tissues provide entry points for fungal invasion, increasing the risk of infection.

Some fungal diseases that commonly occur after summer rain include black spot, brown rot, rust, powdery mildew, mold diseases, black spot disease, anthracnose, etc. In general, if you notice spots, stripes, rot, or powdery substances that continue to spread, it’s likely that the plant is infected.

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Post time: Aug-25-2023