Exploring Plant Diseases Identification: A Guide (Part 2)

• Powdery Mildew & Downy Mildew

  • Powdery Mildew

    Powdery mildew is a common fungus that affects a wide variety of plants. It is easily identified and appears as light grey or white powdery spots usually found on infected leaves, but can also be found underneath, or on stems, flowers, fruit, or vegetables. The spots spread and will eventually cover most of the leaves on the plant, with new plant growth being the most susceptible.

    Powdery mildew thrives in warm, dry climates; however, it also needs fairly high humidity — like the warm days and cool nights in late spring to early summer. Not enough sunlight and poor air circulation also contribute to conditions that encourage powdery mildew.

    Although rarely fatal, if left unchecked it can eventually cause serious harm to your plants by robbing them of water and nutrients. Most infections cause minor damage such as leaves turning yellow or becoming withered or distorted, but plants can also become weak, bloom less, and grow slower.

  • Tips for Controlling Powdery Mildew

    • 1 - Inspect plants that you buy from a greenhouse before purchasing for mildew (and insects).
    • 2 - Wiping off the leaves is not an effective powdery mildew treatment as it will return within days of cleaning.
    • 3 - Because spores overwinter in debris all infected debris should be removed. Trim and remove infected plant parts.
    • 4 - Do not till the debris into the soil or use it in the compost pile.
    • 5 - Space plants are far enough apart to increase air circulation and reduce humidity.

  • • Downy Mildew

      Downy mildews are a group of closely related pathogenic ‘water molds’ that can cause major damage in the nursery, greenhouse, and landscape in the form of leaf spots, blights, and distortions.

      Downy mildew is a type of oomycetes or water mold. Once considered a fungal disease. There are thousands of different types of water molds, most of which are called downy mildew. Most specialize in a particular species or a group of plants. They are a significant cause of plant pathology.

      It is an obligatory parasite and has to have living plants while going through its life cycle. These plant diseases can devastate a crop and kill most of the plants within a week. It is considered an economically important group of pathogens for that reason.

  • Tips for Downy Mildew Treatment

    • Downy mildew needs water to survive and spread. If there is no water on your leaves, the disease cannot spread. Keep water off leaves as much as possible.

    • Because the disease overwinters on dead plant debris, be sure to clean around your plants in the fall to help prevent the disease in the following spring.

  In the next and final blog of this series, we will discuss Blight & Canker plant diseases, keep following us on social media, and check out our in-house magazine e-crop where we explore more topics on sustainable agriculture and precision farming.