Foliage Spots and Cannabis Fungi
Leaf and stems can contract cannabis fungi, including leaf spot that attacks cannabis plant foliage. Spots can show with colors of brown, gray, black, yellow or white spots as well as blotches that develop on leaves and stems, depending on what type of fungi affects the plant.
When infected with fungi, leaves and stems discolor as well as impair plant fluid flow. The growth of fungi will slow plant growth, make harvest prolonged, and in severe cases kill plants.
Fungi disease can be caused by bacteria, fungus, and nematodes. Leaf spots can be caused by cold water that is sprayed on plants while the plant is under the hot sun or HID lights, or temperature stress can cause them to show quicker than if these are not exposed to the plant.
Cleanliness is the best prevention, and using fresh, sterile growing mediums; not reusing old growing mediums will help prevent this. If there is too much light, raise HID lights or place a shade cloth over the plants.
Be sure to not spray your plants with anything earlier than four (4) hours after lights have shut off, as the heat within the leaves can cause damage. Having adequate ventilation and circulation within a grow room or greenhouse can help plants, while also keeping the plants spaced nicely apart.
Be sure to have humidity below 50% and check all times of the day. By using dry heat during the night and raising the temperature 5 – 10° F (3 – 6° C) above daytime heat levels, while keeping the humidity constant.
Be sure to remove all damaged leaves to help the plant and these cannabis fungi problems can be an issue if there is too much nitrogen.
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