Although diseased cannabis plants can be intimidating, they become manageable once you understand what is happening and learn how to protect your crop.
According to an article on Leafly.com, a leading online cannabis resource, there are three common cannabis plant diseases that you should know about.
Root Rot (Pythium)
Identifying root rot can be done in a number of ways. Hydroponic systems grant visible access to the plants’ roots, so check for roots that are brown in color, slimy, and lack the vigor you see in healthy roots. If you do not have access to the roots, you will notice the infected plants drinking less water, growing at a slower pace, and a myriad of nutrient deficiencies. Root rot is nearly impossible to fix and results in either nutrient-deficient, stunted plants, or having to discard the plants entirely.
Initially, you will find powdery mildew on the lower branches of a plant where there is less sun exposure, airflow, and higher levels of humidity. It appears as a white powder that sits on the surface of the leaves. Once it appears, it spreads rapidly and can quickly make its way onto bud sites. Fortunately, because powdery mildew is so visible, it’s rare for a plant to die from it. The main concern is it renders the product unfit for sale.
Leaf septoria is a harsh-looking disease that shows up first on the lower branches and causes leaves to scab and yellow. It reveals itself during the summer when high temperatures combined with summer rains or moisture from watering leave the foliage damp. Nitrogen deficiencies can also serve as a catalyst to the disease. Although leaf septoria will not kill your plants, it will reduce yields. Once you notice the infection, it’s important to remove and dispose of the leaves. Avoid putting the infected material in your compost pile to prevent future outbreaks. Spraying plants with Bacillus subtilis fungicides can also help slow the spread of the disease.
For tips on how to manage each of these diseases, check out the Leafly article.