I have a problem, my plants have leaves that are yellowing from the bottom with tiny spots; the lowest leaves have started to dry up and brown. Can you help?
Hello, Thanks for your question. Yellow leaves can be due to a lot of things, but the fact that you told me you have little spots (speckling) leads me to think you have an infestation of some sort. Also, the brown and dry leaves are often a symptom of an infestation. The pests are sucking the juice out of the plant leaves. When it gets bad enough your leaves can brown and dry out. The little dots you see are where individual insects have sucked a meal of plant juice.
You should look and see if there is any webbing between the leaves, if so you have spider mites. Look closely, if you have a magnifying lens you can look for small crawly things. You could also have aphids. I have written about both on the blog, please click on the linked words and read my suggestions about how to deal with this problem. There are a lot of products sold by HTGSupply.com, but none are an easy solution. Oftentimes I suggest finishing up your plants then cleaning the room with a 10% bleach or hydrogen peroxide solution. If your grow area is open to the outside, you may want to change this or you may have a recurring problem every time you grow.
Dr. E. R. Myers