Black and yellow coloring on the tips of tomato plant leaves can be caused by early or late blight, septoria leaf spot or bacterial canker. These problems occur because of either fungal or bacterial infestations.Continue Reading
Early blight or late blight, both of which cause fungus, can cause tomato leaves to turn yellow and black at the tips. Early blight is characterized by leaves that develop yellow circles that eventually become brown. The leaves eventually drop off, complicating the process for the plant to produce fruit. Late blight can kill the entire plant. It is the fungal infestation that caused the Irish potato famine. The leaves form yellow or green patches that turn into black rot. This occurs later in the growing season and is exacerbated by cool, humid weather.
Another fungal infection that can cause yellowing and blackening of leaves is septoria leaf spot. As the name suggests, this disease appears as small black spots that are ringed with yellow.
Bacterial canker forms yellow bands on the foliage, with black on the edges and tips of the leaves. Plants that have this bacterial infection must be removed immediately in order to prevent the spread to other plants. There is no spray or cure for bacterial canker.Learn more about Outdoor Plants & Flowers