But as you reach down under the prickly zucchini leaves, the newer fruits appear lumpy, strange circular patterns mar the green skin, and the young leaves have an irregular color pattern. If this sounds familiar, your plants may be infected with a virus. Once inside, viruses not only disfigure fruit and foliage, but also stunt growth and reduce yields. Exactly how viruses do this is unclear. But we have learned much about viruses' makeup, how they move among plants, and how gardeners can prevent infection by plant viruses, which is always incurable.
Viruses have minimal equipment.
They are merely a short strand of genetic material with a protein coat. They are too small to be seen, even with a microscope. Yet all plants are susceptible to a long list of viral diseases. All three viruses may be present in the same plant at the same time, and all can significantly reduce yield. All three viruses stunt growth, cause mosaic, and leave fruits deformed and mottled.