Viruses

Plant-pathogenic viruses differ from microorganisms such as fungi, bacteria, and yeasts. They are much smaller and do not have their own metabolism. Therefore, they depend on host plants and their cells: These are reprogrammed so that the plant cells become production factories for new viruses.

This causes the plant to suffer; it grows weaker, produces less, and may ultimately die as a result. The resulting significant decline in the quality and quantity of the harvest has major economic implications.

There is virtually no treatment. In horticulture, resistant varieties are used, and the spread is prevented through hygiene measures. Well-known examples include CGMMV, ToBRFV, and the tobacco mosaic virus (TMV). Viroids have an even simpler structure than viruses, yet they can still cause massive damage.