Besides insects, how can viruses be spread among plants?

Viruses can spread among plants through several vectors and methods, and the information regarding nematodes and infected plant parts is particularly relevant in this context. Nematodes, which are microscopic, worm-like organisms, can act as carriers of viral pathogens. When they invade a plant root system and feed, they can introduce viruses into the plant. Additionally, infected plant parts, such as cuttings, grafts, or even debris, can serve as a source of virus transmission to healthy plants. This method of spread is significant because it highlights the importance of maintaining plant health and ensuring that propagation practices do not inadvertently transmit viruses.

Other methods, while relevant to plant disease spread, are less directly associated with viral transmission in comparison to the role of nematodes. For example, while water can transport pathogens, it typically serves as a medium for bacteria or fungi rather than directly for viruses. Similarly, while winds may disperse spores of fungal pathogens, they do not effectively carry viruses in the same manner. Soil transfer may involve some bio-organisms, but again, nematodes specifically have a more direct association with viral transmission. Therefore, the role of nematodes and infected plant parts is the most accurate answer in the context of virus spread among plants.