What are the importance of viruses in agriculture or crops?

Viruses can affect crops just like they would any other organism. Viruses don't usually kill crops but they can infect crops causing damage or reduced output. On the flip side, viruses can be beneficial by attacking bacteria and fungi that would infect the crops. So in essence, viruses can be both good or bad for crops. There's a growing industry that bio-engineers viruses specifically to attack bacteria, fungi and even insects that would attack crops.