Complex sentence: Major damage occurs on garlic, onion, carrot, alfalfa, oats, strawberry, hyacinth and tulip, but it is estimated that this pathogen infects 400-500 plant species worldwide.
Split into simpler sentences: Major damage occurs on garlic, onion, carrot, alfalfa, oats, and strawberry. It is estimated that this pathogen infects 400-500 plant species worldwide.