What does purple blotch do to onion plants?
Infected leaves are weakened, can be girdled, easily blown over or die. In general, older leaves are more susceptible than younger leaves. However, when plants are infested by onion thrips, younger leaves are more susceptble and, the severity of the disease is much higher when compared to infected plants not infested by onion thrips. In addition to above ground damage, bulbs at harvest or during storage are susceptible to infection. During harvest or storage, the fungus can enter through the neck or via injuries sustained during harvest.