Linked from
The 17 pages that link to Plant disease, each with the reason it gives.
MonocultureRelated: Closely spaced, similar host plants can allow infections to spread rapidly.
Plant tissueRelated: Disease symptoms often reveal which tissues have been damaged.
OlericultureRelated: Diseases can reduce vegetable yield, quality, and storage life.
Plant nurseryRelated: Disease prevention is essential when many nursery plants grow close together.
HinokitiolRelated: Hinokitiol has been investigated as a compound for suppressing plant pathogens.