Late blight of potato and tomato caused by Phytophthora infestans is a devastating disease worldwide and led to the Irish potato famine in 1845. Under favorable weather conditions, tomato and potato crops can be destroyed within days if left untreated. Yield losses caused by late blight and the cost of control measures have been estimated to exceed 6.7 billion dollars annually and the disease is a major threat to food security worldwide. Knowing where the disease is present can help improve the efficacy of fungicide treatments.

Phytophthora ramorum is the cause of both Sudden Oak Death (SOD), a forest disease that has resulted in widespread dieback of several tree species in California and Oregon forests, and ramorum blight, which affects the leaves and twigs of numerous other plants in forests and nurseries. SOD has killed millions of trees in the US.

Pseudoperonospora cubensis is a species of water mould known for causing downy mildew on cucurbits such as cantaloupe, cucumber, pumpkin, squash and watermelon. It is a highly damaging pathogen for all of these crops in areas with suitable conditions such as the eastern United States. It has become one of the most important diseases in cucumber production.