Downy Mildew Identification Pocket Loupe

A simple pocket magnifier such as this 5-10-15X hand lens can help distinguish downy mildew from other pathogens such as powdery mildew. Downy mildews can lead to plant death and commercial impact on  greenhouse operations especially. “Key factors contributing to the extent of these losses are delayed recognition and misidentification with other foliar diseases.” Catching the infestation early has obvious advantages.

Downy mildews infect the leaves, stems, flowers and fruits of a diverse range of plants. They are single & multi-celled eukaryotic protists whose photosynthetic organelles contain chlorophyll c. Infection by downy mildew disease can also promote the growth of E. coli O157:H7 & Salmonella enterica on lettuce, enteric bacteria that are both known human pathogens

Downy mildew symptoms start as pale-yellow to light green patches on upper leaf surfaces or as irregular, angular lesions. These translucent spots can eventually spread to the an entire leaf, stem, flower or fruit as a downy, gray-white fuzz. This can go unnoticed until severely infected leaves turn brown, shrivel, and drop. Close examination is necessary to confirm the cause as downy mildew.