Oedema, that physiological disorder that appears during periods of low light and high humidity.  There’s been quite a bit of it reported in Ontario greenhouses this spring, and unfortunately it’s related to the long rainy (or snowy!) spring we’ve been having.  If you’ve noticed salt-like crystals, odd tumour-like growths or water-soaked spots on either side of your plant leaves this disorder might be the culprit.

The disorder affects a wide variety of greenhouse ornamentals.  It’s usually noticed in spring crops like sweet potato vine (ipomea), geranium, begonia and/or petunia. Continue reading “Oh dear! It’s Oedema.” →