What causes white leaf spots on trees?
Pseudocercosporella capsellae causes white leaf spot across a wide range of brassica plants including oilseed, vegetable condiment and forage brassicas worldwide. P. capsellae produces a purple-pink colored toxin called cercosporin, which have been implicated in white leaf spot disease initiation in brassica crops. P. capsellae may be carried across seasons within thick-walled mycelium on crop debris and produces conidia when the weather is favorable. Conidia infect plants causing white or pale beige lesions on leaves. Infections are favored by wet weather conditions.
Several GSL-derived ITCs induce stomatal closure in A. thaliana in a dose-dependent manner. More so, rapid stomatal closure occurs in resistant B. carinata following recognition of pathogen presence, a characteristic considered a winning pre-invasive defense barrier developed by plants. By limitation potential entry ports by resistant B. carinata, this appears to be a major mechanism of resistance against P. capsellae. Hence, efforts geared at elucidating the phytochemicals associated with this structural-resistant response may characterize future research.