Inorganic salts for suppressing powdery mildew in cucurbits--a worldwide survey

The present review provides an update of recent progress in the use of inorganic salts to manage powdery mildew (Sphaerotheca fuliginea and Erysiphe cichoracearum) in cucurbits (Cucurbitaceae). A literature survey identified 16 salts, mainly bicarbonates (e.g. KHCO3), phosphates (e.g. K2HPO4) and silicates (e.g. Na2SiO3), as having potential to suppress powdery mildew in cucurbits. The percentage suppression compared with untreated controls was calculated from the best treatment of each of 20 peer-reviewed studies and this ranged from 41-99%. The high efficacy of inorganic salts in suppressing cucurbit powdery mildew coupled with the abundance of formulated inorganic salt-based products may enable a reduction in the number of conventional fungicide applications needed to control the disease. Overall, the survey revealed that spray or hydroponic applications of inorganic salts can be a useful component in the integrated management of cucurbit powdery mildew, leading to potential environmental and financial benefits.