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What you see in these pictures is just powdery mildew on roses and on verbenas, it causes a reduction in quality and a lost sale. This potted verbena was worth $10. If you lost 10 of them, that is a $100 in lost sales. Diseases like these bite into your profits, and now is the time to pay attention to this disease.
Baking soda has long been used to manage this type of disease. More recently, products which contain potassium bicarbonate are now registered for management of many fungal diseases, in both Canada and US. In Canada, Milstop is registered for control or suppression of powdery mildew on selected commercial greenhouse vegetables and ornamentals. This product is also acceptable in organic production.
Bicarbonates control fungal diseases by disrupting the potassium balance in the fungal cells, causing the cell walls to collapse.
And, don’t forget another use of potassium bicarbonate. It is used to increase the pH of growing medium in geraniums and any other crop showing acidic pH. The thing to remember is that it should be used alone, not in combination with fertilizers, and it may take up to 3-4 applications to bring pH up to the desired level. |
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