There are mold fungicides and lawn fungicide and one can’t be substituted for the other. There are different types of fungicide to deal with different forms of fungus. “The biggest problem I encountered was with the Phlox I planted,” Dan wrote. A study found that “a one percent neem oil treatment was effective in managing powdery mildew on hydrangeas, lilacs and phlox. That doesn’t mean its safe for all situations. So I will try to keep it updated for you. Tips to Prevent Fungus. Once a determination is made that a fungicide is needed, when to use fungicide on your plants depends on the type of fungus. 12-hr reentry. It usually doesn't kill plants, but it can weaken them and lead to poor growth and yield. Using it appropriately is important. Compass 50 WDG at 1 to 2 oz/100 gal water. 4-hr reentry. Keeping your plants healthy will help minimize damage, but sometimes you need the aid of a fungicide. Using copper fungicides is confusing, but knowing exactly when to use copper fungicide is the key to success. Copper fungicides are often the first line of defense, especially for gardeners who prefer to avoid chemical fungicides. 12-hr reentry. Copper’s a strong fungicide. When I first spotted it, I did some research and decided to use an organic fungicide. It is less effective as a cure once the fungus has taken hold. Group 11 fungicide. Copper’s an OMRI-listed organic fungicide. 24-hr reentry. Group 7 + 11 fungicide. Powdery mildew refers to a group of fungal diseases that all show up as a powdery white coating on plants, especially when humidity is high. “The leaves developed a terrible fungus and it slowed its growth terribly. Group 11 fungicide. 11/3/2020 – I wrote this post over ten years ago, but it still remains popular. Fungal diseases can be a real problem for gardeners, especially when the weather is warmer and wetter than usual. Organic Fungicide Treatments. Group 3 fungicide. Types of Fungicide. Heritage at 1 to 4 oz/100 gal water plus a non-silicone-based wetter sticker. If you don’t want a do-it-yourself solution, there is a variety of commercial treatment options that are just as environmentally friendly and approved for organic gardening. 7/6/2010 – Last week on the N.C. If you know a plant is affected by powdery mildew year after year, as is the case with many monarda, phlox, and lilacs, then spraying early in the season may prevent any occurrence that year. By going this route, you also know exactly what types of pests the treatment will kill and which types of plants it’s most helpful for. ” However, a horticultural oil spray generally works better for powdery mildew control and a bicarbonate solution works even better – see: Baking Soda, a Home Remedy Fungicide – the Cornell Formula. When you can, you should always try to avoid getting fungus in the first place so you don’t have to turn to the big guns. That worked alright, but the fungus came back. They can’t cure the problems. Eagle 20 EW at 6 to 12 fl oz/100 gal water. Cooperative Extension Horticulture Agents listserv, there was a discussion about homemade fungicides and whether extension agents should recommend them or not. Do not use organosilicate additives. Water.