Trying to figure out if I have an soil or fungus issue?
Hello, I have a small garden in my backyard that contains the following plants: - 1 Russian sage - 2 Hybrid Geraniums - 2 Perennial Phlox For a few weeks now, I have noticed that the leaves on the Phlox had white spots on it, then have been turning yellow, then now they're black/brown, and I also noticed the geraniums have black circles on its' leaves, and lastly some brown leaves on the sage as well as some white spots on the stems. I'm trying to figure out if this is an issue with the soil or if there's some type of fungus and I need to apply something to kill it all over the garden. Any advice will be greatly appreciated!
Fortunately, much of what you are seeing is normal for this time of year. The white spots on the Russian sage stems are buds for next year. The brown arc on zonal geranium is usually present all the time and is a normal and common pattern. The phlox has a mild case of powdery mildew; no treatment is needed at this point in the season. Phlox is prone to PM. You can discourage its development by pruning out some stems at ground level. This improves air circulation and sunlight penetration. Try to water at soil level and prevent splashing as this may spread PM. Here is more info on phlox care: https://www.gardeningknowhow.com/ornamental/flowers/phlox/growing-garden-phlox.htm