Q.Our Knock OUt roses are getting too much water on them, we feel, from a sprinkler system…
The leaves are turning brown and looking somewhat eaten… It looks like possibly from fungus. We reside in a condo complex and do not have any control of the Sprinkler system.. Also the roses are somewhat shaded by a Hydrangea tree.. now…so perhaps not getting enough sun….
I can't speak to your situation but most automatic sprinkles are set for 15 to 30 minutes which delivers only a small amount of water. Try setting out a tuna or a pet food can (straight sides) and measure the water. Roses need a minimum of one inch per week, two in hot, windy or very dry weather. On the other hand, not getting at minimum of 6 hours direct sunlight daily is a problem. The rose will lose vigor and be more susceptible to disease and insect invasion. There seems to be a lot of rose slug damage this year. Look into that as the culprit in the leaf issues. And, of course, it is Japanese beetle time so get out the soapy water bucket and sweep the beetles into it twice daily. They are voracious rose leaf/bud eaters. More on rose slugs follows. You can expect another generation of them to appear in mid to late July. https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-slugs.htm
