In some very humid, wet areas, you may see signs of black spot, which appears as somewhat circular black spots on foliage. Don’t worry. While the plant may drop some leaves, it won’t be detrimental to the overall health of the plant. You can trim out any infected parts, which will allow the plant to put more energy into clean, new growth. Make sure when you water your plants, that you’re watering at the base of them. Watering overhead, with a sprinkler or hose, leaves water on the foliage, which is an invitation for fungal disease. Your plants will be much happier if you water at the base. Also, they prefer a long drink of water every once in a while rather than short, frequent watering.
Powdery mildew can be a common problem of roses and shrubs, particularly when conditions are favorable in spring and fall. Powdery mildew is a fungal disease that appears as a soft, white coating on stems, leaves, and buds of plants. It commonly occurs when there are many overcast days with high humidity and mild temperatures. Generally speaking, powdery mildew becomes less of a problem after the arrival of summer, which typically brings with it long, hot, sunny days. The mildew should go away with improved weather conditions. Here are a few options for correcting the problem:
Rose Rosette Disease (RRD) is spread by a tiny, windblown Eriophyid mite. RRD is a disease that can affect all hybrid roses. Unfortunately, there is currently no known cure for it, but we are working vigorously with other institutions to learn about, research and combat this disease. RRD causes a variety of symptoms ranging from red growth to excessive thorniness, elongated shoots, deformed blooms and pliable canes.
If you believe your roses are infected with RRD, immediately remove the plant and discard of it by containing it in a sealed plastic bag. Do not add the infected plant to your compost bin or yard waste pile, and do not burn the plant, as this can cause the mites to “balloon” upwards and travel to other plants. Once the area is completely cleared of the infected plant debris and all its roots, it is safe to re-plant in that area. Pruning your roses in early spring each year will help to keep RRD from infecting your plants.
Pick each beetle off and drop them into a bucket filled with warm soapy water. Putting a bird feeder nearby may also help. Japanese Beetles won’t be detrimental to the overall health of the plant, so if you can stand them, it’s fine to leave them alone too. You may want to try a product like Milky Spores to control them, but we generally recommend just pulling them off one by one—not fun but effective!
If you’re seeing leaf damage on your roses, this could be from what’s called rose slug or sawfly. Look at the underside of the leaves. Do you see any tiny, green, inchworm-looking critters? Rose slugs will chew the foliage of plants, leaving trails where they’ve munched through. They won’t be detrimental to the overall health of your roses, and it’s not necessary to do anything about them. They typically move on within a few days, so we suggest just leaving them alone.
Many of our roses and shrubs are very tough, so even if bugs get after them, they should be fine. If the bugs are particularly bad in your area, you can use a spray product formulated for your rose or shrub from your local nursery to eliminate them.
Unfortunately, most roses and shrubs are not deer resistant, and as you probably know, when deer are hungry, they’ll munch on anything. Not to worry though, because many of our varieties are re-blooming, so their flowers will not be lost forever if the deer decide to eat them. You may want to try a product like Liquid Fence to keep the deer and other animals away if they are a big nuisance in your area
Traps and poisons are the two most successful methods of controlling voles, mice, squirrels and other rodents that can sometimes damage your plants. If you want to try the organic route, there is a product called Shake-Away Rodent Repellent, which discourages rodents from burrowing into the soil beneath your plants. The product is in a powder form that can be sprinkled around the plants you wish to protect.