Summer is in full swing and so begins the annual watch for signs of pests and diseases in the garden. Roses are especially susceptible to troubles as temperatures and humidity rises, but rose problems are general easy to manage. The key is early detection and identification.
Looking for help with your rose woes? Read this excerpt from my eBook Garden 101: Growing and Caring for Roses.
What do you think is the most carefree rose? Tell me for a chance to win a copy of Garden 101: Growing and Caring for Roses for your Kindle or to read on your computer. I'll select a winner on Monday July 16, 2012. Read the official rules.
Congratulations to Adele, Susan, Susan O., Cindy M. and Jo S. You gals won a copy of my eBook!. Check your email for confirmation. Thank you to everyone for entering! I especially enjoyed reading the deer tips!
Gardening 101: Growing and Caring for Roses "Common Rose Problems"
Now, some may say that roses are prima donnas that are susceptible to all kinds of maladies. Really, though, roses only have a few problems. The truth is, many of these issues can be prevented with good cultural practices and simple treatments. My best advice is to choose the right rose for your conditions and then make certain that the rose is growing in the right place. Happy roses are healthy roses.
Know the Enemies ...
Admittedly, gardeners aren't the only ones who love roses. Lots of bugs love roses, too. When dealing with insect pests, I like to use methods with low environmental impact. I keep everything orderly to make the garden as inhospitable as possible to these unwelcome guests. I handpick them or use bug traps. On occasion, I'll use a spot spray of insecticidal soap or pyrethrum-based insecticides. A stealth tactic such as using garlic or marigolds in the garden sneakily repels insects, too.
Here are some of my best tips to prevent and control specific pests.
Japanese Beetle: If you see that your rose leaves are skeletonized and the flowers have been eaten, it's a good bet you have Japanese beetles. The beetles have coppery-green wings with five little white "tufts" on their sides. Your best defense is to handpick the adult beetles and drop them in a jar of soapy water. Natural repellents include catnip, chives, garlic and tansy, or you can use an insecticidal soap. If the garden is too overwhelmed with them, try bacterial controls or bug traps.
Aphids: Look for reduced shoot growth and distorted or pale foliage with small insects clustered on stems and shoots. Many natural enemies, such as ladybugs, exist that can eat many of the aphids. A strong jet of water can wash away the colonies from the buds. You can also spray thoroughly with an insecticidal soap.
Sawfly Larvae (Rose Slugs): When upper-leaf surfaces are skeletonized or complete leaves have been devoured with only the midvein remaining, you have rose slugs. If the infestation is manageable, handpick the rose slugs and the affected leaves. If the rose slugs persist, then spray with an insecticidal soap.
Spider Mites: You have mites if the leaves are rough and appear stippled with tiny, light-colored dots. To beat spider mites, you have to be persistent. Make sure you spray under the leaves to be effective, because that's where spider mites live. Spray every seven to 10 days, alternating between a hot-pepper spray and an insecticidal soap. Other pest arsenal options are neem tree oil, BT, garlic insect repellent and pyrethrins.
An Ounce of Prevention ...
Roses are susceptible to a number of fungi such as black spot, powdery mildew, downy mildew and rust. I'd like to alert you to some symptoms so you can be on the lookout. When trouble crops up, you can be ready with a quick solution.
Black Spot: Black spot is your culprit if you see circular to irregularly shaped black spots on the upper surface of the rose leaves or if you find leaf yellowing, leaf drop or canes with raised purple-red blotches that turn black with age. Carefully prune and discard the affected plant parts when the foliage is dry. I like to use a three-in-one spray (fungicide, insecticide and miticide) made with neem oil that also controls insect pests.
Powdery Mildew: Symptoms of this problem include a powdery, white growth covering the leaves' upper surface that can also distort the leaves. Prune to improve air flow around the rose shrub as well as around the surrounding plantings. Once I've trimmed, I'll use neem oil to treat the powdery mildew.
Rust: Orange, powdery spores that are usually confined to the lower-leaf surfaces signal a rust problem. If left untreated, orange-brown spots will appear later in the season on the upper-leaf surfaces, and infected young stems and sepals may become distorted. The best offense is a good defense — so again, avoid crowding and prune your roses and the plantings around them to improve air circulation. When you first see rust pustules on lower-leaf surfaces, apply fungicide at regular intervals. Spray every seven to 10 days, except during extreme heat and drought. Again, I have a lot of success with neem oil.
Thorns or no thorns, many animals will eat a rose bush to the ground. If an animal is hungry enough, it will eat anything. Bird netting is one way to keep out those unwanted garden guests, since many animals shy away from the feel of the plastic. Using the bird netting won't mar the appearance of the landscape either, since it's hard to see from a distance. I've also had luck with liquid repellents, but I have to remember to apply them after every rain.
A Special Note About Keeping Out Deer
Deer are a problem nationwide and I receive questions about deer everywhere I go. Strangely enough, I haven't had any deer problems in my rose beds at the farm. I also realize I may be tempting fate with those words, considering the fact the Retreat is surrounding by woods. There have been plenty of deer sightings, so I know it won't last forever. I have some tricks up my sleeve to deter them, yet I'm mindful that they were here first, so my defensive measures will at the very least keep me in their good graces.
Deer Fence: Deer can jump pretty high, but they don't like to jump across a double barrier. So a fence inside a fence is much more effective than one tall fence. At the farm I'm building two 4-foot fences that are 5 feet apart. The space between the fences will be wide enough for a wheelbarrow or lawn mower to get through, but it will be too far for a deer to jump across.
Deer Netting: Deer netting can be draped over plants or attached to existing fencing. Deer don't like the way it feels on their muzzles so they avoid it and whatever it protects.
Plant Choices: Avoid traditional deer favorites such as rhododendron, azaleas and hostas. Why tempt them with their favorite salad bowl? I also planted daffodils instead of tulips because deer won't eat them. Deer also dislike plants with a pungent fragrance, including marigolds, lavender, boxwood and herbs. Fuzzy foliage plants such as lamb's ear are also not on a deer's menu. Very few plants are actually deer proof, but, it never hurts to try.