Rose Problems and Solutions
I'm a diehard devotee of roses. I don't think a garden can have too many. Now, some may say that roses are divas that are susceptible to all kinds of maladies but really there are only a few common problems. These issues can be prevented with good cultural practices and simple treatments.
To ensure success get to know a rose before planting it in your garden. Roses have different personalities; some are actually quite carefree while others are confirmed trouble makers. Find out which roses will perform best in the particular conditions of your garden and select proven, disease-resistant varieties.
For the general health of roses, plant them in a spot that receives at least 8 hours of sun each day with good air circulation. This will promote good bloom and cut down on diseases. Prune roses in early spring before the leaves emerge, even if all you do is cut out dead branches. Get in the habit of feeding roses after every bloom cycle and make sure they have consistent moisture.
Common Rose Ailments
Gardeners aren't the only ones who love roses. There are a number of insects that love roses too. When dealing with insect pests I like to use methods with low environmental impact. I keep everything tidy to make the garden inhospitable, hand pick or trap bugs and spot spray insecticidal soap and pyrethrum-based insecticides. Rose bedfellows such as garlic and alliums will repel insects from the area. There are also steps to prevent and control specific pests.
Look for coppery-green wings with 5 little white "tufts" on each side. Japanese beetles will eat both flowers and foliage. Cut buds before they open to use in bouquets. Do this just as they start to show color. This will reduce the number of beetles attracted to the plant and you will be able to enjoy the blooms before the beetles do. Check your garden for Japanese beetle grubs. Treat with milky spore disease if their numbers are high.
Sawfly Larvae (Rose Slugs)
Look for caterpillars that "skeletonize" rose foliage. Start checking for them in May. They are most commonly found on the undersides of leaves. Hand-pick and spray with insecticidal soap.
Look for clusters of tiny translucent bugs on stems, buds and foliage. Aphids are green, black, orange or woolly. Damage includes weakened plants with stunted growth, deformed, yellowing leaves and/or defoliation. You can knock out an infestation by spraying the colony with strong jets of water or try saturating the plant with an insecticidal soap.
No see-ums that can be detected by the damage they cause. Look for leaves that are rough and appear stippled with tiny, light colored dots. To beat spider mites you have to be consistent. Spray every 7 to 10 days, alternating between a hot pepper spray and an insecticidal soap. Other options are neem tree oil, BT, garlic insect repellent, and pyrethrins.
Bad Hair Cut
I receive a lot of questions about repairing a rose that has been accidentally pruned by a line trimmer, animal, or overzealous "garden helper." About all you can do is clean up the cuts to removed ragged ends and then say a little prayer. Use sharp, clean pruners and make your cuts just above outward facing leaflets or leaf buds. Most roses are pretty resilient and will grow back. If it's a grafted rose like a hybrid tea and has been cut to the ground, it might grow back from the root stock, which means it will be completely different than what you planted.
Fungus Among Us
Roses are susceptible to a number of fungi such as blackspot, powdery mildew, downy mildew and rust. This is where getting to know a rose comes in handy. Unless you just like a challenge, plant roses that are disease resistant. To prevent fungi, spray roses with a fungicide in early spring right after you prune them. Soak the plant and the surrounding ground. Dispose of all plant debris in the trash after pruning and when you clean up the garden in fall. This will keep fungus spores from wintering over. Fungi thrive on moist leaves so water in the morning so leaves can dry quickly. Use soaker hoses or a low sprinkler to keep water off of leaves. Start treating fungi as soon as they appear and be vigilant. Spray every 7 to 10 days, except during periods of extreme heat and drought. I use a three-in-one spray made with neem oil that also controls insect pests.
One would think the thorns might be a deterrent, but many animals will eat a rose bush to the ground. If an animal is hungry enough it will eat anything. One way to keep out critters is with bird netting. Many animals will shy away from the feel of the netting. Plus it's hard to see from a distance, so it won't mar the landscape. I've also had luck with liquid repellents. I just have to remember to apply them after every rain.