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Cloud Cover, Wilt Pruf
Biofungicide (Bacillus subtilus)
Serenade Garden Disease Control, Bayer Advanced Natria Disease Control
Bonide All Seasons Horticultural and Dormant Spray Oil, Monterey Horticultural Oil, Summit Year Round Spray Oil
Bayer Advanced Natria Neem Oil, Bonide Neem Oil, Bonide Rose RX 3 in 1, Garden Safe Fungicide 3, Monterey 70% Neem Oil, Southern AG Triple Action Neem Oil
Dr. Earth Final Stop Yard and Garden Insect Killer, Dr. Earth Final Stop Rose and Flower Insect Killer (both in concentrate or ready to use spray)
Monterey Bi-Carb Old Fashioned Fungicide, Organic Labs Organocide Organic Fungicide
Slow Release Fertilizer
Dr. Earth Organic Rose and Flower Fertilizer, E.B. Stone Organics Rose and Flower Food, Osmocote
Several brands at your local nursery
You can grow beautiful roses without insecticides and fungicides that can kill beneficial insects and pollute local creeks, rivers, bays, and the ocean. These tips will help you to protect your family’s health and the environment while you grow strong, healthy roses with glorious blooms.
Do some homework before you choose! Before buying a rose, find out whether it’s a good match for your garden. Learn how much sun the rose needs, how well it will tolerate your garden’s climate, and whether it is prone to diseases such as rust and powdery mildew.
When you buy a new rose, be sure to start with a healthy plant. Either buy bare-root plants (usually sold in December and January), or buy grown-on plants in peat pots. Look for glossy foliage and an evenly moist rootball. Avoid root-bound plants with spindly stems or discolored or spotted leaves. Potted roses can stay in their pots for several months, as long as you give them enough water.
Before you buy, be sure you have a good spot in your garden for your new rose.
It is important to give your roses the right amount of water. Waterlogged soil will kill roses, and drought conditions can stress plants, making them more susceptible to pests and diseases.
Roses prefer slightly acidic soil (pH 6.2 to 6.8) that is not high in salt.
If you are concerned about the quality of your soil, have it tested by a professional lab. The lab will recommend ways to improve your soil so that you don’t need to use a lot of fertilizer. Ask your nursery or garden center to recommend a soil-testing lab, or contact your county agricultural extension office. To find your office, go to http://ucanr.edu/County_Offices/.
Mulching with organic materials, like compost and shredded bark or leaves, helps to keep soil moist, control weeds, and improve soil structure. Mulching also keeps roots cool in summer heat. Mulch can prevent the spread of diseases like black spot by keeping fungus spores in the soil from splashing up onto the plant. Spread a two- to four-inch layer of mulch around each plant. Keep the mulch a few inches away from the trunk.
Careful pruning helps keep roses healthy and prevents disease and pest problems. Pruning allows you to remove dead, spindly, or diseased parts of the plant, shape plants and promote flowering and new growth, and ensure good air circulation to discourage diseases. Use sharp tools so you won’t tear the bark or damage the cane.
Many common pests and diseases that affect roses can be controlled without resorting to chemical pesticides. Inspect plants regularly to detect any diseases or pests before they become a problem. Become familiar with the pests and diseases that are common in your area. Before you treat plants for insect problems, look for beneficial insects (good bugs) such as ladybugs, lacewings, syrphid flies, and orange-and-black soldier beetles. If you see these natural enemies of rose pests in your garden, don’t use an insecticide, because you are likely to kill more beneficial insects than pests. (See Less-toxic Chemical Controls.)
Tiny(1/8”), sucking insects that feed on plant sap. Often found in groups on new shoots and flower buds, especially on over-fertilized plants. May cause leaves to discolor or turn black as sooty mold grows on the honeydew that aphids deposit. Natural predators can reduce aphids’ numbers. Control: Wipe off by hand or spray off with water, prune off infested growth, or spray with insecticidal soap or horticultural oil. Use slow-release fertilizers to prevent growth spurts, as aphids are attracted to tender young plant growth.
Sawfly larvae feed on rose leaves beginning in mid-spring. Look for white spots, which become holes in leaves. Larvae are very small and difficult to see, but you may be able to find them in folded-over leaves. Control: Pick off larvae by hand or spray the plant with a sharp stream of water to dislodge them. If you must use a pesticide, try a plant-based insecticide with garlic extract, and apply it in early morning or at the end of the day so that leaves won’t burn in the hot sun.
Fungal disease that shows as circular black spots with fringed edges on leaves and stems. Leaves may yellow and drop. Optimum conditions for infection: 64°F to 75°F and 95 percent relative humidity, so it is more common near the coast. Spores must be continuously wet for 7 hours for infection to occur. Control: Choose resistant varieties. Strip leaves and/or prune away and destroy infected plant material, increase air circulation, and mulch to prevent spread of spores.
Fungal disease that causes curled leaves and a white or gray powdery coating on leaves, shoots, and flower buds. Optimum conditions for infection: Night temperatures around 61°F and 95 to 99 percent relative humidity; daytime temperatures up to 81°F and 40 to 70 percent relative humidity. Grows well on young leaves and buds. Control: Plant disease-resistant rose varieties, wash leaves in early afternoon with a strong spray, avoid heavy fertilization or heavy pruning that causes spurts of new growth.
Fungal disease that causes orange or yellow spots on any green portion of the plant, showing first on the undersides of leaves. Leaves may drop. Optimum conditions for infection: 64° to 70°F and continuous moisture for 2 to 4 hours. Less likely in areas with cold winters and very hot summers. Control: Choose resistant rose varieties, remove and destroy infected and fallen leaves, mulch to prevent spread of spores, remove and destroy infected shoots (look for dark, corky spots). Use soaker hoses or drip irrigation.
If disease or pest problems can’t be managed by good garden housekeeping, you may want to use a less-toxic pesticide. Because these products prevent but do not cure disease, treatments must begin before symptoms are widespread. To avoid burning leaves and flowers with chemical spray, water plants the day before you treat them and test a few leaves and petals before spraying the whole plant. Be sure to coat both sides of the leaves.