Like clockwork, customers are coming into the store with branches of their roses wondering why they are turning yellow and the leaves are falling off. It’s that time of year when roses get blackspot or are attacked by aphids.
Blackspot is very common on roses and very easy to identify. It looks exactly like it sounds. The leaves have blackspots on them surrounded by yellow rings. The entire leaf eventually turns yellow and drops off and if not taken care of will defoliate the plant. The disease can overtake a rose very quickly in wet weather or when it is hot and humid.
The best way to not get this disease on the roses is by taking some preventive measures. When watering your roses try not to wet the foliage. Use a soaker hose around the base. If this is not possible, water them in the morning so the leaves have all day to dry. Keep them pruned properly to keep good air circulation around the plant. Also, when first planting roses, give them proper spacing to help with air circulation. Most roses prefer 3-4 feet between them. If you get attacked, cleanup of the fallen leaves and pruning of infected branches is crucial in preventing spreading of this disease. Start spraying them with a fungicide in early May such as Bonide Fungonil as this will prevent blackspot in being able to attack the plant. Follow with a repeat application every 2-3 weeks over the course of the growing season especially in the hot humid months of the summer.
Aphids are another pest that likes to attack roses. They are tiny insects that are very easy to see as they usually will congregate on the buds or stems. It is very hard for an aphid infestation to kill a healthy rose bush but they can damage flower blooms and for the rose enthusiast they just don’t look good on the plant. If your rose is unhealthy and not taken care of they can do enough damage to kill the plant. Aphids don’t take bites out of the plant. They suck the juices out of it. The byproduct of this is called honeydew which is a sticky sweet sap that attracts dust on the plant called sooty mold. Even though sooty mold can’t hurt the plant it just looks ugly. Honeydew also attracts a lot of ants who eat the honeydew. The easiest way to control aphids is spraying with Bonide Rose RX or release lady bugs in your garden. If you have both blackspot and aphids a combination spray such as Ortho Orthonex will take care of both problems at the same time.
Having a rose is just like being in a high maintenance relationship. With a little TLC and preventive measures you and your rose can have a beautiful friendship together.