Maintaining Beautiful Roses

Few flowers are as beautiful or popular as roses. With careful attention, roses can bloom from early spring through late fall.

Disease control is critical for maintaining healthy roses. Blackspot is the most widespread and damaging disease of roses. The disease causes brown or black circular spots on the leaves.

Usually blackspot appears first on the leaves at the base of each cane. As the disease progresses, the leaves turn yellow and fall to the ground. If blackspot is not controlled, the plant may loose nearly all its leaves by late spring. If severe drought or cold weather conditions further stress blackspot-damaged roses, the plants may die.

Blackspot fungus can survive winter in spots on diseased canes and fallen leaves. It also can be spread by wind or splashing water.

The best way to control blackspot is regular fungicide applications. Among the fungicides that will control blackspot are Danoncil 2787, Funginex rose disease control and Halt 50W.

For effective control, begin fungicide applications shortly after bud break in the spring and continue spraying at seven to 14- day intervals until the first hard frost. During periods of frequent showers, shorten the time between fungicide applications to five to seven days. Be sure to spray both upper and lower leaf surfaces until the fungicide drips from the leaves. Adding 1/2 teaspoon of liquid detergent can help improve effectiveness with wettable powder fungicides such as Halt 50W.

The best time to apply fungicide to roses is early evening. Some fungicides will burn rose petals and leaves if applied on a hot, sunny day. Collecting fallen leaves and adding fresh mulch will also help control disease.

Prune diseased or weakened canes at the bud swell and replace the bark mulch in late winter or early spring.

Plant roses in full sun and space them far enough apart to allow air to circulate. Water roses at the base of the plant. If this is not possible, water plants during the middle of the day so foliage won't be wet as long.

When buying new roses, select black-spot resistant varieties such as Tropicana, Queen Elizabeth, Tiffany and Montezuma. These cultivars will need to be sprayed regularly with a fungicide to maintain plant health and promote flowering. Many antique roses are nearly immune to blackspot. Check with a local nursery to find out which cultivars are right for you. SOURCE: AUSTIN HAGAN, Extension, plant pathologist, Alabama