SUMMER ROSE CARE

With the arrival of warm summer temperatures, interest in rose gardening often wanes because the flowers are small, of poor quality and the colors are faded. Proper care at this time will insure attractive foliage and an abundance of flowers throughout next fall and early winter.

Roses are heavy users of nutrients and require regular applications of fertilizer for optimum growth. With new growth in the spring, apply fertilizer at the rate of 2 pounds of 19-5-9 slow-release per 100 square feet of bed area. The soil should be moist before applying fertilizer. Spread the fertilizer over the surface of the bed and work it into the surface of the mulch with light cultivation. Water the bed thoroughly after applying fertilizer. Repeat the fertilizer applications every 6 to 8 weeks.

For optimum growth and flower production, avoid moisture deficiency or over watering. Frequency of watering depends upon the soil type, climatic conditions, the growth stage and development. During periods of drought and high temperature, watering may be needed every 3 to 4 days.

Roses may be irrigated by flood or sprinkler irrigation. If the sprinkler system is used, schedule watering early in the morning to allow the foliage go dry before exposure to the hot sun. This method also helps prevent fungal diseases caused by the foliage remaining wet during the night.

Another important cultural practice with roses is mulching. Using a 2-inch layer of mulching material, such as shredded pine bark, is an excellent cultural practice. It conserves moisture, keeps soil insulated against heat and reduces weed growth.

Undoubtedly the most common topic discussed and cussed about roses is insect and disease control. Here are a few guidelines from the experts.

Black spot is the biggest disease problem of roses. This fungal disease appears on the leaves as circular black spots with fringed edges. The leaves may turn yellow and drop prematurely. Prevent this disease by 1) eliminating excess water on the foliage when irrigating and 2) by regular spraying of an approved fungicide. According to several professional rose growers, Funginex or bayleton (FungAway) are the best fungicides for black spot.

Another rose disease that occurs every year is powdery mildew. This disease appears on young leaves, shoots and buds as a white powdery mass of fungal spores. Powdery mildew is worse when the days are warm and the nights cool. Control immediately after identifying the disease in the spring. Again, most rose growers recommend Funginex or bayleton (FungAway) for effective control.

The two major insects on roses are aphids and thrips. The aphids are tiny insects that cluster on young shoots and flower buds. They have soft bodies and are green, brown or red. Aphids suck the juices of the plant and give it an unthrifty appearance. Several insecticides will control aphids, such as diazinon, Malathion and Orthene. The product Orthene is the most widely used by most rose growers because it is systemic (goes into the plant and provides longer protection).

Thrips are sucking insects that are very tiny, cigar-shaped and cream-colored. The evidence of a thrip infestation is deformed flowers, especially on white varieties. If damage is severe, flower buds may not even open. Break open the deformed flowers and you should find hundreds of tiny thrips having a field day. Orthene insecticide is again the recommendation of most rose growers.

A weekly pesticide spray schedule is essential to control these and other pests in order to produce top quality roses. In consulting some of the best rosarians in San Antonio, they offered this advise. Fertilize your roses monthly and spray thoroughly every ten to twelve days throughout the growing season with a combination spray of Funginex and Orthene.

As always, read the labels of all pesticides you use. Follow the directions to the letter and keep the chemicals away from the children.

For more information about growing roses in Texas, see:

http://aggie-horticulture.tamu.edu/plantanswers/publications/roses/rose.html