|WHEN AND HOW TO PRUNE MATURE ROSES IN TUCSON AND TREAT BLACK SPOT ON SAME.|
|Different types of roses have different pruning requirements, but generally prune in late winter/early spring (in the desert that would be January/February) just before new growth begins. Cut back only about 1/3 of the bush at a time. If you have hybrid teas, here are the basics: Remove the dead and damaged canes as far back as necessary. Then, remove any suckers that arise from below the graft union, if there is one (the
swelling near the base of the plant). Next, select the healthiest canes (thicker and bright green) and cut off the rest. If your roses are just a couple of years old, save about 3-5 canes. Save more on older plants. Lastly, cut the
flowering canes back by one-third to one-half. Make your cuts about 1/4" above an outward-facing bud.
In the low desert, roses are lightly pruned again in mid-September or so to prepare for their second bloom of the year in fall.
Roses for Dummies by Lance Walheim and the NGA is a good reference book that contains illustrations of pruning. Also, rose garden clubs often give pruning demonstrations, which is extremely helpful if you've never done it before. Check for clubs in your area, or contact the address below for a nearby club.
The American Rose Society, PO Box 30,000, Shreveport, LA, 71130-0030, 318/938 5402, 318/938-5405 fax.
Black spot thrives in humid, warm conditions. Sometimes it starts out with yellowing leaves. To determine if you do in fact have black spot, check daily to see if more yellow leaves are appearing and if any have blackened areas. You can prevent black spot from returning by being very careful with watering practices, do not water in the evening, water early in the day so no moisture sits for very long on the foliage. The best way to prevent it is to plant disease resistant varieties, clean up and destroy leaf drop and prunings, which causes reinfection, and use a dormant spray that includes lime sulfur. A dormant spray smothers insect eggs and disease organisms before they get started. Apply the spray right after you prune in late winter. Other remedies include neem oil, and the fungicides triforine.