How to Save a Rose Bush

Disease

• Roses are susceptible to several diseases, most of them caused by fungal pathogens like black spot and powdery mildew, but bacterial and viral infections are also common. Symptoms of fungal infections include leaf spots, powdery growths, cankers and even bud and flower death. Most fungal infections can be controlled by pruning out infected plant parts, destroying or disposing of plant debris and by pruning and thinning plants to improve airflow and light penetration. One common infection, the rose mosaic virus, causes yellow mottling on leaves. It isn't deadly, but does detract from the plant's appearance. There is no cure for rose mosaic virus; removing infected plants is the only option. The bacterial infection crown gall also has no cure; the only option is to remove plants that show signs of swelling at the roots. These swellings, called galls, disrupt nutrient and water flow and contribute to the decline of the bush.

Pests

• Damage done by pests generally falls into two categories: chewing damage done by larger pests like beetles and caterpillars and sucking damage caused by smaller sap-feeding pests like aphids and mites. It's possible to control large pests by picking them off plants; use gloves and drop the insects into a bucket of bleach water at a concentration of 1 part bleach to 4 parts water. Small pests, like aphids, thrips, mites and midges, cause distorted leaves and flowers as well as fine stippling and discoloration. Insecticidal soaps and horticultural oils are often effective against these small sap-feeding pests. A strong jet of water from the hose is an effective control method for both large and small pests. Smaller pests will be killed by the jet of water, and larger pests are easy to destroy on the ground once they've been knocked off the plant.

Abiotic Problems

• Abiotic problems with roses are caused by environmental conditions as opposed to pests or disease. Nutrient deficiencies like the lack of iron, zinc or nitrogen can cause premature leaf drop and yellowing of leaves. Soil that is too high in nutrients can also cause problems; excesses of salt or boron can cause leaf yellowing and stunted growth. Most county extension offices can help you with information regarding soil testing. Soil testing can help you determine which nutrients you have, which are absent, and their quantities.

  Damage from pesticides and weed killers causes crispy, brown foliage. Limit the use of herbicides around your roses, and use pesticides with caution. Winter injury, caused by excessively cold weather or frequent warming and cooling periods, causes leaves, twigs and buds to die. Sunburn can also cause foliage damage. Sunburned canes and leaves have blackened spots. Mulching can help prevent winter damage and providing your roses with afternoon shade can help prevent sunburn. If sunburn is a persistent problem, transplant your roses to a shadier site.

Rose Care Tips

• Fertilize your roses as soon as they begin to leaf out in the spring. Continue to fertilize after each blooming period, but stop fertilizing about six weeks before the first frost. Mulch heavily in the fall to conserve moisture and prevent root injury. Roses require copious amounts of water for optimal growth. Water deeply and slowly when you water to promote a deep root system, and never allow roses to dry out. If you aren't watering enough, you rose will wilt, leaves will fall off and blooming will stop. Too much water causes the leaves to drop from the bottom of the plant.