Roses in desert gardens are still susceptible to pests and diseases, despite the fact that there may be fewer insects and soil-borne plant diseases in the desert.
Pests such as aphids, red spider mites, borers and thrips can still affect damage to your roses, and diseases like powdery mildew, canker, cane blight and crown gall continue to be problems as well.
Aphids. There are two types of aphids which can infest your roses. The first, larger one is green or pinkish. It attacks the growing tips of the plants and the buds. Symptoms include small, off-color roses. Another symptom may be the browning of the whole bud, which will then not open.
The other aphid is smaller and green. This one sucks the juices from the underside of leaves. It also produces honeydew, and may be accompanied by ants, which herd the aphids and feed off the honeydew.
A strong stream of cold water will dislodge both types of aphids and wash them to the ground. This should make them manageable. If they continue to infest your plants, try installing ladybugs (ladybird beetles) in your garden. These are voracious eaters and, if used in sufficient numbers, will devastate the aphids. To read more about aphids, you might try this website.
Red Spider Mites. This arachnid, also known as the two-spotted spider mite, can cause serious damage to your roses. They attack the foliage, and are so small that they are often missed until they’ve done a great deal of damage. (If you suspect spider mites, try a magnifying glass to make sure.)
As with aphids, a strong stream of water will dislodge many and wash them away. This should keep them within a manageable level. If your roses are heavily infested, you may have to resort to chemical controls.
Borers. Several species of borers, particularly the flat-headed apple tree borer, may damage your roses, especially if they are not healthy to begin with. But even the best laid plans gang oft allay. Even if you’ve used good soil, and have fertilized and watered properly, these borers may still get in to damage your plants. However, if your plants have been properly cared for, and are otherwise healthy, borers shouldn’t pose a serious problem. For information on proper care of your plants, see Watering Roses in Your Desert Garden, and Fertilizing Desert Garden Roses.
Thrips. An indication that thrips may infest your roses is the browning of the outer petals of flowers start to brown and die. This is referred to as “blasting.” Thrips tend to be more active in plants that grow in partially-shaded areas rather than those planted in full sun. Control of thrips is difficult, but there are chemicals which can help control them.
Please remember that in any chemical application, make sure that the product is labeled for the specific plants and is designed to kill the insect you want destroyed. Also, read the entire label carefully and follow all directions. If you have a question, either email me or ask the supplier.
Powdery Mildew. In the west and southwest of North America and in other desert areas, powdery mildew is one of the diseases most often found on roses. Climbers are especially susceptible.
Powdery mildew attacks buds, new leaves, and shoots. This will distort new growth. Control of this disease requires spraying of fungicides throughout the growing season. It seems to be most prevalent in late summer and early fall during hot days and cool nights, and among plants in shady and damp areas. Overcrowding plants can also contribute to powdery mildew disease.
Canker. Canker, cane blight and dieback are other diseases that kill many roses in desert gardens. Plants that are particularly susceptible are those that have been wounded by pruning or by freezing in winter. There are a number of bacterial and/or viral causes to these diseases. If your plants are healthy, you are careful in pruning, and give them the proper winter care, they will be less likely to develop or be harmed by these diseases.
Crown Gall. Symptoms of crown gall are swellings on the roots, the main stem or the canes of your plant. This is caused when the plant has been injured by cultivating it. That’s one of the reasons I recommend mulch and weed pulling by hand. Mechanical tilling or hoe cultivation can damage the plant and allow the bacteria entrance. Crown gall also infects other plants, such as apples, grapes, peaches, pecans and many others.
When you purchase a plant inspect it very carefully for swellings or rough galls near the union of the graft or in the crown of the plant. If symptoms like this are present, reject the plant. If you already have a plant in the ground which exhibits these symptoms, discard the plant (not in compost). The soil is also infected, and should lie fallow for at least three years. If you’re uncomfortable with so long a period, remove the soil that surrounded the plant, and put in “clean” soil before you plant anything else there.
See also:
Most homeowners have probably spent hours looking at the different types of garden seeders. You may have even come across…
When it comes to vehicle lovers, cleaning their cars on a regular basis is essential to maintaining the paint job's…
Gas chainsaws are the perfect tool for a variety of outdoor tasks, including chopping up logs for firewood, clearing brush…
A home can be a daunting project, one that takes some time and energy to maintain. With hard work, determination,…
Today ginger is grown all over tropical and subtropical regions in Asia, in parts of Africa and South America, and…
Onions are one of the most popular vegetables in the world, and growing onions is a snap in the home…