Rose Bush Pests

If you are an avid gardener, you know that there are many beneficial insects as well as those that are Rose bush pests. Unfortunately, those that do harm get our attention more readily You must resist the urge to grab a bottle of mega-insect-killer and treat the pests individually, rather than with a scorched earth policy.

Insects are a part of the natural world. As gardeners in general and Rose gardeners in particular, we need to realize that while we can try to control rose bush pests in our gardens, we cannot, nor should we want to, eliminate all insects. Scientists estimate that there are 200 million insects for every human on earth. And all of these insects have a place in the natural cycle, they either eat or are eaten by something, pollinate or otherwise have a symbiotic relationship with other plants or animals, and yes, they sometimes eat what we want them not to.

Major pests of Roses are Japanese beetles, slugs and snails, caterpillars, aphids, mealy bugs, scale and white flies- oh my!

Japanese beetles are a major rose bush pest which have an approximately six week window in July and early August where they are the most destructive. For ways of controlling them, visit our Japanese Beetles web page.

Aphids are tiny greenish to brownish critters that like to suck the life blood out of plants. Fortunately they are easy to see and control by rinsing them off, spraying them with insecticidal soap or controlling them with lady bugs or lacewings.

Cane Borers are the larvae of other insects that like to lay their eggs on the cut end of a rose stem. The borers then eat their way down the stem. Prevention is the easiest way to deter them. Simply coat the freshly cut stem  end when you do your pruning with white glue, fingernail polish, wax, tree wound paint, or anything that will coat the end and make it hard for the insect to lay eggs.

Spider mites are opportunistic pests that thrive in hot, dry conditions. They can be controlled by keeping your Roses watered well in dry periods. Neem oil is an organic pesticide that work  well against spider mites as well as most of the other pests mentioned herein.

Scale sucks. I mean really, they suck the vital juices out of your roses just like aphids. They usually appear on the stems and look like tiny brown bumps. Fortunately they are easily removed with your fingernail. They may also be treated with dormant or agricultural oil as well as insecticidal soaps.

Slugs like to chew on everything. It’s easy to see the damage they cause to leaves and know that it was them by the slimy trail they left. Slugs are nocturnal and like to hide under things such as your mulch during the heat of the day. There are various products, both organic and inorganic, that all have varying levels of success. The one thing that I see over and over again is to keep shallow containers buried at ground level with beer in them. I’ve never had success with this method and it seems like a waste of good beer also. Trapping them under a board seems to work well. Pick up the board during the day and collect those that sought refuge and dispose of them. I usually toss them in the compost pile to let them work for, instead of against me.

Earwigs are more frightening than damaging. They like to hide during the day in the same places that slugs do, so using the same methods of trapping them may help to control them. They eat both live and dead plant material. If you have infestations of them or they are getting into your home, a soil drench with an insecticide labeled for use on them may be the answer.

Thrips are another sucking insect that attack the ready to open blossoms rather than the leaves and stems. Insecticidal soap can have some effect on them, but watching for damaged buds and removing those that don’t seem to want to open and disposing of them is the best control.

Whiteflies and mealy bugs are closely related to aphids, thrips, mealy bugs and scale. They all feed by sucking sap from the affected plant. The control methods are also similar. Whiteflies are, as their name implies, small white flies. Mealy bugs look like little fuzzy white patches, usually on the underside of leaves.

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Rose Diseases

The best way to avoid Rose diseases is to grow strong, healthy plants. By planting your Roses where they get plenty of sunshine, have good soil, sufficient water, and keeping the beds weed free, you will have plants that are better suited to fend off Rose diseases. Planting disease resistant varieties also helps. Notice I said “disease resistant.” Resistance can be bred into plants, but if they aren’t healthy, they can still succumb to disease.

Most fungal Rose diseases attack the foliage which weakens the plant by damaging its ability to gather sunlight which powers the miracle of photosynthesis.

Rust appears as small brownish-orange spots on the undersides of leaves with corresponding yellow spots on the tops.

Plants infected with Black Spot disease are characterized by yellowing leaves with irregular black spots.

Anthracnose infected Roses have dark purple spots on the leaves which turn lighter in the center as the infected area dries out.

Powdery mildew infected plants have leaves that are covered with fine white powder as if dust had been sprinkled on them.

Yellowing leaves, while they can be a symptom of the above diseases, can also be caused by insufficient or irregular watering.

Most of the above symptoms can be treated with organic pesticides that contain sodium bicarbonate, sulfur or neem oil. Prevention of rose diseases is one of those situations where an ounce of prevention is worth a pound of cure. As mentioned above, good cultural practices and housekeeping will go a long way towards having healthy plants that can defend themselves. Regular treatment with fungicidal soaps and products containing the organic remedies listed above will help keep your Roses healthy. There is also some evidence that spraying your Roses with manure or compost tea will help to keep diseases at bay as well as fertilize the plants.

If, despite your best efforts, your roses still get something, be aggressive in your control by removing infected plant parts and disposing of them in the trash- do not compost them. Be sure to clean your pruning shears with a mild bleach solution after trimming diseased plants so that the disease is not transmitted to your other plants.

 

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Types of Roses

There are basic types of Roses into which all the different varieties can be classified.

The most popular type, the Hybrid Tea Rose, is usually grown as a specimen plant in the garden. They have single flowers borne at the end of long stems. It’s for this reason that they are used for cutting, and they are grown commercially for their use in the florist trade.

At the other end of the spectrum is the Miniature Rose. These diminutive varieties are perfect for those who have small spaces or want to grow roses in containers. They also can find a place in your garden as a border plant.

Floribunda Roses have the beautiful large blossoms of the Hybrid Teas, but more of them. The flowers are borne in clusters, rather than one to a stem. These roses make a bold statement when planted in clusters.

The Grandiflora Rose is one of the largest roses growing up to six feet. These tall, stately plants are a cross between the Hybrid Tea and the Floribunda. They bloom throughout the season with clusters of flowers that are a bit smaller than the Hybrid Teas.

There are few garden focal points as elegant as a white arbor adorned with Climbing Roses. These roses have long canes that can be trained to climb an arbor or trellis.

Shrub and Landscape Roses have a low growing habit and lots of blooms all summer long. They come in all shapes, sizes, and colors. They can be used as a ground cover or kept in containers. They grow well in a variety of climates and require little maintenance.

The Tree Rose is a man-made creation that adds special charm to the family of Roses. It is a rose bush grafted to a long stem that is grafted on a hardy root stock. These plants add beauty to a balcony or deck when kept in a container, or they can be used to line a path or drive. Due to the nature of the plant they may need additional protection in areas with harsh winters.

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Growing Roses

Growing roses might seem intimidating to the new gardener thinking of adding some of these gorgeous plants to their landscape. While there are some important items that need attending to when gardening with roses, these are all easily manageable tasks similar to any other perennial plant.

The two most important considerations are location and soil.

Location is usually the most important thing to consider when choosing a site for any perennial plant and roses are no different. Roses need at least four to five hours of direct sunlight daily and should really be planted in an area that has full sunlight (six hours or more). A common mistake that new gardeners make is to plan their garden location in the spring before the trees have all of their leaves. For any planting bed, imagine or remember how the area looked in mid summer when the trees were full.

Proper soil is the next most important consideration when planting. This is especially true when planting perennials that will possibly not be moved for years. An old gardening maxim states that “You don’t plant a ten dollar plant in a five dollar hole.” Proper soil preparation is key to your success. Soil for roses should be loamy, free draining, and have a high organic content. The soil should also be slightly acidic with a pH of 6.0 to 6.5. You can have your soil tested, but doing your own pH testing is easy to do with one of the many soil test kits on the market.

If you are not blessed with deep loamy soils in you yard, don’t despair, most of us aren’t. If you live in the suburbs, the developer probably removed any topsoil before building the development, and this left you with a yard that is mostly clay. If this is the case, you may be better off building raised beds in which you can modify the soil to create a healthy growing environment for your roses.

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