Rose Care

Credit: Clemson University

Rose rust is a disease caused by the fungi Phragmidium species. It causes orange-colored spots to appear on stems and leaves. When rust is severe, an orange dust-like substance may be present on the plant surface and on the ground below the plant. Rose rust attacks all plant parts except the roots and petals. Severely diseased leaves of highly susceptible cultivars may turn yellow or brown and drop.

Prevention and Treatment: Provide good air circulation. Do not plant roses in crowded areas and prune plants to keep the centers open. Water plants before noon and avoid getting the leaves wet. Remove and destroy diseased leaves and plants. Fungicides containing either ferbam, mancozeb, propiconazole or lime sulfur are recommended for homeowner use. Apply all chemicals according to directions on the label.

Mancozeb 37.0%

A broad spectrum fungicide for use on a wide variety of vegetables and ornamentals. Controls leaf spot, downy mildew, blights, anthracnose, botrytis and other listed diseases. Use 2-5 teaspoons/g. Restricted in ME. Not for sale in NYS.

• Label
• MSDS

Bayer Advanced™ Disease Control for Roses, Flowers & Shrubs Concentrate

This product provides 3-way action: it kills existing fungi, forms a protective barrier on the outside of the plant and is absorbed into the plant to keep on protecting regardless of weather conditions.

• Label

Clearys 336

Bayer Advanced™ Disease Control for Roses, Flowers & Shrubs Concentrate

This product provides 3-way action: it kills existing fungi, forms a protective barrier on the outside of the plant and is absorbed into the plant to keep on protecting regardless of weather conditions.

• Label

Verticillium Wilt

Verticillium wilt is caused by the soil-borne fungus Verticillium albo-atrum. The disease becomes evident when temperatures are hot (late June to August). Initial symptoms begin with the wilting of new leaves and yellowing of older leaves. Permanent wilting occurs after a few days and leaves eventually turn brown and die. This disease can be confused with other problems such as insect infestations or environmentally related causes. Make sure Verticillium wilt is positively identified by an appropriate plant disease clinic before following control measures. To control the disease, remove and destroy infected plants. Because the fungus responsible for the disease survives in the soil, do not plant roses in contaminated soil for three years or longer.

Clearys 336

BOTRYTIS BLIGHT

Rose petals infected with Botrytis blight.

Rose flowers and buds are often infected with the gray-brown fuzzy growth of the gray mold fungus Botrytis cinerea. The fungus is most active when temperatures are 62 to 72 °F and conditions are moist. Infected canes have discolored, sunken areas (cankers) and dieback that can extend down the stem from the flowers. Diseased flower petals have small, light-colored spots surrounded by reddish halos, which can quickly expand into large, irregular blotches. Buds fail to open and often droop. Thrips can cause similar damage to half-open buds, so inspect plants carefully.

Prevention and Treatment: Keeping the area clean is more important than anything else. Collect and discard all fading flower blossoms and leaves. Provide good air circulation, and avoid wetting the leaves when watering. Disease easily develops on canes that have been damaged and canes that are kept too wet by a manure mulch or wet leaves. If chemical control is necessary, fungicides containing captan, chlorothalonil or neem oil (clarified hydrophobic extract) are available for homeowner use. Use neem oil on a trial basis, especially on open blooms and during hot weather. On dormant bushes PCNB or copper sulfate pentahydrate can be used. Apply all chemicals according to directions on the label.

Neem Oil A broad spectrum insecticide, miticide, and fungicide that controls numerous diseases as well as insects. Use on vegetables, fruit trees, ornamentals, etc. A naturally occurring compound made from the neem tree that is grown in India.

Bayer Advanced™ Disease Control for Roses, Flowers & Shrubs Concentrate

This product provides 3-way action: it kills existing fungi, forms a protective barrier on the outside of the plant and is absorbed into the plant to keep on protecting regardless of weather conditions.

• Label

Rose mosaic virus

Clemson University

Clemson University Extension Fact Sheet, Rose Diseases

The symptoms associated with Rose mosaic virus (RMV) are highly variable. Yellow wavy line patterns, ring spots and mottles in leaves will occur on some varieties of roses sometime during the growing season. In general, symptoms are most evident in the spring. Yellow net and mosaic symptoms on the leaves are also associated with RMV and detract from the overall quality of the plant. Infected plants become weakened and are more sensitive to damage caused by other stresses, such as drought or low temperatures.

Prevention and Treatment: Virus-infected plants cannot be saved. Rose mosaic spreads slowly, if at all, in established rose plantings through root grafts. Infected plants should be removed from highly prized plantings and destroyed. Buy only healthy plants from a reputable dealer; especially avoid purchasing plants showing any mosaic symptoms.

Unlike blackspot, wet conditions actually inhibit the development of powdery mildew. It can not reproduce in water. It thrives during high humidity but forms on dry leaves. Warm dry days, cool dry nights are ideal for powdery mildew.

One of the best ways to avoid powdery mildew is to keep things as airy as possible. Roses planted too close to a wall may not get enough airflow. Prune away crossing canes and open the center of the bush to allow sunlight and airflow.

Bayer Advanced™ Disease Control for Roses, Flowers & Shrubs Concentrate

This product provides 3-way action: it kills existing fungi, forms a protective barrier on the outside of the plant and is absorbed into the plant to keep on protecting regardless of weather conditions.

• Label

Also, spraying the foliage with a mixture of 1 T. baking soda per 1 gallon of water can be effective.

Bill Chandler

Aphids has a close working relationship with ants. TalstarOne is the best choice for this insect problem and many more.

Talstar
(This is a great product for insect control).

You can also use Generic brand Bifen and save money. It has the same ingredient as Talstar One.





Thrips

Flower thrips are almost microscopic insects, only a 16th of an inch long, whose larvae, or caterpillar stage, bore into the unopened rose flower, damaged the petals, and then lap up the juices. The result is misshapen, brown stained petals, or like this one, a water marked petal, or one with holes in it. Sometimes the flower buds don't open. I've seen flower thrips in daylilies too. The best way to control is by using Delta Dust. Growing a good rose demands a good deal of effort and even hard work on your part.

1-Control the thrips then follow these rose care tips to bring the plants back into bloom 2-Remove all damaged or declining flowers..

3-Apply monthly feedings of a rose fertilizer or use a slow release product as instructed on the label.

4-Ensure adequate moisture by watering when the surface inch begins to dry to the touch.

5-Control black spot a disease with fungicides as needed

DeltaDust is the world’s first and only 100% waterproof insecticide dust, so it works in the wet and damp places that insects love. Nothing short of running water will disturb it, making DeltaDust an ideal crack and crevice treatment.

You can also use Generic brand Bifen and save money. It has the same ingredient as Talstar One.

Organic Insect Control

Life History -Rose chafers appear in late May or early June and feed on roses, peonies, and sometimes iris and other flowers. They also feed on grapes and at times may damage elms, birches, and other trees severely. The adults live for about 4 to 6 weeks. Eggs are laid about 15 cm deep in sandy or grassland soil, and they hatch in 1 to 3 weeks. The eggs are laid in groups of 6 to 40, but each egg is deposited in a separate cavity. The larvae feed on the roots of turf and ornamental plants. They apparently move down into the soil for moisture. The larvae spend the winter deep in the soil. In early spring the grubs migrate upward and pupate in early May in earthen cells. There is one generation per year.

Chemical: Most foliage and flowers can be protected by spraying or dusting. However, insecticides will not fully protect roses, which unfold too fast and are especially attractive to beetles. When beetles are most abundant on roses, nip the buds and spray the bushes to protect the leaves. When the beetles become scarce, let the bushes bloom again. Timeliness and thoroughness of application are very important. Begin treatment as soon as beetles appear, before damage is done. Japanese beetle traps are of no value. with Sevin-10 Bug Killer --do not apply when wet or damp-- dust applied with dust mizer.

Use insecticide products only on plants for which they are indicated.

Hazard to honeybees: Some dust or sprays are highly toxic to honeybees. If application is necessary during the bloom period, do not apply during hours when bees are visiting the flowers. If larger than yard and garden plantings are to be treated, you may want to contact nearby beekeepers, in advance, so that they can protect their colonies.

Larvae or grubs
Rose chafer larvae may damage grass and nursery crop roots sufficiently to require controlling.

Cultural: The pupa in its earthen cell is extremely sensitive to disturbances. High pupal mortality can be achieved by plowing, cultivating, or harrowing to a depth of 3 inches or more. This should be done in late May or early June for best results. Keeping heaviest soils in grass and sod and using sandier soils for cultivated crops reduces rose chafer numbers. Keep all weeds and grasses controlled in grape arbors.

Chemical: Rose chafer grubs in lawns and grassy areas can be controlled with one of several insecticides. Granulated formulations are the easiest to disperse uniformly and are less likely to drift to other areas during application. Most may be applied with a fertilizer spreader. Emulsifiable concentrates (EC) or wettable powders (WP) mixed with water may be sprayed on. After application, water the insecticide in, avoiding puddling. Treated turf may be mowed, watered, and fertilized as usual. Heavy thatch may reduce effectiveness.

Landscape rose with chlorotic, underdeveloped blossom and puckered needlelike shoots caused by glyphosate (Roundup) herbicide.

Excellent reading about roses at www.mc.edu/campus/users/nettles/rofaq/rofaq-faq.html#FAQ_qa_aphids

• can improve the quality of the soil by contributing organic matter.
  
  
• contribute the micro-nutrients which contribute to strong and healthy growth.
  
  
• are an excellent way to add specific nutrients particular to a plant's needs.

• Alfalfa Meal (2-7-0, 5-2-8)
  Well-balanced, slow release fertilizer
  
  
• Blood Meal (13-2-0)
  Rapidly available nitrogen
  
  
• Bone Meal (3-2-0.5) 24% calcium
  Rapidly available phosphorous; increased pH slightly
  
  
• Cottonseed Meal (8-2-2)
  Rapidly available nitrogen
  
  
• Epsom Salts (0-0-0)
  Excellent source of magnesium sulfate
  
  
• Fish Emulsion (5-2-2)
  Rapidly available nitrogen
  
  
• Fish Meal (10-4-4)
  Rapidly available nitrogen
  
  
• Soybean Meal (6-1-2)
  Magnesium, micronutrients, and rapidly available nitrogen.
  
  
• Messenger
  Delivering stronger, healthier plants...naturally
  
  

Pruning roses is not difficult though it can be painful. As a rose flower fades, prune back its shoot to the upper crotch of a five leaved leaflet. Prune out spindly branches and one of any two branches that 'cross' or touch each other. Good air circulation helps prevent disease. Prune to encourage growth out from the center of the plant.