Roses & blackspot?

Question

What is the best way to prevent roses from getting blackspot and other diseases. I keep on spraying, but would like to try other preventative measures.

Answer 1

The best way to prevent roses from getting blackspot is to water them alot with the hose. I'm not kidding...Any year that has been more rainy, than others, my roses have flourished. When I worked as a horticultural assistant at the Toronto Botanical garden, I was told this by many people in the know. Apparently roses are more susceptable to disease when the season is too hot and dry.

Answer 2

You do not say what you are spraying on the plant. Nor do you say what you do with the soil. The blackspot is a sign of disease /fungi.
Since Roses are just beginning to grow, carefully remove any lower leaves and branches from ground level to approx to two or three foot. Gently remove any old and new mulch from the base and for four foot minimum from the base of each plant. Any plant material showing a hint of the black remove by hand by pinch while wearing rubber gloves, and any branch with a pruning shear. Provide yourself with a small bucket of Bleach (1/4 cup per quart) and dip both your hands and the pruning shear after each cut!!!
Check the exterior of your home immediately! You may find that there is a similar problem from the garden to the tops of the plantings. This is a fungi/mold. If you find the problem on the exterior or any other evergreen planting you need to remove ALL the existing mulch ASAP.
Use a heavy rake (not a lawn rake) and remove the mulch. This will help turn the soil as well. Purchase a granular fert with a 1-2-2 ratio (5-10-10, 10-20-20, etc.). Apply it to the soil before mulching. The last two elements help in root and disease resist. Do not ever use the clippings from these bed plants for a compost pile for at least three years!
While it is expensive, purchase a shreeded Cypress Mulch.
Redo the mulching with a three inch of this mulch. Keep the mulch a minimum of one inch from the base of all the plants ( I prefer two inches). I will tell you that this mulch is not cheap and only in bags (unless you can find bulk). It reduces the spread of the problem.
Buy some granular Mir-Gro to spread at the base of the Roses and evergreen plantings. Spread it at the minimum level of rec. Do it before or after the mulching. Be prepared to apply another one to two inches of mulch of the Cypress in the fall. (sorry).
Continue to prune by hand and shears with the Bleach solution about everyother week if possible. Remove any dead heads in any passing of the bed. Water the bed once a week at 1". Water the roots with a minimum of water to the actual plant. Water at the dripline of the plant and not the base! Fertilize with a granular 10-10-10 minerals (cheap) at the dripline every six weeks.
You probably will not believe this, however, to control the weak plant, after you have remove the diseased, weak, dead, you will spray with a mixture of Pure Ivory Liquid Dish Detergent. Mix at a ratio of 1/4tb per quart. You can add a little mir-gro at 1/2 the minimum rec. Spray the plant from the bottom to top. Spray the soil, the wooden, raise the leaves by hand and spray underneath of the leaves. Overspray the Roses, until it drips. Do this now and do it again in Mid-Sept.
This solution and process will work with both the Roses and any of the evergreens in your garden. The Azaelea will love this as the lacebugs and chewing bugs will be suffocated.
Roses, in a garden, spread disease and insects. Watch your other plantings. The Cypress will help. The health of a plant reduces the incidents of diseases and insects. I would add a granular application of Sevin for today and future insects. The Sevin can be used in both the garden and turf!
Make sure you water the Sevin in to reduce many wide range pest for your turf and garden.
Roses need attention on a minimum of three times a week. They need the fert and protection. If you can not provide such care consider a shrub rose (Meidlander) as a replacement.
Sorry to be so long. Fifteen years ago I was told I could not grow roses in Downtown Phila. Using the Meidlander I was giving cuttings on Christmas Eve the next year. Used this formula and it worked. My Roses outlived the Mums and fall plantings in the designs I did.
Call back if this helps. It is a lot of work. Look to the home first then the plants. Good Luck ([e-mail])

Answer 3

Hi, If you do any kind of spraying, do it in the morning. That gives them time to dry before night. Also use systemic products, there is an all in one for roses. It grows inside with the plants,so like if bugs eat them, they will die from it. It is made by Bayer and is in a blue bottle.Also, keep the beds free from leaves,because decaying vegetation promotes black spot and rust and other diseases. Water only from the bases, and let them have long cool drinks.In other words let the water slowly sink in from the bottom of the plants.In the heat,I would say twice a week. Also put some Banana skins in the dirt. That's potassium and they really like that. Bye

Answer 4

I try and try, but it still comes back. I spray mine with baking soda+water solution, and I also sprinkle corn meals around the base of plants. I heard this before (corn meals and baking soda both fight with fungus) and I am trying it because I don't want to lose my roses! The thing I do everyday is to take any diseased leaves off and never leave them on the ground, so it won't spread anymore.

Answer 5

Because the fungus spore must have free water on the leaf or cane in order to germinate and penetrate, take steps to insure that plant surfaces dry quickly.
Avoid dense plantings.
Maintain good weed control so that air circulation around the plants is good.
Avoid wetting the plants when irrigating.
If plants are misted or sprinkler irrigated, only do so early on days when the plant surfaces will dry quickly.
Because the fungus survives from year to year in infected material, remove infected material by raking and destroying fallen leaves. Prune out any canes that have the symptoms of blackspot disease.
Apply a fungicide registered for use on roses to control black spot. Begin applying the fungicide in the spring as daily temperatures reach the high 50oF range and repeat every 7-10 days to protect newly emerging foliage. Spraying may be omitted during hot, dry spells in summer. Resistant varieties are available.
http://www.uvm.edu/~uvmext/publications/gardendisease/gd24.htm


The fungus overwinters on fallen leaves and diseased canes. Microscopic spores are then splashed to newly emerged leaves and stem tissue in the spring. Under ideal conditions of leaf wetness, humidity and temperature the spores can germinate and infect in 1 day, cause symptoms in 4 to 5 days, and produce new spores that can infect additional leaf, flower and cane tissue within 10 to 11 days. Spores are easily spread to new locations by air currents.

Control Hints
Keep foliage dry. Plant roses in sunny locations to encourage drying after rains. Avoid sites with dense surrounding vegetation, so that good air movement will dry leaves. Avoid overhead irrigation, especially late in the day. Black spot is most severe in summers with sustained rainy periods.

Sanitation. Remove all black spotted leaves from and around plants. This should be done throughout the season. Before winter, remove and clean up all diseased leaves and remove diseased canes where possible.

Disease resistance. Listing susceptibility and resistance of all roses would take volumes. In addition, the occurrence of local races of the pathogen often result in a particular cultivar being listed as susceptible in one area and resistant in another. However, some lists have general usefulness; see Table 1. Also, consult local Extension publications and books, consult local rosarians and garden center horticulturists, and make observations of relative disease incidence in local rose collections and your own gardens.

Preventive fungicide applications. Fungicide controls are not successful if cultural and sanitation practices listed above are not followed. For fungicides to work, applications must be made preventively, providing a protective fungicide barrier which kills germinating fungal spores that have landed on plant tissue.

If conditions for infection are present and a high level of control is desired, preventive spray programs often start as soon as rose foliage emerges in the spring and continue throughout the summer at frequent intervals (as frequently as every 7 to 10 days in wet weather). Frequently used fungicides for black spot control include triforine (Funginex), and phaltan.

Answer 6

Bury a banana peel under the soil near the roots. It'll boost the nitrogen and help the plant!

Answer 7

Basic Cornell Spray from Cornell U.
Use horticultural oils in the control of black spot, powdery mildew and rust. Use a mixture of 1-2 tsp. of Baking Soda with 2 Tbs. of Horticultural Oil in 1 Gallon of Water.
Look for SunSpray Ultra-fine oil or similar for summer use.
Do not substitute vegetable oil spray for the summer weight agricultural oil, it doesn't emulsify in suspension when water is added. Potassium bicarbonate is a good substitute for baking soda.

Vinegar Fungicide
Mix 3 T of natural apple cider vinegar in one gal of water. Spray during the cool part of the day for black spot on roses and other fungal diseases. Adding molasses at 1 T per gallon will help.

Another really good method is milk spray ...... 1 part milk to 7 parts water. Dried milk works as well as fresh. In 1999, a Brazilian scientist found that milk helped control powdery mildew on cucumbers, it has since been found to be an affective control of black spot on roses. Spray weekly.

Cornmeal
Dust the ground around roses with cornmeal, and water in. 1-2 lb per 100 square feet. This helps to eliminate black spot spores that attack roses, and also helps to eliminate the spores in the soil around roses.
Green Lights Rose Defense Neem Oil but not when flowers are blooming as it is harnfull to insects also..

Feeding your roses with foliar sprays has been helpful in controlling BS.
Compost tea
Manure compost tea is effective on many pests because of certain microorganisms that exist in it naturally.
Fill a 5-15 gallon bucket half full of compost and finish filling with water. Let the mix sit for up to10 days stirring at least once a day to aerate the mix for better decomposition and better aerobic microbial population growth. After 10 days, the tea will contain only anerobic microbes and this smells of hydrogen sulfides- rotten eggs.

Dilute and spray on the foliage of all plants, including roses, regularly attacked by insects or fungal pests. It's very effective on black spot on roses and early blight on tomatoes.
A rule of thumb is to dilute the tea down to one part tea to four to ten parts water. It should look like iced tea. Strain the solids out with old pantyhose, cheese cloth, or row cover material. Add 2 T of molasses to each gallon of spray for more power. Add citrus oil for even greater pest killing power.
Howard Garret uses: "Cornmeal Juice is a natural fungal control for use in any kind of sprayer. Make by soaking horticultural cornmeal in water at one cup per gallon of water. Put the cornmeal a nylon stocking bag to hold in the larger particles. The milky juice of the cornmeal will permeate the water and this mix should be sprayed without further diluting. Cornmeal Juice can be mixed with compost tea"

For BS on Roses
You can reduce chemical spraying by 50% by giving luxury amounts of sulphate of potash - 1/2 handful or approx 25 gms per sq. metre around each bush every month until June as an essential fertilizer. This boosts flowering, too.
Safer fungicide uses sulfer.
Best to alternate treatments because the black spot fungi, like all quickly reproducing organisms, are selected for resistance to whatever you use. This rapidly leads to non kill.

Answer 8

keep them in the refregated