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Dealing with Bugs and Disease

The roses we offer in our catalog are tough, yet beautiful plants. However, you're not going to be the only one who likes them. There will be days when you go out to the garden and cry, "what's been eating my roses?!" Or "what's wrong with my roses--they have spots on the leaves!" What to do? First, don't panic! Second, find out what's causing the damage before you get out the sprayer and the poisons. Remember, the key to dealing with problems is finding out what is causing them first. Then, you can work on fixing what's wrong.

• Rose Diseases
• Insects
• Supplies for Insect and Disease Control - available on our Amazon store

Diseases

Most of the hardy roses we sell are relatively disease resistant or tolerant and don't need chemical sprays. However, if conditions are right, blackspot and mildew can become a problem on some plants. And, if you have a lot of roses, you'll want to control these diseases before they spread to other plants. Blackspot and powdery mildew are spread by spores that require specific temperature, moisture and humidity conditions to spread. Generally, these diseases are the worst in early summer and early fall when temperatures at night are cool and moisture or humidity is high.

Disease prevention and control: Keep your roses healthy by watering them consistently and adequately, preferably in the morning so the leaves have a chance to dry off in the morning sun. Providing the right amount of nutrients through fertilizer or compost also keeps your roses healthy. A healthy rose is less susceptible to disease.

Good housekeeping practices help to reduce the spread of diseases. Disease spores can overwinter on dead leaves and reinfect new growth the following spring. To prevent this, pick-up dead leaves in the fall or spring and burn or dispose of them. Or, cover the leaves each spring with a new two-inch blanket of mulch to prevent the spores from spreading. Also remove and burn or dispose of dead canes and prunings.

In addition to the above, you have three choices for controlling blackspot and powdery mildew:

1. Tolerate some blemishes on your roses, and do nothing. However, remember that if a rose looses too many leaves, the plant will become weakened and may eventually die. The disease will also then become established in your garden and may spread to other roses.
2. Establish a routine spraying program using commercially available fungicides labeled for roses, such as Funginex (Triforine) or Daconil 2787. Spray your susceptible varieties every 7 to 10 days starting in early spring. Be absolutely sure to follow the instructions on the containers, and wear goggles and a respirator to protect your eyes and lungs! Remember that for most sprays to be effective, they must be applied every 7 to 10 days throughout the growing season.
3. Use "organic" sprays. As with choice #2, you must follow a regular spraying schedule (every 7 to 10 days throughout the growing season) to prevent the disease problems from occurring. These sprays can also be used after the disease first appears to prevent it from spreading. However, unlike option #2, organic materials are less hazardous to human health and the environment, with the exception of fungal diseases.

   Organic disease control can be achieved using commercially-available fungicides containing sulfur, copper or Neem, which are very effective against many leaf spot diseases. To find these products, check out our sources for supplies at the bottom of this page. Or, make your own spray using a mixture developed and proven effective by Cornell University's Plant Pathology Department. Add one tablespoon of baking soda and 2½ tablespoons of Sunspray ultrafine horticultural oil per gallon of water. Mix well and apply in the early morning or late evening. Be sure to follow this recipe, since higher concentrations of both baking soda and horticultural oil can cause leaf damage. This recipe is very effective against powdery mildew.

   If you don't feel confident about this method, or any other sprays, you may want to test your spray mixture on a small part of your rose plant before you completely spray the plant to make sure there are no phytotoxic reactions (leaf drop).

Important Note: Use caution before you spray rugosa roses! Most rugosas are "allergic" to chemical sprays; some sprays will cause their leaves to yellow and fall off. Fortunately, most Rugosas are completely disease resistant and don't need to be sprayed. However, there are a few exceptions. If your rugosa is exhibiting signs of blackspot, it's probably because its breeding includes a nonrugosa variety that is susceptible to blackspot. Test your spray on a part of the plant and if it doesn't drop its leaves, go ahead and spray the whole plant if you see blackspot.

Insects

The common insects that attack roses are aphids, cane borers, Japanese beetles and sawfly larvae. Over time, you can observe the life cycles of insects that are common in your area. You'll begin to recognize just when certain insects appear and become a problem for your roses. This kind of observation is very important for minimizing the amount of insect control you have to do, and the amount of pesticides you use -- organic or not. Using pesticides, even organic ones, disrupts the natural cycle of predator and prey in the insect world. Therefore, you want to be sure not to kill the "good" insects -- the ones that eat the ones you don't like. Here are some guidelines to follow:

• Know your enemy! Know what it is and understand its lifecycle. Maybe you only need to spray once instead of spraying all summer "just in case..."
• Before killing off the pest, if possible, wait a few days to see if a natural predator can control them for you. For example, in the early summer, lady bugs seem to come out of nowhere and eat all the aphids in our garden. However, for the second flush of aphids that show up in late summer, I need to release lady bugs to control the pests.
• Spray or dust when the pollinators are NOT collecting nectar, such as in the early evening (at dusk).
• Follow up each application of pesticides with another application a few days later if the pest is still around. This is especially effective for controlling aphids.
• Ask yourself if you're willing to tolerate the pest. Don't flip out the first time you see a bug on your roses. Bugs are part of the natural world and can be quite interesting if you have an open mind about it. Find out if you can tolerate what it might be doing to your roses (again figure that out first before you kill it). If not, then you know what to do.

Remember, all pesticides -- organic or not -- are designed to kill a pest. Therefore, they can't be good for your lungs, eyes, skin, etc. Wear protection! Goggles, respirator, longsleeved pants and shirts.

Aphids: To control aphids, use insecticidal soap, or spray them off the plants with water from a hose. Another way to control aphids is to buy good bugs that eat the aphids. We release lady bugs every 4 to 5 days in our gardens starting in late May. They provide almost 100% control of aphids in early summer. We have to release lady bugs again starting in mid July through August to keep the late summer aphid populations down, which are a bit tougher to control.

Cane borers: If the tips of your rose canes wilt, then you probably have cane borers. Look for a hole on the cane where the borer entered and cut back the cane until you find the culprit, and then squish it. You may want to cover the cut with vaseline to prevent diseases from entering the wound.

Rose Stem Borers (Agrilus aurichalceus): The adult beetles lay eggs in rose canes and their larvae eat their way around the diameter of the cane causing it to swell -- usually in a 1- or 2-inch area on the lower part of the cane. The top of the cane above the swollen section usually dies. In addition, the swollen section readily breaks off in the wind or if you move it around. Cut the infected cane back to the ground, and cover the cut with vaseline or elmers glue. Dispose of the infected cane to prevent the larvae from surviving, maturing and eventually laying eggs in other canes. It's important to remove infected canes as soon as you notice a problem to prevent it from spreading. In some areas, Rugosas seem to be most susceptible to stem borers.

Japanese beetles: Use powdered rotenone or pyrethrum-based insecticides to kill Japanese beetles. Another method is to kill the beetle larvae using biological controls such as beneficial nematodes or a product called "milky spore." A new Neem-based product is available that repels the beetles. Or, manually knock them off your roses into a jar filled with water and kill them. Or trap them with specially designed Japanese Beetle traps that use a pheremone to attract them.

Rose Chafers: These pests are usually only a problem in areas with sandy soils. They also only seem to be a problem in early summer. Control methods are similar to Japanese Beetles. Use powdered rotenone or pyrethrum-based insecticides to kill Chafers. Another method is to kill the chafer larvae using biological controls such as beneficial nematodes or a product called "milky spore." A new Neem-based product is available that repels the chafers. Or, manually knock them off your roses into a jar filled with water and kill them. Or trap them with a specially designed Rose Chafer trap that uses a pheremone to attract them.

Sawfly larvae: Sawfly larvae (or rose slugs) are a bit harder to control since they remain on the undersides of leaves where they are hard to reach with spray. Sawfly larvae are small (½-inch long) green worms that are easy to identify because they tend to wrap themselves in a tight circle.

For organic control, shake the plant and step on the worms as they fall on the ground (this can be either repulsive or very gratifying), or spray them with Bioneem™ or insecticidal soap. Again, be sure to follow the instructions and precautions listed on the containers.

Another control method is provided by birds; specifically, wrens. Place wren houses around your rose garden and watch the birds do the work! Wrens are very tolerant of human activity and they relish sawfly larvae. Wrens can raise up to three clutches per summer; consequently, they never stop hunting for food. The birds may not provide 100 percent control, but they help tremendously, and add to the enjoyment of your garden through their wonderful songs.

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