YANKEE DISTRICT OF THE AMERICAN ROSE SOCIETY

To Be a Sprayer or Not To Be a Sprayer?

Is that the question?

By Linda K. Shamoon

 

Mike Chute, a past president of the Rhode Island Rose Society, wrote in a Rose Review article that he used to spray his roses approximately twenty-three times a season. Marie Giordano, the RIRS's most passionate organic rose gardener, does not spray at all. They reflect one of rose growing's most important decisions: to spray or not to spray.

Actually, like all of rose horticulture, the question is clear but the answer is not so simple.   In fact, within the RIRS, most members’ fall somewhere in between the Chute-Giordano frequency-of-spray schedule. I spray about ten to twelve times a season, Ed Cunningham, who has a large and varied rose garden, says he sprays about four times, Marie admits to an occasional blast at a select bush with an aerosol can, and Mike has shifted his spraying to about twelve times a year. Clearly, the answers to the questions of "should I?" and "when?" to spray are constantly changing and complex. The answers are found in both the traditional rules of rose growing and on-the-bush experi­ence.

Traditional Advice

Traditional advice about spraying sounds deceptively simple: spray for fungus preventatively, before any sign of infection shows on the bush; spray for pests responsively, after signs of damage or infestation. Simple, right?

Yes, there are some aspects and decisions about spraying that should be fol­lowed, simply and rigidly. I will not present every detail of advice about spraying here; I will give only the highlights in the order I follow when I spray. I urge anyone who sprays to read a more comprehensive guide avail­able both on the internet and in almost any worthy printed source on growing roses. The RIRS library has many such guides that members can borrow and peruse.

First, anyone who sprays should be overcautious about exposure to the spray material. All spray materials are meant to kill something (or establish a thick coating). Rosarians do not want to inhale spray material or have skin or eye contact with any of it. Therefore, before buying any spray, I recommend get­ting nitrile gloves, appropriate goggles, a respirator and select or buy spray-resistant clothing (including a hat) and shoes. The American Rose Society suggests that clothes used for spraying should not be used for anything else, and that boots or shoes other than sneakers should be worn. These items (and spray equipment) are widely available from places like Home Depot, Lowes and Sears and on-line from a great resource like www.rosemania.com.  When suited up for spraying, you will look very strange and scary, so stay away from the neighbors and don the outfit. The ARS recommends that any gar­ments worn during spraying be immediately aired and then washed twice. This is your life you are protecting.

Next, select the right spray equipment. The patio rose gardener and Marie Giordano may be able to get through the summer with a few ready-mixed spray bottles or aerosol cans, but the rest of us probably need more serious equipment. A two-gallon hand-pumped sprayer will probably supply enough spray material for the small rose garden (30-40 rose bushes). Larger gardens will need higher capacity, more sophisticated equipment. Rosarians will also need a good collection of measuring spoons, cups or calibrated containers. Use the equipment only after being suited up, wash everything immediately after spraying, and store in a secure, child-proof area.

Now select the right spray materials and read the directions thoroughly. The topic of spray materi­als is quite large and keeps changing, as the government continues to approve or ban particular chemicals, and as suppliers continue to research and develop new materials. It is crucial, therefore, to keep abreast of developments by reading rose publications like the RIRS Rose Review and the ARS magazine (whose main advertisers are the suppliers, so read with caution), and by monitoring on-line sources and attending RIRS meetings.

Here are a few tips about spray material; I urge you to read other sources be­fore embarking on a full spray program.

1.       Choose the right spray for the job. Pesticides include the following: fungi­cides, insecticide, miticides, an all-purpose spray and herbicides. Also keep an eye on the toxicity level, which is printed clearly on the label in one of four categories: "danger," which is highly toxic; "warning," moderately toxic; "caution," which is slightly toxic; and "caution" which may be simply topic. I stay away from the "danger" category and still grow fine roses. I aim for the cau­tion category whenever possible. Use the lowest toxicity possible and follow the directions in terms of the amount to mix and frequency of applica­tion.

2.       Fungicides: Roses are vulnerable to fungi; fungi make our bushes and blooms look spotted, coated with weird colors, or wilted and sad. Fungi are best dealt with by preventative spraying. In our geographic area black spot is the primary bane of roses, and powdery mildew shows up suddenly, as soon as the nights get cold but the days are still warm. Our bushes can succumb to other fungi, but most of us spray for these two, so we select fungicides that promise to prevent these, at least. We also use at least two different fungicides in rotation (maybe more), to prevent the build-up of resistant strains of fun­gi. We also select the fungicides based on their different ways of behaving on the bush. One category, protectants, works by coating the bush; the other category, systemic, works by translocation within the leaves and roots. Plan to use both types for full protection. A few fungicides claim to kill the disease, but traditional wisdom says that prevention is the only cure.

3.   Insecticides: Traditional wisdom says monitor roses for insect dam­age, identify the insect, then select the spray material. Vigilant rosarians take daily walks through their garden, studying the leaves (both sides), blooms, buds, canes and branches for signs of damage and unwelcome pests, such as aphids, white fly, cucumber, Japanese and other beetles, cane borers, slugs, midge, thrips, and more. It is a busy insect world out there! It is worth re­mem­bering, too, that not all insects are harmful. Ladybugs and praying man­tises dine on other insects, bees help with pollination, and earthworms are abso­lutely needed to break down elements in the soil. In fact, some insect damage may be tolerable if the roses are not headed for the show table, and some in­sects may sometimes be controlled through manual removal or a strong water spray. Move cautiously when choosing to spray against insects, since in-secticides do not distinguish between the specific destructive beastie on the rose and the helpful critter who is devouring the bad guy. The insecti­ide will, most likely, eradicate them all.

There is no doubt, however, that some insects, such as midge and thrips, are voracious and need to be stopped in their tracks. The worst pest I have en­countered is midge, which has a talent for chewing new stems and blooms at their most succulent moment, thus preventing plant or bloom growth. Elimi­nating this pest involved my treating both the soil and the bush with insecti­cides that target these insects. Thrips are similarly damaging and call for the same two-pronged treatment. Japanese beetles succumb to tar­geted spraying with Windex, but cucumber beetles sim­ply enjoy the bath. The best approach is to keep a rose grower's handbook handy that features (color) photos or drawings of the insect and the kind of damage it inflicts. Then choose the right spray ma­terial.

4. Miticides: Arachnids, I am told, are not true insects. You could have fooled me! They are tiny and crawly, and some are damaging to roses. Seems insect-like to me. Nevertheless, they need their own pesticide for eradication. Once again, however, caution might be urged. The two-spotted spider mite shows up on our roses as soon as the weather gets hot, and they take up residence on the undersides of the leaves, sucking the sap relentlessly until the rose is de­pleted or until the rosarian takes action to eliminate them.  If a bush is look­ing droopy but with no apparent disease or damage, look on the underside of the leaves. If you see a tiny layer of salt and pepper, it's spider mites.

When treating for spider mites, I have had success by spraying the undersides of all the leaves on my rose bushes with a strong, steady jet of water.  A good spraying twice a week during the hottest part of the summer seems to control this enemy. Thus, in the middle of the summer I get into my bathing suit and give the roses and myself a hosing. We both enjoy it. However, a severe in­festation of spider mites can denude a rose bush, and a treatment with a miticide may be the only cure.

5. Pesticide alternatives: There are many alternatives to chemical sprays that include naturally derived chemicals, horticultural oils, insecticidal soaps, bene­ficial insects, anti-transpirants, and companion planting. A good guide to or­ganic or "natural" gardening will provide excellent instructions about these alternatives, and they are worth learning about and trying with a moni­toring plan in place. I heard, for example, that Japanese beetles are repelled by the aroma emitted from geraniums, so each summer I plant geraniums amongst my roses. I have had few Japanese beetles in my garden, which may or may not be due to the geraniums. On the other hand, I tried insecticidal soap against aphids and white fly, but both species seemed to enjoy the dowsing. I did have success, however, simply wiping off the aphids from the buds and new leaves. Enough leaves and buds survived for a beautiful dis­play.  Pesti­cide alternatives sometimes work just fine.

 

On-the-bush Experience

Traditional wisdom says spray regularly to prevent fungal damage, spray in response to visible insect damage. My "on-the-bush experience" leads me to my own rose growing wisdom.

One on-the-bush experience: This past spring I noticed that just as new buds and leaves were sprouting, they would disappear, leaving a burnt, exposed, denuded tip. Sure signs of midge!   Luckily, RIRS member Tony Silva had just written a wonderful article about dealing with pests, including midge. He described the same problem and advised the treatment of the soil with an in­secticide, followed within three or four days with a spray on the bushes. He advises doing this at the beginning of April with or without visible damage, as a preventative to a midge infestation. I will probably follow this advice.

Another on-the-bush experience: two summers ago, I waited for spider mites to show up and then pursued my water treatment. I wound up constantly res­cuing droopy, weakened bushes all summer long. Last summer, I started the water treatment with the first arrival of hot weather and continued the treat­ment for three weeks. I had no spider mite damage.

A third on-the-bush experience: This summer I simply could not keep to a regular spray plan for fungus. I was away from my garden too much. By the fourth week of absence, blackspot had overrun several bushes. Traditional wisdom said my entire gar-den would be doomed. However, I carried out an attack of my own. I pulled off nearly all of the infected leaves and trimmed off branches and canes of especially stricken portions of a bush. I then sprayed with my most successful fungicide, and sprayed as soon as advisable with a differently acting fungicide. Within three weeks or so, the garden looked just fine. Yes, some degree of blackspot continued to show up on a few bushes, but this was more visible to my trained eye than to the casual visitor. The garden survived in fine condition.

My current wisdom: first, maintain a fungal spray program of personal choice, allowing for a personal level of comfort regarding infestation, damage, exposure to spray material, and time in the garden; second, treat preven­tatively for midge and spider mites, be vigilant and canny against other in­sects, and use the least toxic or non-toxic treatment possible.

In conclusion: if you choose to spray, spray safely, and give yourself time to develop your own "traditional" wisdom. 

 

 

Reprinted from RI Rose Review, Feb. 2004 issue

 

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