Rose Exhibitors Forum

Transcription

1 Rose Exhibitors Forum Vol. 29, No. 2 Robert B. Martin Jr., Editor Spring 2014 Let Us Spray By Robert B. Martin, Jr. Escondido, California petrose@aol.com Baldo s Dream Spray Rig Introduction In 1986, as a budding rosarian, I began to participate in the annual Roses in Review survey of the American Rose Society. Then as now it asked the question, Do you spray regularly? I wondered what percentage of the participants answered it Yes. None of the articles that presented the results of that survey provided me an answer to that question. Several years later I asked our then district Roses in Review Coordinator, Dr. Justin Ekuan, what percentage of district reporters for Roses in Review sprayed their roses regularly. He smiled patiently at me and answered, They all do. That was then and this is now, and maybe, as Bob Dylan sang in 1964, The Times They Are a-changin. Or are they? The Roses in Review survey has itself changed. It is now online and there is more outreach to the casual rosarian and even to non-members of the ARS. And, it would seem from the increase in articles and A Quarterly Publication of the American Rose Society

2 books on the subject that there is more interest in growing roses without spraying. So one might assume that many of the reporters now answer the question No. But we don t really know because there is still no reporting of the results of the question about spraying. What about rose exhibitors? In 2001, as Editor of Rose Exhibitors Forum, I conducted a spraying survey of the top exhibitors that produced 50 responses. I did not actually ask, Do you spray regularly? I didn t have to because I already knew the answer to that question, They all do. Thinking it was time to revisit this subject, I have again conducted a spraying survey of the top exhibitors. I expanded the number of invitations and received 58 responses from exhibitors in 25 different states. Again, I did not ask, Do you spray regularly? That is because the answer remains the same, They all do. Yes, Virginia, if you want to exhibit roses successfully, you need to spray regularly. But how do you spray? What do you spray? And, what sprayer should you use? In this issue I address those questions, not always in the form of a recommendation, but more often by explaining what I do and reporting on what other exhibitors are doing. And, as you will see, the problems faced by exhibitors in growing roses vary by regions, as does their approach to controls. In the end, you will need to find your own way. But hopefully knowing of the experiences and practices of others will help. We begin here with instruction on how to spray. In a subsequent article I will review the findings of the survey, both in the pest and disease problems commonly encountered, and the methods of control commonly used. Following, I will address the selection of a sprayer for the rose garden, again with reference to the survey responses that disclose what other exhibitors use. I will then address the interesting subject of adjuvants, including the continued dispute over the efficacy of foliar feeding. Concluding, Robbie Tucker of Rosemania has contributed an article detailing some of the newest products for pest and disease control. Finally, I add as a supplement an updated Chemical Guide with detail on the chemicals found by exhibitors to be effective. I trust this will be of assistance in the upcoming 2014 rose show season. Let us spray. May all of your roses live well and prosper. Amen. First, Consider Your Environment I begin by asking you to consider the environment. The environment I refer to is not the Brazilian rain forest. According to dictionary.com, the environment is the aggregate of surrounding things, conditions, or influences. It is the here and now of the condition today in your rose garden. Do not plan to spray if it is very windy as you cannot control coverage and will wind up spraying everything in sight, including yourself. Do not plan to spray when it is too hot but do plan to allow enough daylight after spraying to permit drying. Rose Exhibitors Forum Spring

3 Water your roses first to deter spray burn. Do not spray when other wildlife are active, such as bees, butterflies, birds, cats, dogs and children. The best time to spray is early morning when it the wind is still and the rest of the world is still sleeping or at coffee. The alternative is to spray at the end of the day, leaving enough sunshine so that your foliage will dry before dark. Dress for Success The toxicity of garden chemicals is generally minimal, however it should be remembered that sprays are intended to be toxic to rose pests and disease, Therefore, even minimally toxic sprays can be harmful to the rosarian. Tank tops, shorts and sandals are poor fashion for spraying. Wear a long sleeve shirt and long denim pants. Wear boots or other protective footwear. And, always wear eye protection. Consider wearing a pesticide respirator if you re going to do a lot of spraying; but don t let the fact that you re wearing one permit you to become sloppy. Finally wear good chemical-resistant gloves. Boots are particularly important because the spray material always winds up on your feet. I like wearing pull on rubber boots because they can be easily rinsed off at the end of the day. Walmart makes an excellent pair of inexpensive men s boots (~$20) called Men s 12 Tiller Lug-Sole Rain Boots. They are easy to pull on in the garage. Getting boots off is even easier if you use a boot jack that works well in gripping rubber, rather than one designed for pulling off leather-soled cowboy boots. The one I like is the Intrepid International PVC Boot Jack, which I found at Amazon.com. Hard plastic is also easier to keep clean and wears better for wet boots than does wood or iron. Intrepid International PVC Boot Jack For eye protection you should consider a product like the chemical splash goggles available at the Rosemania.com website for about $20. These goggles have wraparound anti-fog lens and indirect side vents that protect the eyes in the event of a splash. Alternatives are available at Magid Glove & Safety, These include the Encon Chemical Goggles that are inexpensive and can be thrown away after several uses. This incidentally is a very good website for safety equipment of all types. They also sell a box of lens cleaning towelettes (Item M100D) for less than $9 that can be used to clean off the goggles after use. Rose Exhibitors Forum Spring

4 Encon Chemical Goggles Head protection is also advisable, even if you plan to wear a respirator. I wear a Cleveland Indians baseball cap but I do not recommend this unless you want to feel disappointment year after year. Wear something so you don t get your spray material in your hair. Maybe a shower cap would do but vanity prevents me from trying that solution. Spray Fashion Photo from Martin garden by Dona Martin You also need to wear gloves. Do not use your regular garden gloves. Goatskin, leather, fabric and other materials commonly used for gloves are absorbent and will hold the chemical you are spraying. What you need are disposable unlined chemical resistant gloves made of a material such as nitrile. Rosemania carries N-DEX Nitril disposable gloves that I have ordered in the past but they tear too quickly. That is because they are only 2 mil thick. I much prefer the N-DEX Plus 8005 Blue Disposable Lightly Powdered 8 mil Nitrile Gloves that are four times thicker and do not tear. At $20/box including shipping, they cost about the same and actually last longer since you will not have to replace a torn glove in the middle of your spray routine. I get these from Magid Glove & Safety (Item No: 8005PF-XL). The XL in that number is for extra large disposable gloves tend to run small and it is a good idea to order a size up even if you have small hands. Rosemania also carries Tyvek coveralls that they recommend. I have never worn them and that may be because I have seen a video in which Robbie Tucker is dressed Rose Exhibitors Forum Spring

5 in them and I am sorry, Robbie, but it really looks dumb. Protection is important but I think you also need to think about comfort. It gets hot here in Southern California and dressing up in coveralls for spraying roses does not strike me as comfortable nor easy. I am also concerned about the message I deliver to my neighbors with such an outfit. Consider that for a moment. You come out on Saturday morning dressed like you are going on a spacewalk to spray God-Only-Knows-What chemicals on your roses that are planted right next door to your neighbor s lovely lawn on which their dog and cat, not to mention their child, is known to roam. I know and you know that you are not spraying anything that is particularly toxic or that has much residual effect. BUT YOUR NEIGHBOR DOESN T KNOW THAT. The fact is that the protection I describe above is adequate to your task and dressing up like you are spraying Agent Orange is not going to provide you with much more protection. Instead, it is going to creep out your neighbors and turn them off from ever growing roses or inviting you over for a barbecue. Mix With Caution Keep in mind that the mixing process is the most dangerous part of spraying. This is because you are working with the concentrated material and are in danger from splashing. So be sure to put on your protective gear before mixing and exercise caution in handling the pesticide while mixing. You can reduce the risk of clogging your sprayer by mixing ingredients carefully in clean water. Powders and emulsifiable concentrates ( EC ) are sometimes better pre-mixed in a jar of warm water. Follow Directions Select the chemicals you plan to spray. Then learn the exact application required and use it. Unfortunately it is often difficult to find the proper application for roses amidst the governmental warnings and other fine print on the label or accompanying pamphlet that you will have lost. Find a good spray reference like the one in this issue. You can also download one at Rosemania here: Reference March 2012_for print.pdf. It is a good idea to post a copy of your spray reference in your garage or garden shed for convenient reference. And, once you ve determined the recommended application amount, take a black permanent marker and write it down on the label of the pesticide so you can find it the next time you use it. Keep in mind that more is not better nor is less necessarily safer and more environmentally correct. Lots of research has gone into the manufacturer s recommendation so don t try to secondguess them. Also don t guess at the right amount. Invest in a good set of measuring spoons and cups and use them exclusively to measure chemicals precisely. Do not use cups and spoons you find in the kitchen you will be made to regret doing that. Buy a set exclusively for use with your garden chemicals. Rose Exhibitors Forum Spring

6 Rosemania offers an excellent set of regular size stainless steel measuring spoons that have an elongated, oval shape that fits nicely in most pesticide containers. The sizes are 1/8 teaspoon, 1/4 teaspoon, 1/2 teaspoon, 1 teaspoon and 1 tablespoon. In addition, Rosemania offers a corresponding set of odd size measuring spoons that are very useful. Many modern pesticides require application at very small rates which when calculated by reference to the quantity of spray material you plan to use, produces an odd size. These sizes include 1/8 teaspoon, 2/3 teaspoon; 1.5 teaspoons; and 2 teaspoons. There is also a very small one for a pinch which is said to be 1/16 teaspoon. I have never used that one though I have been tempted to use it as a pinch to grow an inch. Odd Size Cuisipro Stainless Steel Measuring Spoons Keep Your Distance Most sprayers come with very short 12-inches or so spray wands. That is too short. It stands to reason that the closer your spray nozzle is to you when you spray, the more likely it is that you will get spray material on yourself. Get yourself a sprayer wand extension. I have a 48-inch curved extension that was sent to me anonymously years ago by my friend Carl Mahanay. I have used it ever since. It also extends my reach in spraying so it is easier to reach to the top of climbers and that rose that is behind the one in front. You can see me holding it in the photo above. Sprayer Wand Extension 48-inch Curved Keep Your Nozzle Clean The best nozzle for sprayers is made of brass but any nozzle will become clogged from time to time no matter how careful you may be. When your sprayer is not in use keep the tank top loosely on so that foreign material will not fall into the tank. Be prepared for clogs by not over-tightening the nozzle thus permitting you to screw Rose Exhibitors Forum Spring

7 it off by hand. Use a clean metal object to poke the obstruction out of the nozzle, not back into the tank where it will inevitably surface again. Consider wrapping a paper clip around the strap for this purpose so you don t have to wander all over the yard and garage looking for a pin. Finally do not point the wand at your face when you are cleaning the nozzle. Poke the obstruction out of the nozzle and if you want to be sure the wand is clear spray some material on the ground around a rose to flush the system before reattaching the nozzle. Attack Downwind Even though you have selected a windless time to spray, the wind will begin to blow as soon as you ve filled up the tank. Take note of its direction. Spray downwind away from your body so the overspray cloud floats away from you. Get Good Coverage Take your time in spraying to do it right and you won t have to do it as often. Spray in two passes. On the first pass turn your nozzle up and carefully spray the underside of the foliage. This is where most of the pests and disease reside. Finish with a quicker pass over the top. Spray in all cases to the point of water run-off. The trick is to cover the whole plant without getting any on yourself. Empty the Tank Estimate the amount of spray material you need and load only this amount. This may take some trial and error. According to my survey the maximum amount of spray material used by exhibitors varied widely. The amount needed depends upon the time of year, as bushes in the spring with little foliage will require much less. Also, the maximum amount needed is influenced by the types of roses grown, the size and maturity of bushes, and the type and capacity of the sprayer used. As a rough rule of thumb, a gallon of spray material will service approximately 28 fullsize roses. Adjustments will need to be made for your own garden. I spray my climbers and larger shrubs last since it is difficult to get good coverage of large bushes and this is a good place to empty the rest of the tank. If you have spray material left over, plan to use it on other landscape shrubs such as azaleas and camellias. This is a plausible reason to grow companion plants for roses as they provide a good outlet for excess spray material. The ideal is to have none left over as you will want to avoid dumping it into the sewer or otherwise risk contaminating the water supply. Clean Up Carefully As a final matter it is important to clean up after yourself. Rinse your measuring cups and spoons. Tighten the bottle caps and rinse off the bottle tops if necessary. Put them away in a high, safe, and secure dark place. Lock them up to keep them out of the hands of children. Rinse out your sprayer and put it away as well. Throw your clothes in the washer and take a shower. Wait till the spray material dries before going among your roses to stake up that fallen cane you noticed while spraying. There will be time enough to do that later or on another day. Rose Exhibitors Forum Spring

8 Wrapping it up Chapter VIII of the ARS Consulting Rosarian Manual contains a good general discussion of pesticides and garden safety. It is worth reviewing, particularly by older exhibitors who may have been Consulting Rosarians for years but have not examined the newer version of the Manual released in November It is available as a download in the Members Only area of the ARS website at You will need the password to access the latest issue. That is found in the Departments section of the latest issue of the American Rose magazine. By Robert B. Martin, Jr. Escondido, California petrose@aol.com!!! A Spraying Survey In 2001, as Editor of Rose Exhibitors Forum, I conducted a survey of the spraying practices of top exhibitors I thought then it would be interesting to readers to learn of the pests commonly encountered in the gardens of exhibitors throughout the United States, and the control measures they use. So to determine these facts, I devised a questionnaire that I sent to a selected group of top exhibitors throughout the United States. In all, I received 50 responses from exhibitors in 21 different states. The results of that survey were published in the Spring 2001 issue of Rose Exhibitors Forum, which as I recall was well received. I also used the results of that survey in my book, Showing Good Roses. Thinking it was time to revisit this subject, I have again conducted a spraying survey of the top exhibitors. This time, I expanded the number of invitations and received 58 responses from exhibitors in 25 different states. This incidentally represents an incredible 65% response rate and once again I was pleased with the extraordinary generosity and kindness of the top exhibitors in answering my questions. This response rate is again testimony to the greatness of the exhibitors in this country and their willingness to educate us all on their methods of growing beautiful roses. Now as then, the questionnaire was divided into two parts. The first part set forth various fungus diseases and insect/mite pests that commonly afflict roses. In each case I asked the exhibitor to indicate the extent of the problem in their garden and the control measures used. The second part made inquiries of the sprayer used by each exhibitor and on certain spraying practices, such as frequency of spraying and whether the exhibitor used adjuvants and foliar feeds. The results of the portion of the survey are addressed in separate articles in this issue. Rose Exhibitors Forum Spring

9 As expected, every top exhibitor sprays their roses to protect them from fungus diseases as well as insects and mites. The good news is that the number of problems faced is generally limited and, with few exceptions, exhibitors report that their spray methods are effective. Roses are not that tough to grow even when you spray; in fact they are easier to grow when pest populations are kept in control. I pause here to comment on the word sustainable as it applies to growing roses. It has become seemingly a popular word of late but I am frankly at a loss to understand how it applies to growing roses, particularly insofar as it suggests to some that spraying roses is not a sustainable practice. In the context of growing things, dictionary.com tells me that the word sustainable is an adjective that means something that pertains to a system that maintains its own viability by using techniques that allow for continual reuse: sustainable agriculture. Thus, for example the practice of harvesting trees faster than they will grow is not sustainable because you will eventually run out of trees. Or, another example is overfishing, which is not a sustainable practice because if you harvest fish faster than they grow, you will run out of fish. But how does this apply to roses? Certainly caring for your roses will increase their growth and life. It is not as if you will eventually run out of roses by taking care of them. Another definition of sustainable offered by dictionary.com is able to be supported as with the basic necessities or sufficient funds: a sustainable life. In this context, it could be said that spraying roses, which as exhibitors we know to be necessary to sustain their health and growth, could be said to be sustainable rose gardening. About The Survey At the outset, I have a confession to make about the construction of the survey. I pulled up the survey that I used in 2001 and made some changes to it to add new insects and diseases of interest, as well as to add a few additional questions that I thought had been overlooked in the prior survey. That is all well and good, But what I didn t do before sending it out was to read the issue of Rose Exhibitors Forum in which I presented the results of the survey. If I had done so, I would have recalled some problems with the survey that I there discussed. In my prior article on the subject, I commented on the fact that I had asked the reporters to indicate if the disease or pest was (i) a continual and major problem ; (ii) a seasonal problem ; (iii) an infrequent problem ; or (iv) not a problem. Exhibitors, however, spray for problems on a preventative basis and the controls used were reported as generally effective. Therefore many exhibitors have no problems or infrequent problems with many diseases and pests because they spray. I had intended, now as then, that the questions be answered on a before spraying basis, but I could tell in reviewing the responses that several answered the question by reference to the result they achieved with their spraying regimen. And, Rose Exhibitors Forum Spring

10 in order to correct this problem, I made several adjustments in the responses based upon the context. Still, this problem permeates the entire survey since exhibitors by and large know what they are doing in dealing with fungus and insect pests and it is often difficult for them to report accurately what problems would exist in the absence of an effective spray program. It therefore is likely that the answers continue to understate the significance of the problems to non-sprayers, particularly in the case of the answers, not a problem and an infrequent problem. The reports should be viewed with this in mind. Another problem with reporting the results of the survey pertains to the products mentioned for the control of the problem. In a large majority of the cases, the respondents reported on the use of two or three control products, usually combined or alternated in some manner. This of course is good practice to avoid the development of resistant strains. But it does produce quite a few combinations that are difficult to summarize. It also produces a long laundry list of available controls. To organize these, I have updated my Chemical Chart from the 2001 issue and present it elsewhere in this issue. The fact that many of these are used in combination should also be kept in mind in reviewing the discussion on controls used. Blackspot Not surprisingly, the big two fungus diseases continue to be blackspot and powdery mildew. As a general rule, those faced with blackspot appear to have fewer problems with powdery mildew and vice versa. For example, nearly all of the reporters from the Southwest reported no problem with blackspot at all; this was also true in other drier areas of the South. At the same time, such areas report a higher incidence of powdery mildew. Blackspot requires water and moderate temperature to develop infection. Infection can occur at and the optimum is 75. The spores must be immersed in water and be continuously wet for at least seven hours for infection to occur. As a result, the disease does not develop in dry air and hot temperatures. It is therefore rarely observed in areas that have long periods of hot, dry temperatures. It also will not survive in the soil, but does overwinter in fallen leaves and infected canes. Blackspot spores are airborne only in water drops and are dispersed by rain and watering. This is therefore the source of the oft-quoted advice to avoid overhead watering of rose foliage in the evening, when quick drying is not likely to occur. Blackspot infection is manifested by characteristic circular black spots with a feathery edge that appear on the upper leaf surface. The center can be whitish or black or even purplish as the fruiting bodies of the fungus are found there. To my eye, blackspot looks as if someone has been extinguishing cigarettes on the leaves. Rose Exhibitors Forum Spring

11 Blackspot Photo Courtesy Baldo Villegas Good air circulation and prompt drying of leaf surfaces after watering are important in the control of blackspot. Avoidance of heavy overhead watering slows down the spread of the spores. Removal of fallen leaves and pruning of infected canes is also of considerable value. The first question in the survey was about blackspot. Here is a summary of the results: Blackspot: # % A continual and major problem % A seasonal problem % An infrequent problem % Not a problem % As can be seen, blackspot continues to be the biggest disease problem that exhibitors face. More than 58% of the respondents in fact reported it as a continual and major problem. Ray Guillebeau of Jacksonville Florida described it as the plague of the Deep South District. At the other corner of the country, Gretchen Humphrey of Tigard Oregon says, This is Portland, after all. In the Houston area, Gerald Jones comments on his wet, humid, coastal climate. And, in the heartland, Dan Keil of Decatur Illinois says, With our humidity we always have a chance. Cindy Dale of Peachtree City, Georgia commented that blackspot was especially bad last year with much more rain than normal. In fact, she went on to say there was so much rain that the foliage stayed wet all the time and nothing worked from about July on. Turning to the controls used, the products most often mentioned were Banner Maxx and Honor Guard, both products that contain Propiconazole as their active ingredient. Honor Guard is typically cheaper and available in a smaller container, but otherwise the products are essentially the same. Honor Guard was specifically mentioned by 22 respondents, while Banner Maxx was mentioned by 21. In all, nearly every reporter that cited blackspot as a problem used one or the other of these products Rose Exhibitors Forum Spring

12 The second most common control mentioned was a product containing Mancozeb, a broad spectrum fungicide containing manganese and zinc ions. Mancozeb is marketed under a number of product names, including Dithane M-45, Fore TO, Manzate 200DF, Pentathlon DF and Protect T/O, which see in this guide. Mancozeb is also closely related to the generic products maneb and zineb. Mancozeb products drew in total 45 mentions, however several exhibitors mentioned more than one. Most often, exhibitors using a Mancozeb product simply reported that they used Mancozeb, without mention of a brand name. The most common brand names mentioned were Manzate 200DF and Pentathlon DF, both of which are reported to be very effective. An alternative product used by 11 exhibitors is Compass, one of the newer strobilurin fungicides. Strobilurin chemistry is derived from a fungus that has a suppressive effect on other fungus. It has been found to be most effective when used in rotation with other fungicide classes. And, in every case it was mentioned as being used in rotation with another fungicide, typically Banner Maxx/Honor Guard, or a Mancozeb product. Daconil, an old standby containing the active ingredient Chlorothalinol was mentioned by 10 exhibitors. Although generally described as effective, a couple of exhibitors said it was fairly or somewhat effective, suggesting that it may be a good product to be used in rotation but is not as a first line defense. Another product that may be good to add to the rotation is Cleary s 3336-F, a fungicide containing Thiophanate-Methyl, which is based on a different chemistry than those descirbed above. It was mentioned by 10 reporters, all of whom said it was effective. Exhibitors by and large do not buy their chemicals from their local nursery or home center. That is because most of the effective products are not formulated for the casual gardener and are not available in such retail locations. The products available in such locations are also commonly diluted or in low concentrations, probably in an effort to minimize liability lawsuits from their misuse by casual gardeners. And, the products are typically much more expensive than would be the case when bought in larger quantities, perhaps because the manufacturer is accumulating funds to pay the lawyers for such lawsuits. Still, there are a few products commonly available that are used by exhibitors and mentioned as effective. Most often these are found under the Bayer Advanced Label. In the case of blackspot, Bayer s Advanced Disease Control contains Tebuconazole, which turns out to be a reasonably good fungicide for blackspot that can be added to a rotation, or even used alone in a small garden. It was specifically mentioned by seven respondents. Anthracnose/Downy Mildew Blackspot is often confused with fungal leaf spot diseases such as anthracnose, alternaria and cercospora, as well as downy mildew. Rose Exhibitors Forum Spring

13 Anthracnose The latter are all water-borne diseases like blackspot, with the two most troublesome for roses being anthracnose and downy mildew. I asked about both of the these diseases in the survey with the following results: Anthracnose # % A continual and major problem 0 0.0% A seasonal problem % An infrequent problem % Not a problem % Downy Mildew: # % A continual and major problem 2 3.4% A seasonal problem 3 5.2% An infrequent problem % Not a problem % As can be seen, 90% of the respondents considered downy mildew an infrequent problem or no problem at all. Similarly, 80% reported anthracnose as an infrequent or no problem. Downy Mildew Photo Courtesy Baldo Villegas Rose Exhibitors Forum Spring

14 Products labelled for the control of blackspot are typically also labeled for anthracnose. Ray Guillebeau said, if you keep up a blackspot spray schedule, anthracnose usually stays under control. Those that did report anthracnose as a seasonal problem mentioned the same control, and in fact the most common control mentioned was same as blackspot. I theorize that anthracnose is actually a much more common problem than indicated in the survey but that it is being kept under control by the measures undertaken by exhibitors to control blackspot. Downy mildew is also a water-borne fungus and control is reported through use of the same products as for blackspot, especially the Mancozeb related products. However, downy mildew also enters the bush internally and spreads down to its roots, causing considerable damage. Mancozeb kills spores but once the mycelium and haustoria of downy mildew have become established the damage continues. To counter the internal effect of downy mildew, the rose s system needs to be purged with a systemic fungicide. Of the respondents to the survey who mentioned downy mildew as a problem, eight specifically mentioned the use of Alliette, an aluminum-based fungicide. Alliette is highly acidic and should not be used with a spreader-sticker or combined with any other chemical. Another treatment for downy mildew that has shown effectiveness is a soil drench with the fungicide metalaxyl, a widely used agricultural fungicide. However, it is very difficult to find a product with metalaxyl registered for garden use or directly for roses. Some products with metalaxyl are labeled for use on outdoor roses to control root rot diseases caused by Phytopthera, a genus of fungus diseases that includes the family Peronosporacae, one of the members of which is downy mildew of roses. In such a case, as long as the dosage is not increased beyond that recommended it is legal to use it. Survey respondents concerned with downy mildew specifically mentioned Subdue MAXX for this purposes. Agri-Fos, a new product labelled for downy mildew of roses with a good environmental profile was mentioned by two respondents. It is a systemic fungicide containing di-potassium salts of phosphorous acid, and labelled for effective control of downy mildew, phytophthora and pythium. It has been reportedly approved for use in organic gardening and may well become the product of choice for the specific control of downy mildew. Powdery Mildew Powdery mildew spores germinate at high humidity and cool temperatures. The presence of films of water on the leaves, however, inhibits germination. The release of new spores increases as relative humidity decreases. The most favorable conditions for powdery mildew are cool damp nights followed by drier sunny afternoons. Nighttime temperatures of with high humidity are most favorable for spore germination. Daytime temperatures of with medium humidity allow optimum production. Several repeated day-night cycles such as these are necessary for an epidemic to develop. The disease is therefore most prevalent in the spring and late fall. Rose Exhibitors Forum Spring

15 Powdery mildew spores are carried to new infection sites by air currents. Under favorable conditions the spores begin to germinate within several hours after being deposited on the leaf. The organism can overwinter in infected buds, canes and fallen leaves. Powdery Mildew Photo Courtesy Baldo Villegas Early symptoms of powdery mildew are slightly raised, blisterlike, often red areas on the upper leaf surface. White growth of the fungus appear as discrete patches on the leaf surfaces of young leaves, which become twisted and distorted. The fungus also attacks the blooms, particularly on unopened buds. Fungal growth also develops on young stem tissue, particularly at the base of thorns and on peduncles. Mature leaves are not usually infected. The effects of powdery mildew are not fatal; it results primarily in damage to leaf growth and photosynthetic ability, thereby diminishing resulting plant growth. It also causes blooms of low quality with some failing to open at all. Powdery Mildew: # % A continual and major problem % A seasonal problem % An infrequent problem % Not a problem % As can be seen, nearly half of the exhibitors cite powdery mildew as a seasonal problem, while ten percent describe it as a continual or major problem. As previously mentioned, several of those are in the Southwest, where blackspot is not a problem. Although powdery mildew and blackspot are much different fungus diseases, the leading control for both turns out to be the same fungicide, namely Banner Maxx or Honor Guard, both products containing Propiconazole. In the case of powdery mildew, 12 respondents mentioned Banner Maxx for control, while eight mentioned Honor Guard. Nearly all reported the products as effective, typically used in a rotation, most commonly with Compass. The latter was mentioned by 11 of the respondents. Compass, as mentioned in the discussion of blackspot, is a strobilurin fungicide, and there have been several new fungicides introduced that are also based on Rose Exhibitors Forum Spring

16 strobilurin chemistry. The top exhibitors do not as a general rule flock to the newest products, being content to use that which they know works. But several did mention newer strobilurin fungicides, including Heritage, Pageant and Quadris. Several other products for powdery mildew received mention from a handful of exhibitors. They include old standbys, Rubigan and Triforine, mentioned by four each. Three exhibitors suggested the use of E-Rase, a jojoba seed oil-based fungicide that smothers existing infections of powdery mildew but leaves an oily residue on the foliage. Alone among the reporters, I also reported some success with the use of Terra-Guard, an imidazole fungicide containing Triflumizole that also provides some control of botrytis and rust. As with blackspot, the responses showed that exhibitors often use two or more of the controls for powdery mildew, generally in a program of alternation. The most common alternatives cited were Banner Maxx and Compass. Miscellaneous Disease Rust occurs primarily in coastal areas that experience cool temperatures and high moisture during certain parts of the year. Only two respondents reported rust as a seasonal problem, and eight said it was an infrequent problem. Most of those were from coastal Southern California and the Pacific Northwest. Rust Photo Courtesy Baldo Villegas The chemical controls used for rust largely parallel the controls used for powdery mildew or blackspot; therefore such control methods generally eliminate problems with rust. Ron Gregory of Temecula, California notes that he has not found a control since Plantvax was discontinued. Of more concern to exhibitors was botrytis, which as can be seen from the following is considered a seasonal problem by 36% of respondents: Botrytis # % A continual and major problem 3 5.2% A seasonal problem % An infrequent problem % Not a problem % Rose Exhibitors Forum Spring

17 Botrytis generally requires extremely wet and cool weather and is observed principally in late fall and early winter. Buds of infected roses fail to open and become covered with a grayish brown growth. For exhibitors, the disease most often occurs when the rose shows are over and the most common control cited is to simply remove the offending blooms. Gretchen Humphrey says, Yes, it rains in Portland. I employ umbrellas. Botrytis Those concerned with botrytis during the show season sometimes turn to a fungicide specifically labelled for botrytis. The most common, cited by five respondents, is Decree 50 WDG. According to the literature, Decree is supposed to prevent botrytis spores from attaching themselves to the plant, or stops the growth of spores if the disease is already active. Those that have used it appear unconvinced, in every case describing its effectiveness as somewhat, moderate or it helps. Similar lack of enthusiasm is expressed by the two exhibitors who mentioned Medallion, also specifically labelled for the control of botrytis. Rose Rosette Disease Rose Rosette Disease is a viral disease that has been the subject of many alarming reports in the national press. Although there have been no reports of the disease in California gardens, I have been curious as to what exhibitors on other areas might have experienced. Those results are as follows: Rose Rosette Disease # % A continual and major problem 4 6.9% A seasonal problem 0 0.0% An infrequent problem % Not a problem % The four exhibitors reporting Rose Rosette Disease as a major problem are located in four widely separated states, specifically Tennessee, Arkansas, New Jersey and Florida. And, as can be seen from the chart, it is being reported as an Rose Exhibitors Forum Spring

18 infrequent problem by 23 exhibitors, most typically with a report that they might lose one or two bushes a year. Rose Rosette Disease Photo by Dona Martin There is no treatment for a rose bush infected with Rose Rosette Disease, which explains why 21 of the respondents report their control as removal of the bush. (Several dryly noted that this control is very effective ) It is known that the disease is vectored, or transmitted by a tiny eriophyid mite that is specific to the disease and often associated with wild stands of rosa multiflora. Although academics that seldom venture into a rose garden have expressed skepticism, several exhibitors have observed that many miticides are in fact labeled for the control of eriophyid mites, and report experimenting with their use for the control of Rose Rosette Disease. Rafiq and Suni Bolar of Hillsborough, New Jersey report that they have been using Avid for this purpose and believe that it helps a lot, citing the fact that they lost 18 roses two years back, but only lost one rose this year. Bob House of Loma Linda Missouri says he plans to use Avid and Forbid this year. Such efforts might have effect in controlling the transmission of the disease in the garden, but the results so far are at best preliminary. Don Myers of Wake Forest North Carolina reports that the ARS has sponsored a research project at the University of Tennessee to better understand transmission and prevention of the disease. Aphids Turning our attention to insects and mites, we begin with aphids. Aphids attack new growth and favor conditions with cool nights and warm days. They are usually found on the newly developing buds and typically appear in early spring. The threat of aphids continues until the weather gets hot and often abates during the summer, only to reappear with the new growth of the fall bloom. Aphids are the best known of rose pests and are often described in the general garden literature as if they were a major pest of roses. I have even found one example online where aphids are listed among the Ten Most Un-Wanted Pests. Perhaps this is because of their creepy ability to give birth to live young and multiply rapidly. Rose Exhibitors Forum Spring

19 Aphid Giving Birth to Live Young Rose exhibitors, however, basically yawn when it comes to dealing with aphids. In fact, I cannot recall the last time I saw an aphid in our garden, Aphids: # % A continual and major problem 3 5.2% A seasonal problem % An infrequent problem % Not a problem 1 1.7% As seen from the above, only three exhibitors identified aphids as a major problem; however 69% identified them as a seasonal problem, which is fair description. The reason that aphids are not much of a problem to exhibitors is that nearly everyone reported effective methods of control. Here the leading control is the insecticide Merit, used by 19 exhibitors. Merit contains the active ingredient Imidacloprid, a contact and systemic neonicotinoid insecticide. I have used Merit since the 1999 season and it has provided excellent and complete control of aphids. Imidacloprid is currently the most widely used insecticide in the world. However, research has suggested that widespread agricultural use of Imidacloprid may be contributing to honey bee colony collapse disorder, the decline of honey bee colonies in Europe and North America. As a result, several countries have restricted use of Imidacloprid and other neonicotinoids. The U.S. Environmental Protection Agency instituted new pesticide labeling requirements on August 15, 2013 to better protect honey bees. Under these requirements, new pesticide labels are being developed to prohibit use of some neonicotinoid pesticide products where bees are present. The new labels will have a bee advisory box and icon with information on routes of exposure and spray drift precautions. The label change affects products containing the neonicotinoids, including Imidacloprid. Exactly how or if it will affect the use of Merit on roses is as yet unknown. Rose Exhibitors Forum Spring

20 New EPA Bee Advisory Label Box Four of the survey respondents reported the use of Bayer Complete Insect Killer to control aphids. This is a widely available product that comes in a ready to use spray bottle and it only practicable for small gardens. It contains both Imidacloprid and Cyfluthrin, the latter a pyrethroid insecticide that kills about everything. The concentration of both insecticides in the Bayer product is quite low since it is premixed. A more concentrated (11.8%) product containing Cyfluthrin is Tempo SC Ultra, used by two exhibitors in the battle against thrips, a subject we will come to shortly. In controlling aphids, 14 of the respondents rely on the old standard Orthene. The fact that aphids are pretty easy to control is also suggested by fact that 12 of the respondent reports control simply with a water spray. Other exhibitors report a smattering of other insecticides, including Dave Stever of New York, who said any insecticide will do. Spider Mites Spider mites are microscopic arachnids that appear on the undersides of leaves and turn them yellow. Left unattended they can defoliate a plant in a few days. They like hot conditions and are the primary pest of summer. They are often the unintended result of the overuse of insecticides, resulting in the destruction of mite predators and an explosion of mite populations, sometimes with spectacular results in the rose garden. Rose Exhibitors Forum Spring

21 Spider Mites Out of Control on Lavaglut Photo from Martin Arizona garden by Dona Martin Spider mites are a significant pest problem reported by exhibitors in my survey, 70% in fact report they have a major or seasonal problem. Gerald Jones of Orange Texas sums up the exhibitor view nicely: hate um. Only four exhibitors report mites as no problem at all. Although I had expected that the problems with mites would be more severe in the hotter areas of the country, the survey did not bear this out and mites seem an equal-opportunity pest in all areas. Spider Mites: # % A continual and major problem % A seasonal problem % An infrequent problem % Not a problem 4 6.9% The spider mite makes its living by sucking the fluids of roses. And so it will be found on the lower side of the leaves where the stomata give off moisture. It is therefore essential that any control, whether a strong stream of water or a more powerful miticide, be applied directly to the underside of the leaf. Mites can often be controlled with a water wand spray on the undersides of the leaves at the base. This is a major method of control mentioned by 17 of the respondents in my survey. I suspect even more use this method as their first line of defense since my survey tended to invite chemical responses. Mites reproduce in three days and do not limit their families to 2.2 children. Instead they lay thousands of eggs. Some of the adult mites are missed by watering or hang fairly tough in their webbing. More importantly, the tiny eggs hang on very well. As a result, in three days a new population will be on its way to becoming established. The key then to any attack on spider mites is to either attack the eggs with an ovicide and/or repeat the attack in three days to eliminate the newly emerging children. The resiliency of mites and their eggs to water washing is the reason that at some point water alone may not be enough to do the job. This usually occurs when Rose Exhibitors Forum Spring

22 the weather becomes very hot and dry since for reasons unknown to me the reproduction of mites increases geometrically with the temperature. This is therefore the time to pull out a heavy weapons. At this point it is important to emphasize that mites are not insects. They are arachnids, which puts them in with spiders. As a result most common insecticides have little or no effect on mites. Instead, to control mites you need to use a miticide, also referred to by academics as an acaracide. The most effective weapon available to control spider mites is Avid, which is used by 29 exhibitors. The active ingredient in Avid is abamectin, a natural product produced by the soil microorganism streptomyces avermitilis, which has the unique life mission of killing mites. It is not disruptive to natural predators or beneficial insects and can be used in good conscience by even the most ardent organic gardener. It is extremely effective and a 1-2 punch will eliminate mites from your garden for weeks. A number of exhibitors expressed concern that Avid was no longer doing the job, although these reports were in the clear minority. This concern may be influenced by the fact that Avid is most effective when sprayed alone. That is to say, it is best not mixed with other chemicals. Why, I do not know, but I suspect it has something to do with the fact that Avid is formulated from a living soil organism. It is also likely that the continued use of Avid may result in the build up of resistant populations of mites. Also, Avid has no effect on the eggs of mites, nor much of a residual effect. As a result, the eggs go about merrily hatching into new mites a couple of days after Avid is applied. The foregoing problems can be alleviated through the use of a second miticide that also has ovicidal activity, which means it kills eggs. The product of choice for this purpose, used by 24 exhibitors, is Floramite, which also kills adult mites on contact and has a long residual. It is also relatively inactive against beneficial/predacious mites and insects. It is very expensive, but at the rate of 1/4 to 1/2 teaspoon per gallon, you don t use a whole lot of it at a time. Spider mites are a major problem to the greenhouse grower and that has provided a market for a steady flow of new miticides, some of which exhibitors reported using for control. These include Tetra San 5 WDG (6 reports), Shuttle 15 SC (5 reports); and Forbid 4-F (4 reports). All are brutally expensive but are reported to be effective controls. Eddie Garcia of San Antonio, Texas mentions that Shuttle is very effective on the spider mites attracted by the hot temperatures of his area. Further detail on all the miticides can be found in the Chemical Guide in this issue. Flower Thrips Flower Thrips are the tiny winged insects that crawl in the blooms themselves, particularly white and lightly colored blooms. They appear later in the spring and often abate in the heat of the summer. They typically reappear, usually with less intensity, in the fall. Rose Exhibitors Forum Spring

23 Thrips Damage on White Rose Photo Courtesy Baldo Villegas Although there are several types of flower thrips, including the ubiquitous Western Flower Thrips and now the Eastern Flower Thrips, they are generally known to rosarians simply as thrips. Of note, the singular of the word thrips is thrips, as is the plural word, and there is no such thing as a thrip (maybe because you never see just one.) Thrips are easy to kill on contact with about any insecticide. The problem is that all their relatives fly in for the funeral the next day. They also snuggle deeply into multi-petaled blooms and are tough to contact. Thrips are without question the most vexing problem facing rose exhibitors. Of those surveyed, 26 or 44.8% reported they are a continual and major problem. An additional 26 reported they are a seasonal problem. In all, nearly 90% of exhibitors report significant problems with thrips. Flower Thrips # % A continual and major problem % A seasonal problem % An infrequent problem 3 5.2% Not a problem 3 5.2% The respondents who listed thrips as a continual and major problem are located in all areas of the country; in fact I count 15 different states. The problem seems particularly acute in the Southwest and South Central areas. Jim Small of Maitland, Florida observes that they are Always with us really bad when oranges are in bloom. The significance of the problem has also produced an unusual multitude of proposed solution. Twenty different control solutions were cited by exhibitors, with many noting that the solution is but brief and far from perfect. These solutions ranged from the frequent use of powerful insecticides to that proposed by Lynn Snetsinger of Arcadia, California who says she doesn t plant white roses any more. Rose Exhibitors Forum Spring