Re: [apple-crop] Kasugamycin for fire blight
Hi Dave! Always a pleasure to read you! I always learn something new! 1. Blossom Protect is ridiculously expensive compared to strep. Of course, I agree. But since we pay a ridiculous amount for strep in Canada, BP is almost affordable. We should really start a business = I send Canadian pharma to USA, you send strep to Canada. ;-) So far as I can tell, that pretty much negates the value of our blossom blight models I don’t agree. You are right to point out that BP is less flexible, but we time applications of BP with RIMpro nonetheless. The caveat is that you must spray no later then on the day before infection. and ensures that the Blossom Protect folks will sell at least three applications per year regardless of weather conditions. I don’t agree. Once a cohort is sprayed, it’s sprayed. So it’s only new flowers that open after spray you need to worry about. Frankly, that’s similar to strep. (but BP cannot be sprayed on infection day of after contrary to strep) Where BP is used, no more than 2 sprays are used in most instances. We might get better at timing BP spray with more experience, but we’re not there yet. A lot of data from Europe and from Western USA is available. Less in the East, I agree. 3. As noted on the Blossom Protect label, it is not compatible with most of our commonly used fungicides, so you get to pick whether your prefer scab or fire blight. As you know, No one knows exactly how much efficacy of strep is lost when mixed with fungicides… Yes, I know that you have a few fungicide options that are compatible with BP, but without mancozeb and captan most folks will run into trouble. The restriction is troublesome, yes. warning on the label is perfectly on-target, but that still means that BP will present problems for blight control on some cultivars. Could we imagine “killing off” the yeast once we don’t need it? i/e Give it time to antagonize FB and then spray a “potent” fungicide to avoid russet? interesting data at IFTA in Nova Scotia showing how a strep alternative (I think is was oxytet) provided blossom blight control equivalent to strep, but then the trees treated with the alternative developed much more shoot blight We rate both blossom and shoot blight and I’m sure anyone carrying efficacy tests do the same. So, a product with “good” blossom efficacy but poor on “overall” FB would simply be rated… poor. Most (all?) BP results published show it at “par” with strep, so the overall efficacy. Not just blossom efficacy. Until we get much, much more published data that validates alternatives, I’ll continue to put my trust in strep. Strep has advantages over everything else. No question. But very good control of FB without strep is very possible. I don’t doubt that one could survive without strep, but at this point I don’t see the incentive to do so. What market wants, we deliver… ;-) Human health risks from using strep or other antibiotics during bloom on apples and pears is virtually undetectable Unfortunately, the customer is always right, even when they are wrong. ;-) that food safety folks looking at agriculture have much bigger fish to fry than the trivial amount of strep that is applied in apples. It’s not real risk, it’s perception of risk. Something we can’t control so much. Somehow, we’re back at the Artic apple… As you know, before Cesare Gessler retired, he released a GALA apple that is both resistant to SCAB and FB. It’s not even a transgenic. It’s a “cysgenic”, meaning it only carries APPLE genes. Much more useful than Artic… But will you see this apple in the market in the near future? Vincent PS, Spring is FINALLY just around the corner. Expecting budbreak on…. April 28th! ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Kasugamycin for fire blight
Hello, Vincent — I believe that the problem Brian had in the year where 6 step sprays were required was lack of chilling hours to complete dormancy. If apples do not get enough chilling, they produce flower buds over a very long interval, and new flowers just keep opening. Concerning comments about Blossom Protect as a substitute for strep, there are still major differences that make strep a much more logical choice: 1. Blossom Protect is ridiculously expensive compared to strep. 2. BP must be used prophylactically to get populations of the biocontrol it contains established on the stigmas before Ea gets there. So far as I can tell, that pretty much negates the value of our blossom blight models and ensures that the Blossom Protect folks will sell at least three applications per year regardless of weather conditions. We might get better at timing BP spray with more experience, but we’re not there yet. 3. As noted on the Blossom Protect label, it is not compatible with most of our commonly used fungicides, so you get to pick whether your prefer scab or fire blight. Yes, I know that you have a few fungicide options that are compatible with BP, but without mancozeb and captan most folks will run into trouble. 4. As the BP label notes, applications after mid bloom may cause russetting on russet sensitive cultivars, yet in some years applications during late bloom may be essential for controlling fire blight. Thus, growers of SweeTango, and to a lesser extent Golden Delicious, which is less blight sensitive, will also have the choice between blight or russet. And I know that that label warnings are valid because in 2013 we ran a trial where applications of BP at late bloom did cause russetting on Golden Delicious. I was pleased to learn that those same applications did not cause russet on Redcort or Jerseymac that were sprayed on the same schedule. Thus, the warning on the label is perfectly on-target, but that still means that BP will present problems for blight control on some cultivars. 5. BP, like oxytet, prevents bacterial multiplication but does not kill bacteria that contact it. As I recall, George Sundin presented some interesting data at IFTA in Nova Scotia showing how a strep alternative (I think is was oxytet) provided blossom blight control equivalent to strep, but then the trees treated with the alternative developed much more shoot blight than the trees that had been treated with strep during bloom, presumably because EA populations had been suppressed but not killed by the strep substitute. Until we get much, much more published data that validates alternatives, I’ll continue to put my trust in strep. I don’t doubt that one could survive without strep, but at this point I don’t see the incentive to do so. Human health risks from using strep or other antibiotics during bloom on apples and pears is virtually undetectable compared to the risks from the continued and legal use of antibiotics in animal production, especially in chickens. Thus, I would argue that food safety folks looking at agriculture have much bigger fish to fry than the trivial amount of strep that is applied in apples. Now to open another can of worms, how many folks are aware that the World Health Organization (WHO) just issues a report in which they suggest that they have enough data to indict glyphosate as a probable human carcinogen? On Mar 24, 2015, at 4:41 PM, Vincent Philion vincent.phil...@irda.qc.camailto:vincent.phil...@irda.qc.ca wrote: Hi, I’m late in this exchange, but my grain of salt… First, I entirely agree with Dave… except for this: would argue that strep is still the cheapest, most effective, and most proven product for controlling blossom blight, and I see no reason to use other products except where strep resistance has been documented or is suspected due to failure of well-timed strep sprays. In many markets, use of antibiotics is illegal or questioned. I have a good number of growers happy to see real alternatives to strep such as blossom protect. In fact, alternating with biologicals or with oxytet may actually be counter-productive because they may allow more bacteria to survive, thereby leaving larger populations to be controlled by strep and/or allowing some infections to become established and thus carry the disease through until the next year. At the end of the day, when a number of trials give results “at par” with strep, I don’t see how we can argue that ‘more bacteria survive’ Vincent Philion, agr., M.Sc. Microbiologiste/Phytopathologiste (pomiculture) ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Kasugamycin for fire blight
Hi, I’m late in this exchange, but my grain of salt… First, I entirely agree with Dave… except for this: would argue that strep is still the cheapest, most effective, and most proven product for controlling blossom blight, and I see no reason to use other products except where strep resistance has been documented or is suspected due to failure of well-timed strep sprays. In many markets, use of antibiotics is illegal or questioned. I have a good number of growers happy to see real alternatives to strep such as blossom protect. In fact, alternating with biologicals or with oxytet may actually be counter-productive because they may allow more bacteria to survive, thereby leaving larger populations to be controlled by strep and/or allowing some infections to become established and thus carry the disease through until the next year. At the end of the day, when a number of trials give results “at par” with strep, I don’t see how we can argue that ‘more bacteria survive’ Vincent Philion, agr., M.Sc. Microbiologiste/Phytopathologiste (pomiculture) Institut de recherche et de développement en agro-environnement Research and Development Institute for the Agri-Environment www.irda.qc.cahttp://www.irda.qc.ca Centre de recherche 335, Rang des Vingt-Cinq Est Saint-Bruno-de-Montarville (Québec) J3V 0G7 vincent.phil...@irda.qc.camailto:vincent.phil...@irda.qc.ca Bureau: 450 653-7368 poste 350 Cellulaire: 514-623-8275 Skype: VENTURIA Télécopie: 450 653-1927 Verger expérimental 330, Rang des vingt-cinq Est Saint-Bruno-de-Montarville (Québec) J3V 4P6 Téléphone et télécopieur : 450 653-8375 Local pesticide: 450-653-7608 ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Kasugamycin for fire blight
Hi! Thanks for the follow-up information, Brian. Using six strep sprays during bloom, while I can see how it may be necessary, Actually, I don’t understand how 6 sprays on the same flowers can be necessary. Once open flowers are sprayed with strep, the likelihood of building a sufficient bacterial population in those flowers is very limited. Of course, a few sprays may be needed to cover flowers as they open. As Dave said = possibly to or 3… But 6 ? Vincent Philion, agr., M.Sc. Microbiologiste/Phytopathologiste (pomiculture) Institut de recherche et de développement en agro-environnement Research and Development Institute for the Agri-Environment www.irda.qc.ca Centre de recherche 335, Rang des Vingt-Cinq Est Saint-Bruno-de-Montarville (Québec) J3V 0G7 vincent.phil...@irda.qc.ca Bureau: 450 653-7368 poste 350 Cellulaire: 514-623-8275 Skype: VENTURIA Télécopie: 450 653-1927 Verger expérimental 330, Rang des vingt-cinq Est Saint-Bruno-de-Montarville (Québec) J3V 4P6 Téléphone et télécopieur : 450 653-8375 Local pesticide: 450-653-7608 ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Kasugamycin for fire blight
Good point Vincent! Makes sense to me. Kerik At the end of the day, when a number of trials give results “at par” with strep, I don’t see how we can argue that ‘more bacteria survive’ -- Kerik D. Cox, Ph.D., Associate Professor Plant Pathology and Plant-Microbe Biology Section School of Integrative Plant Science Cornell University 221 Barton Lab NYSAES 630 West North Street Geneva, NY 14456 USA E-mail: kd...@cornell.edu Faculty Office: (315) 787-2401 Fruit Pathology Lab: (315) 787-2402 FAX: (315) 787-2389 ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Kasugamycin for fire blight
While dealing with getting Kasumin 2L registered here in MA, it was pointed out that on the Federal label it says: • Do not apply kasugamycin in orchards in which the soil has been fertilized with animal waste/manure. • Animal grazing in treated areas is prohibited. The public must be notified by posting restriction signs along the perimeter of the treated area. Attached is the sign our state Ag Dept. is considering. No real guidance on placement other than perimeter of the treated area. Just thought you might be interested... Jon On Mon, Mar 23, 2015 at 9:04 AM, David A. Rosenberger da...@cornell.edu wrote: Thanks for the follow-up information, Brian. Using six strep sprays during bloom, while I can see how it may be necessary, does make me a bit more uneasy about selecting for strep resistance. In northeastern United States, we often need two sprays during bloom, sometimes three, and very rarely four. I’ve not been concerned about using four sprays if needed. However, I doubt that anyone has enough experience with the impact of 6 early-season sprays to be certain of the outcome. One theory about how strep resistance develops (and I think this is still valid) is that the initial selection for resistance is not in Erwinia, but rather in other bacteria that exist in the orchard environment. These other bacterial species may then pass on the strep-resistance genes to Erwinia because bacteria have mechanisms for transferring useful DNA (i.e., DNA that enhances survival) from one species to another. When strep is applied to apple and pear flowers in springtime, the over-all bacterial populations on leaves and in soil are still rather low because bacterial population build slowly as plants and soil warm up. Therefore, there is less selection pressure for resistance in the non-Erwinia species when strep is applied during bloom as compared to after bloom. Bacterial populations in the orchard environment increase very rapidly as temperatures rise, so summer applications of strep impact a much larger universe of bacteria and therefore are presumed to be more likely to trigger resistance that can later be transferred to Erwinia. Strep is broken down in sunlight, but each application may contribute to residual accumulations in the ground cover, duff, or soil surface where the accumulation from multiple applications might persist long enough to enhance selection for resistance in soil bacteria as soil temperatures rise. I really don’t know how long strep persists in orchard soils, and there is undoubtedly huge variations depending on rainfall, orchard cover, soil type, etc. I’m sending this post simply to indicate that there is still a lot of things we don’t know about how our agrichemical products impact the total orchard environment. Given that uncertainty, I’m still willing to bet, based on our history in the Northeast, that limiting strep applications to blossom time in areas that average only two or three strep sprays per year will never result in selection for strep resistance even if growers occasionally use one additional application after bloom to suppress trauma blight following hail or wind storms. However, if you will need more than four strep sprays on a regular basis, that makes me a bit less comfortable and you may want to break up that string of strep sprays by including Kasumin in your blossom spray strategies. On Mar 21, 2015, at 10:09 PM, Brian Heatherington beechcreekfa...@earthlink.net wrote: No resistance from bloom sprays is good news. I have had no control problems with copper prior to green tip, strep timed by Maryblyt, Apogee to minimize pruning/harden shoots to possible shoot blight, and control of aphids/leafhoppers at petal fall/1st cover. A few years ago, however, we had a long, extended bloom with Pink Lady. Maryblyt called for a total of 6 sprays (predicted EIP over 100), which exceeds most recommendations of 4 max. I went with the 6 applications and came out OK, but have always wondered if this might trigger resistance. I will stick with strep during bloom and leave the Kasumin for those that need it. I did just put in a block of CrimsonCrisp and haven't thought about putting copper on them. Good advice. Thanks. On 3/21/2015 10:36 AM, David A. Rosenberger wrote: While Kasugamycin works about as well as streptomycin, oxytetracycline is generally a bit less effective and has the disadvantage of preventing bacterial multiplication without killing off all of the bacteria contacted by the spray. Of the three antibiotics, it is my understanding that only strep is absorbed into apple tissue, thereby giving it a bit of an edge over both of the other products, especially in cases where a few infections might have been initiated a few hours before the product is applied. Kasugamycin, like strep, kills bacterial cells that it contacts, but it has the disadvantage of being considerably more expensive
Re: [apple-crop] Kasugamycin for fire blight
Thanks for the follow-up information, Brian. Using six strep sprays during bloom, while I can see how it may be necessary, does make me a bit more uneasy about selecting for strep resistance. In northeastern United States, we often need two sprays during bloom, sometimes three, and very rarely four. I’ve not been concerned about using four sprays if needed. However, I doubt that anyone has enough experience with the impact of 6 early-season sprays to be certain of the outcome. One theory about how strep resistance develops (and I think this is still valid) is that the initial selection for resistance is not in Erwinia, but rather in other bacteria that exist in the orchard environment. These other bacterial species may then pass on the strep-resistance genes to Erwinia because bacteria have mechanisms for transferring useful DNA (i.e., DNA that enhances survival) from one species to another. When strep is applied to apple and pear flowers in springtime, the over-all bacterial populations on leaves and in soil are still rather low because bacterial population build slowly as plants and soil warm up. Therefore, there is less selection pressure for resistance in the non-Erwinia species when strep is applied during bloom as compared to after bloom. Bacterial populations in the orchard environment increase very rapidly as temperatures rise, so summer applications of strep impact a much larger universe of bacteria and therefore are presumed to be more likely to trigger resistance that can later be transferred to Erwinia. Strep is broken down in sunlight, but each application may contribute to residual accumulations in the ground cover, duff, or soil surface where the accumulation from multiple applications might persist long enough to enhance selection for resistance in soil bacteria as soil temperatures rise. I really don’t know how long strep persists in orchard soils, and there is undoubtedly huge variations depending on rainfall, orchard cover, soil type, etc. I’m sending this post simply to indicate that there is still a lot of things we don’t know about how our agrichemical products impact the total orchard environment. Given that uncertainty, I’m still willing to bet, based on our history in the Northeast, that limiting strep applications to blossom time in areas that average only two or three strep sprays per year will never result in selection for strep resistance even if growers occasionally use one additional application after bloom to suppress trauma blight following hail or wind storms. However, if you will need more than four strep sprays on a regular basis, that makes me a bit less comfortable and you may want to break up that string of strep sprays by including Kasumin in your blossom spray strategies. On Mar 21, 2015, at 10:09 PM, Brian Heatherington beechcreekfa...@earthlink.netmailto:beechcreekfa...@earthlink.net wrote: No resistance from bloom sprays is good news. I have had no control problems with copper prior to green tip, strep timed by Maryblyt, Apogee to minimize pruning/harden shoots to possible shoot blight, and control of aphids/leafhoppers at petal fall/1st cover. A few years ago, however, we had a long, extended bloom with Pink Lady. Maryblyt called for a total of 6 sprays (predicted EIP over 100), which exceeds most recommendations of 4 max. I went with the 6 applications and came out OK, but have always wondered if this might trigger resistance. I will stick with strep during bloom and leave the Kasumin for those that need it. I did just put in a block of CrimsonCrisp and haven't thought about putting copper on them. Good advice. Thanks. On 3/21/2015 10:36 AM, David A. Rosenberger wrote: While Kasugamycin works about as well as streptomycin, oxytetracycline is generally a bit less effective and has the disadvantage of preventing bacterial multiplication without killing off all of the bacteria contacted by the spray. Of the three antibiotics, it is my understanding that only strep is absorbed into apple tissue, thereby giving it a bit of an edge over both of the other products, especially in cases where a few infections might have been initiated a few hours before the product is applied. Kasugamycin, like strep, kills bacterial cells that it contacts, but it has the disadvantage of being considerably more expensive than strep. Some of my pathologist colleagues may disagree with me, but I see no reason to pay the extra price for kasugamycin in established orchards that have no history of strep resistance. (An exception would be in countries like Canada where the strep labels allow a maximum of 3 applications/yr.) In eastern New York and New England, we have used strep exclusively for fire blight control for more than 60 years without encountering resistance. Resistance to strep has only appeared in regions where nurseries or fruit growers have used it repeatedly during summer (as many as 12 times/yr) to
Re: [apple-crop] Kasugamycin for fire blight
I should have added one more thought: Probably the very best strategy for avoiding selection for strep-resistant Erwinia amylova (Ea) is to prevent fire blight from becoming established in the orchard in the first place. To that end, the integrated strategy that Brian described (copper early, strep as required by a timing model, and Apogee to make shoots more resistant) reduces the likelihood that he will ever have visible fire blight or even high populations of Ea in his blocks. You can’t get resistance if the pathogen of interest never becomes established, even if non-Erwinia species in the sprayed blocks may have detectable levels of strep-resistance. On Mar 23, 2015, at 9:04 AM, David A. Rosenberger da...@cornell.edumailto:da...@cornell.edu wrote: Thanks for the follow-up information, Brian. Using six strep sprays during bloom, while I can see how it may be necessary, does make me a bit more uneasy about selecting for strep resistance. In northeastern United States, we often need two sprays during bloom, sometimes three, and very rarely four. I’ve not been concerned about using four sprays if needed. However, I doubt that anyone has enough experience with the impact of 6 early-season sprays to be certain of the outcome. One theory about how strep resistance develops (and I think this is still valid) is that the initial selection for resistance is not in Erwinia, but rather in other bacteria that exist in the orchard environment. These other bacterial species may then pass on the strep-resistance genes to Erwinia because bacteria have mechanisms for transferring useful DNA (i.e., DNA that enhances survival) from one species to another. When strep is applied to apple and pear flowers in springtime, the over-all bacterial populations on leaves and in soil are still rather low because bacterial population build slowly as plants and soil warm up. Therefore, there is less selection pressure for resistance in the non-Erwinia species when strep is applied during bloom as compared to after bloom. Bacterial populations in the orchard environment increase very rapidly as temperatures rise, so summer applications of strep impact a much larger universe of bacteria and therefore are presumed to be more likely to trigger resistance that can later be transferred to Erwinia. Strep is broken down in sunlight, but each application may contribute to residual accumulations in the ground cover, duff, or soil surface where the accumulation from multiple applications might persist long enough to enhance selection for resistance in soil bacteria as soil temperatures rise. I really don’t know how long strep persists in orchard soils, and there is undoubtedly huge variations depending on rainfall, orchard cover, soil type, etc. I’m sending this post simply to indicate that there is still a lot of things we don’t know about how our agrichemical products impact the total orchard environment. Given that uncertainty, I’m still willing to bet, based on our history in the Northeast, that limiting strep applications to blossom time in areas that average only two or three strep sprays per year will never result in selection for strep resistance even if growers occasionally use one additional application after bloom to suppress trauma blight following hail or wind storms. However, if you will need more than four strep sprays on a regular basis, that makes me a bit less comfortable and you may want to break up that string of strep sprays by including Kasumin in your blossom spray strategies. On Mar 21, 2015, at 10:09 PM, Brian Heatherington beechcreekfa...@earthlink.netmailto:beechcreekfa...@earthlink.net wrote: No resistance from bloom sprays is good news. I have had no control problems with copper prior to green tip, strep timed by Maryblyt, Apogee to minimize pruning/harden shoots to possible shoot blight, and control of aphids/leafhoppers at petal fall/1st cover. A few years ago, however, we had a long, extended bloom with Pink Lady. Maryblyt called for a total of 6 sprays (predicted EIP over 100), which exceeds most recommendations of 4 max. I went with the 6 applications and came out OK, but have always wondered if this might trigger resistance. I will stick with strep during bloom and leave the Kasumin for those that need it. I did just put in a block of CrimsonCrisp and haven't thought about putting copper on them. Good advice. Thanks. On 3/21/2015 10:36 AM, David A. Rosenberger wrote: While Kasugamycin works about as well as streptomycin, oxytetracycline is generally a bit less effective and has the disadvantage of preventing bacterial multiplication without killing off all of the bacteria contacted by the spray. Of the three antibiotics, it is my understanding that only strep is absorbed into apple tissue, thereby giving it a bit of an edge over both of the other products, especially in cases where a few infections might have been initiated a few hours
Re: [apple-crop] Kasugamycin for fire blight
Hi Dave, I've wondered about this. In several of our orchards. All of the epiphytes all nearly have 100% of the population strep resistance even at the start of the season, so in theory no applications of strep would just as bad as several. The predominance changes over the season and it makes me wonder if one of the species that comes in later in the season is more like to transfer the plasmid. Also, feel like there probably has to active cankers or shoot blight to get some Ea present before the transfer could occure. The other bacteria seem to be better epiphytes and it's getting hard to even get Ea on shoots in Kiersten's experiments. We do need more seasons of data though. One theory about how strep resistance develops (and I think this is still valid) is that the initial selection for resistance is not in Erwinia, but rather in other bacteria that exist in the orchard environment. These other bacterial species may then pass on the strep-resistance genes to Erwinia because bacteria have mechanisms for transferring useful DNA (i.e., DNA that enhances survival) from one species to another. When strep is applied to apple and pear flowers in springtime, the over-all bacterial populations on leaves and in soil are still rather low because bacterial population build slowly as plants and soil warm up. Therefore, there is less selection pressure for resistance in the non-Erwinia species when strep is applied during bloom as compared to after bloom. Bacterial populations in the orchard environment increase very rapidly as temperatures rise, so summer applications of strep impact a much larger universe of bacteria and therefore are presumed to be more likely to trigger resistance that can later be transferred to Erwinia. -- Kerik D. Cox, Ph.D., Associate Professor Plant Pathology and Plant-Microbe Biology Section School of Integrative Plant Science Cornell University 221 Barton Lab NYSAES 630 West North Street Geneva, NY 14456 USA E-mail: kd...@cornell.edu Faculty Office: (315) 787-2401 Fruit Pathology Lab: (315) 787-2402 FAX: (315) 787-2389 ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Kasugamycin for fire blight
I should be at 4 sprays or less (3 last year) most of the time. The six sprays occurred after the "year without a winter" several years ago, when the low for the entire winter was 15F and that was only reached twice. We were 5 below here last year, and normally get plenty of consistent chill hours, which results in a uniform bloom. The need for alternate products will not be common. We're reaching tight cluster here this week, and projected bloom looks very consistent and uniform. In future years, when Kasumin drops in price and becomes more available, I think it might be a good option if a protracted bloom shows up again. I should mention that this problem has been unique to Pink Lady/Cripps Pink as its low chill requirement makes it a blooming machine. It is however the best apple we grow here, and it stores very well along with Fuji and Goldrush. Fascinating stuff: the transfer of DNA from other bacteria. I had no idea. On 3/23/2015 9:44 AM, David A. Rosenberger wrote: I should have added one more thought: Probably the very best strategy for avoiding selection for strep-resistant Erwinia amylova (Ea) is to prevent fire blight from becoming established in the orchard in the first place. To that end, the integrated strategy that Brian described (copper early, strep as required by a timing model, and Apogee to make shoots more resistant) reduces the likelihood that he will ever have visible fire blight or even high populations of Ea in his blocks. You can’t get resistance if the pathogen of interest never becomes established, even if non-Erwinia species in the sprayed blocks may have detectable levels of strep-resistance. On Mar 23, 2015, at 9:04 AM, David A. Rosenberger da...@cornell.edu wrote: Thanks for the follow-up information, Brian. Using six strep sprays during bloom, while I can see how it may be necessary, does make me a bit more uneasy about selecting for strep resistance. In northeastern United States, we often need two sprays during bloom, sometimes three, and very rarely four. I’ve not been concerned about using four sprays if needed. However, I doubt that anyone has enough experience with the impact of 6 early-season sprays to be certain of the outcome. One theory about how strep resistance develops (and I think this is still valid) is that the initial selection for resistance is not in Erwinia, but rather in other bacteria that exist in the orchard environment. These other bacterial species may then pass on the strep-resistance genes to Erwinia because bacteria have mechanisms for transferring useful DNA (i.e., DNA that enhances survival) from one species to another. When strep is applied to apple and pear flowers in springtime, the over-all bacterial populations on leaves and in soil are still rather low because bacterial population build slowly as plants and soil warm up. Therefore, there is less selection pressure for resistance in the non-Erwinia species when strep is applied during bloom as compared to after bloom. Bacterial populations in the orchard environment increase very rapidly as temperatures rise, so summer applications of strep impact a much larger universe of bacteria and therefore are presumed to be more likely to trigger resistance that can later be transferred to Erwinia. Strep is broken down in sunlight, but each application may contribute to residual accumulations in the ground cover, duff, or soil surface where the accumulation from multiple applications might persist long enough to enhance selection for resistance in soil bacteria as soil temperatures rise. I really don’t know how long strep persists in orchard soils, and there is undoubtedly huge variations depending on rainfall, orchard cover, soil type, etc. I’m sending this post simply to indicate that there is still a lot of things we don’t know about how our agrichemical products impact
Re: [apple-crop] Kasugamycin for fire blight
Would oxytetracycline be an effective economical alternative in those borderline instances? Mo Tougas On Fri, Mar 20, 2015 at 10:18 PM, Smith, Timothy J smit...@wsu.edu wrote: HI Brian, Yes, that would work well. Kasumin has worked well in Michigan. Tim *From:* apple-crop-boun...@virtualorchard.net [mailto: apple-crop-boun...@virtualorchard.net] *On Behalf Of *Brian Heatherington *Sent:* Thursday, March 19, 2015 1:29 PM *To:* Apple-Crop *Subject:* [apple-crop] Kasugamycin for fireblight Planning ahead for bloom: In an area where fireblight is still effectively controlled by streptomycin, would it be advisable to rotate to kasugamycin for one or more sprays, purely for resistance management? Perhaps when models show a borderline need for application? How effective has Kasumin been in Michigan? -- Brian Heatherington Beech Creek Farms and Orchards 2011 Georgia Highway 120 Tallapoosa, GA 30176 770-714-8381 ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop -- Maurice Tougas Tougas Family Farm Northborough,MA 01532 508-450-0844 ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Kasugamycin for fire blight
No resistance from bloom sprays is good news. I have had no control problems with copper prior to green tip, strep timed by Maryblyt, Apogee to minimize pruning/harden shoots to possible shoot blight, and control of aphids/leafhoppers at petal fall/1st cover. A few years ago, however, we had a long, extended bloom with Pink Lady. Maryblyt called for a total of 6 sprays (predicted EIP over 100), which exceeds most recommendations of 4 max. I went with the 6 applications and came out OK, but have always wondered if this might trigger resistance. I will stick with strep during bloom and leave the Kasumin for those that need it. I did just put in a block of CrimsonCrisp and haven't thought about putting copper on them. Good advice. Thanks. On 3/21/2015 10:36 AM, David A. Rosenberger wrote: While Kasugamycin works about as well as streptomycin, oxytetracycline is generally a bit less effective and has the disadvantage of preventing bacterial multiplication without killing off all of the bacteria contacted by the spray. Of the three antibiotics, it is my understanding that only strep is absorbed into apple tissue, thereby giving it a bit of an edge over both of the other products, especially in cases where a few infections might have been initiated a few hours before the product is applied. Kasugamycin, like strep, kills bacterial cells that it contacts, but it has the disadvantage of being considerably more expensive than strep. Some of my pathologist colleagues may disagree with me, but I see no reason to pay the extra price for kasugamycin in established orchards that have no history of strep resistance. (An exception would be in countries like Canada where the strep labels allow a maximum of 3 applications/yr.) In eastern New York and New England, we have used strep exclusively for fire blight control for more than 60 years without encountering resistance. Resistance to strep has only appeared in regions where nurseries or fruit growers have used it repeatedly during summer (as many as 12 times/yr) to prevent shoot blight. Thus, there is an abundance of observational evidence that repeated applications of strep after bloom DEFINITELY WILL result in strep-resistant Erwinia amylovora (Ea) whereas, so far as I know, there is absolutely no evidence that multiple applications during bloom have ever resulted in strep resistance. Thus, I would argue that strep is still the cheapest, most effective, and most proven product for controlling blossom blight, and I see no reason to use other products except where strep resistance has been documented or is suspected due to failure of well-timed strep sprays. In fact, alternating with biologicals or with oxytet may actually be counter-productive because they may allow more bacteria to survive, thereby leaving larger populations to be controlled by strep and/or allowing some infections to become established and thus carry the disease through until the next year. Given that there is increasing evidence that fire blight is sometimes present in symptomless nursery trees, one could argue that strep-resistance may show up anywhere as a result of distribution via nursery trees. This is a very real and valid concern. To diminish the likelihood that strep-resistance might be introduced with nursery stock, we in NY have been recommending that all newly planted trees be sprayed with copper shortly after they break bud and then with copper plus strep during bloom. The basis for this recommendation is that copper should knock out strep-resistant Ea on plant surfaces whereas strep will still be more effective for preventing local sources of Ea from infecting flowers on newly planted trees. Using several sprays of Kasugamycin on newly planted trees when they produce flowers during the first year of planting might be even better than copper plus strep for preventing establishment of strep-resistance brought in with nursery stock. Finally, it should be obvious that all new apple plantings should be observed very carefully for evidence of fire blight symptoms for several months after the trees begin to grow, and any diseased trees should be removed immediately. We probably had more fire blight in newly planted trees in 2014 than in any prior year, but it is not a new phenomenon. I ended up with some blight-infested nursery trees in 1986 when I was establishing one of my research orchards. Both in that
Re: [apple-crop] Kasugamycin for fire blight
HI Brian, Yes, that would work well. Kasumin has worked well in Michigan. Tim From: apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Brian Heatherington Sent: Thursday, March 19, 2015 1:29 PM To: Apple-Crop Subject: [apple-crop] Kasugamycin for fireblight Planning ahead for bloom: In an area where fireblight is still effectively controlled by streptomycin, would it be advisable to rotate to kasugamycin for one or more sprays, purely for resistance management? Perhaps when models show a borderline need for application? How effective has Kasumin been in Michigan? -- Brian Heatherington Beech Creek Farms and Orchards 2011 Georgia Highway 120 Tallapoosa, GA 30176 770-714-8381 ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
