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 mailto: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 prevent shoot blight. Thus,
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 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 > t
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 mailto: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 mailto: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. Kasugamyci
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. Rosenbergerwrote: 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 impac