Re: [apple-crop] Looking for comments on fire blight management
Re: virulence of E. amylovora. Here is another good (in depth) article. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4490474/ best regards, Tim Smith From: apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Smith, Timothy J Sent: Tuesday, August 18, 2015 1:17 PM To: Apple-crop discussion list apple-crop@virtualorchard.net Subject: Re: [apple-crop] Looking for comments on fire blight management Re: The bacteria (in the hypanthium) need to thrive in the nectary in order to reach numbers sufficient to switch on their virulence. Once this is accomplished you have an infection. Do you have a good reference for me on this specific topic? When I reviewed the literature, I only found a few things from Pusey. This might explain some cases. Hi Richard, Yes, bacteriologist have been dropping the term “quorum sensing” over the past few years, which is a trait within both pathogenic and beneficial bacteria that allows them to be non-virulent when in low numbers, then, when they sense when numbers are sufficient to overwhelm the host, they all “switch on” their virulence, or if beneficial, the next action they are building up to. This may allow them to avoid triggering host defense mechanisms until it is too late for the plant to successfully defend itself. Look on Google for that term “Quorum sensing” + Erwnia amylovora and you will find some good recent journal articles. Try those below for a start. https://en.wikipedia.org/wiki/Quorum_sensinghttps://urldefense.proofpoint.com/v1/url?u=https://en.wikipedia.org/wiki/Quorum_sensingk=EWEYHnIvm0nsSxnW5y9VIw%3D%3D%0Ar=VR1vaGJPOzxhk9dUVIL5%2Bg%3D%3D%0Am=jW7ergoT5LqD39LktaREL2bgAhj7venJm67AYoMtfoI%3D%0As=030042055b8c2df784ceff8c21df217091314157e37d12539e4cc7a4c600bfb0 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1082838/https://urldefense.proofpoint.com/v1/url?u=http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1082838/k=EWEYHnIvm0nsSxnW5y9VIw%3D%3D%0Ar=VR1vaGJPOzxhk9dUVIL5%2Bg%3D%3D%0Am=jW7ergoT5LqD39LktaREL2bgAhj7venJm67AYoMtfoI%3D%0As=de38e438a398996dab0c9c6a38d5316c3526d9a981b0b0f5f60b8c009e1aa56f http://www.ncbi.nlm.nih.gov/pubmed/17092294https://urldefense.proofpoint.com/v1/url?u=http://www.ncbi.nlm.nih.gov/pubmed/17092294k=EWEYHnIvm0nsSxnW5y9VIw%3D%3D%0Ar=VR1vaGJPOzxhk9dUVIL5%2Bg%3D%3D%0Am=jW7ergoT5LqD39LktaREL2bgAhj7venJm67AYoMtfoI%3D%0As=6010e2c1671af0092105563ed81394abfad76ed01012d04e7b230ef89c997ba2 From: apple-crop-boun...@virtualorchard.netmailto:apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Weinzierl, Richard A Sent: Friday, August 14, 2015 2:27 PM To: Apple-crop discussion list apple-crop@virtualorchard.netmailto:apple-crop@virtualorchard.net Subject: Re: [apple-crop] Looking for comments on fire blight management U of I Kane County Extension Office, 535 South Randall Road, St. Charles, IL Rick From: apple-crop-boun...@virtualorchard.netmailto:apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Vincent Philion Sent: Friday, August 14, 2015 12:49 PM To: Apple-Crop apple-crop@virtualorchard.netmailto:apple-crop@virtualorchard.net Subject: Re: [apple-crop] Looking for comments on fire blight management Hi Tim! nice to read you! I think there are more sources of fire blight bacteria in the general environment in the northeastern USA due to your woodlots and forests (with feral apples and native hosts such as Hawthorne) as contrasted with the treeless conditions around many eastern Washington orchards. I agree! But still is fascinating to see whole areas without FB and others with FB, despite similar weather. We often make “false positive” predictions because of this = conditions are great for FB, but not FB develops because bacteria are simply not there. We have nice qPCR data throughout bloom to prove it. The bacteria (in the hypanthium) need to thrive in the nectary in order to reach numbers sufficient to switch on their virulence. Once this is accomplished you have an infection. Do you have a good reference for me on this specific topic? When I reviewed the literature, I only found a few things from Pusey. This might explain some cases. We can learn a great deal about interpreting models by looking at the weather data around the time that we are fairly certain that isolated infection events occurred. We can also look at when expected infections did not occur. It would be very helpful to me if any of you would share weather data including rainfall, hourly temperature (or daily temps) and especially leaf wetness readings. Please send data that covers days from first bloom to about 3 to 4 weeks after petal fall. Excel files are a real time saver. We’re Also looking for the same type of data…! Vincent ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Looking for comments on fire blight management
Re: The bacteria (in the hypanthium) need to thrive in the nectary in order to reach numbers sufficient to switch on their virulence. Once this is accomplished you have an infection. Do you have a good reference for me on this specific topic? When I reviewed the literature, I only found a few things from Pusey. This might explain some cases. Hi Richard, Yes, bacteriologist have been dropping the term “quorum sensing” over the past few years, which is a trait within both pathogenic and beneficial bacteria that allows them to be non-virulent when in low numbers, then, when they sense when numbers are sufficient to overwhelm the host, they all “switch on” their virulence, or if beneficial, the next action they are building up to. This may allow them to avoid triggering host defense mechanisms until it is too late for the plant to successfully defend itself. Look on Google for that term “Quorum sensing” + Erwnia amylovora and you will find some good recent journal articles. Try those below for a start. https://en.wikipedia.org/wiki/Quorum_sensing http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1082838/ http://www.ncbi.nlm.nih.gov/pubmed/17092294 From: apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Weinzierl, Richard A Sent: Friday, August 14, 2015 2:27 PM To: Apple-crop discussion list apple-crop@virtualorchard.net Subject: Re: [apple-crop] Looking for comments on fire blight management U of I Kane County Extension Office, 535 South Randall Road, St. Charles, IL Rick From: apple-crop-boun...@virtualorchard.netmailto:apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Vincent Philion Sent: Friday, August 14, 2015 12:49 PM To: Apple-Crop apple-crop@virtualorchard.netmailto:apple-crop@virtualorchard.net Subject: Re: [apple-crop] Looking for comments on fire blight management Hi Tim! nice to read you! I think there are more sources of fire blight bacteria in the general environment in the northeastern USA due to your woodlots and forests (with feral apples and native hosts such as Hawthorne) as contrasted with the treeless conditions around many eastern Washington orchards. I agree! But still is fascinating to see whole areas without FB and others with FB, despite similar weather. We often make “false positive” predictions because of this = conditions are great for FB, but not FB develops because bacteria are simply not there. We have nice qPCR data throughout bloom to prove it. The bacteria (in the hypanthium) need to thrive in the nectary in order to reach numbers sufficient to switch on their virulence. Once this is accomplished you have an infection. Do you have a good reference for me on this specific topic? When I reviewed the literature, I only found a few things from Pusey. This might explain some cases. We can learn a great deal about interpreting models by looking at the weather data around the time that we are fairly certain that isolated infection events occurred. We can also look at when expected infections did not occur. It would be very helpful to me if any of you would share weather data including rainfall, hourly temperature (or daily temps) and especially leaf wetness readings. Please send data that covers days from first bloom to about 3 to 4 weeks after petal fall. Excel files are a real time saver. We’re Also looking for the same type of data…! Vincent ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Looking for comments on fire blight management
Hello Tim! thank you for the article. The last time I reviewed this, quorom sensing was not described for E. amylovora. Vincent Le 18 août 2015 à 17:23, Smith, Timothy J smit...@wsu.edumailto:smit...@wsu.edu a écrit : Re: virulence of E. amylovora. Here is another good (in depth) article. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4490474/ best regards, Tim Smith From: apple-crop-boun...@virtualorchard.netmailto:apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Smith, Timothy J Sent: Tuesday, August 18, 2015 1:17 PM To: Apple-crop discussion list apple-crop@virtualorchard.netmailto:apple-crop@virtualorchard.net Subject: Re: [apple-crop] Looking for comments on fire blight management Re: The bacteria (in the hypanthium) need to thrive in the nectary in order to reach numbers sufficient to switch on their virulence. Once this is accomplished you have an infection. Do you have a good reference for me on this specific topic? When I reviewed the literature, I only found a few things from Pusey. This might explain some cases. Hi Richard, Yes, bacteriologist have been dropping the term “quorum sensing” over the past few years, which is a trait within both pathogenic and beneficial bacteria that allows them to be non-virulent when in low numbers, then, when they sense when numbers are sufficient to overwhelm the host, they all “switch on” their virulence, or if beneficial, the next action they are building up to. This may allow them to avoid triggering host defense mechanisms until it is too late for the plant to successfully defend itself. Look on Google for that term “Quorum sensing” + Erwnia amylovora and you will find some good recent journal articles. Try those below for a start. https://en.wikipedia.org/wiki/Quorum_sensinghttps://urldefense.proofpoint.com/v1/url?u=https://en.wikipedia.org/wiki/Quorum_sensingk=EWEYHnIvm0nsSxnW5y9VIw%3D%3D%0Ar=VR1vaGJPOzxhk9dUVIL5%2Bg%3D%3D%0Am=jW7ergoT5LqD39LktaREL2bgAhj7venJm67AYoMtfoI%3D%0As=030042055b8c2df784ceff8c21df217091314157e37d12539e4cc7a4c600bfb0 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1082838/https://urldefense.proofpoint.com/v1/url?u=http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1082838/k=EWEYHnIvm0nsSxnW5y9VIw%3D%3D%0Ar=VR1vaGJPOzxhk9dUVIL5%2Bg%3D%3D%0Am=jW7ergoT5LqD39LktaREL2bgAhj7venJm67AYoMtfoI%3D%0As=de38e438a398996dab0c9c6a38d5316c3526d9a981b0b0f5f60b8c009e1aa56f http://www.ncbi.nlm.nih.gov/pubmed/17092294https://urldefense.proofpoint.com/v1/url?u=http://www.ncbi.nlm.nih.gov/pubmed/17092294k=EWEYHnIvm0nsSxnW5y9VIw%3D%3D%0Ar=VR1vaGJPOzxhk9dUVIL5%2Bg%3D%3D%0Am=jW7ergoT5LqD39LktaREL2bgAhj7venJm67AYoMtfoI%3D%0As=6010e2c1671af0092105563ed81394abfad76ed01012d04e7b230ef89c997ba2 From: apple-crop-boun...@virtualorchard.netmailto:apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Weinzierl, Richard A Sent: Friday, August 14, 2015 2:27 PM To: Apple-crop discussion list apple-crop@virtualorchard.netmailto:apple-crop@virtualorchard.net Subject: Re: [apple-crop] Looking for comments on fire blight management U of I Kane County Extension Office, 535 South Randall Road, St. Charles, IL Rick From: apple-crop-boun...@virtualorchard.netmailto:apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Vincent Philion Sent: Friday, August 14, 2015 12:49 PM To: Apple-Crop apple-crop@virtualorchard.netmailto:apple-crop@virtualorchard.net Subject: Re: [apple-crop] Looking for comments on fire blight management Hi Tim! nice to read you! I think there are more sources of fire blight bacteria in the general environment in the northeastern USA due to your woodlots and forests (with feral apples and native hosts such as Hawthorne) as contrasted with the treeless conditions around many eastern Washington orchards. I agree! But still is fascinating to see whole areas without FB and others with FB, despite similar weather. We often make “false positive” predictions because of this = conditions are great for FB, but not FB develops because bacteria are simply not there. We have nice qPCR data throughout bloom to prove it. The bacteria (in the hypanthium) need to thrive in the nectary in order to reach numbers sufficient to switch on their virulence. Once this is accomplished you have an infection. Do you have a good reference for me on this specific topic? When I reviewed the literature, I only found a few things from Pusey. This might explain some cases. We can learn a great deal about interpreting models by looking at the weather data around the time that we are fairly certain that isolated infection events occurred. We can also look at when expected infections did not occur. It would be very helpful to me if any of you would share weather data including rainfall, hourly temperature (or daily temps) and especially leaf wetness readings. Please send data that covers days
Re: [apple-crop] Looking for comments on fire blight management
Hi Dan! The best we have so far is that it was so dry during bloom in most areas that even though epiphytic populations of bacteria were tremendous, they never got washed into flowers to cause infection. Another possibility is that the extremely dry weather suppressed bacterial growth, something not taken into account in the models. The first hypothesis would be my guest. I don’t think bacteria would be inhibited to grow on stigma in dry weather. But high epiphytic populations and no infection trigger are not rare. Vincent ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Looking for comments on fire blight management
Hi! Maine had two bouts of fire blight weather during bloom, one at very beginning and second at very end. We rarely observe symptoms in relation to the first recorded infection event during bloom. Actually, while validating the RIMpro-erwinia model (http://www.actahort.org/books/896/896_43.htm), we observed that FB was better predicted starting from the 2nd infection event. Johnson and Stockwell regularly report that Erwinia populations are too low to detect in early bloom, so it would be nice to understand a bit more what’s going on early bloom. I imagine moving bacteria from overwintering cankers to flowers as they open occurs more slowly than we think, despite temperatures favorable for FB. Originally fire blight was not a disease that required attention in Maine. That era ended about 15 years ago. We have the same story up here. Unfortunately. ;-) with only one or two strikes, but a few with considerably more. Unfortunately I think the trees are on M26. Across Maine. there seems to be much more fire blight on Paula Red than other cultivars this year. Honeycrisp and Cortland in this same block hardly affected. Timing of bloom with weather favorable for FB during Paulared bloom? be any more helpful than one? Post harvest copper make any sense? Nope. Reply: “ It should slow down with trees ceasing terminal growth. Makes no sense to spend time pruning out FB from August to October. Wait November! (After harvest) where appropriate to reduce shoot growth and thus shoot blight spread. Daily monitoring and removal of fire blight strikes starting a petal fall until end of August. Why end of August? Don’t leave fire bight cuttings in the orchard as fire blight bacterial can remain active in dried ooze for 2 years. Burn, bury, or compost the fire blight cuttings. I don’t think you need to worry about prunings. Really. 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] Looking for comments on fire blight management
Hi Tim! nice to read you! I think there are more sources of fire blight bacteria in the general environment in the northeastern USA due to your woodlots and forests (with feral apples and native hosts such as Hawthorne) as contrasted with the treeless conditions around many eastern Washington orchards. I agree! But still is fascinating to see whole areas without FB and others with FB, despite similar weather. We often make “false positive” predictions because of this = conditions are great for FB, but not FB develops because bacteria are simply not there. We have nice qPCR data throughout bloom to prove it. The bacteria (in the hypanthium) need to thrive in the nectary in order to reach numbers sufficient to switch on their virulence. Once this is accomplished you have an infection. Do you have a good reference for me on this specific topic? When I reviewed the literature, I only found a few things from Pusey. This might explain some cases. We can learn a great deal about interpreting models by looking at the weather data around the time that we are fairly certain that isolated infection events occurred. We can also look at when expected infections did not occur. It would be very helpful to me if any of you would share weather data including rainfall, hourly temperature (or daily temps) and especially leaf wetness readings. Please send data that covers days from first bloom to about 3 to 4 weeks after petal fall. Excel files are a real time saver. We’re Also looking for the same type of data…! Vincent ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Looking for comments on fire blight management
U of I Kane County Extension Office, 535 South Randall Road, St. Charles, IL Rick From: apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Vincent Philion Sent: Friday, August 14, 2015 12:49 PM To: Apple-Crop apple-crop@virtualorchard.net Subject: Re: [apple-crop] Looking for comments on fire blight management Hi Tim! nice to read you! I think there are more sources of fire blight bacteria in the general environment in the northeastern USA due to your woodlots and forests (with feral apples and native hosts such as Hawthorne) as contrasted with the treeless conditions around many eastern Washington orchards. I agree! But still is fascinating to see whole areas without FB and others with FB, despite similar weather. We often make “false positive” predictions because of this = conditions are great for FB, but not FB develops because bacteria are simply not there. We have nice qPCR data throughout bloom to prove it. The bacteria (in the hypanthium) need to thrive in the nectary in order to reach numbers sufficient to switch on their virulence. Once this is accomplished you have an infection. Do you have a good reference for me on this specific topic? When I reviewed the literature, I only found a few things from Pusey. This might explain some cases. We can learn a great deal about interpreting models by looking at the weather data around the time that we are fairly certain that isolated infection events occurred. We can also look at when expected infections did not occur. It would be very helpful to me if any of you would share weather data including rainfall, hourly temperature (or daily temps) and especially leaf wetness readings. Please send data that covers days from first bloom to about 3 to 4 weeks after petal fall. Excel files are a real time saver. We’re Also looking for the same type of data…! Vincent ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Looking for comments on fire blight management
Hello Everyone, Re: Fire Blight and models. I was quite interested in the comment that despite the models indicating high risk, that you generally did not experience much blight this year.Also, that it may have been the abnormally dry conditions that may explain this. This situation occurs more often than not in the Pacific Northwest. The infection process modeled by both MaryBlyt and CougarBlight requires (in this order): First, Open blossoms, something easy to see, but often overlooked post primary bloom, when secondary bloom are often present especially on trees with dwarfing rootstocks. Second, Contamination of the stigma surface by E. a. bacteria, which is difficult to detect rapidly, but there is ongoing research on this issue. “CougarBlight” asks you to adjust your temperature risk thresholds and use your orchard history and judgment here. This contamination is not present on most flowers in most orchards, but if there are cankers nearby, this situation degrades rapidly, and many flowers are contaminated, the closer to the canker source, the higher the risk. I think there are more sources of fire blight bacteria in the general environment in the northeastern USA due to your woodlots and forests (with feral apples and native hosts such as Hawthorne) as contrasted with the treeless conditions around many eastern Washington orchards. Third, Sufficient heat over sufficient time to enable the bacterial colony to reach the numbers necessary to cause flower infection. There is an interaction between this factor and the number two factor. Larger initial colony size will reduce the amount of time and total heat necessary to colony to reach this hundred thousand to 1 million bacteria colony size necessary for infection. IT sounds as if these conditions were met very well in the East this season. Fourth, the sufficiently contaminated flowers must be lightly wetted to allow the bacteria to move from the stigma surface into the nectaries. Then the battle begins. The bacteria need to thrive in the nectary in order to reach numbers sufficient to switch on their virulence. Once this is accomplished you have an infection. In the Pacific Northwest we have plentiful supply of open apple and pear flowers over an extended period of time. Fire blight is relatively rare in any given region most seasons, so most growers can assume little pressure from the bacteria during most seasons. We spent a lot of time emphasizing sanitation because a little fire blight one year can carry over and lead to great deal of fire blight the next year. Because of this documented common lack of contamination of flowers by E. a., we very often experience a series of days of temperatures sufficient to lead to fire blight, but with only scattered subsequent fire blight showing up over the next two or three weeks. We are often able to attribute that scattered blight to dew formation on flowers, as it often occurs in areas that are more prone to dew, such as frost pockets or other low areas in the orchard. When we have a rainy day after a series of warm days, those areas that have been in bloom during those warm days have increased experience with more common and severe fire blight, which in this case depends on the presence or absence of E. amylovora. CougarBlight was developed where blossom wetting is an exceptional event. I try to counsel people using this model in areas where blossom wetting is common to look at the heat risk as primary, and to assume the blossom wetting will occur, often almost every night. Dew and rain are the rule rather than the exception in many areas where apples and pears are grown. This doesn't change the principle of the model that heat is the driver for infection, the blossom wetting is the trigger for the infection event. We can learn a great deal about interpreting models by looking at the weather data around the time that we are fairly certain that isolated infection events occurred. We can also look at when expected infections did not occur. It would be very helpful to me if any of you would share weather data including rainfall, hourly temperature (or daily temps) and especially leaf wetness readings. Please send data that covers days from first bloom to about 3 to 4 weeks after petal fall. Excel files are a real time saver. Thank you. Tim Smith WSU (Emeritus) 4. From: apple-crop-boun...@virtualorchard.net [mailto:apple-crop-boun...@virtualorchard.net] On Behalf Of Daniel Cooley Sent: Wednesday, August 12, 2015 11:22 AM To: Apple-crop discussion list apple-crop@virtualorchard.net Subject: Re: [apple-crop] Looking for comments on fire blight management A group of us wrote the article attached for the UMass/Rutgers publication Fruit Notes/New Jersey Horticultural News. http://umassfruitnotes.com/v80n2/Cover802.htmlhttps://urldefense.proofpoint.com/v1/url?u=http://umassfruitnotes.com/v80n2/Cover802.htmlk
[apple-crop] Looking for comments on fire blight management
Maine had two bouts of fire blight weather during bloom, one at very beginning and second at very end. I suspect that the rapid shift to hot days just before and leading into bloom (after slow cool period from bud break to pink) may have shocked the trees and resulted in more straggled bloom than usual. While we have not had an epic fire blight year comparable to what other states have experienced in other recent years, there seems to be a transition this year. Originally fire blight was not a disease that required attention in Maine. That era ended about 15 years ago. Then, fire blight used to be something that showed up in a few orchards in some years, usually but not always relatively minor extent. This year, it seems that most orchards have a little bit of fire blight. No devastating epidemics this year, but a lot more than growers want to see. Following is off the cuff reply to apple grower dealing with fire blight strikes that keep showing up in Paula Reds. He was wondering if he can ever dig his way back out of recurring fire blight infections. The fire blight has been in the block at low level for past 3-4 years and despite repeated, (though not always immediate) sanitation removal, it is back again this year. Still not at catastrophic level but it does seem to be increasing year to year. Rough guess is that this year 20-30% of Paula Red trees in the block are affected. Most with only one or two strikes, but a few with considerably more. Unfortunately I think the trees are on M26. Across Maine. there seems to be much more fire blight on Paula Red than other cultivars this year. Honeycrisp and Cortland in this same block hardly affected. I'm looking for comments. Did I miss any key points? Anything erroneous? I'm aware of kasugamycin and other alternative materials, but this wasn't the place for getting into that kind of detail. I don't think we have strep resistant E.a., should get some more samples tested though. Is two early season copper applications likely to be any more helpful than one? Post harvest copper make any sense? Thanks for your help, Glen ** Grower message: Fire blight looks like heck in the Paula Red’s! We are just cutting what we can and summer pruning. Is there no hope? Reply:It should slow down with trees ceasing terminal growth. I'm sure you have other things you'd rather be doing, but getting rid of the fire blight now will at least cut down work load later, and might be the thing that prevents further spread that gets to the point where you are looking at replacing trees. Copper every spring. Strep on hand so you can react quickly to blossom blight infection period forecast that you need to check daily because they can change so fast. Factor fire blight into cultivar and rootstock selection. Blossom removal on first year trees.Fertility management to prevent overly lush growth. Consider Apogee where appropriate to reduce shoot growth and thus shoot blight spread. Daily monitoring and removal of fire blight strikes starting a petal fall until end of August. Strep on hand in case hail or strong wind storm creates risk of fire blight spread (up until strep PHI gets in the way). Be careful that you don't mix summer pruning and fire blight removal. They should be handled as two separate jobs.I suspect it would be best to complete fire blight removal first. Summer pruning before fire blight removal will create open wound surfaces. Going in after to handle fire blight material could mobilize bacteria which can infect those wounds. Thus, better to remove fire blight before creating summer pruning wounds. Same thing applies to sucker removal. Thoroughly sterilize tools after using them for fire blight removal before using for anything else. Ugly stub pruning to allow winter removal of cankers created by sanitation cuts. Don't leave fire bight cuttings in the orchard as fire blight bacterial can remain active in dried ooze for 2 years. Burn, bury, or compost the fire blight cuttings. It is possible to work your way out of a moderate fire blight outbreak. But it can take an extended period of sanitation vigilance. There are no silver bullets. ** -- Glen Koehler University of Maine Cooperative Extension Pest Management Office Voice: Office 207-581-3882, Cell 207-485-0918 491 College Avenue, Orono, ME 04473 ___ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
Re: [apple-crop] Looking for comments on fire blight management
There seemed to be a lot of late, tail-end bloom(rat-tail) bloom this year especially on Paulared. Every tree had 3-4 clusters on borse shoots into mid-June. We did use one strep spray on several varieties with this bloom. Also it is probably not a good idea to neglect cutting root suckers that may eventually bloom and be susceptible to fire blight. On Tue, Aug 11, 2015 at 12:07 PM, Glen Koehler glen.koeh...@maine.edu wrote: Maine had two bouts of fire blight weather during bloom, one at very beginning and second at very end. I suspect that the rapid shift to hot days just before and leading into bloom (after slow cool period from bud break to pink) may have shocked the trees and resulted in more straggled bloom than usual. While we have not had an epic fire blight year comparable to what other states have experienced in other recent years, there seems to be a transition this year. Originally fire blight was not a disease that required attention in Maine. That era ended about 15 years ago. Then, fire blight used to be something that showed up in a few orchards in some years, usually but not always relatively minor extent. This year, it seems that most orchards have a little bit of fire blight. No devastating epidemics this year, but a lot more than growers want to see. Following is off the cuff reply to apple grower dealing with fire blight strikes that keep showing up in Paula Reds. He was wondering if he can ever dig his way back out of recurring fire blight infections. The fire blight has been in the block at low level for past 3-4 years and despite repeated, (though not always immediate) sanitation removal, it is back again this year. Still not at catastrophic level but it does seem to be increasing year to year. Rough guess is that this year 20-30% of Paula Red trees in the block are affected. Most with only one or two strikes, but a few with considerably more. Unfortunately I think the trees are on M26. Across Maine. there seems to be much more fire blight on Paula Red than other cultivars this year. Honeycrisp and Cortland in this same block hardly affected. I'm looking for comments. Did I miss any key points? Anything erroneous? I'm aware of kasugamycin and other alternative materials, but this wasn't the place for getting into that kind of detail. I don't think we have strep resistant E.a., should get some more samples tested though. Is two early season copper applications likely to be any more helpful than one? Post harvest copper make any sense? Thanks for your help, Glen ** Grower message: Fire blight looks like heck in the Paula Red’s! We are just cutting what we can and summer pruning. Is there no hope? Reply:It should slow down with trees ceasing terminal growth. I'm sure you have other things you'd rather be doing, but getting rid of the fire blight now will at least cut down work load later, and might be the thing that prevents further spread that gets to the point where you are looking at replacing trees. Copper every spring. Strep on hand so you can react quickly to blossom blight infection period forecast that you need to check daily because they can change so fast. Factor fire blight into cultivar and rootstock selection. Blossom removal on first year trees.Fertility management to prevent overly lush growth. Consider Apogee where appropriate to reduce shoot growth and thus shoot blight spread. Daily monitoring and removal of fire blight strikes starting a petal fall until end of August. Strep on hand in case hail or strong wind storm creates risk of fire blight spread (up until strep PHI gets in the way). Be careful that you don't mix summer pruning and fire blight removal. They should be handled as two separate jobs.I suspect it would be best to complete fire blight removal first. Summer pruning before fire blight removal will create open wound surfaces. Going in after to handle fire blight material could mobilize bacteria which can infect those wounds. Thus, better to remove fire blight before creating summer pruning wounds. Same thing applies to sucker removal. Thoroughly sterilize tools after using them for fire blight removal before using for anything else. Ugly stub pruning to allow winter removal of cankers created by sanitation cuts. Don't leave fire bight cuttings in the orchard as fire blight bacterial can remain active in dried ooze for 2 years. Burn, bury, or compost the fire blight cuttings. It is possible to work your way out of a moderate fire blight outbreak. But it can take an extended period of sanitation vigilance. There are no silver bullets. ** -- Glen Koehler University of Maine Cooperative Extension Pest Management Office Voice: Office 207-581-3882, Cell 207-485-0918 491 College Avenue, Orono, ME 04473
