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.ca<mailto: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)
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