Yea, look at me, given my old(er) age -- the NRVART (Newspaper Readability Venturia Ascospore Release Threshold) depends on: the light level (civil twilight, nautical twilight, astronomical twilight? see: http://en.wikipedia.org/wiki/Twilight) , distance reading the Newspaper (far is probably better I am farsighted, oh not really, actually I am presbyoptic, see:http://en.wikipedia.org/wiki/Presbyopia), font size (obviously), and whether or not I can find my eye glasses. (Forgetfullness, sorry, not in Wikipedia, but my bi-focal glasses are no-line TransitionsTM, CriizalTM no-glare/reflections, about $250 each at Costco or WalMart if I buy the cheaper frames.) Oh, and does the NRVART include reading the newspaper on an iPad?
But BTW, I can perfectly relate to the PDBA fireblight index! Sorry to downgrade an otherwise excellent discussion! :-) Jon On Sun, Apr 24, 2011 at 6:20 PM, Dave Rosenberger <da...@cornell.edu> wrote: > Hey, Dan -- > I believe that the "reading a newspaper" threshold for ascospore > discharge was a verbal comment from either Gadoury or MacHardy. Given my > failing memory, I can't be absolutely certain that my recollection is > correct. Anyway, this may be one of those "rules of thumb" that never make > it into the scientific literature, probably for the same reasons that my > personal discomfort model for timing strep sprays for blossom blight will > never make it into a refereed journal. After all, we're concerned about > trying to calibrate leaf wetness meters: Just think about trying to > calibrate humans as biological sensors!! > >> David, >> >> The original night-time release study was published by MacHardy and >> Gadoury in 89. It's here: >> >> http://www.apsnet.org/publications/phytopathology/backissues/Documents/1989Articles/Phyto79n03_304.pdf >> >> In 98, Gadoury, Stensvand and Seem revised this to take into account some >> night-time release, saying that in high inoculum orchards night-time release >> could be a problem. That article is here: >> >> http://apsjournals.apsnet.org.silk.library.umass.edu/doi/pdfplus/10.1094/PHYTO.1998.88.9.902 >> >> I've been looking all over for the source article for Dave Rosenberger's >> Newspaper Readability Venturia Ascospore Release Threshold, but haven't >> found it. I did, however, find his Personal Discomfort Blight Alert for >> blossom blight: >> >> "... severe blossom blight infection periods often occur on days when >> moderate physical activity causes me to break into a noticeably >> uncomfortable sweat. The discomfort comes from a combination of high >> temperature, high humidity, and lack of acclimation to summer temperatures. >> If I sense PDBA conditions when trees are in bloom, then I know that a >> blossom blight spray is needed immediately." >> http://www.scaffolds.entomology.cornell.edu/2007/070507.html#disease >> >> Degree days and leaf wetness sensors are interesting and helpful, but >> sometimes nothing beats the low-tech approach! >> >> Dan >> >> On Apr 21, 2011, at 11:33 PM, David Doud wrote: >> >>> thank you Dave for the time and effort you put into this post - >>> >>> short of input from specmeters, I'll slightly exaggerate and say that >>> the Cornell model will predict scab infection after a short heavy dew, while >>> the WA model requires rainforest conditions for a couple of days before it >>> indicates concern - I made the assumption that if growing McIntosh in NY one >>> had better be very careful, while desert conditions don't provide the >>> humidity or inoculum to result in scab infections except under the most >>> severe circumstances - I talk to growers at the Ohio River and south and >>> they don't worry much about scab, it's a minor consideration in their >>> climate - >>> >>> the Mills table (and modified Mills - I attended a number of the MI IPM >>> schools in the '80s when Jones and Howitt and Bird and crew was cutting >>> edge) has been reliable here and referred to for as long as I have been >>> spraying apple trees - I used to get up in the middle of the night, check >>> temperatures, shake limbs to judge free moisture, then refer to the chart to >>> find out just how much trouble I was in - much, much easier to let the >>> instrument keep track of conditions - and until this little event, I hadn't >>> really considered that it would possible to confuse the program - I feel >>> lucky to have some decades of experience to guide decisions, hence the long >>> day today putting a protectant cover on in anticipation of the 4 wet days >>> forecast for the immediate future - >> >> > >>> >>> I have heard talk from various sources on the ascospore/light >>> association, but have never read any source material - can you point me >>> toward the research that led to this conclusion? >>> >>> I find nothing to disagree with and little to add to your observations >>> about decision factors - thank you - >>> David >>> >>> >>> >>> the Mills table has been an effective tool here >>> On Apr 21, 2011, at 11:13 AM, Dave Rosenberger wrote: >>> >>>> Hello, David -- >>>> I really don't know how the Spectrum instruments are programmed, >>>> and I don't know what they are using for the Washington scab model. Thus, >>>> this response may be of limited usefulness. >> >> >> I suspect that that the differences between the Cornell and the >> Mills (MI) models relate to two key differences among these models. Again, >> I don't know this for a fact because I don't know how Spectrum programmed >> their unit, but I would guess that the Mills (MI) model uses the modified >> Mills Table that was published by Al Jones and he put into the original >> Reuter-Stokes scab caster. If so, that program will not discount wetting >> periods that start after dark, and it will use slightly longer wetting >> requirements for light infections than those used by the Cornell model. >>>> >>>> The Cornell model presumably does not count wetting periods that >>>> start after dark because relatively few ascospores are released in the >>>> absence of light. In a high inoculum block, those few that do discharge at >>>> night can still create problems, but in most commercial blocks night-time >>>> discharge will not be significant, especially early in the season. In my >>>> opinion, ignoring night time discharge is a bit more risky by the time one >>>> gets to pink bud (when most ascospores are maturing), and it is absolutely >>>> foolhardy to ignore night time discharges between pink and petal fall if >>>> the >>>> rains in question come at the end of a relatively long warm dry period. In >>>> this latter situation, the swelling ascospores cause the pseudothecia to >>>> explode and the light-triggered release mechanism may be by-passed. >>>> The Cornell model was based on lab trials that showed ascospores >>>> can infect in the same relatively short periods that Bill Mills had >>>> initially described for secondary infections. Thus, the Cornell model will >>>> trigger 'infected' before the Mill's MI model. Although NY has adopted the >>>> 'Cornell model' because it is technically more correct, I still prefer the >>>> modified Mill's table that was developed by Jones (although I do believe in >>>> discounting night-time wetting, especially early in the season). >>>> Bill Mills developed his scab model by actually looking at what >>>> happened to trees outdoors. As a result, his model and the modified Mill's >>>> table from Al Jones actually represent an integration of minimum infection >>>> conditions AND spore numbers. Conidia are always produced in much greater >>>> quantities than ascospores under conditions in commercial orchards. Thus, >>>> with conidia, large quantities arrive and infect leaves within 6 hr at >>>> optimum temperatures. If you artificially put large quantities of >>>> ascospores on leaves, you also get infections within 6 hr at optimum >>>> temperatures. In reality, however, it takes some time for an economically >>>> significant dose of ascospores to arrive on leaves in a commercial orchard >>>> because there are relatively few of them. Mills and Al Jones therefore used >>>> 9 hr as the minimal wetting period at optimum temperatures to account for >>>> the fact that their data suggested it would require an extra three hours to >>>> accumulate an economically significant >> >>> dose of ascospore as compared to conidia. (Some of my plant pathology >>> colleagues my wish to quibble with these broad generalizations because I've >>> skipped a lot of details and also done some "reading between the lines." >>> Nevertheless, I think my general conclusions in comparing the two models are >>> valid.) >>>> >>>> The Cornell model also provides only a yes/no response to >>>> infection, whereas the original Mills table and the Jones version of the >>>> Mills table still provides gradations of light, moderate, or heavy >>>> infection >>>> based on duration of the wetting periods at various temperatures. Again, >>>> because ascospores are relatively limited in number in most orchards, it >>>> makes sense to parse out the severity of infection for ascospores whereas >>>> just the minimal wetting/temperature requirements are enough to trigger >>>> conidial infections if conidia are present because conidia are either >>>> present in large numbers or not at all. >> >> >> By having information on light-moderate-heavy infection, one can >> adjust one's on-site risk factors based on other details of the specific >> orchard situation. For example, in a clean orchard with trees just at green >> tip, I would ignore the "light" Mills period and begin to worry only after >> triggering at least a "moderate" Mill's period because there are so few >> spores at green tip that the marginal conditions for a light infection >> period will be unlikely to result in noticeable scab. However, even in a >> clean orchard, I would NOT ignore a light Mills period when trees are at >> tight cluster or pink. >> >> I hope others will chime in on what differences may be >> incorporated into the Washington model. >>>> >>>>> Is anyone else on this list using Spectrum instruments to monitor >>>>> weather and model disease? - I've had a 'Watchdog' for several years now, >>>>> and yesterday had an anomaly, with complete disagreement and >>>>> inconsistencies >>>>> between the three scab models - >>>>> >>>>> The software uses models from Cornell, Washington State, and Mills >>>>> (MI) - I'm used to Cornell being very conservative and WA being the >>>>> opposite >>>>> - this event, Cornell indicated 'infected', WA 'none', and Mills 'heavy' - >>>>> I've never modeled an event with Mills being 'heavy' and WA 'none' - >>>>> >>>>> circumstances were such that we were cruising along in the lower 40'sF >>>>> monday and then an overnight rain till 7AM tues morning - a two hour dry >>>>> period, followed by a rain, followed by the violent front (no damage here, >>>>> but tremendous light show) - while that front was moving thru, >>>>> temperatures >>>>> rose above 50*F for about 6 hours, peaking at 56*, before declining back >>>>> to >>>>> the lower 40's again - >>>>> >>>>> to add to the mystery, if I model tuesday, from the two hour dry thru >>>>> the end of the event, I get the 'infected', 'none', 'heavy' analysis from >>>>> the program - if I run the model from the start of the rainy event monday >>>>> so >>>>> to include the rainy monday night/early tues thru the end of the event >>>>> wednesday morning, the Mills model indicates 'light' infection (Cornell >>>>> indicates 'infected', WA 'none) - >>>>> >>>>> as a practical matter, at our stage of development, these >>>>> temperatures, and specific schedule of the wet periods, I normally >>>>> wouldn't >>>>> worry much about scab infection - but seeing that 'heavy' infection >>>>> indicated from the Mills model is disconcerting - >>>>> >>>>> dunno - any thoughts? >>>>> >>>>> thanks, >>>>> David Doud >>>>> grower, IN >>>>> _______________________________________________ >>>>> apple-crop mailing list >>>>> apple-crop@virtualorchard.net >>>>> http://virtualorchard.net/mailman/listinfo/apple-crop >>>> >>>> >>>> -- >>>> ************************************************************** Dave >>>> Rosenberger >>>> Professor of Plant Pathology Office: 845-691-7231 >>>> Cornell University's Hudson Valley Lab Fax: >>>> 845-691-2719 >>>> P.O. Box 727, Highland, NY 12528 Cell: 845-594-3060 >>>> http://www.nysaes.cornell.edu/pp/faculty/rosenberger/ >>>> >>>> _______________________________________________ >>>> apple-crop mailing list >>>> apple-crop@virtualorchard.net >>>> http://virtualorchard.net/mailman/listinfo/apple-crop >>> >>> _______________________________________________ >>> apple-crop mailing list >>> apple-crop@virtualorchard.net >>> http://virtualorchard.net/mailman/listinfo/apple-crop >> >> _______________________________________________ >> apple-crop mailing list >> apple-crop@virtualorchard.net >> http://virtualorchard.net/mailman/listinfo/apple-crop > > > -- > ************************************************************** Dave > Rosenberger > Professor of Plant Pathology Office: 845-691-7231 > Cornell University's Hudson Valley Lab Fax: 845-691-2719 > P.O. Box 727, Highland, NY 12528 Cell: 845-594-3060 > http://www.nysaes.cornell.edu/pp/faculty/rosenberger/ > > _______________________________________________ > apple-crop mailing list > apple-crop@virtualorchard.net > http://virtualorchard.net/mailman/listinfo/apple-crop > -- JMCEXTMAN Jon Clements cleme...@umext.umass.edu aka 'Mr Liberty' aka 'Mr Honeycrisp' IM mrhoneycrisp 413.478.7219 _______________________________________________ apple-crop mailing list apple-crop@virtualorchard.net http://virtualorchard.net/mailman/listinfo/apple-crop
