Thanks Glen. Have you been getting the scouting reports we do and are they of any use to you?
Art Kelly Kelly Orchards Acton, Me On Jul 3, 2014, at 1:05 PM, Glen Koehler wrote: > Hi Art > There is no OBLR pheromone trap treatment threshold that I know of. As > Jon said, the traps are used for timing not threshold detection. > > That said, and with a big "buyer beware" cautionary note that we really > can't extrapolate from one pest to another, I still find it "informative" to > note that the MidAtlantic Orchard Monitoring Guide mentions three pheromone > trap based thresholds for apple Lep pests: Codling moth (5 CM per week per > trap), Tufted apple budmoth (roughly 15 TABM per trap per week based on > Figure 11.1), and Lesser appleworm ( 5 LAW per trap per week, which is based > on the CM threshold, so maybe we can extrapolate between pests!). > > The problem with using pheromone traps for thresholds is that the traps > attract males and the pest population depends on number of females laying > eggs, and the number of larvae of both sexes, neither of which may be very > well correlated with male captures in pheromone traps. Add in the > variability caused by trap placement, wind direction, flight temperatures > etc., and it's not hard to see why pheromone traps are more useful as > presence/absence detectors for timing degree day models to estimate optimum > time for direct observation than for making population density measurements. > > When populations are low, I don't even trust pheromone traps that much > as biofix detectors unless a large number of traps are used and are regularly > checked. My concern there is that with a low population and an inefficient > trapping system, the appearance of moths in the traps may be delayed past the > date when emergence began. Thus it may be better to use both degree day > model to estimate the adult emergence date or other biofix and trapping and > compare them to decide which seems more realistic for setting biofix for > subsequent degree day estimate to identify optimum sampling date. Of > course, is the population is high, only the pheromone traps will indicate > that. > > My guess is that 7.5 per trap is definitely enough to schedule time for > making larval count, but not enough to lose sleep over until you get those > scouting results. The threshold for larval observation is 3 infested > terminals with living OBLR larvae per 100 terminals checked. The degree day > estimate for start of OBLR flight at Sanford Ag-Radar site near you was June > 18. Based on that, the optimum sampling date is July 11, with a July 15 > followup if the first check is below threshold. ( I don't think the July 3 > egg hatch date is relevant because your trap catch levels are not high enough > to indicate convincing need for treatment, so better to wait for scouting > observations.) > > I entered your June 20 biofix and that nudged the optimum scouting date > to July 13 with July 17 followup. We'll make that part of the scouting visit > that week, but we will only be able to do one check vs. the recommended two > check protocol. > > - Glen > > > On Tue, Jul 1, 2014 at 6:25 PM, Jill Kelly <[email protected]> wrote: > Thanks Jon. > On Jul 1, 2014, at 12:42 PM, Jon Clements wrote: > >> Art, there is no "threshold" as far as I know. Pheromone traps are typically >> used to establish a biofix to time the best treatment. See: >> >> http://www.fruitadvisor.info/tfruit/clements/models/oblr.html >> >> According to AgRadar, you should be out spraying for this pest July 3 so you >> can relax on the 4th. But, your namesake tropical depression/storm/hurricane >> Arthur may have something to say about that too! >> >> http://pronewengland.org/AllModels/MEmodel/ME-Sanford-InsectDates.htm >> >> Jon >> >> >> On Mon, Jun 30, 2014 at 2:55 PM, Arthur Kelly <[email protected]> >> wrote: >> Is there a treatment threshold for pheromone trap captures for OBLR? We >> averaged 7.5/trap today. We trapped the first adults on 6/20, one per trap. >> >> -- >> Art Kelly >> Kelly Orchards >> Acton, ME >> >> _______________________________________________ >> apple-crop mailing list >> [email protected] >> http://virtualorchard.net/mailman/listinfo/apple-crop >> >> >> >> >> -- >> Jon Clements >> aka 'Mr Honeycrisp' >> UMass Cold Spring Orchard >> 393 Sabin St. >> Belchertown, MA 01007 >> 413-478-7219 >> umassfruit.com >> _______________________________________________ >> apple-crop mailing list >> [email protected] >> http://virtualorchard.net/mailman/listinfo/apple-crop > > > _______________________________________________ > apple-crop mailing list > [email protected] > http://virtualorchard.net/mailman/listinfo/apple-crop > > > > > -- > 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 > [email protected] > http://virtualorchard.net/mailman/listinfo/apple-crop
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