I bought my first Specware instrument in 2001, and it was a huge improvement over manual judging and logging of environmental data -
I believe that you and I are using different versions, as my program does not have the features you describe - I always felt the 'actual degree days' data was a huge leap forward over the averaging methods formerly used, surely modern research utilizes this mechanism - the display on my computer shows both GDD and 'actual' - during this last event, there was about a 30% difference between the two - 10 years ago I felt that spectrum offered the best value/features of IT for horticulture - I've not done much investigation recently, but am unaware of anybody else offering anything comparable - because I had 25 years of apple spray programs before I purchased this capability, I feel very much enabled by the data collecting done by the data logger and the collating/analysis provided by the computer - it would be difficult to go back - we are at tight cluster here - it's been many years since we reached the 22 of April without more development than this - the year has been close to the long term average to this point - but the record temperatures for april 22 here are 87*, recorded in 1986, and 27*, recorded in 1985 - just as in the GDD, averages are misleading - regards - David - On Apr 21, 2011, at 10:45 PM, Brian Heatherington wrote: > David, > > I've been using Specware for about 12 years with great success in targeting > sprays for scab and especially fireblight. I don't recall ever seeing the > Mills and Wash. models in disagreement, but I admit I usually just go with > the Mills model. The Cornell model has always signaled infected before Mills > signals light infection. Without knowing your stage of bud development or how > "clean" the block was in terms of scab last year, I generally use the model > as follows: > > Set the start date to coincide with your last SI/protectant, stroby, or spray > of a protectant (i.e. Mancozeb, Captan) at full rate, program in 3 -4 days > anticipated weather forecast, and target the next spray for a light or medium > infection under the Mills model. A more conservative date would be "infected" > under the Cornell model. This is the safest approach, subject to > interpretation of previous spray coverage, bud stage, susceptibility of > cultivar to scab, efficacy of SI's at your site, etc. I find it best to reset > the start date every time I spray, although this approach works best with the > fireblight models. If I recall correctly the Mills and Wash model differ in > wet leaf hours somewhere around 47 degrees. The discrepancy you are seeing > must be due to a number of wet leaf hours hovering around 47. I personally > don't use the Wash scab model because I have had clean blocks using the above > approach and the Mills model. I think the program does overpredict scab > infection, but that's better than missing them entirely. Setting the leaf wetness threshold to 7 instead of 6 might be more realistic. > > For fireblight I do the same, with a target EIP of 100. I did a poor job of > estimating Strep sprays prior to getting this system. With late blooming > cultivars in warm weather and heavy dews, EIP can go from 0 (reset with Strep > spray) to 100 in 2 days, which is why it's easy to miss a fireblight > infection by guessing at a 3-5 day schedule. Other times, when I would assume > a spray would be necessary, the program has allowed me to back off, as long > as 7 days. Temperatures have to be very cool for this to occur, so the > absence of potential fireblight infection is offset by the probability of > poor pollination. My target EIP of 100 is very conservative and is subject to > interpretation, especially of relative humidity during warm days, which is > not part of these models. The Cougarblight model is useful to determine how > far past 100 you want to go. With the original Maryblyt you could estimate > heavy dew as a .1 inch rain, but this system is more accurate as it factors > in temperatur e when dew is present. Once I began to follow this approach, along with incorporating Assail into petal fall or first cover, shoot blight has become very rare. > > Also note that, to my understanding, most of the disease and insect models > were developed using grower degree days, so you need to set up the software > preferences for GDD. In the future, it would be useful for researchers to > refine models based on the ability of data recorders to monitor "actual > degree days" instead of GDD, which were originally based on reading a min-max > thermometer and using a system of averages. It is likely that the 2 > approaches would yield different results, but I've never taken the time to > compare the 2 within Specware. "Single sine" is another option within the > program, but you have to leave the disease models, change DD settings, then > recalculate disease models. > > Cynthia Turski at Specmeters can provide more info on how their models are > programmed. Granted, the company could use an entomologist or pomologist on > staff, and their products are a bit pricey, but flying with instruments is > always better than flying without. > > > > At 09:22 4/21/2011, you wrote: >> 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 > > Brian Heatherington > Beech Creek Farms and Orchards > Tallapoosa, GA > _______________________________________________ > 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
