Claud, I did use Javelin... years ago when I was in the Army. It was part of their selected software before Lotus 1-2-3, then MS Excel took over. I'm not expecting to do anything beyond basic math, or a little algebra for this project, though.
Rick & Mary Stella, I certainly do want to find extremes in data. That might help to show if there is something else that has a very strong effect other than daily temperatures. I have thought about daylight hours and possibly the moisture as variables. That would take a LOT of information to be able to break down the various influences. The only way I really see that as being possible would be to design an experiment and pay growers across the country to produce specific tomatoes in controlled conditions. What I hope to do, instead, is to average out the influences of day length and moisture by averaging the GDD for a tomato in one area with tomatoes in another area. That will give a generalization for that tomato that, hopefully, is more accurate than the generic DTM. My assumption is that the growing degree days will provide a forecast of harvest that is more accurate simply because it incorporates the temperatures for the growing location. I don't expect it to be perfect, but I do expect it to tell the grower what to look forward to with various maturity tomatoes in their garden.
Also,someone asked why transplant dates? I picked the transplant date because that's what I think I will be able to find. I am hoping to get data from individual growers, but I'm counting on finding data in field trials from universities and commercial growers. Transplant date is a commonly stated value, and it can be used to compare the DTM with the calculated GDD for a tomato. For other vegetables, normally direct seeded, I would try to use germination/emergence.
For tomatoes that get up-potted to fairly large containers, I would think that the date those containers go out would serve as the start date. In those cases I think the final transplant date might produce artificially short GDD values.
Thanks to everyone that has expressed interest! I'm looking forward to any comments or growing data.
DR
