Fruits and Votes just completed its first six months of existence. The first post in the fruit block (actually a bit under six months ago) was about the last pluot of the 2005 season. Now, with a very warm week having come to an end, it seems that the chill count that started in early December has probably come to and end. Will we get any pluots in 2006?
This was quite a mild winter, even by our standards. And while we could still get more chill hours before some varieties break dormancy, the warm spell (up to 90 one day, and four straight over 80) means quite a setback in the accumulation of chilling. At this point, I would estimate the peaks to have been 200 up high on Ladera Frutal and 400 down at the bottom of the hill. That is, of course, an amazing difference, and really shows how elevation matters. These two locations are not far apart horizontally, but are separated vertically: the lower portion is over 150 feet lower on a steep slope than is the upper location.
Still, 400 is not enough for many of the varieties planted down in a location that is expected to get 500 or more. With 404 hours of chill having been reached, according to my calculations, on 8 February, we are now back closer to 390 after the warm spell. Any variety growing down at the elevation for which 400 is sufficient has thus had its chilling requirement satisfied, but the prospects for further significant gains above 400 seem bleak this late in the season. Up higher on the slope, the 200 peak was reached on 5 February, and with the warmer nights higher up the hill combined with the warm days, that location is at only 166 hours now. Surely, chilling accumulation has ended there, but most of the varieties planted there require 300 or less. (The Arctic Star nectarine is listed at 300 hours in catalogs, but looks ready to burst into full bloom, so it must be lower.*)
Some varieties of pluots need 500 hours, and so we might have a lighter crop this year. It is possible that my “cheating” on chill has allowed the row closest to the taller grapefruit trees to have obtained closer to 500 hours.
And there are some encouraging signs. There is a bloom already on the Autumn Glo apricot, a late-fruiting variety that is said to need at least 500 hours. There are also several blooms on one pluot, the Geo Pride. So far, these varieties–both of which are located in the cheating row–are not showing a lot of swelling buds and so it remains unclear whether they will bloom fully, or are just sending out “feelers” to see if spring is really here (groundhog blooms?). Even without adequate chill, a stone fruit tree will break dormancy when it has accumulated some (unkown) number of “warm hours” whether or not it has had the adequate accumulation of chill hours. But only with the chilling requirement met will it bloom fully and set a good crop of fruit.
* Assuming my estimation technique is reasonably accurate. Given many years of experience with it, I think it is as good as any other estimates available.