I See Grapes Blooming…

bloom in our Pinot HVS block, May 23, 2012 I’m calling the start of bloom at our Estate vineyard. This is what I saw uniformly throughout the block of HVS Pinot today. In fact, pretty much all the blocks of cane-pruned heritage selection Pinot looked like this. The precocious Dijon clone 943 was not far behind, and bloom was starting in the cordon-pruned Dijon clones 115, 667 and 777.

In contrast none of the Rhône varieties have popped, nor has the Tannat. About a month ago, budbreak in the Tanant was uncharacteristically ahead of all the other varieties but with respect to bloom it has taken its proper place in the scheme of things. At this point it looks as though the Grenache could bloom before the other varieties. The Counoise is still bringing up to the rear.

My best guess at this point is that based on the number and size of flower clusters, the Pinot and Grenache could yield heavier than average this year. The Syrah and Mourvedre will be lighter than average. The Tannat and Counoise look to have thrown an average set of flower clusters.

Suckering and lifting wires May 23, 2012The crew was out today finishing up crown and trunk suckering. They are starting to lift the lower trellis wires, and doing some shoot thinning for excess density. I’m looking for just two fruitful canes per spur position on the cordons, and just one upward-pointing shoot per bud on the canes.

5 rows for partner-only wineAnybody recognize this? Hint: it’s not Pinot, or a Rhône variety. We will see if it can actually set this much crop—this variety tends to shatter and shell if the weather cools suddenly.

Aye, and there’s the rub; the weather forecast calls for a late-season cold front to blow through Friday. Temperatures, which have been in the 80s, won’t get out of the low 60s, and there is a chance of showers, thunderstorms, and even hail.

4 thoughts on “I See Grapes Blooming…

  1. Peter O'Connor

    I’m sorry to bring this discussion back, but regarding your comment on 2011’s solar radiation levels on Blake’s blog, I checked the official numbers (CIMIS, CALCLIM) and they don’t confirm your impression: the average (2000-2011) accumulated horizontal solar radiation per growing season (Apr-Oct/244 days) for Bennet Valley is 1,393 KWh/m2. In 2011 it stood at 1,260 KWh/m2.
    Assuming a daily average of 5.71 KWh/m2 (1,393/244) per growing season, we can conclude that 2011 had a deficit of 23.3 sunshine days, when compared to the historical average.
    This partially explains the season’s lower Brix levels and validates the fact that phenolics continue to evolve above a certain temperature threshold (64°F?) despite the lack of (late season) sunshine, high temperatures and/or sugar accumulation.

    1. John M. Kelly Post author

      Thanks for weighing in, Peter – no apology necessary! I have no issue with your numbers, except to ask what the standard deviation is around the average, and then whether or not the 2011 season was within or without one sigma. Also, I’d be really interested in seeing an average for more than 11 years’ data.

      But aside from these minor points of interest, I’m actually concerned about the utility of “growing season” data. I argue that it is only the insolation between veraison and harvest that directly impacts sugar accumulation and other light-associated ripening parameters.

      Insolation between budbreak and veraison is much less important, but no more important than that occurring between harvest and budbreak, as the latter impacts not only soil warming (hence root temperature and thus timing of budbreak) but also the light-dependent development of primordia inside the buds.

      Even with these caveats, the raw growing season insolation figures are a very blunt instrument for explaining lower Brix levels at harvest. Site-by-site variations in the total area of active canopy (which encompasses not only the leaf count but the age of the leaves, the degree of senescence in the early canopy cohort, the trellis configuration, and the row orientation) relative to the total crop load are not taken into account. In 2011 crop levels in some varieties and locations were already extraordinarily low and I observed that canopies were rarely trimmed to balance this light crop load. Offsetting this, I did generally observe a greater degree of early leaf senescence in 2011 than what I usually expect.

      Finally, I am increasingly coming to suspect that there exist day-length-dependent “rescue” mechanisms in grapevines that assure nominal levels of ripeness under conditions of temperature and/or insolation deficit.

  2. Peter O'Connor

    Except for a few historical weather stations there is no solar radiation data for CA from before 1999.
    I made the previous calculation with 244 days when the correct number is 214, but the results seem consistent. Below you can check the adjusted statistics for 214 days.
    Growing Season:
    Descriptive statistics (accumulated horizontal solar radiation (KWh/m2); APRIL-OCTOBER for Bennett Valley): Max/1395 (2001); Min/1106 (2011); Mean/1245; Median/1265; Std. Deviation/85.
    (2011= -1.64 Sigma)
    Veraison to Harvest:
    Descriptive statistics (accumulated horizontal solar radiation (KWh/m2); AUGUST-OCTOBER for Bennett Valley): Max/530 (2003); Min/398 (2011); Mean/470; Median/466; Std. Deviation/33.
    (2011= -2.18 Sigma)

    1. John M. Kelly Post author

      That’s very good information! I have no doubt that decreased insolation to the extent of over 2 sigma from average decreased sugar accumulation. The question I have is whether the decreased sunshine also contributed to the earlier than normal occurrence of other elements of ripening: basal leaf senescence, increased K+ and pH, decreased tartaric, phenolic ripeness in skins and seeds, and breakdown of skin and pulp.


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