Growers should be careful using
bud dissection results to estimate
yield. Studies have found that bud dissections
may explain from as low as
50% to as high as 90% or the variation
in actual yield.4 Several years of data
comparing bud dissections to actual
yield will help growers interpret
results with more confidence.10
Bud dissection sometimes strongly
underestimates bud fruitfulness.11 This
suggests that tiny inflorescences overlooked
by inspectors may still produce
clusters. Also, a random sample of all
canes on a vines may show lower fruitfulness
than a sample of the stronger
canes favored by pruners. Growers
must be careful to take a sample representative
of the canes they expect will
remain on the vine after pruning.
If bud analysis is accurate, a grower
can calculate the average number of
flower clusters per vine for different
numbers of spurs or canes. Of course,
there are limits to the number available.
When pruners leave more spurs
or canes, they may include more of the
weaker or sub-standard choices.
Bud analysis can tell which nodes
have the most fruit. If the buds on a 2-4
bud spur are unfruitful, longer spurs
may be needed to include more fruit,
or the grower may need to add a
“kicker cane” or two.
However, because of apical dominance
caused by auxins moving out
along the spur, leaving more nodes on
the cane tends to suppress sprouting of
the nodes near the base.11 For example,
if the first two buds have more fruit
than the next two, retaining the fourth
bud in pruning may actually reduce
the number of bunches by suppressing
bursting of the first bud. The grower
needs accurate knowledge of which
buds will bring the best return.
Growers are also leery of adding extra
nodes on spurs (three or four bud spurs),
because that makes the vines taller and
harder to prune the following year.11
Virtually all of the material on
inflorescence was taken from research
and literature reviews given to me by
Dr. Luis A. Sanchez, who studied bud
differentiation for his Ph.D. dissertation
at U.C. Davis and now works for
E&J Gallo Winery. The Srinivasan
paper is also a good review, but Dr.
Sanchez includes that information in
his review. Dr. Sanchez kindly
reviewed the present paper.
1. Sánchez, Luis A., and Nick K.
Dokoozlian. 2005. “Bud microclimate and
fruitfulness in Vitis vinifera L” Am. J. Enol.
& Vitic. 56:4 (2005).
2. Sánchez, Luis A., Nick K.
Dokoozlian, and Martin C. Goffinet. 2007.
“Variations in the nodes of Vitis vinifera L.:
double compound buds” Proceedings of
the 1st Annual National Viticulture
Conference. July 18–20, 2997. Davis CA.
or online pdf
3. Srinivasan, C., and M.G. Mullins.
1980. “Physiology of flowering in the
grapevine—Areview” Am. J. Enol. & Vitic.
32 (1) 47–63.
4. Williams, L.E. 2000. “Bud development
and fruitfulness of grapevines,” In
Raisin Production Manual. L.P. Christiansen
(Ed.) Pp. 24–29. University of California
Division of Agriculture and Natural
5. Vasudevan, Lakshmi, 1997. Anatomical
developments and the role of carbohydrate
or mineral nutrient deficiency in bud necrosis
of Riesling grapevines. Ph.D. dissertation,
Virginia Polytechnic Institute. See website
6. Collins, C., and B. Rawnsley. 2005.
“Factors influencing primary bud necrosis
(PBN) in Australian vineyards” Acta Hort.
(ISHS) 689:81–86 VII International Symposium
on Grapevine Physiology and
Biotechnology. See website.
7. Bernard, Martina, Melissa Carew,
Pamela Hurst, Paul Home, and Ary
Hoffinann. 2003. “Integrated management
of grapevine bud mites (Colomerus vitis)
in Australian vineyards. Preliminary recommendations”
In Strategic Use of Sulphur
in Integrated Pest and Disease Management
(IPM) Programs for Grapevines. FINAL
REPORT to GWRDC. December 2003. See online pdf
8. Grape Pest Management, second edition.
University of California, Division of
Agriculture and Natural Resources. 1992.
By Eli Carlisle, Dept. of Plant Sciences,
David R. Smart,
Dept. of Viticulture & Enology, UC Davis
Joe Browde, California Sustainable
Andrew Arnold, SureHarvest
From September/October 2009