gifted with a warm growing season and many sunny days, has the opportunity to
successfully produce numerous fruit crops ranging from peaches to blueberries.
However, until recently, viticultural producers have been restricted to growing
native muscadines and hybrid bunch grapes due to the looming presence of
Pierce’s Disease (PD), caused by Xylella
fastidiosa, an endemic xylem clogging bacterium that is deadly to
susceptible Vitis vinifera (European)
Figure 1 A,
B. Ripening clusters of V. vinifera selection
‘502-01’ within fruiting zone of a VSP trained vine (A) and high productivity
of early season selection ‘502-10’ (B) at the Chilton REC, AL, 2015.
U.C. Davis grape breeding program, in response to the spreading threat of PD,
is working to develop and release high quality PD resistant V. vinifera bunch grapes. Three of these
experimental 87.5% V. vinifera PD
resistant selections were obtained and planted in 2010 at an experimental
vineyard at the Chilton Research and Extension Center (CREC) located in Chilton
County, AL to examine the feasibility of growing PD resistant vines amidst
Alabama’s high disease pressure environment. Due to the promise observed in
previous years’ preliminary results, more detailed research is now being
conducted to assess the phenological, physiological, and fruit characteristics
for the three experimental V. vinifera PD
resistant selections: ‘502-10’, ‘502-01’, and ‘501-12’.
new crop for Alabama, V. vinifera
vines are trained in a different manner than muscadine grapes. The training
system facilitates the upright growing habit of V. vinifera grapes. Rather than allowing fruiting canes to grow
downwards, V. vinifera fruiting canes
are instead trained upwards and periodically directed within a vertical shoot
positioning (VSP) system. This training system facilitates efficient pest
management practices, while concentrating the crop load within a compact
fruiting zone (Fig. 1 A).
the vines’ development throughout the growing season allows for development of
proper management techniques in a given set of environmental conditions. For
the three selections, bud break had occurred by the first week of April and
canopy formation and establishment were completed by April 20th in
2015. Flowering was initiated in the first days of May, and all selections were
considered in full bloom within a week.
is the stage associated with grape ripening. It starts when the berries start
turning their color from green to black or fully colored berry, and sugar
accumulation increases. Veraison takes about 40-50 days depending on the
particular cultivar and continues until harvest. The three selections studied
varied in color accumulation timing, with ‘502-10’ being fully colored in July.
As a result, ‘502-10’, was harvested in mid-August. The remaining two
selections finished fully developing their berry coloration in early
early ripening selection ‘502-10’, produced an average yield per vine of 24 lb.
Based on the planting distance of 7 X 12, this translates to a yield of
approximately 6 tons per acre, though crop load manipulation is a factor that
will need to be determined in a site specific context to ensure maximum fruit
quality (Fig. 1 B). With healthy clusters averaging roughly a pound per
cluster, the vine ripened fruit can be processed into juice or wine, high in
health promoting antioxidants such as anthocyanin and resveratrol.
produced grapes are a critical component of local juices and wines. We look
forward to the upcoming harvests so that we can share more about the quality
and yield of these three unique selections possessing innovative traits such as
PD resistance, opening the doors for V.
vinifera roots in southeastern soils.
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