Page 42 - Grapevine JanFeb 2021_REV

Around The Vineyard

vineyard. Just as described above for black foot can become pathogenic during stress situations.
disease, these pathogens strive in compact soils
with poor drainage. It is known that the effect of grapevine fungal
pathogens increases as the vineyard ages (the
Disease Management and Control fungal pathogen population build up over time).
Therefore, growers must adopt management and
The best disease management and control mea- control measurements as soon as the vines are
sure I recommend is to prevent the introduc- planted in order to prevent and minimize the prop-
tion of pathogens in the vineyard. None of the agation and dispersal of fungal pathogens.
US-certification programs exclude trunk disease
pathogens. Therefore, propagation material is Management at the vineyard should include
most likely infected with A. vitis and various fungal expertly trained personnel for pruning activities. In
pathogens. It is encouraging to learn that work California where the rainy season coincides with
at Marc Fuchs laboratory at Cornell University has the pruning season it is recommended to prune as
shown that it is possible to eliminate A. vitis from late as possible. If the vineyards are large, the dou-
vines using the standard meristem tissue culture ble pruning method can be applied. This consists in
technique. the mechanical pre-pruning of vines, leaving canes
of 1-2 feet long. In the spring or late winter, the
The availability of clean planting material (tested pruning is completed by leaving the desired final
to be free of A. vitis) are most important in areas number of buds per spur. In all cases, after prun-
that are prone to freezing such as the North East ing, the pruning waste must be removed from the
and Mid-Western United States vineyards. vineyard as soon as possible. The freshly produced
wounds should be protected using fungicides or
The implementation of appropriate sanitation SafeCoat VitiSeal.
measures at the nursery is most needed to pro-
duce high quality planting grapevine material. It is The recommendation of pruning as late in the
known that one infected vine can produce between season as possible is related to the healing of
100 -200 vines each year, potentially producing a the wounds. Since the vine is more active in the
significant number of infected grafted plants. The spring, it is expected that healing will occur faster.
use of hot water treatment (HWT) for 30 minutes Another reason is that most fungal trunk disease
at 50C (122F) at the nursery has shown a reduction pathogens release spores during the rainy season.
of fungal pathogens in propagated vines. However,
there are mix reports on the effect of the HWT on Therefore, by the end of the winter or early
bud mortality. Reports in warmer winegrowing spring, the proportion of spores is expected to have
regions (e.g., Spain) have shown a lower effect on been reduced to a minimum (in areas with predom-
bud mortality compared to HWT in cool climate inantly winter precipitations).
regions (e.g., Australia). Because fungal pathogens
cannot be eliminated in the vineyard once intro- However, wound protection will still be required
duced, it is important to learn and apply the best because fresh wounds are more susceptible to
management practices available. infection and can remain susceptible for long peri-
ods of time. Things to avoid during pruning are:
When planting a new vineyard, it is important to producing large wounds, cutting near the trunk,
inspect the quality of the planting material (graft pruning after long periods of rain, and leaving vine
union integrity, lack of galling, streaking or pitting) residues in the vineyard floor. It is also important
and plant in well prepared and drained soil, at the to respect the flow of sap, which is accomplished
correct season. The best practices in the vineyard by cutting always on the same side of the vine.
must be applied (i.e., enough water, nutrients, etc.)
as many of the fungal pathogens are endophytic Economic studies performed by Dr. Kendra
(can live in the vine without causing damage) but Baumgartner and colleagues (USDA in UC Davis,

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