Hi Dear
Readers!
From this
point on in the Blog series, I will be focusing on pre-harvest practices.
This canopy management post may be seen as reaching you a little late, but as
we should avoid hedging or topping after Veraison, there is still room for this
discussion.
The information from the following posts was gathered from several sources. Please see the bottom of the article for links and more information.
Why focus
on hedging specifically?
Most of
us take on the practice, but we may not understand that the timing of the
practice has important implications for fruit quality.
By this time of the season, most canopy management practices may be finished- or if not – completed very soon. Shoots should be tucked (to avoid “scalping when hedging!) and leaf removal/hedging close to completion.
What
is Hedging/Topping?
Hedging is
the removal of about 25 cm or more of the shoot apex (shoot tips) of vigorously
growing primary shoots (these may be lateral shoots if growing rapidly) and
non-fruitful shoots. It is a
practice that can be used at various times throughout the season to provide an
adequate microclimate for developing clusters and open up the canopy for good
pest control and spray coverage.
Physiology Behind Hedging
The
rationale behind hedging is to avoid excessively dense canopies (shading of fruit
and internal leaves), to allow for ease of movement through the block
especially for vigorous hybrid cultivars and to encourage movement of carbohydrates
from new leaves at shot tips and directing
those sugars toward the grapevine clusters as well as the trunk and roots (vine
reserves for overwintering and vine hardiness). From veraison onwards, the sinks for photosynthates
are expanding shoot tips, bunches, shoots and roots. Generally, 50% of the carbohydrates go to the
clusters and the other 50% go to the permanent vine structure (reserves). Our objective is to optimize the clusters as
sinks and ensure that the bunches achieve optimum maturity.
Timing is Important
To reap the benefits of hedging, or of any cultural practice for
that matter, good timing is essential.
Primary
Goal of Hedging at Veraison
Crowded, dense canopies result in shaded fruit with low sugar
accumulation, high acidity and delayed ripening.
It
takes about 15 to 25 mature leaves (depending on leaf size and cluster size) to
ripen each grape cluster. Leaves above the cluster provide the sugars for
ripening and those below, send their sugars essentially to the shoots, trunk
and roots. Hedging during Veraison encourages the sugars to travel to the
berries, encourages periderm formation ( cane maturity) critical for winter hardiness for
overwintering canes (as FYI: this is not
lignification – that is part of xylem activities and not part of what we see
externally – lignin is colourless!) . Be sure to avoid where possible hedging
withing 30 days of harvest to avoid stimulating new shoot growth which will
complete for carbohydrates that we want destined for the clusters.
Secondary
Goals:
Removing
excess primary and lateral shoot growth from the top and sides of the canopy prevents
shading and entanglement of shoots between vine rows and allows workers and
tractor traffic through the vineyard.
Other Benefits of Hedging:
Ø It improves the micro-climate of the canopy: it encourages better light penetration, good air movement through
the canopy and clusters and helps minimize humid environmental micro-conditions
which favor the development of various diseases.
If you have any questions about this information, please don’t
hesitate to contact me.
A quick note about netting:
Netting:
Netting should be done with the onset of Veraison. Depending
on the netting methods used, you may be able to still complete hedging
(topping), but spraying may be more difficult. If using “over the canopy” netting, you may to be able hedge
if needed. Still, please ensure that your spray coverage is not affected- or
affected as little as possible.
GROWTH STAGE REPORT
Phenological
stages of three varieties of grape by date for the KRDC Research Vineyard. Bud break
for all three varieties was between May 18 and May 20, 2024.
|
Date of Assessment |
Marquette |
L’Acadie blanc |
New York Muscat |
|
1-August |
Berries beginning to soften |
Berries still hard and green-beginning to soften. |
Berries still hard and green-beginning to soften. |
Personal
Observations:
Chardonnay
and Pinot Noir are at bunch closure- still green and firm to the touch.
Marquette-
Berries are beginning to soften- in the Kentville/ Wolfville area. North and
South shore – berries are still green and hard to the touch.
Frontenac Blanc, L’Acadie Blanc and New York Muscat are also
green and hard to the touch.
Be on the lookout for these varieties as they will be
coming most likely within the next week or so-in the valley:
- Lucy Khulman,
- Petit Milo,
- Marechal Geoffrey
- Baco Noir
- and Osceola Muscat
PRECIPITATION AND GDD:
(All temperature data were recorded at the Kentville Research and Development Centre).
|
Month |
25-Year
Average (mm) |
Current
Year (mm) |
|
April |
81.5 |
54.0 |
|
May |
74.0 |
29.8 |
|
June |
95.5 |
83.0 |
|
July |
81.3 |
201.7 |
|
August |
94.5 |
10.7** |
|
September |
104.1 |
|
|
October |
115.8 |
|
*Up
to August 8, 2024
|
Growing
degree days, base of 10 °C starting on April 1 |
|
|
Current
Year |
10-Year
Average |
|
795.7 |
687.1 |
*Up to August 8, 2024
PESTS:
Sphinx Moth Caterpillar Phylloxera
Phylloxera: Currently present in Ontario, will be here again
in approximately two weeks. Please keep on top of your sprays.
DISEASES:
Black Rot:
Following through on the last blog-
please ensure that your spray intervals are tight, and you are rotating between
products. With the rain this weekend, we will be seeing this blight continue to
surface and inflict damage. Spray every row, and ensure complete coverage.
Downy Mildew
This is prime infection time for Downy Mildew- the upcoming
blog will delve deeper into the pathology of the disease, but with the humidity,
heat and rainfall- these are the prime conditions for the blight to develop.
Ensure proper ventilation of the canopy with leaf pulling if
not already done so. Please consult the Perennia Pest Management Guide for
pesticide information. And please, rotate the sprays and ensure full coverage.
We are in the home stretch!
Go clean into veraison and stay clean throughout. Don’t stop spraying too soon.
The crop is looking great this year- from all sides of the
province. Let’s ensure that we continue the trend. Do look out for pre-harvest
intervals and make sure you comply with the labels and contractors purchasing
your fruit.
Thank you all for your time, and I look forward to seeing you in person
next week at the GGANS Summer Tour.
Cheers!
Katarina Vucic
Viticulture Specialist
References and Acknowledgements: Hedging information is gathered by the following sources: Please see these links for further information:
Hedging and Canopy Management in Grapes: https://onfruit.ca/2020/07/17/hedging-and-canopy-management-in-grapes/
https://www.guadoalmelo.it/en/cosa-stiamo-facendo-ora-in-vigna-giugno-e-le-cimature/#:~:text=Let's%20go%20into%20detail%3A%20why%20do%20we%20do%20the%20topping%3F&text=The%20topping%20makes%20the%20vines,for%20the%20available%20water%20resources.
To Hedge or Not to Hedge: https://lodigrowers.com/to-hedge-or-not-to-hedge/
Koblet, W. (1987). EFFECTIVENESS OF SHOOT TOPPING AND LEAF REMOVAL AS A MEANS OF IMPROVING QUALITY. Acta Horticulturae, (206), 141 156. doi:10.17660/actahortic.1987.206.8 10.17660/ActaHortic.1987.206.8
Perennia Food and Agriculture
Email kvucic@perennia.ca
Office 902-678-7722
Cell 902-599-1390
