The Crush March 2023 - 1

Volume 49 | Issue 3 | March 2023
Article by Ted Rieger
An increase in the number and type of extreme weather
events are predicted as a result of climate change, and
these include low-temperature events with the potential
to cause crop and vine damage. The most common type
of low-temperature vine damage in California is from
late winter/early spring radiation frost events that occur
after bud break and commonly result in lower crop yields
at harvest. Below-freezing temperatures in April 2022 in
California after bud break resulted in lower harvests in
several locations, notably in the Clarksburg (District 17)
and the Sierra Foothills (District 10) AVAs that each had
35 percent less harvested tonnage than in 2021, based
on the 2022 Preliminary Grape Crush Report. Nearly all
winegrape varieties showed lower tonnages statewide
in 2022 compared with 2021, but earlier budding white
varieties such as chardonnay, riesling, and pinot gris
showed more significant reductions, likely in part, due to
spring frost damage.
Winter cold vine injury resulting in vine death, or crop
losses in subsequent growing seasons due to vine
damage, is more common in cold climate vineyards in
the U.S. and globally, rather than in California. However,
another type of vine cold injury event occurred recently
in the Lodi AVA and other Northern California vineyard
locations. Five days of overnight below-freezing
temperatures from November 8-12, 2020 occurred
post-harvest but before vines had reached winter/
cold season dormancy. This resulted in stunted and
restricted vine growth the following growing season
in Spring 2021 due to damaged vascular tissues, crop
losses, and lower yields in 2021. Younger and recently
planted vines are more susceptible to this type
of cold injury, but damage was also observed in
vineyards up to 20-years-old. More information on
this event and possible prevention/
mitigation can be found at: www. (see
2021 Spring issue).
Preventing and mitigating low-temperature vine injury
was a topic at recent regional grower meetings, and the
subject of a session at the 2023 Unified Wine & Grape
Symposium that featured information and experiences
from growers in California, Oregon, and Washington.
Viticulture Professor Markus Keller of Washington State
University in Prosser emphasized the importance of
vineyard location and site characteristics in relation to
cold temperature. " Cold air is heavy, it drains down
slopes and pools in draws, so it is best to avoid planting
in risky sites, " Keller said.
Site factors presenting frost risk are low-lying and
wind-sheltered areas where cold air can pool without
adequate drainage. During vineyard development,
grading can reduce areas of cold air pockets. Also, be
aware of obstructions that can block cold air drainage
such as trees/vegetation, hedgerows, fences, buildings,
etc., and avoid planting vines nearby or remove the
obstructions. During a presentation at the 2023 Lodi
Grape Day in February, UC Cooperative Extension
(UCCE) San Joaquin County Viticulture Farm Advisor
Napa Valley vineyards experienced low snow fall and freezing
temperatures in early 2023

The Crush March 2023

Table of Contents for the Digital Edition of The Crush March 2023

The Crush March 2023 - 1
The Crush March 2023 - 2
The Crush March 2023 - 3
The Crush March 2023 - 4
The Crush March 2023 - 5
The Crush March 2023 - 6
The Crush March 2023 - 7
The Crush March 2023 - 8
The Crush March 2023 - 9
The Crush March 2023 - 10
The Crush March 2023 - 11
The Crush March 2023 - 12