April
Spring is finally here and
with that, the workload seems to have doubled in the vineyard. By
April, all the buds have pushed and the small shoots are rapidly
growing. Any unwanted shoots are removed at this stage before they
become lignified (harden off). The process is called suckering,
in which unwanted shoots are pruned out. Frost protection is in
full swing during April. As soon as the temperature alarm hits 35°F
(usually in the early morning hours), we are diligently in the vineyard
turning on all the sprinklers to protect the young, succulent tissue
(see March 2003).
Cultivation
has begun and the cover crops in certain parcels are being mowed
down and disced under the ground. This decreases competition with
the vines in some lower vigor sites. It also adds organic matter
to the soil (for later use by the plant). April is also a time to
irrigate some of the hillside parcels to make sure the plant gets
off on the right foot in spring (most of the flat parcels do not
need irrigation because they get water from the sprinklers during
frost protection). Fertilizers are added to young and less vigorous
parcels to ensure proper growth of the young tissue. Monitoring
for certain pests also commences during April.
Suckering is a very important process in vine maintenance. The buds
left during pruning are called compound buds. Each of these buds
contains three “true” buds referred to as the primary,
secondary, and tertiary buds. Often, more than one of these buds
pushes during bud break. Only one of these small shoots is desirable,
so that shoots do not compete for light (shading the fruit thereby
reducing fruit quality). The other shoots must be removed. Opening
the interior of the canopy also increases airflow, which creates
less hospitable environment for fungal pathogens. Along with removing
these shoots, any shoots that develop on the trunk or cordon arising
from latent buds (buds that have been dormant for more than a year)
are removed. Suckering is very important in removing any unwanted
shoots because it keeps the form of the vine that was painstakingly
established during pruning.
An important part of St. Supery’s integrated pest management
approach begins with springtime monitoring. Once the temperature
begins to increase, the over-wintering (hibernating) insects wakeup
and become active again. By keeping a close watch on the insects,
we can determine if the populations reach certain thresholds (guidelines
set by the University of California through intensive experimentation).
Only when the populations exceed this threshold do we consider treatment.
This can greatly reduce the amount of pesticides needed (if any
at all) over a traditional calendar spray regime. This ties in to
St. Supéry’s ideals of sustainability. We try to decrease
the negative impacts on our ecosystem (decrease spraying, use narrow
range insecticides which do not kill beneficial insects, plant cover
crops which among many other benefits create a habitat for beneficial
insects).
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