"Like the build-up to the tropical wet season, or the week before a Grand Final; so too there's electricity in the air a couple of weeks before harvest.
You can see and feel the static. Everyone's on edge, twitchy or downright irritable. These are the weeks of highest tension.
There is no exception to this rule in any winemaking community. It’s all the watching and waiting that heightens anxiety." - Toby & Emmanuel Bekkers.
How much disease is around?
Fortunately the
weather this week has not significantly increased the amount of botrytis but
there is a real risk of crop loss if rain or heavy dews occur before your crop
is safely picked. We have heard reports this week
of one vineyard being rejected in Langhorne Creek due to botrytis infection, this shows that it is
a threat.
Check your vineyards now for botrytis progression in the thick and
dense parts of the canopy where bunches sit in top of each other.
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| Botrytis a in bunch of Sangiovese. |
In
general the severity is low (1 berry per bunch) with the diseased
berries appearing to be drying. Infections are dropping out of the bunch when
they are shaken. There are significant infections in Chardonnay and Shiraz
that has fruit stacked on top of other fruit. The
highest level seen has been in tight bunched varieties (i.e Grenache,
Zinfandel, Dolchetto, Sangiovese, Chardonnay) 5 bunches part infected per panel
(approx. 1 bunch per meter). View a video of this level of Botrytis
activity: (70Mb download).
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| Salt burn. |
Why is there some fresh burn to leaves after the rain?
Recent rainfall
has caused the mobilization of sodium chloride, more simply called salt, in the
soil and the vineyards pictured – right - are showing
foliar signs of burn.
As soil
moisture reduces during summer vines pull water from the soil. The drier the
soil the harder they pull (plants create a negative pressure from the leaves to
the roots - pulling harder means a higher negative pressure).
Recent rainfall
re-wets the top soil and vines pull up more water from previously dry areas of
soil. They take up more salt with the water. Eventually the concentration in
the leaves becomes toxic and the leaves 'burn.'
This foliar
burn decreases the health of the vines. Sodium and Chloride levels in the
developing fruit are also likely to have increased which can have a detrimental
effect on wine quality. If you are worried about this request a test of must
from your winery.
In high salt
situations it is essential that salt is leached from the soil to reduce
excessive build-up over seasons. Typical leaching fractions may be in the range
of 10 to 20%, and are best applied prior to bud-break if soil testing shows
salinity levels were not reduced sufficiently by winter rainfall.
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