Control of pests and diseases is one of the
most important –and controversial- aspects of viticulture. Some of them can
seriously harm your vines, and thus yields, or even affect the quality of your
grapes in a very direct way. Gray rot (botrytis) is one of the most feared, as
it occurs shortly before harvest, normally after prolonged rain and periods of
moisture. If not removed of eradicated, the rotten grapes give dirty flavors to
the wine, and fermentation becomes much more difficult.
Keeping a vineyard in good shape is in some ways
similar to keeping yourself healthy. First of all, a healthy soil and adequate
nutrition are similar to eating healthy, nutritious food. Too much fertilizer,
and the plant will grow in excess, much like your own stomach.
In general, plants with excess growth tend
to create a lot of shade for themselves, where fungi and insects thrive. Very
quick growth also gives thinner leaves and shoots that are less resistant to
pests and diseases. Especially the incidence of grey rot is associated with an
excess of nitrogen fertilizer.
But however healthy and robust your vines
are, sooner or later they will be affected by some disease or other, that, if
left untreated, will ruin your crop or even your vineyard. There are basically
two ways of dealing with pests and diseases: using chemicals or not. The people not using
chemicals are normally certified as practicing organic or biodynamic
agriculture, and will never spray pesticides that were invented after the
1940s. I deliberately avoid the word “natural” pesticides in these cases, as they can still
use (petroleum derived) mineral oils, sulfur, copper sulfates and other
inorganic salts, some of which are not very good for the environment.
On the other hand, conventional agriculture
has been relying probably too much on the use of pesticides, much in
the way human medicine has been relying too much on antibiotics, leading to resistance of pathogens which makes their control increasingly difficult.
Personally, I think the practice of organic
and biodynamic agriculture has shown us that that a lot can be done without the
use of pesticides, however, practicing it dogmatically seems like missing the
goal. Some of the sprays are not very effective, very expensive or even bad for the
environment, like the copper salts used against downy mildew.
We're now boiling our own lime-sulfur as a general winter disinfectant. It is obtained by boiling lime and sulfur together for 50 minutes and then spraying it on the vineyard. It is caustic and smells bad, but otherwise pretty harmless, and avoids a lot of heavier sprays in spring. I found the recipe in a USDA manual printed in 1922!
Apart from trying to use as few pesticides
as we can -saving a little money along the way!- here at Lagar de Bezana we try
to increase natural health of our vines as much as we can. This year has seen the use of horses to eliminate winter weeds and add some natural fertiliser to the soil!
Otherwise, this winter has been cold and rainy, as it should be. While I write this, the Andes are giving me some beautiful sights in the afternoon.
