It is often said that to make a small fortune in the wine industry, one must start with a large one. Choosing to make an income from wine is invariably a gamble.
You start by gambling on the weather, hoping that conditions will be adequate to sufficiently ripen your grapes. Next, you are gambling on no freak or extreme, like frost, weather wiping out your entire crop at the point of harvest. Finally, you are gambling on your own ability to prevent or control the myriad of pests and diseases that want to call your vineyard their home.
Names and dangers of said pests and diseases can be confusing. For this reason, we’ve put together the following guide of what to look out for, as well as preventative procedures:
Common Vineyard Diseases
Native to California, Pierce's Disease is spread by the glassy-winged sharpshooter. There is currently no cure for Pierce’s disease, which can be identified by an early yellowing of vine leaves followed by a reduction in growth rate and eventual death of the vine. The key to its prevention lies in combating its carrier using insecticides and biological control methods, such as parasitic Wasps or Lacewings.
Also known as Oidium, Powdery Mildew attacks both vine and grapes, covering them in a fine, powdery fungus. Once it takes hold, it is very difficult to combat, and thus, should be prevented by any means instead. This is done using a solution containing Copper Sulphate and Slaked Lime, known as the Bordeaux Mixture.
Otherwise known as Peronospora, Downy Mildew can be identified by the presence of an oily stain on vine leaves. Downy Mildew kills leaves, making it impossible for the plant to photosynthesize. As with Powdery Mildew, it is very difficult to rid a vine of this disease once it takes hold and is therefore it is best to prevent it in order to save the crop. Again, this can be achieved using the Bordeaux Mixture.
Black Rot affects both vine and grapes in hot, humid climates. Affected grapes appear mummified and hard. In areas that experience such climates, vineyards should be planned to allow sufficient air circulation as well as good exposure to sunlight. Once vines start to grow, copper-based fungicides can be used to prevent any onset of rot.
This grapevine virus is spread by infected root-eating nematodes, who have themselves contracted the virus from other infected vine roots. Once contaminated with Fan Leaf, the vine can not be saved, and all affected vines must be removed from the earth. The earth should then be left fallow until roots of infected vines have rotted. Planting new vines in the infected soil surrounding the previous vines with result in the loss of the new crop to the disease as well.
Known most commonly as Botrytis, Grey Rot is a fungus that only affects grapes. It usually takes hold when grapes are still developing and comes as a result of long periods of increased humidity. Once installed, Grey Rot multiplies rapidly and little can be done to stop its destruction. As with other fungi, efforts are much better expended in prevention, including pruning to ensure good aeration between vines.
It should also be noted that under certain conditions, and in certain white grape varieties, Botrytis can actually be beneficial. Infected grapes produce spectacular Dessert Wines, and in this instance the fungus is instead referred to as Noble Rot.
Common Vineyard Pests
Arguably one of the most infamous of pests that has had profound historical effects on the wine industry, Phylloxera is a microscopic aphid that feeds on the roots of grapevines, this pest was the sole cause of the biggest blight in the history of winemaking. Originating in North America, the louse was accidentally brought over to vineyards in France, and Switzerland in the 1860’s. At this time, phylloxera was unknown, as American rootstocks are resistant to it. However, very soon it started devastating European vineyards, and this event was called the Great French Wine Blight, and 70% of the country’s vines were lost. (Learn more in "How the Great French Wine Blight Changed the Global Wine Industry.")
When the resistance of American rootstocks was eventually discovered, it became apparent that therein lay the solution. The only preventative cure to this pest would be to graft European vines onto American rootstock where compatible. Phylloxera still exists today, and there are still vineyards that choose to use vines with pre-phylloxera European rootstock. Yet these are only common in areas where there have been no recorded instances of the pest, including Western Australia, Tasmania and Chile.
Otherwise known as Roundworms, these minute pests occupy the area around and inside vine roots. Like phylloxera, they feed on the roots, and once installed, there is no way of eliminating them. Instead, their effect can be prevented using special, resistant, rootstock when planting vines.
Moths that feed on grapes and vines can be a significant danger because of their ability to survive year-round. Furthermore, they can cause damage in each part of their life cycle (after they have hatched) as they feed on different parts of the plant. Population of this insect can be controlled fairly easily using specific contact insecticides.
Vines can tolerate a fairly high population of this insect. However, intensive feeding and infestation can devastate vineyards, causing loss of crops (grapes) and damage to vines, affecting next year’s cycle. The pest can be controlled using biological (introducing predators or parasites) or chemical (insecticides) methods.
Birds and Animals
There are a number of species of birds and animals to be wary of when owning a vineyard, depending on where in the world a vineyard is situated. Examples stretch from wild boars in Argentina to monkeys in South Africa. The main danger from these animals comes from their desire to feed on grapes. Preventative methods include different forms of netting, but if problems persist, vineyard owners may be forced to look at hunting as the only form of control, though situations such as these are likely to raise ethical dilemmas.