In order to successfully protect your vines and thus your vineyard from the attacks of diseases and pests, you need to know well the symptoms that appear and develop after the attack itself.
Diseases of the grapevine
To prevent diseases on the vine, it is necessary to know the biology of the disease itself, the conditions under which it appears and develops, and ultimately how to prevent them and how to protect the plant with chemical means if the disease occurs.
Flame of the vine
Grape downy mildew is better known in our country under the name downy mildew, and it arrived in Europe from the USA through the American species Vitis, which was imported at the end of the 19th century as a basis for the development of species resistant to phylloxera.
Flame blight can attack saplings, flowers, leaves, berries and bunches, and is caused by a fungus called Plasmopara viticola.
In the past, numerous vineyards were damaged by this disease, but today, with the use of useful fungicides, attacks and damage have become much less.
Damage from blight is not exclusively and only direct on berries. In case of severe infections, the leaves are damaged, and due to the lack of assimilation surface in the berries, there is less accumulation of sugar.
Berries and leaves are most often attacked, and flowers, shoots and tendrils are less frequently attacked. The disease first appears on the lower young leaves, where light green and yellow spots appear, which over time increase to a diameter of up to 1 to 3 cm. After that, white coatings appear, and the infected zones soon take on a red-brown color. On the older leaves, yellow and red fields are formed, which together with the veins form a mosaic in combination with the green parts of the leaves.
The infected parts of the leaves begin to turn brown over time, the tissue begins to die and dry. The mycelium of the fungus enters the leaves, and the spot starts to spread more and more. Ultimately, when larger parts of the leaves are affected, they dry up and fall off.
The leaves sometimes drop as early as July, and the infection is dangerous because other parts of the plant can easily be infected, especially the flower, i.e. the flower cap, which turns brown and starts to dry. Sometimes the infection also occurs on the petiole of the flower, which bends at the same time.
The infection also occurs on berries, which can be infected from the time they are laid. In the end, they shrivel and take on a purple-brown color. Most often, there are several infected berries on each bunch, while the rest are healthy and developing well.
Young people are rarely affected by this disease, and are most susceptible to it when they are 10 to 15 cm long. In case of infection, a white coating appears on them. The affected parts die, and if the disease affects most of the sapling, it begins to dry.
The disease most often occurs when the soil is moist, and the temperature in one day does not exceed 8 to 10 degrees Celsius. Drops of water remain on the leaves for four to six hours. Secondary infection occurs when 10 to 11 mm of rain falls in two to three days, and the temperature is above 11 degrees Celsius.
It is recommended to think about growing more resistant varieties immediately before planting. The fungus appears more often when plantations are raised on low grounds and on those where water remains for a long time. Plant creeping grafts in the direction of the winds, which will dry the plant and thus prevent infection.
Although, in addition to the above measures, there are others that can facilitate the protection of the vine, it is completely possible only with the application of appropriate fungicides. In the case of not using protection, the vine could not last more than a few years, and its main enemies would be downy mildew and powdery mildew.
Nowadays, the number of sprays with protective fungicides is reduced, and approximately four to six sprays are required
Powdery mildew
Powdery mildew or Uncinula necator in Latin is the first disease that arrived in Europe, and it has a foreign origin. It was first recorded in a place not far from London in 1845, and soon spread to all Mediterranean countries. Today it is common in places where vines are grown. It causes enormous damage to grapes, and the yield can be reduced by 80 to 90 percent.
The disease can attack leaves, tendrils, shoots, berries and flowers, and is caused by a fungus called Uncinula necator.
The disease can appear on all green parts of the plant, including berries. Powdery mildew can attack leaves at all stages of growth, and appears in the form of a white coating that comes from oidia and mycelium. Attacked leaves lag behind in development, twist and curl. In case of somewhat stronger infections, the entire leaf dries up. However, the damage to the leaves is incomparably small compared to the bunches, where the fungus causes a stronger attack.
Saplings can also be attacked, on which ashy and then bluish spots appear. The mycelium darkens over time, and the tissue dies.
The attack on the flower can happen even before fertilization, and it is more common to attack flowers that grow next to each other. A fungus develops on them, whose gray mycelium leads to the drying and falling of the flowers.
The biggest damage from powdery mildew is on the berries, and the attack can occur from fruit set to the formation of color. In severe infestations, the berries may look as if they are completely covered with ash. If the disease on the berries appears later, the damage is not so great. They are more aesthetic and reduce the market value of grapes.
The disease occurs when the oidium from the buds begin to multiply at a temperature above 5 to 6 degrees Celsius. They breed best at temperatures of 25 to 28 degrees Celsius. When air temperatures exceed 30 degrees Celsius, oidium no longer reproduces, and at 40 degrees Celsius they die. The mycelium is no longer active at a temperature of 45 degrees Celsius.
Powdery mildew already reproduces at 30 percent air humidity, although it reproduces faster at higher humidity percentages.
Without regular application of fungicides, it is difficult to achieve a good yield and grow grapes. The alternating use of fungicides with surface action (sulphur and dinocap), combined fungicides and systemics (pyrimidines and triazoles) is recommended.
Red vine burning
Red blight of the grapevine or in Latin Pseudopezicula tracheiphila, is a disease that originates from Europe, and which occurs in areas where there is not enough water and on slightly lighter soils. In our areas, it usually occurs in the area of Moslavina vineyards and in Plješivica, and the most sensitive is Portugizac.
The disease attacks the leaves and is caused by a fungus called Pseudopezicula tracheiphila. The parasite enters the bundles of leaves through the mycelium and thus prevents the development of juices. The tissue runs out of water, so the leaves between the veins dry out and die. There is the development of spots that take on the appearance of triangles. The color of the resulting spots changes, from the initial light yellow to red-brown.
Symptoms of the disease usually appear at the end of May and in June, and rarely in August and September.
Infection occurs when the leaf is moist for at least 48 hours at an air temperature of 15 degrees Celsius, and for 16 hours at a temperature of 20 degrees Celsius. It can take three to five weeks from the onset of infection to the first symptoms. Incubation lasts longer because the first symptoms only occur when the mycelium reaches the conductive bundles.
The infectious potential of the disease is reduced by plowing the leaves. Two sprays are recommended when the plant develops three, five and seven leaves if it rains during that period. Among the fungicides, carbamates are recommended, which can also help control the fungus Phomopsis viticola.
Gray mold of the vine
Grapevine gray mold or Botrytis cinerea in Latin causes damage to leaves, shoots, petioles and berries. The main cause of the disease is a fungus called Botrytis cinerea.
The fungus causes double damage – it reduces the yield by 3.5 percent, and sometimes by significantly more, and causes poor quality of must and wine. Namely, the fungus consumes larger amounts of sugar and acid from the berries, the taste of which eventually takes on the taste of apple cider vinegar.
The disease manifests itself on the leaves in the form of yellow spots that can later turn brown. In wet places, gray patches will appear from the freckle. The fungus can attack the green shoots and the stem of the bunch even before flowering, and the whole bunch can fall off.
Berry fungus causes two types of symptoms. While the berries are still green, it attacks them and causes them to decay, and in the second case, which is more common, the infection occurs before ripening itself.
The infection usually occurs at the end of June and the beginning of July, when the berries and petiole turn brown, and a gray coating appears on them. The attack comes from the berries that are located in the inner part of the cluster and thus spreads to the neighboring ones. The worst symptoms of the disease appear before ripening.
In order for infection to occur, green grape berries must be damaged, and the damage usually occurs before ripening, when the skin of the berries becomes thinner due to the higher sugar content. Fungal spores germinate at temperatures of 20 to 23 degrees Celsius, and a sufficient amount of moisture is required at the same time.
It is recommended to plant less sensitive varieties and use less lush substrates. The vines should be oriented in the direction of the wind, as this will reduce the amount of moisture. The amount of moisture can be reduced by removing the stems and leaves, which will expose the bunch more to the sun.
In addition to the mentioned measures, it is also necessary to spray with suitable fungicides. Four sprays are recommended:
- after flowering – broad-spectrum fungicides
- after closing the bunches – broad-spectrum fungicides
- when the varieties change color or the berries soften (depending on the variety) – specific botryticides
- three to four weeks before harvest (depends on the fungicide grace period) – specific botryticides
Rozgva black spotting
The black spot of the rose or the Latin Phomopsis viticola was discovered only in 1973. After the use of fungicides based on sulfur and copper was reduced, the aforementioned disease became an increasing problem.
It is a disease that gradually depletes the plant, and the yield decreases more and more every year. According to the available data, damages can be higher than 30 percent.
The disease attacks saplings, leaves and branches, and is caused by the fungus Phomopsis viticola.
Symptoms of the disease appear on the stems where dark brown zones surrounded by a lighter edge appear. Sometimes the infection also attacks the leaves, which causes a yellow ring to appear on them, and the leaves are eventually deformed.
At the end of May, long dark blue necrosis forms on the saplings, which can easily break under the influence of the wind. The bark begins to take on a silver color, and the buds are late in opening. The mycelium from the one-year-old rosewood can transfer to the older wood, which affects the rotting of the vine. Such plants grow slowly, the leaves often dry up, and eventually the branch dies.
The optimal conditions for the development of this disease are an air temperature of 23 degrees Celsius and 98 to 99 percent relative humidity.
Do not overdo it with fertilizing, especially with nitrogen, and when pruning, try to remove infected vines and remove them from the vineyard.
If there is an infection in the vineyard, do a winter spraying with copper-based fungicides (before the start of the growing season). After that, do three more sprays – two sprays, one in stages B and C and one in D to E (Baggiolini).
Vine pests
In order to recognize the pest that attacked your vine, it is necessary to recognize the symptoms that the pest leaves on the generative and vegetative parts of the plant. After that, you can think about protection with chemical or organic means. You can apply protective agents before the appearance of pests as a sign of prevention or after you notice that one of the pests has appeared. It is recommended to carry out regular control of the vineyard, as this is the only way to save the plantations in a timely manner.
Phylloxera (vine aphid)
Phylloxera or Latin Viteus vitifoliae, better known as vine aphid, was brought to Europe, more precisely to France, around 1980 from America. It quickly spread throughout all European countries and left behind thousands of ruined vineyards.
Soon, all European species were grafted onto American rootstocks, which are resistant to the aforementioned aphid. Today, only in some places along the Danube and on some islands where sandy soil predominates, you can find European types of vines that are not grafted onto the American one. Namely, cane aphid cannot develop on these fields.
Vine aphid attacks:
- leaves – American vine
- root – European vine
It is a small pest that is only 0.7 to 1.4 mm long, and rare forms grow up to 2 mm. It attacks so that a filet comes out through the stalk, with which it pierces the tissue of the plant and thus sucks the juices from it.
Phylloxera differs in American and European vines. On the European louse, it develops on the root system (parthenogenetically), and the larvae can overwinter. There are four to nine generations in one year. On the American vine, the aphid attacks the leaves so that small swellings are formed in which the aphids live and exit through the openings.
On European vines that have been vaccinated, control of this pest is not necessary, and on American vines, aphids are controlled during dormancy by spraying with insecticides that kill the eggs.
Cluster moth
Cluster moth or Latin Lobesia botrana; Clysia ambiguella includes yellow and ash moths which, although called moths, belong to the group of benders. It is one of the most significant vine pests.
The ash moth can be found all over Croatia and is widespread everywhere except in the northwestern parts of Croatia where the yellow moth is more widespread.
It attacks fruits (grape berries) and flowers. It can grow up to 7 mm, while its wingspan is from 11 to 15 mm, depending on the species. One is ash gray, the other yellow, and each of them has a pupa from which a caterpillar emerges. In the ash moth the caterpillar is green with a yellow or brown head, while in the yellow moth it is pink when young and later white.
The yellow grape moth has two generations per year, while the ash moth has as many as three.
Caterpillars from the first generation attack the flower, those from the second attack green grape berries (they gnaw them so much that sometimes only the seed remains). Caterpillars of the third generation attack ripe grapes, and in addition to the berries being damaged, this generation of moths can cause gray mold infection, or Botrytis.
Although they belong to the same group, the two mentioned moths differ not only in their appearance, but also in their attack on vines. The yellow cluster moth needs high humidity, but not heat, while the ash moth requires slightly less humidity, but extremely warm weather.
The ash moth appears periodically, it appears suddenly in the first two years, while it disappears in the third. And the appearance of the yellow moth is much more uniform.
Protection against grape moth is carried out with protective insecticides to control caterpillars. The main goal is to suppress the first generation in order to reduce the risk of attacks during the second generation when the clusters are already formed.
Vine pine mite
Lozine pine mites differ from other arachnids in that they have two pairs of legs. They are small, oblong, 0.03 mm wide and 0.6 mm long. Their body is white. Since they are very small, they can sometimes only be seen with the help of a magnifying glass.
The most famous varieties of the pine mite are:
- acarinosis – Latin Calepitrimerus vitis
- erinoza – Latin Colomerus vitis
Acarinosis
Acarinosis attacks leaves and buds. The female pest hibernates under the bark on the bark or on the bud under the shell and thus lays eggs. After ten days, a larva develops, which in the next eight to ten days moves to young leaves. They are activated in the spring months during cold weather when vine growth is slower. If there are a lot of mites in the bud, then the damage does not depend on weather conditions. There are three to five generations a year, and in some cases even more.
The pest causes damage to buds and leaves. The bud turns brown and bends, and the leaves remain damaged, hollow and with a characteristic dark edge that is raised. If the leaves are attacked during the summer, they take on a dark color due to numerous dark spots, and then their color appears to be purple.
Erinosis
Erinoza attacks the leaves so that the female overwinters inside the bark. A pest can have up to seven generations in one year, and it can cause three types of damage.
The first symptoms appear on the leaves in the form of red or purple swellings, and later green. On the reverse, there are woolly coverings of white color, but with a purple or red sheen. At the end, they turn yellow or brown. Over time, mites move to young plants.
The second type of damage occurs on the buds, while in the third type, the leaves are curled without first forming a woolly coating. Over time, the leaves turn yellow and brown and fall off.
Grapevine cone mites can overwinter in adult form, so it is necessary to treat them during the winter when the bud starts to swell. High-quality spraying with oil-based oragonophosphorus agents is necessary.
During the growing season, the mites emerge from the buds and move to the shoots, where they further attack the leaves. In this case, use products based on endosulfan and phenazaquin.
Cigarette smoker
Cigaroš or Latin Byctiscus betulae is a pest that appears most often in Dalmatia and Istria. Attacks leaves and buds.
Adult pests have a body of different colors, from light green and shiny to blue and copper and metallic. They can grow from 6 to 9 mm. The larva of this pest has no legs, is 6 mm long and white in color.
They hibernate in remote places, and appear during April and May, in the spring months. Then they feed on the swollen buds, and later on the leaves. They have only one generation per year.
Their way of laying eggs is interesting. Namely, the female rolls the withered leaves into a wrapper that looks like a cigarette, and lays eggs inside each one. One female can make up to 20 clutches. The eggs develop into larvae that live and feed in the shell, and at the end of development they pupate in the soil.
The adult pest leaves bites on the leaves, and when the buds open and the vines turn green, they begin to bite the petioles of the leaves, which leads to wilting. In some cases, they can also damage the shoots near the top.
This pest is controlled by removing and destroying the shells with larvae and eggs, as this reduces the number of attacks the following year. The adult pest is also easily visible, so it can be removed and destroyed.
Suppression with chemical means can be carried out when there are not many beetles and adult pests are numerous. That could be in May. Means based on fenthion, endosulfal, fenitrothion and phosalone will help you.
Lozina thrips
Grape thrips or Latin Drepanothrips reuteri is a common pest in vineyards in the continental part of Croatia and in the coastal areas. The pest attacks young shoots, leaves and bunches.
An adult pest is smaller than 1 mm and its color is light yellow.
An adult female can overwinter on the branches of the vine, which in the spring begins to feed on the young shoots of the plant. On average, one female can lay up to 100 eggs. Larvae emerge from the eggs after six to ten days, they feed on leaves and bunches. They develop from six to nine days, and there are several generations during one year.
The damage can be enormous because the pest attacks the vine at the very beginning of the growing season when the shoots are still young. As such, they lag behind in growth. Later, the larvae work on the petiole of the leaves and young clusters. The leaves dry, and the developed grape berries take on a dotted appearance.
Means based on imidacloprid or organophosphorus insecticides can be applied.
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