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Grapevine diseases and pests: identification guide with images

Like all plants, grapevines are subject to attacks by pests and diseases caused by viruses, bacteria, and fungi. In this practical guide, we will provide an overview of the main plant diseases that damage grapevines. For each disease or insect, you will find a link leading to a more complete description, since it is not possible to cover every topic in full detail in this technical sheet. We therefore invite you to explore the subject that interests you by clicking on the relevant links.

To facilitate and speed up identification, each disease or damage agent is described with photos and images. This technical guide is divided into three sections: disease agents (viruses, phytoplasmas, and fungi), damage agents (insects and mites), and physiological disorders of grapevine.

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Disease agents: fungal diseases and phytoplasmas

Grapevines are affected by a wide range of fungi and oomycetes that can cause significant damage. Below we analyze the most important ones and the remedies that can be applied to prevent and control them.

Downy mildew of grapevine

The pathogen attacks leaves, shoots, flowers, and fruit. The symptoms of grapevine downy mildew are quite characteristic. On the upper surface of leaves, yellowish and translucent round spots can be observed. These are commonly referred to as “oil spots”.

Oil spot symptoms on grapevine leaves.
Figure 1 – Oil spot symptoms on grapevine leaves.

On the underside of the leaves, corresponding to the oil spots, a white mold appears, composed of the pathogen’s asexual reproductive structures. Eventually, the spots become necrotic. In rare cases, the white mold may appear without oil spots or vice versa.

Affected inflorescences become covered with white mold, which can evolve into necrosis of the entire inflorescence. In other cases, only the tip becomes deformed, bending into a hook shape and turning brown before being covered by white mold.

After fruit set, the pathogen begins to attack young grape clusters. In this case, it is referred to as “Latent downy mildew infection”, which appears as browning, dehydration, and partial or complete drying of the cluster.

Downy mildew symptoms on grape clusters.
Figure 2 – Downy mildew symptoms on grape clusters.

Control of grapevine downy mildew includes both agronomic practices and plant protection treatments. The most useful agronomic practices include:

  • Removing abandoned vineyards to reduce pathogen inoculum in the environment
  • Proper pruning and appropriate training systems to reduce humidity within the canopy
  • Balanced nitrogen fertilization to avoid excessive vigor and facilitate canopy management
  • Removing crop residues where possible to reduce overwintering inoculum

For organic treatments, applications of copper salts should begin when favorable conditions for the pathogen occur. This typically triggers preventive treatments every 7–10 days using copper-based products.

At present, the most effective organic control remains preventive copper treatments, often supported by other products. Additional products include:

  • Copper peptides (with caution due to possible phytotoxicity)
  • Sodium or potassium silicate
  • The antagonistic bacterium Bacillus subtilis, available in several commercial formulations

In conventional agriculture, several plant protection products are available for both preventive and curative treatments.

For the complete technical guide and additional solutions, please refer to our full article Downy mildew of grapevine (here)

Powdery mildew of grapevine

This pathogen affects all green organs of the plant, particularly leaves and clusters during spring and summer. On leaves, powdery mildew appears as white-grayish patches with a powdery mold-like appearance, and leaves may later become deformed.

Powdery mildew symptoms on grapevine leaves.
Figure 1 – Powdery mildew symptoms on grapevine leaves.

Grape clusters infected with powdery mildew also develop the characteristic white-gray mold. Berries tend to become necrotic in affected areas, causing deformation and reduced growth compared to healthy areas. This leads to berry cracking, which predisposes the fruit to infections by Botrytis cinerea, Penicillium, Aspergillus, and other fungi.

Powdery mildew symptoms on grape clusters.
Figure 2 – Powdery mildew symptoms on grape clusters.

Organic control mainly relies on sulfur-based treatments and other compounds such as sodium and potassium bicarbonate.

Recent developments in biological control have introduced highly effective solutions against grapevine powdery mildew, including:

  • COS–OGA (chito-oligosaccharides and oligogalacturonides), and chitosan – these products act as elicitors, activating the plant’s natural defense mechanisms
  • Cerevisane, a systemic resistance inducer derived from cell wall extracts of the yeast Saccharomyces cerevisiae
  • Laminarin, an oligosaccharide extracted from the brown alga Laminaria digitata that stimulates plant defenses
  • Sweet orange essential oil, which acts both as an insecticide and fungicide through direct contact, disrupting insect cuticles and fungal structures

Finally, two bacteria used in biological control against grapevine powdery mildew should be mentioned:

  • Bacillus amyloliquefaciens, an antagonistic bacterium useful in reducing infections
  • Bacillus pumilus, another antagonistic bacterium that controls fungal diseases

For the complete technical sheet and additional solutions, please refer to the full article grapevine powdery mildew (here).

Botrytis or gray mold

Also called gray mold, it appears on affected grape clusters as a gray-colored fungal growth (see figure 1). The infected tissues lose turgor and the affected berries are irreparably damaged. Table grapes affected by botrytis are unsellable, while wine grapes undergo biochemical changes that alter the flavor of the wine, resulting in a loss of quality.

Damage caused by botrytis (Botrytis cinerea) on grapes at harvest.
Damage caused by botrytis (Botrytis cinerea) on grapes at harvest.

The main entry point (though not the only one) occurs on clusters during the veraison stage, when the fungus invades the host by exploiting lesions of biotic origin (such as damage from grape moth, thrips, or powdery mildew) or abiotic origin (hail or strong wind damage). At this phenological stage the berries no longer have stomatal openings, but the reduced presence of organic acids and the increase in sugars make infection highly aggressive.

In organic farming, botrytis management relies primarily on vineyard agronomic practices and secondarily on the use of plant protection products approved for organic agriculture. Essential agronomic practices include:

  • The varietal characteristics of the grape cultivar are important. Varieties with loose clusters should be chosen, as these allow better air circulation and reduce moisture accumulation between berries.
  • Calcium plays an important role in disease management. Plants well supplied with calcium have stronger tissues and greater resistance to pathogen attacks.
  • Green pruning and leaf removal improve air circulation. Removing leaves around the clusters is particularly important, as it exposes the clusters to ultraviolet radiation and promotes the formation of phytoalexins, compounds involved in plant defense.
  • Training systems such as vertical trellis systems (e.g., Guyot) should be preferred. These provide better air circulation compared with pergola systems, where humidity stagnation is more common.
  • In vineyards or areas particularly prone to botrytis infections, crop residues from the previous season should be promptly removed, burned, or buried.

As mentioned earlier, botrytis can establish itself as a secondary pathogen following damage caused by grape moth or powdery mildew. Therefore, controlling these pests and diseases is essential for proper botrytis management.

Direct control of botrytis in organic agriculture can be carried out using several biological plant protection products and plant-strengthening substances. Among the classic products used are copper salts (used for downy mildew control, they also thicken the berry cuticle and act as contact fungicides). The side effect of sulfur, used against powdery mildew, should also be mentioned. On its own it is not sufficient to control the infection, and in most commercial formulations registered in Italy for botrytis control sulfur is combined with copper.

It is also worth mentioning potassium bicarbonate, which has fungitoxic and fungistatic effects by increasing the pH of the leaf surface and causing dehydration of fungal hyphae.

For the complete technical sheet and additional solutions, please refer to our full guide gray mold (here).

Black rot of grapevine

The disease is caused by the ascomycete fungus Guignardia bidwellii, which generally behaves as a secondary pathogen in vineyards. However, since the 1980s, damage caused to grapevines has become increasingly frequent, particularly affecting grape clusters.

The first symptoms appear on leaves with the formation of necrotic spots with irregular margins measuring 4–10 mm (see figure 1).

Black rot of grapevine on grapevine leaf
Figure 1 – Black rot on grapevine

Later, depressed areas with a boiled appearance and hazelnut color appear on young berries. These areas tend to dry out the berry over the following days, forming what are known as mummies (see figure 2).

Before the berry dries completely, small black dots appear on its surface. These are the pycnidia and/or perithecia of the fungus, which are its reproductive structures. Pycnidia and perithecia also develop in the leaf lesions. Over time, leaf spots tend to enlarge and spread, eventually causing the entire leaf to dry out. Affected berries dry completely and sometimes the entire cluster can be lost.

Black rot on grapevinecluster
Figure 2 -Advanced symptoms of black rot on grapevine

Prevention is therefore based on removing infected clusters through green pruning, and if possible also removing affected leaves. The removed plant material should be taken out of the vineyard and buried.
It is also essential to improve canopy aeration through appropriate green pruning and early leaf removal where possible. During winter pruning, all remaining infected clusters should be removed and taken away.
In any case, treatments based on copper and sulfur also have an effect against grapevine black rot.

For the complete technical sheet and additional solutions, please refer to our full guide black rot (here).

Esca disease

Present worldwide, esca disease results from infection by several fungi; therefore it is more accurate to describe it as a pathogen complex that causes the symptoms commonly known as esca disease.

This complex causes two main types of damage in grapevines:

  1. Tracheomycosis, which involves the blockage of vascular tissues.
  2. Wood decay, which leads to the deterioration of affected tissues.

The disease appears characteristically on leaves (see figure 1), producing various discolorations of the leaf blade that start between the veins and move toward the center of the leaf without affecting the main veins. This creates the typical “tiger stripe” symptom.

Grapevine leaf showing tiger stripe symptoms. Note how the main veins remain intact.
Figure 1 – Grapevine leaf showing tiger stripe symptoms. Note how the main veins remain intact.

After these initial symptoms, the leaves begin to dry out completely, followed by partial or total dieback of branches (see figure 2).

Grapevine with partial esca symptoms. Note the drying of branches and clusters.
Figure 2 – Grapevine with partial esca symptoms. Note the drying of branches and clusters.

Control of this disease is mainly preventive and consists of several agronomic practices, including:

  • Removing dead or severely affected plants
  • Regularly disinfecting pruning tools such as scissors and saws
  • Applying copper-based treatments after severe hail events
  • Applying protective pruning paste on large cuts
  • Applying Trichoderma-based products after winter pruning

Copper has antifungal activity and helps protect the plant from pathogen entry after strong winds or hail. Treatments should be applied promptly, within 24–48 hours after the damaging event.

One of the most important preventive tools is the use of Trichoderma, a beneficial fungus capable of preventing attacks by pathogenic fungi. Trichoderma should be applied preventively in two ways:

  • Through irrigation systems or soil inoculation to protect the root system from soil-borne diseases.
  • Through aerial application immediately after pruning, which is even more important for protecting pruning wounds.

For the complete technical sheet and additional solutions, please refer to our full guide grapevine Esca (here).

Phomopsis cane and leaf spot

Phomopsis cane and leaf spot is a fungal disease caused by Phomopsis viticola, favoured by cool and wet spring conditions. It mainly affects young shoots, where small dark lesions and tissue cracking can develop. Small necrotic spots may also appear on leaves, often associated with the veins. The fungus overwinters in infected canes and spreads through rain splash. Early diagnosis is essential to limit disease spread within the vineyard. Prevention relies on the removal of infected wood and proper canopy management. In organic production systems, disease control is based primarily on copper-based products applied during the early stages of vegetative growth.

For the complete technical sheet and additional solutions, please refer to our full guide grapevine Phomopsis (here).

Flavescence dorée of grapevine

This disease is caused by a phytoplasma whose scientific name is Candidatus Phytoplasma vitis. Affected plants show symptoms in late summer, which appear as changes in leaf color: yellowing in white grape varieties and reddening in red grape varieties. Another characteristic symptom is the downward curling of the leaf margins, giving the leaf a triangular shape (see photo below).

Typical triangular leaf curling caused by flavescence dorée
Typical triangular leaf curling caused by flavescence dorée. Photo source: www.cavb.fr

In general, the leaves of infected plants become thicker and develop a papery texture. The plants show reduced vigor and the shoots fail to lignify properly. On the fruit, symptoms may include drying of the rachis and berry drop.

The main vector of this disease is the insect Scaphoideus titanus, which transmits the pathogen from infected plants to healthy ones while feeding.

There is no cure for infected plants, which must be removed from the vineyard. The main containment strategy consists of controlling the insect vector, mainly through insecticide treatments and appropriate agronomic practices.

Most common fungicides available online

Damage agents: insects and mites

Grapevine moth

The grapevine moth (Eupoecilia ambiguella, also known as Clysia ambiguella) is a lepidopteran insect present in most grape-growing areas of southern Italy. Damage occurs both during flowering (first generation) and on berries during the berry enlargement and veraison stages (second generation). Damage to clusters during berry enlargement is extremely harmful for growers because lesions caused by the moth easily allow the development of botrytis and sour rot. In table grape varieties, even a few damaged berries can negatively affect product quality. Very similar damage is caused by Lobesia botrana.

larvae of grapevine month on grape berry

A proper control strategy against Clysia ambiguella relies on appropriate sampling techniques, followed by insecticide treatments when necessary. In recent years, the mating disruption technique against this insect has been refined and, when applied correctly, can effectively control this lepidopteran pest on its own.

Mating disruption can be applied in vineyard areas larger than 10 hectares or in isolated vineyards. Otherwise, fertilized females may migrate from surrounding areas and lay eggs in the vineyard.

This technique is very effective and, in many cases, can protect vineyards against grapevine moth infestations by itself. If this is not sufficient, insecticide treatments combined with monitoring of adult flights must be carried out.

Several types of monitoring traps are available on the market, all based on the use of pheromone attractants. In organic vineyards it is essential to periodically check for the presence of the insect using both pheromone traps and field inspections.

The treatment threshold for the first generation (flower-feeding stage) is between 30–40% of infested flower clusters. For the second generation, whose larvae are the most damaging, the intervention threshold is 10 males captured per trap per week.

Natural remedies that can be used in the field, once a strong presence of males and the first eggs on the berries has been detected, include products based on Bacillus thuringiensis and spinosad. Mineral oil can also be used against the eggs of this insect, acting by suffocation.

For the complete technical sheet of the insect and additional solutions, please refer to our full guide.

European grapevine moth

The European grapevine moth (Lobesia botrana) is a lepidopteran insect widespread throughout Italy, particularly in the central and southern regions. Control of this insect is carried out at the same time as the control of the grapevine moth, Eupoecilia ambiguella.

Damage occurs both during flowering (first generation) and on berries during the berry enlargement and veraison stages (second and third generations). Damage to clusters during berry enlargement is extremely harmful for growers because lesions caused by the larvae easily allow the development of botrytis and sour rot.

Control and management strategies are essentially the same as those used for the grapevine moth (Eupoecilia ambiguella), described above.

For the complete technical sheet and additional solutions, please refer to our full guide.

Flavescence dorée leafhopper

The flavescence dorée leafhopper is mainly found in northern Italy and is particularly feared because of the disease it can transmit to grapevines known as flavescence dorée. This insect, with the typical shape of a leafhopper, measures about 6 mm in length. Adults show a marbled coloration with brownish and whitish elements and clearly visible black wing veins (see figure 1).

adult of flavescence doree leafhopper
figure 1 – Adult of flavescence doree leafhopper

The direct damage caused by this leafhopper is negligible and appears as necrosis and discoloration of the leaves at the feeding puncture sites. What makes Scaphoideus titanus dangerous is its ability to transmit the disease flavescence dorée through its feeding punctures.

This disease is caused by a phytoplasma that induces stress in the plant, manifested by leaf yellowing, leaf drop, drying of clusters, and thickening of the leaf blade.

Agronomic practices that help reduce leafhopper presence in vineyards include burning pruning residues from both winter and spring pruning in order to reduce the number of eggs. Removing suckers and basal shoots from the vine also helps contain infestations, since juvenile stages of the leafhopper tend to develop on these parts of the plant.

Wild grapevines should also be removed because they may act as reservoirs for flavescence dorée.

Insecticides used for treatments against this insect include:

For the complete technical sheet and additional solutions, please refer to our full guide.

Drosophila suzukii (spotted wing drosophila)

Adults of Drosophila suzukii are small yellow-brown flies (3–4 mm) with red eyes (see image below).

adult od spotted wing drosophila
Adult od spotted wing drosophila

The spotted wing drosophila is known for laying eggs in healthy, intact fruits, unlike other fruit flies that prefer damaged or overripe fruits. Two characteristics make Drosophila suzukii a particularly dangerous pest for small fruits and, in rare cases, also for red grape varieties:

  • Its preference for ripening fruit, rather than fully ripe fruit.
  • The serrated ovipositor of the female, which can pierce the fruit skin and cause physical damage during egg laying.

Egg-laying wounds often allow secondary infections by other insects and pathogens, including fungi, yeasts, and bacteria, which lead to further losses.

Particular care must be taken not to confuse adult Drosophila suzukii with Drosophila melanogaster, which typically lays its eggs in fruit that is already decaying or previously damaged.

In Italy, some cases of damage to grapes have been reported, especially in northern regions. At present it is not considered a major concern in vineyards, but where infestations occur they are particularly difficult to manage due to the insect’s rapid reproduction and the lack of highly effective control measures.

For the complete technical sheet and additional solutions, please refer to our full guide.

If you want, I can also improve some titles for international viticulture terminology, because for example:

  • “European grapevine moth” is usually used for Lobesia botrana in English viticulture literature.
  • Some insect names can be made more standard for English-speaking agronomists and winegrowers.

Grapevine phylloxera

This insect, more precisely an aphid, caused extremely severe damage to European viticulture in the past and was considered a real scourge during the 19th century.

The most characteristic symptom is the development of galls on the underside of the leaves (see figure 1). Inside these galls the insects develop, producing several generations per year. Since it is an insect with a heteroecious life cycle, it spends part of its life not only on leaves but also on the roots.

On the roots it causes the formation of root galls, which lead to plant decline. European grapevines are particularly susceptible to root attacks but less susceptible to leaf infestations. Conversely, American grapevines are less susceptible at the root level but highly susceptible to leaf attacks.

Grapevine phylloxera damange on leaf

Because American grapevines proved useful as rootstocks, the practice of grafting a European scion onto an American rootstock results in plants resistant to phylloxera, preventing the insect from completing its life cycle.

Although some outbreaks of phylloxera have recently been recorded on grafted vines, the insect is currently under control throughout Europe and no longer causes significant damage.

Phylloxera galls on grapevine
Figure 1 – Phylloxera galls on grapevine leaf

Grapevine eriophyid mite

The grapevine eriophyid mite is a very common pest that can be easily found in almost all vineyards. It is a mite belonging to the Eriophyidae family, whose scientific name is Colomerus vitis.

This mite is present throughout Italy and in all grape-growing regions worldwide. The characteristic symptom that develops on affected leaves is the formation of blister-like swellings on the upper leaf surface (see figure 1).

symptoms of grapevine eriophyid mite
Figure 1 – Typical leaf blistering caused by grapevine eriophyid mite

Beneath these swellings, inside the cavity that forms, a dense white felt-like hair growth develops with a spongy appearance (see figure 2).

Grapevine eriophyid mite damage
Figure 2 – Grapevine eriophyid mite damage

Given the relatively low harmfulness of this mite, specific treatments are generally not required. This pest is easily controlled by sulfur-based treatments used to control grapevine powdery mildew.

For this reason, in organic viticulture it rarely reaches damaging levels. In conventional viticulture, where powdery mildew is often controlled with synthetic fungicides instead of sulfur, eriophyid mite infestations may occasionally reach problematic levels. However, one or two sulfur treatments per year are usually sufficient to stop any infestation.

For the complete technical sheet and additional solutions, please refer to our full guide.

Most common insecticides available online

Grapevine physiological disorders

Iron deficiency

Iron deficiency in grapevine appears as yellowing of the apical leaves. At first the symptom develops between the leaf veins, while the veins themselves remain green. As the deficiency worsens, the veins may also turn yellow. Prolonged iron deficiency leads to leaf drop, reduced plant vigor, and consequently lower yields.

Biologically available iron in the soil may be lacking either due to its natural scarcity or because it forms insoluble compounds under high pH conditions. In the first case, the problem can be corrected by applying iron sulfate or chelated iron. In the second case, soil pH can be adjusted using sulfur or fertilizers with an acidic reaction. If symptoms are already visible, a foliar fertilizer containing iron can be applied.

Magnesium deficiency

Magnesium deficiency in grapevine appears as interveinal chlorosis that starts from the outer edge of the leaves and gradually moves toward the center of the leaf. In red grape varieties the discoloration appears reddish. The veins usually remain green. The symptom first appears on the basal leaves of the shoots, therefore on the oldest leaves (see figure 1).

Symptoms of magnesium deficiency in grapevine
Figure 1 – Symptoms of magnesium deficiency in grapevine

There are several reasons for magnesium deficiency. In soils excessively rich in potassium or calcium, nutrient competition reduces magnesium uptake. Soils with very acidic or very alkaline pH can also lead to magnesium deficiency. In addition, some rootstocks such as 3309C may have difficulty absorbing this element, as well as rootstocks that induce excessive vegetative vigor.

Magnesium deficiency leads to low sugar production and drying of the rachis. When deficiency occurs, treatment is carried out with foliar magnesium fertilizers.

Potassium deficiency

Potassium deficiency appears as yellowing followed by reddening of the leaf margins. Over time the discoloration spreads to the entire leaf except for the veins. In severe cases the leaf margins become dry and necrotic (see figure 1).

Symptoms of potassium deficiency in grapevine
Figure 1 – Symptoms of potassium deficiency in grapevine

A lack of available potassium may occur in soils with high levels of calcium or magnesium, where nutrient competition limits potassium uptake. In clay soils, potassium may become fixed in the soil and unavailable to the plant. Some rootstocks such as SO4 may have difficulty absorbing this element.

When symptoms appear, treatment generally consists of one or more foliar fertilizations, often using a balanced fertilizer such as 20-20-20, combined with soil fertilization using fertilizers rich in potassium, such as potassium sulfate.



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