Diseases

American Powdery Mildew (Sphaerotheca)

Pathogen: fungus Sphaerotheca mors-uvae (syn. Podosphaera mors-uvae). The disease was introduced to Europe from North America (Dankov, 2015).

Symptoms: a white powdery coating appears on young leaves, shoots, petioles, and ovaries – this is the fungal mycelium and its sporulation. Over time, the coating darkens, becomes greyish, and black dots (winter fruiting bodies) become visible. Affected shoot tips become twisted, dry up, leaves become smaller, brittle, curl up, and fall prematurely (Dankov, 2015). Berries become covered with the coating and lose marketable quality.

Conditions for development: the disease appears shortly after flowering, first on the upper parts of the bush, then spreads downwards. High air humidity, dense plantings, and warm weather promote development. Affected bushes lag in growth and may die within 2–3 years (Dankov, 2015).

Control measures:

• Prevention – choose resistant varieties ('Golubka', 'Seyanets Golubki', 'Binar', etc. (Kurennoi et al., 1985)), thin plantings, ensure good ventilation.
• Treatment – spray with sulphur-based fungicides (colloidal sulphur, thiram) or biological products (e.g., based on Bacillus subtilis). Apply before flowering, after flowering, and at the first signs of disease. Sources mention liquid lime‑sulphur spray applied at the green‑cone stage and 2–3 weeks after flowering (Bowling, 2000). Important: some products may be phytotoxic, so strictly follow the label instructions.

Anthracnose

Pathogen: fungus Pseudopeziza ribis (syn. Gloeosporium ribis).

Symptoms: small, brown, diffuse spots appear on leaves, often merging. Leaves turn yellow, curl, and fall off. Ulcers form on petioles, fruit stalks, and young shoots. Severely affected shoots lignify poorly, buds develop weakly, and the next year’s yield drops sharply. With long‑term infection, bushes stop producing new growth (Dankov, 2015). In gooseberry, anthracnose affects only the leaves.

Conditions for development: the disease spreads actively in rainy weather. The pathogen overwinters on fallen leaves and in shoot cankers. Dense plantings, low areas, and the presence of weeds favour epiphytotics (Dankov, 2015).

Control measures:

• In autumn, carefully collect and burn fallen leaves.
• Carry out sanitary pruning, removing diseased shoots.
• In spring, before bud break, spray bushes and soil with 3% Bordeaux mixture or its substitutes. During the growing season, apply fungicides (copper‑based products, systemic fungicides) according to instructions. The number of treatments depends on the weather (usually 2–4 times per season).

Septoria Leaf Spot (White Spot)

Pathogen: fungus Septoria ribis (syn. Mycosphaerella ribis).

Symptoms: small (2–3 mm) angular or round spots appear on leaves. Initially brown, they later become whitish in the centre with a reddish‑brown border. Black dots (pycnidia) – spore‑bearing organs – form within the spots. Severe infection causes massive leaf drop and may also affect berries, forming flat spots on them (Dankov, 2015).

Conditions for development: the fungus overwinters on fallen leaves. In spring, ascospores from fruiting bodies infect young leaves. Wet weather favours spread. Septoria is especially dangerous in dense plantings.

Control measures:

• Collect and destroy leaf litter.
• Thin bushes to ensure good air circulation.
• Spray with copper‑containing products (Bordeaux mixture, copper oxychloride) in early spring and after flowering. In case of heavy infection, additional treatments every 10–14 days.

Cup Rust

Pathogen: fungus Puccinia ribesii-caricis. This is a heteroecious fungus requiring sedge (Carex spp.) as an alternate host for its full life cycle (Dankov, 2015).

Symptoms: in spring, large yellow cushions (aecia) appear on leaves, flowers, and ovaries of currants. Later, cup‑shaped spore‑bearing structures form on the lower leaf surface. Infected leaves may drop prematurely, berries spoil and fall off. The disease is particularly dangerous in regions where sedge is abundant (Kurennoi et al., 1985).

Conditions for development: spores overwintering on sedge are carried by wind to currants in spring. Wet weather favours infection.

Control measures:

• Destroy sedge within a radius of 200–300 m from plantings (Bowling, 2000 recommends removing sedge within reach).
• Spring spraying with copper‑based fungicides before bud break and immediately after flowering.
• In heavy infections, apply systemic products.

Column Rust

Pathogen: fungus Cronartium ribicola (some sources mention a different species, but column rust on currants is often associated with conifers – Siberian cedar and Weymouth pine). It is also a heteroecious fungus.

Symptoms: small yellow spots appear on the upper leaf surface, while yellow clusters of uredospores, later yellowish‑red columns of teliospores, form on the lower side; when fused, they produce characteristic columns (hence the name). Leaves turn brown, die, and drop. The disease usually appears in late summer (August), but under favourable conditions it can become massive (Dankov, 2015).

Conditions for development: the fungus needs conifers (cedar, Weymouth pine) for overwintering. In spring, spores from pine needles are carried to currants. Warm and humid weather in the second half of summer enhances spread.

Control measures:

• Avoid planting currants near conifers (especially cedar and Weymouth pine).
• Remove fallen leaves.
• Apply 1% Bordeaux mixture in spring, as well as treatments after flowering and during berry filling. For severe infections, use systemic fungicides approved for currants.

Gray Mold (Botrytis)

Pathogen: fungus Botrytis cinerea.

Symptoms: brown, watery spots appear on berries and rapidly enlarge. Affected berries become soft and covered with a grey fluffy mould (conidial sporulation). In wet weather, the mould is abundant and spores are easily carried by wind and raindrops. It can also affect leaves and shoots, causing wilting and rot (Dankov, 2015; Buckingham, 2010).

Conditions for development: high humidity, dense plantings, poor ventilation, wet weather. The fungus overwinters as mycelium and sclerotia on plant debris.

Control measures:

• Ensure good ventilation of bushes (regular pruning, removal of excess shoots).
• Collect and destroy diseased berries and leaves.
• Apply preventive spring fungicide sprays (copper‑based, thiram). In rainy years, increase the number of treatments. Important: gray mold often attacks berries at wound sites, so pest control is also important.

Verticillium Wilt (Tracheomycosis)

Pathogen: fungus Verticillium dahliae (and other species). A soil‑borne pathogen that enters the plant through roots (Dankov, 2015).

Symptoms: the disease appears during active growth or in the second half of summer. Leaves first turn yellow, then brown and dry up, starting from the lower part of the bush. Wilting may be sudden or gradual. A cross‑section of affected branches shows darkening of the vessels. Eventually the bush dies, sometimes gradually, with individual branches dying off (Kurennoi et al., 1985).

Conditions for development: the fungus persists in soil for many years. Mechanical root damage, poor drainage, and planting currants after host crops (potato, tomato, strawberry) favour development. High soil moisture and warm weather accelerate the disease.

Control measures:

• Prevention: follow crop rotation, avoid planting after solanaceous crops and strawberry.
• Use healthy planting material.
• Remove and burn infected bushes along with roots.
• Treat the soil after removal with Trichoderma‑based products or fumigate (for large areas). There are practically no chemical treatments for verticillium on currants, so emphasis is on prevention and culling.

Fusarium Wilt

Pathogen: fungi of the genus Fusarium (mainly F. oxysporum). Also a soil‑borne pathogen.

Symptoms: similar to verticillium – wilting of shoots, yellowing and drying of leaves, darkening of vascular tissues. Often the infection starts at the root collar and lower stem. A pinkish or white coating of mycelium and spores may appear on roots and at the base of shoots (Dankov, 2015).

Conditions for development: the fungus survives well in soil and on plant debris. Over‑watering, heavy soils, and root damage promote development.

Control measures: same as for verticillium: prevention, healthy planting material, removal of diseased plants, biological products (Trichoderma, Pseudomonas). Chemical fungicides are largely ineffective against soil‑borne infections.

Alternaria and Cercospora Leaf Spots

Pathogens: fungi of the genera Alternaria and Cercospora, respectively.

Symptoms: Alternaria appears as brown or black spots with concentric rings on leaves and shoots. Cercospora causes small angular spots with a purplish tinge, often with a grey centre. Both diseases lead to premature leaf drop, weaken bushes, and reduce yield (Bowling, 2000; Buckingham, 2010).

Conditions for development: both diseases become active in warm, humid weather, especially in the second half of summer. Pathogens overwinter on fallen leaves and diseased shoots.

Control measures: similar to measures against leaf spots – removal of litter, sanitary pruning, spraying with copper‑based or systemic fungicides at the first signs. Avoid canopy crowding.

General principles for controlling fungal diseases:

1. Pre‑planting measures: choose resistant varieties, healthy planting material, a suitable site (well‑drained, sunny).

2. Agronomy: regular pruning, keep the root zone clean, moderate watering, balanced nutrition (avoid excess nitrogen).

3. Autumn sanitation: remove and burn all plant debris, dig or loosen the soil.

4. Preventive sprays: early spring treatment (before bud break) with Bordeaux mixture or copper sulphate. Repeat treatments as needed, strictly following product instructions. Alternate fungicides from different groups to avoid resistance.

5. Home remedies: spraying with herbal infusions (nettle, horsetail), baking soda solution, or whey may help in early stages, but in serious infections they are inferior to chemical products.

Bacterial Root Cancer (Crown Gall)

Pathogen: bacterium Agrobacterium tumefaciens (syn. Rhizobium radiobacter). A widespread soil‑borne pathogen that affects many woody and shrubby species, including currants (Bowling, 2000).

Symptoms: galls (overgrowths) form on roots, root collar, and sometimes on the lower part of shoots. Initially soft and light‑coloured, they later darken, become woody, and can reach considerable size. Galls disrupt the conducting function of roots and the root collar, weakening the plant. In severe cases, the bush lags in growth, leaves turn yellow, yield decreases. In advanced cases, the currant dies. Above‑ground symptoms are non‑specific (stunting, chlorosis), so diagnosis is made by examining the roots.

Conditions for development: the bacterium persists in soil for long periods (several years) and infects plants through wounds on roots and root collar (damage during planting, cultivation, frost cracks, insects). Neutral or slightly alkaline soil reaction, high humidity, and temperatures of 22–28 °C favour development. Bacterial cancer is especially dangerous on heavy, poorly drained soils.

Control measures:

• Use healthy planting material; visually inspect roots before planting (discard seedlings with galls).
• Follow crop rotation – do not plant currants where crops susceptible to bacterial cancer (tomato, potato, raspberry, fruit trees) previously grew.
• Pre‑plant root treatment with biological products based on antagonistic bacteria (e.g., Agrobacterium radiobacter strain 84, which suppresses the pathogen).
• If infected bushes are found – uproot and burn them together with roots. Disinfect or replace the soil.
• Prevent root and root‑collar damage during cultivation.

Bacterial Wilt (Erwinia)

Pathogens: bacteria of the genus Erwinia (more commonly Erwinia amylovora – the causal agent of fire blight in pome fruits, but other species causing wilt are also known). Bacterial wilt on currants is rare but mentioned in the literature as a possible problem under unfavourable conditions.

Symptoms: sudden wilting of individual shoots or the whole bush. Leaves lose turgor, turn brown, dry up, but remain hanging on the plant. A cross‑section of affected stems shows darkening of vessels and bacterial slime exudation. The disease often starts at shoot tips and spreads downwards quickly. Under high humidity, exudate in the form of milky droplets may appear on infected tissues.

Conditions for development: bacteria enter through wounds, bark cracks, and flower nectaries. Warm (25–30 °C) and humid weather, especially during flowering and active shoot growth, favours development. Vectors may include insects, rain splashes, wind, and contaminated tools.

Control measures:

• Use healthy, certified planting material.
• Early detection and removal of infected shoots (cut 15–20 cm below visible symptoms) followed by burning.
• Treat cut surfaces with copper‑containing solutions or 1% copper sulphate.
• During the growing season, apply approved bactericides (e.g., copper‑based or plant‑derived antibiotic products) according to instructions, especially during high humidity.
• Prevent mechanical damage and control insect vectors.

Bacterial Blight (Pseudomonas)

Pathogen: bacteria of the genus Pseudomonas (on currants, species causing leaf spots are more often mentioned – e.g., Pseudomonas syringae pv. syringae, P. viridiflava). Strictly speaking, true bacterial blight (like fire blight of pome fruits) is not typical for currants, but some pseudomonads can cause similar symptoms – necrosis of leaves, shoots, and buds.

Symptoms: dark‑brown or black, water‑soaked spots appear on leaves, rapidly enlarging. Under high humidity, spots become oily with a yellow halo. Infected leaves dry up but often do not fall. Young shoots develop dark streaks and cracks, then wither. Buds blacken and die. In some cases, the bacterium attacks flowers and ovaries, causing them to blacken and drop (Bowling, 2000).

Conditions for development: the bacterium overwinters on infected shoots, buds, and plant debris. In spring, when temperatures rise above 15 °C and humidity is high, active infection begins. Spread occurs via rain, wind, and insects. Prolonged rains during bud break and flowering are especially dangerous.

Control measures: same as for other bacterial diseases:

• Pre‑plant selection and disinfection of seedlings (e.g., heat treatment of roots in hot water at 48 °C for 13–15 minutes, as recommended for strawberry (Kurennoi et al., 1985), but caution is needed for currants).
• Early spring spraying of bushes and soil with 3% Bordeaux mixture or other copper‑based products.
• During the growing season, apply approved bactericides (e.g., "Fitolavin", as well as copper‑based products) at the first signs of disease. Treatment frequency depends on weather (usually 2–3 times at 7‑day intervals).
• Sanitary pruning (removal of diseased branches) and burning of affected parts.
• Ensure good canopy ventilation and avoid excessive soil moisture.

General preventive measures against bacterial diseases:

1. Healthy planting material – seedlings should be certified and have clean roots without galls or spots.

2. Tool disinfection – during pruning, treat tools (secateurs, saws) with 1% copper sulphate solution or 10% bleach solution after each plant (Bowling, 2000).

3. Remove plant debris – collect and burn all fallen leaves, diseased branches, and berries, especially in autumn.

4. Pest control – insect vectors (aphids, mites) facilitate bacterial spread, so controlling them simultaneously prevents bacterial diseases (Kurennoi et al., 1985).

5. Avoid excess nitrogen – excessive nitrogen fertilisation makes tissues more succulent and susceptible to bacterial infections.

6. Watering – apply at the base, avoiding wetting the foliage, especially in the evening (Buckingham, 2010).

Although bacterial diseases on currants are relatively rare, once they appear there is no time to lose: the infection spreads quickly, and saving an advanced bush is nearly impossible. The best strategy is prevention and early detection.

Blackcurrant Reversion (Doubleness)

Pathogen: phytoplasma (Candidatus Phytoplasma), formerly classified as a virus. This is one of the most dangerous currant diseases, widespread in regions with high populations of the gall mite (Dankov, 2015; Kurennoi et al., 1985).

Symptoms: the disease develops gradually, and in the first year signs may be mild. Characteristic changes:

• Flowers – become double (unnaturally many‑petalled), petals and sepals turn into narrow, scale‑like, reddish‑purple outgrowths; berries do not set (Dankov, 2015).
• Leaves – become three‑lobed (instead of the usual five‑lobed), dark green, glossy, with large sparse teeth along the margin. The leaf blade is elongated and loses the characteristic blackcurrant odour (Dankov, 2015). In advanced cases, leaves become smaller and narrower.
• Bush – becomes dense due to the formation of many thin shoots, but they are weak and stunted. Flowering is sparse or absent, and yield is completely lost (Kurennoi et al., 1985).

Vector: the main vector is the currant gall mite (Cecidophyopsis ribis), which feeds inside buds and transmits the phytoplasma when moving to new plants (Dankov, 2015). In addition, the pathogen is transmitted through cuttings taken from diseased bushes.

Control measures:

• Use only healthy (certified) planting material. Virological testing of seedlings is mandatory (Kurennoi et al., 1985).
• Systematic control of the gall mite (see pest section) – this is the main preventive measure against reversion. High mite populations sharply increase the risk of disease spread.
• Regularly inspect plantings in spring (during flowering) and summer. If characteristic changes in flowers and leaves are found, immediately uproot and burn the bush. Delay leads to infection of neighbouring plants.
• Prune only with clean tools, disinfecting secateurs after each bush, especially if disease is suspected.

Leaf Mosaic

Pathogen: virus (e.g., currant mosaic virus, related to raspberry mosaic viruses). Widely distributed in nature and affects many berry crops (Kurennoi et al., 1985; Bowling, 2000).

Symptoms: characteristic mosaic colouring appears on leaves – alternating light‑green, yellow, and dark‑green areas, often with chlorotic spots along veins. Leaves may become deformed, wrinkled, or curled. Severe infection causes overall bush depression: shoots weaken, internodes shorten, yield drops sharply, berries become small and sour. Unlike reversion, mosaic usually does not lead to complete loss of flowers, but fruit quality suffers greatly (Kurennoi et al., 1985 describe similar symptoms in raspberry, but they apply to currants as well).

Vectors: the virus is transmitted by aphids (especially the currant aphid) when feeding on diseased and healthy plants. It may also persist in weeds and spread through infected planting material.

Control measures:

• Prevention – use healthy planting material, control aphids (insecticide treatments during the growing season).
• Remove and destroy bushes with pronounced mosaic symptoms. In cases of mild expression and high value of the variety, thermotherapy (meristem culture in vitro) may be attempted, but this is not readily available to amateurs.
• Destroy weeds that may serve as virus reservoirs (e.g., many solanaceous species).

Ring Spot

Pathogen: virus (e.g., raspberry ringspot virus, tomato ringspot, or necrotic ringspot). Less common on currants but potentially dangerous.

Symptoms: light‑green or yellow rings (sometimes with necrotic centres) and arc‑shaped lines appear on leaves. Spots may coalesce into complex patterns. Leaves often become deformed and may develop translucent areas. Affected bushes weaken, growth decreases, berries become smaller (Buckingham, 2010; Bowling, 2000).

Peculiarity: ringspot virus is often transmitted by nematodes (soil‑borne roundworms) of the genera Xiphinema and Longidorus, which damage roots and transfer the virus from plant to plant. Transmission through sap during pruning and via planting material is also possible (Bowling, 2000).

Control measures:

• Pre‑plant soil testing for virus‑carrying nematodes (laboratory analysis). If infested, fumigate the soil or choose another site.
• Use healthy, virus‑free planting material.
• Remove diseased bushes.
• Control weeds that may be virus reservoirs and food sources for nematodes.
• In amateur gardens, with isolated cases, you may remove the affected plant and replace the soil in the planting hole.

Witches’ Brooms (Phytoplasma)

Pathogen: phytoplasma (Candidatus Phytoplasma) causing abnormal shoot proliferation. Belongs to the same group as reversion but produces different symptoms.

Symptoms: from one or several buds, a cluster of thin, upright, shortened shoots (up to 20–30 cm) emerges, resembling a “witches’ broom”. Leaves on such shoots are small, pale green or yellowish, often deformed. The bush becomes loose, productivity drops sharply. Flowers may be absent or produce deformed fruits. The disease develops gradually and often progresses over several years (Bowling, 2000; Kurennoi et al., 1985).

Vectors: phytoplasma is transmitted by leafhoppers and other sap‑sucking insects, as well as through infected cuttings.

Control measures: fully analogous to measures against reversion – prevention (healthy planting material, vector control), early detection and removal of infected bushes. No cure exists.

General principles for preventing viral and phytoplasma diseases

1. Buy only certified planting material, preferably from nurseries with virus‑free and phytoplasma‑free certification systems. Visual inspection of seedlings does not guarantee the absence of latent infections.

2. Systematically control vectors (gall mite, aphids, leafhoppers, nematodes) throughout the season. Particular attention – treatment during bud break against mites, as this reduces the risk of reversion spread.

3. Regularly inspect plantings – in spring during flowering (easier to spot flower changes) and throughout summer (unusual leaves, deformations). At the first suspicion of virus/phytoplasma, mark the bush and observe. If symptoms are confirmed, remove immediately.

4. Disinfect garden tools (secateurs, saws) after each bush, especially when working in nurseries or plantings where there is risk of latent infection.

5. Do not take cuttings from unknown plants and do not propagate suspicious bushes. Even a single infected cutting can infect dozens of new seedlings.

6. Destroy weeds, especially perennials – they can be virus reservoirs and food sources for vectors.

Important to remember: if a bush shows reversion, mosaic, ring spot, or witches’ brooms, no fertilisation, watering, or spraying will restore its health. Hope for “self‑healing” is misguided. The only rational course is to remove and burn the diseased bush to protect the remaining plantings. Strict culling is the only guarantee of maintaining a healthy assortment and high yields.

5.1. Pre‑planting Measures

Site selection and soil preparation

• Choose flat or gently sloping (up to 5°) sites that are well‑lit, with good air circulation. Avoid closed depressions, hollows, and areas with cold air stagnation – they increase the risk of frost and fungal diseases (Kurennoi et al., 1985).
• Groundwater should be no closer than 1–1.5 m from the surface. Excessive moisture favours root rots and bacterial diseases (Tarasov et al., 1981).
• Soil: light to medium loams, sandy loams with pH 6.0–6.5, rich in humus, water‑permeable. On heavy, compacted soils, plants are weakened and more susceptible to infections (Kurennoi et al., 1985).
• Follow crop rotation: do not plant currants after crops with common diseases (potato, tomato, strawberry, raspberry). Best predecessors are perennial legumes, green manures, clean fallow (Kurennoi et al., 1985).

Selection of planting material

• Purchase seedlings only from certified nurseries, free from viruses, phytoplasmas, and bacterial infections (Kurennoi et al., 1985). Visual inspection is mandatory: roots should be healthy, without galls; shoots without spots or cracks.
• For new plantations, use regionalised varieties resistant to major diseases, especially powdery mildew, anthracnose, and the gall mite (the main vector of reversion) (Dankov, 2015; Bowling, 2000). For example, varieties of the Siberian subspecies and hybrids (Golubka, Seyanets Golubki, Binar, Leningradsky Velikan, Belorusskaya Sladkaya, etc.) have increased resistance to diseases (Kurennoi et al., 1985).

5.2. Agronomic Measures During the Growing Season

Pruning and bush formation

• Carry out regular sanitary and formative pruning. Remove all old (over 5–6 years), weak, broken, overcrowding, and ground‑lying branches. This ensures canopy ventilation, reduces internal humidity, and deprives fungal spores of a favourable environment (Kurennoi et al., 1985).
• Cut diseased branches immediately burn (do not compost) (Buckingham, 2010).

Tool disinfection

• During pruning, treat secateurs, shears, saws with 1% copper sulphate solution or 10% bleach solution (1 part bleach to 10 parts water) after each bush, especially if viral or bacterial infections are suspected (Bowling, 2000).

Weed control and mulching

• Regularly remove weeds, especially perennials, as they can be virus reservoirs (e.g., angelica is a source of ring spot) and food sources for insect vectors (Bowling, 2000). Keep the soil in row spacings loose and clean; in rows use mulching (peat, manure, compost, straw) with a layer of 5–8 cm, which suppresses weeds, retains moisture, and improves the microclimate of the root zone (Kurennoi et al., 1985).

Moderate watering and nutrition

• Water at the base, avoiding wetting the foliage, especially in the evening. Excessive leaf canopy humidity favours powdery mildew, anthracnose, and gray mold (Buckingham, 2010).
• Provide balanced mineral nutrition: excess nitrogen causes lush, succulent growth that is more susceptible to fungal and bacterial infections. Apply complete complex fertiliser (N‑P‑K) in moderate doses, with a predominance of potassium and phosphorus fertilisers that increase plant resistance (Kurennoi et al., 1985). Potassium fertilisers should be chloride‑free (potassium sulphate, kalimag) (Kurennoi et al., 1985).

5.3. Spring and Autumn Preventive Treatments

In autumn: sanitary cleanup

• After leaf fall, carefully rake and burn all fallen leaves – they harbour overwintering spores of anthracnose, septoria, powdery mildew, and gray mold (Dankov, 2015).
• Remove and burn dry, damaged, and diseased shoots. Loosen soil in the root zones and between rows to destroy overwintering stages of pests and some infectious inoculum.
• If there are signs of bacterial cancer or root rots, disinfect the soil (e.g., drench with copper sulphate solution or biological products based on Trichoderma).

Early spring (before bud break)

• Spray bushes and the ground with 3% Bordeaux mixture or its modern substitutes (copper‑based products) – this kills overwintering fungal spores and bacteria on the bark and bud surfaces (Kurennoi et al., 1985).
• For powdery mildew prevention, apply sulphur‑based products (e.g., colloidal sulphur) or biological products based on Bacillus subtilis at the green‑cone stage (Bowling, 2000). Sources recommend treating with liquid lime‑sulphur at green‑cone and 2–3 weeks after flowering (Bowling, 2000).

During the growing season (as needed)

• Carry out preventive sprays with systemic fungicides or biological products before expected rain, especially at the budding and fruit‑set stages. The frequency depends on weather and variety resistance – usually 2–4 times per season (Tarasov et al., 1981).
• If the first signs of powdery mildew, leaf spots, or rust appear, immediately treat with an approved fungicide, strictly following the instructions and pre‑harvest intervals.

5.4. Control of Infection Vectors

Insects and mites not only damage plants but also actively transmit viruses, phytoplasmas, and bacteria. Therefore, pest protection is an integral part of disease prevention (Kurennoi et al., 1985; Bowling, 2000).

• Gall mite – main vector of reversion. Treatments against mites are carried out during bud break (before flowering) with acaricides (e.g., sulphur‑based products, Fitoverm, Actellik). Early‑spring spraying with colloidal sulphur (1%) is effective against overwintering mites (Kurennoi et al., 1985).
• Aphids and leafhoppers – vectors of mosaic viruses and phytoplasmas. When aphids appear, apply insecticides (contact or systemic) as per instructions. Regularly inspect bushes and remove isolated colonies mechanically or treat with soap solution at early stages (Buckingham, 2010).
• Nematodes – vectors of ring spot. Pre‑plant soil testing, use of resistant rootstocks, and biological agents (nematophages) are the main measures. In amateur gardens, if nematodes are found, it is recommended to replace the soil in the planting hole (Bowling, 2000).

5.5. Choice of Resistant Varieties

The most effective and environmentally friendly preventive measure is planting varieties that are genetically resistant or tolerant to the main diseases in the region. Many modern varieties have complex resistance to powdery mildew, anthracnose, septoria, rusts, and the gall mite (Kurennoi et al., 1985; Dankov, 2015).

For the non‑chernozem zone of Russia, the following are recommended:

• Blackcurrant: Golubka, Seyanets Golubki, Binar, Veloy, Poesia, Peterburzhenka, Orlovia, Leningradsky Velikan, Belorusskaya Sladkaya, Sokrovishche, Yadryonaya, etc. – have high resistance to powdery mildew and anthracnose (Dankov, 2015; Kurennoi et al., 1985).
• Varieties with complex resistance to diseases and the gall mite (e.g., varieties bred by VIR and NIISS named after Lisavenko) are preferable for areas with a high infectious background (Kurennoi et al., 1985).

Before establishing a plantation, consult local specialists on regionalised varieties adapted to your soil and climate conditions.

5.6. Quarantine and Organisational Measures

• Isolate planting material: do not introduce plants of untested origin onto the site. Keep young seedlings separate from mature plantings (especially for the first 2–3 years) for observation.
• Spatial isolation: avoid planting currants near conifers (source of column rust) and sedge (source of cup rust). Remove wild currant bushes within a 200–300 m radius of the plantation – they can be virus reservoirs (Bowling, 2000).
• Systematic monitoring: inspect bushes at least once every 2 weeks from spring to autumn, paying attention to changes in leaf shape, colour, flowers, spots, and coatings. Early detection allows rapid localisation of the outbreak.

Summary: Prevention is a continuous process that includes wise site and variety selection, timely pruning, removal of plant debris, pest control, and balanced nutrition. No single measure gives a complete guarantee, but their combined application creates a reliable protective barrier and allows you to grow blackcurrant without serious losses from diseases (Tarasov et al., 1981; Bowling, 2000).

6.1. Treatment of Fungal Diseases

General strategy:

• At the first signs (spots, coatings, wilting), apply an approved fungicide.
• Repeat treatments at intervals specified on the product label (usually 7–14 days), especially in rainy weather.
• Alternate products with different modes of action to avoid resistance.
• Strictly observe pre‑harvest intervals (the period from the last treatment to harvest) as indicated on the packaging.

Specific diseases and treatment approaches:

6.2. Treatment of Bacterial Diseases

Bacterial diseases are difficult to treat, and often the only option is removal of affected parts or the entire bush.

• Bacterial root cancer (galls): if galls are found on a seedling before planting, discard the material. If the disease appears on an adult bush: for single small galls, you may attempt to cut them out and treat wounds with 1% copper sulphate, but the chance of recovery is low. Usually, the bush is uprooted and burned, and the soil is disinfected (Bowling, 2000).
• Bacterial wilt (Erwinia) and bacterial blight (Pseudomonas): immediately cut out all affected shoots, taking 15–20 cm of healthy tissue below visible symptoms. Disinfect cuts with copper sulphate or strong potassium permanganate solution. Treat tools with alcohol or bleach after each cut. In severe cases, remove the entire bush. As supportive therapy, use copper‑based products (Bordeaux mixture, HOM) and biological products (e.g., based on Pseudomonas fluorescens or Bacillus subtilis) that suppress bacterial development on surfaces (Kurennoi et al., 1985; Bowling, 2000).

6.3. Biological Products and Home Remedies

Biological products are a good alternative to chemicals, especially in home gardens and near harvest time. They are safe for humans, bees, and beneficial insects, but act more gently and require more frequent application (intervals of 5–7 days).

• Based on Bacillus subtilis (Fitosporin‑M, Alirin‑B) – effective against powdery mildew, gray mold, and leaf spots. Suitable for prevention and early stages (Dankov, 2015).
• Based on Trichoderma (Trichoderma veride, Gliocladin) – used to protect roots from soil‑borne pathogens (verticillium, fusarium), applied to soil or planting holes.
• Based on Pseudomonas fluorescens (Pseudobacterin) – suppresses bacterial and some fungal infections.
• New‑generation copper‑based biological products (e.g., with chelated copper) are less phytotoxic than traditional Bordeaux mixture.

Home remedies can help only in very mild infections and as supplementary prevention. Do not rely solely on them in serious outbreaks (Buckingham, 2010).

• Nettle or horsetail infusion (1 kg fresh herb per 10 L water, steep for 24 hours, strain) – spraying to boost immunity and mild antifungal effect.
• Baking soda solution (3 tablespoons per 10 L water) with laundry soap – helps against powdery mildew in early stages.
• Whey or buttermilk (1 L per 10 L water) – forms a film on leaves that hinders powdery mildew spore germination.

6.4. Supporting Weakened Plants

Treatment of diseases is always accompanied by measures to restore the bush:

• Remove all diseased and damaged parts.
• Apply foliar feeding with micronutrients (zinc, manganese, boron) and potassium‑phosphorus fertilisers to strengthen tissues and stimulate healthy shoot regrowth (Tarasov et al., 1981).
• Provide moderate watering, avoiding waterlogging.
• Mulch the root zone with humus or compost to improve root nutrition.

However, remember: treatment is effective only in the early stages of fungal infections. If the bush has lost more than 30–40% of its leaf surface or its root system is affected, it is unlikely to recover. In such cases, it is better to remove the plant to prevent the infection from spreading to neighbours.

Summary on treatment:

• Fungal diseases are treated with fungicides (chemical or biological) strictly following instructions and timing.
• Bacterial diseases require removal of affected parts and disinfection; in advanced cases, complete uprooting.
• Viral and phytoplasma diseases are not curable – only removal and burning of infected bushes.
• Never delay treatment – the earlier you start, the higher the chance of success.
• Alternate products to avoid resistance and do not exceed dosages.

❌ Typical Mistakes in Protecting Blackcurrant from Diseases

Mistake 1. Ignoring preventive treatments

Gardeners often hope that “it will pass” and start acting only when the disease is visible to the naked eye. This leads to lost time: fungi have already penetrated tissues, making control much harder. Prevention is the basis of health, not an optional extra (Bowling, 2000; Kurennoi et al., 1985).

Mistake 2. Using the same fungicides without rotation

Repeated use of products with the same mode of action (e.g., only copper‑based) leads to resistant pathogen strains. Always alternate active substances – copper, sulphur, triazoles, benzimidazoles, biologicals (Tarasov et al., 1981).

Mistake 3. Violating pre‑harvest intervals and dosages

The desire for a stronger effect leads to overdosing, causing leaf burns (phytotoxicity) and accumulation of harmful substances in berries. Strictly follow the label instructions and do not harvest before the specified period (Buckingham, 2010).

Mistake 4. Treating viral diseases with home remedies

“I sprayed with garlic infusion and the reversion disappeared” – that does not happen. Viral and phytoplasma diseases cannot be cured by any preparations. Delaying removal of the diseased bush leads to infection of the entire plantation (Dankov, 2015; Kurennoi et al., 1985).

Mistake 5. Dense plantings and irregular pruning

A dense canopy creates an ideal microclimate for fungi: high humidity, poor ventilation, little light. This triggers powdery mildew, anthracnose, gray mold. Regular thinning is a mandatory health practice (Tarasov et al., 1981).

Mistake 6. Using untested planting material

Seedlings bought second‑hand or from neighbours may carry latent viruses, gall mites, bacteria. Buy only from certified nurseries and inspect roots and buds before planting (Kurennoi et al., 1985).

Mistake 7. Leaving affected leaves and branches on the site

Many gardeners put diseased plant residues into compost, hoping they will decompose. But fungal spores and bacteria survive in compost and return to the beds. All diseased parts should be burned or buried deep off‑site (Bowling, 2000).

Mistake 8. One‑sided nitrogen fertilisation

Excess nitrogen causes rapid growth of succulent shoots that are easily attacked by powdery mildew and aphids (virus vectors). Apply balanced fertilisers with a predominance of potassium and phosphorus, especially in the second half of summer (Kurennoi et al., 1985).

Mistake 9. Neglecting vector control (mites, aphids)

Gardeners often focus only on visible disease symptoms, forgetting that insects and mites actively spread infections. Pest protection is disease protection (Dankov, 2015).

Mistake 10. Planting currants near conifers or sedge

This guarantees annual rust infections. Plan the site in advance, considering the proximity of potential intermediate hosts (Bowling, 2000).

❓ Frequently Asked Questions (FAQ)

Question 1. Why are the branches and leaves of my currant drying up, even though I water it regularly?

Answer. There may be several causes: verticillium or fusarium wilt (vascular infection), bacterial wilt, root damage (e.g., bacterial root cancer galls), or bark damage from frost or pests (clearwing borer, flatheaded borer). Examine a cross‑section of a branch – if dark rings or spots are visible on the wood, it is likely a vascular infection. Such a plant cannot be treated – remove it (Kurennoi et al., 1985; Bowling, 2000).

Question 2. Can I use wood ash infusion to control powdery mildew?

Answer. Yes, ash infusion (1 cup ash per 10 L water, steep for 24 hours) has a mild fungicidal and alkaline effect and may help in early stages as a supplementary measure. However, in serious infections it is ineffective, and it is better to use sulphur‑based or biological products (Buckingham, 2010).

Question 3. What should I do if a bush shows signs of reversion but still bears many berries?

Answer. Immediately uproot and burn the bush, even if it is still yielding. The phytoplasma will gradually spread throughout the plant, berries will become small and sour, and more importantly, the diseased bush will become a source of infection for neighbours via the gall mite. The sooner you remove it, the better the chance of saving the rest (Dankov, 2015).

Question 4. Can I spray currants during flowering?

Answer. Strongly discouraged, especially with chemical products, because it repels bees and may reduce fruit set. Exceptions are biological products and treatments allowed during flowering (according to the label). Plan main treatments before and after flowering (Buckingham, 2010).

Question 5. How can I tell if a disease is viral rather than fungal?

Answer. Fungal diseases are characterised by spots, coatings, cankers, and rots. Viral and phytoplasma diseases cause systemic changes: mosaic colouring, leaf deformations (curling, elongation), flower alterations (doubleness), abnormal shoot growth (witches’ brooms). The key difference: with viruses, you do not see spores or mycelium, and the disease is not transmitted by contact, but only through vectors and planting material (Bowling, 2000).

Question 6. What if I missed the spring treatment and it rains every day?

Answer. In such weather, the risk of fungal infections is maximal. At the first opportunity (even in light rain), apply a systemic fungicide that penetrates tissues and acts regardless of rainfall. After rains, repeat spraying, alternating products. Also intensify prevention: thin the canopy, remove excessive growth, eliminate weeds (Tarasov et al., 1981).

Question 7. Are there varieties that never get sick?

Answer. Absolutely resistant varieties do not exist. However, there are varieties with high field resistance to the main complex of diseases: Golubka, Seyanets Golubki, Binar, Veloy, Poesia, Leningradsky Velikan, Belorusskaya Sladkaya, Sokrovishche, Yadryonaya, etc. They are less affected, but under unfavourable conditions and with infection pressure they can still fall ill. Proper variety choice is important but not the only factor (Kurennoi et al., 1985; Dankov, 2015).

Question 8. What should I do with the soil after uprooting a diseased bush?

Answer. The soil must be disinfected. You can drench the area with 3% copper sulphate solution or biological products based on Trichoderma. After that, do not plant currants there for 4–5 years (minimum for soil‑borne infections). It is best to sow green manures (mustard, phacelia) or plant vegetables not affected by common pathogens (Bowling, 2000; Kurennoi et al., 1985).

Question 9. Can I cure a bush of bacterial cancer by cutting off the galls?

Answer. In the early stage, when galls are small and few, you can try to remove them, clean the wounds, treat with copper sulphate, and cover with grafting wax. However, this does not guarantee complete elimination of the bacterium. In most cases, the affected bush still dies or is severely weakened. It is better not to risk it and replace it with a new healthy seedling in a new location (Bowling, 2000).

Question 10. How can I protect berries from gray mold in a rainy summer?

Answer. Main measures: ensure ventilation (pruning, removal of excess shoots), prevent berries from touching the ground (mulch with sawdust or straw), carry out preventive treatments with copper‑based or biological products before ripening begins. If berries start to rot, collect and destroy them immediately, and treat the bush with an approved fungicide with a short pre‑harvest interval (Buckingham, 2010; Dankov, 2015).