Pests

Foliage damage

If carrot leaves curl, turn yellow, become covered with sticky exudate or become deformed – this is most often the work of sucking pests:

• Carrot psyllid (Trioza apicalis) causes characteristic leaf curling. The leaf blade becomes concave, edges curl inward, and the rosette takes on a “shaggy” appearance (Autko et al., 2012). Chlorosis and leaf dieback usually do not occur.
• Aphids (willow-carrot, plantain, and others) curl leaves into tight balls, they become discoloured and covered with sticky sugary secretions. With heavy infestation, aphid colonies accumulate near the root collar and base of petioles (Akhatov et al., 2013).

If spots appear on the leaves and they later dry out – this may be not only diseases but also a result of damage:

• Carrot psyllid during feeding secretes toxic substances that disrupt growth processes.
• Leafhoppers and some other sucking pests can cause chlorosis and leaf deformation.

Tunnels and damage to the root

These are the most dangerous damages, making roots unsuitable for sale and storage:

• Narrow straight tunnels – a characteristic sign of wireworms (larvae of click beetles). They eat narrow straight channels in the roots, which often then become infected with rots (Akhatov et al., 2013).
• Winding tunnels surrounded by blackened tissue – this is the “autograph” of the carrot fly. Transverse cracks and winding tunnels appear on the roots; the bark darkens and becomes necrotic (Akhatov et al., 2013).
• Large irregular cavities are eaten by the common mole cricket. Hollows appear in the roots, and loose earthen ridges – horizontal tunnels of the pest – are visible on the soil surface.
• Dry sunken spots with cracks may be a sign of nematode or fusarium infection, but sometimes similar damage is caused by beetle larvae as well.

Root with “beard” and deformations

Root system damage often manifests as:

• “Bearding” – many thin lateral roots on the root. This is a characteristic sign of cyst nematode (Heterodera carotae) (Geoffriau & Simon, 2021).
• Branching and “horns” of the root. The cause can be various: nematode damage, damage to the growing point, soil compaction, or excess moisture. But if the root is also covered with characteristic damage against a background of deformation – this indicates pests.
• Galls (swellings, outgrowths) on the roots – a clear sign of root-knot nematodes (Meloidogyne spp.), in particular the northern root-knot nematode (Akhatov et al., 2013).

Biting and chewing

When plants wilt and are easily pulled out of the ground, and chewing marks are visible at the root collar – this is the work of cutworms and mole crickets:

• Cutworm caterpillars (exclamation, winter) gnaw stems at the base and can also eat cavities in roots (Akhatov et al., 2013).
• Mole cricket not only eats roots but also gnaws young plants, destroying them completely.

Important! For correct diagnosis, it is not enough just to see the damage – you need to consider:

• Time of year (each pest has its own season of activity);
• Location of damage (upper, middle, or lower part of the root);
• Accompanying signs (presence of insects, their larvae, excrement, webbing, sticky exudate).

Accurate identification of the pest is half the success in controlling it. In the next chapter, we will take a detailed look at the most dangerous enemy of carrots – the carrot fly, its life cycle, and protection methods.

What does the carrot fly look like and how does it live?

The adult fly is a small insect 4–5 mm long. It has a black shiny abdomen, a brown head, transparent wings lying horizontally on the back, and yellow legs. The larva is worm-like, light yellow, shiny, up to 6–7 mm long. It is the larvae that cause the main damage by gnawing tunnels in the roots (Akhatov et al., 2013).

Life cycle strongly depends on climate:

• In Northern Europe (Norway, Sweden, Finland) – 1–2 generations per year.
• In Central Europe and most of Russia – 2 generations.
• In the south (Southern Europe, Black Earth region) – 2–3 generations, but in the hot climate of southern France, for example, the second generation may enter summer diapause (torpor), which complicates forecasting (Geoffriau & Simon, 2021).

In Belarus and central Russia, there are usually two generations (Autko et al., 2012).

First generation:

• Puparia (false cocoons) overwinter in the soil at a depth of 6–25 cm. The wetter the soil, the shallower the puparia lie.
• Fly emergence begins in the second half of May – early June, when the sum of effective temperatures (above 10 °C) at a depth of 10 cm reaches 185–225 degree-days. Mass emergence coincides with the flowering of black chokeberry (Akhatov et al., 2013).
• Females lay eggs singly at the base of carrot stems and other umbelliferous plants. Eggs are very sensitive to drought and high temperature, so in hot dry weather up to half of the eggs die. Irrigation and rain, on the contrary, favour their development.
• Larvae appear after 5–7 days at a temperature of 21…24 °C. They penetrate the root and feed for about a month, then pupate in the soil.

Second generation:

• Fly emergence begins in mid-July, oviposition continues until the end of August.
• Some larvae manage to pupate in the soil, while others enter storage together with the roots, where they continue to feed and pupate later.

How to recognize carrot fly damage

On plants (in the field):

• Leaves acquire a violet or yellowish tint and wilt.
• Plants are stunted, especially when damaged at the seedling stage.

On root crops (main sign):

• On the surface – narrow winding tunnels surrounded by blackened necrotic bark tissue.
• Transverse cracks and “rusty” stripes.
• Inside the root – tunnels leading to the core. Damaged areas often rot from bacteria and fungi (Akhatov et al., 2013).

Important to distinguish from wireworm damage (wireworm makes straight, deep tunnels, also reaching the core) and from slugs (leave slime and large gouges). Carrot fly larvae more often damage the upper part of the root, near the crown (Geoffriau & Simon, 2021).

Monitoring: how to know when to act

For gardeners and farmers, simple methods of tracking fly emergence are available:

1. Yellow sticky traps – hung at a height of 20–30 cm above the ground, at the edge of the field. Flies are readily attracted to yellow colour. Traps set at a 45° angle to the vertical are more selective for carrot flies (Collier & Finch, 1989, cited in Geoffriau & Simon, 2021).

2. Water traps – containers with fermented kvass or beer placed around the perimeter of the plot. The smell attracts flies.

3. Timing – check traps regularly from the end of May. If 5–10 flies per trap are caught per day – it is a signal to start treatments.

In Europe, predictive models are used (e.g., SWAT – Hommes & Gebelein, 1996) that predict emergence dates based on temperature and humidity. For amateurs – a simple rule: first treatment at the end of May – early June, second in mid-July. But it is better to rely on actual trap data.

How to protect carrots from the fly

Regional specifics

• In Northern Europe (Scandinavia, northern Russia) – only 1 generation, but it is very damaging. Sowing in late May – early June and early harvesting help avoid the peak of infestation.
• In Central Europe and central Russia – 2 generations, the main damage is caused by the second generation (August). Summer treatments and harvesting no later than mid-September are important.
• In the South (Ukraine, southern Russia, Mediterranean) – there can be 2–3 generations, but in dry summers the fly enters diapause and damage is less. However, with irrigation the risk increases.

Brief summary on carrot fly

• Enemy No. 1 of carrots – dangerous at all stages, but especially in the phase of 1–3 true leaves and during storage.
• Early diagnosis – use yellow traps and monitor changes in tops colour.
• Integrated approach – crop rotation, sowing dates, nets, resistant varieties, and only if necessary – insecticides.
• Biological protection – preserve beneficial ground beetles, use nematodes where possible.

The main conclusion: control of carrot fly is not a one-time action but a system of annual preventive measures. Only a combination of agrotechniques, monitoring, and sensible use of chemicals gives a stable result.

*To be continued... In the next chapter, we will discuss soil pests – wireworms, mole crickets and other ground-dwellers.*

3.1. Wireworm (larvae of click beetles)

What it is. Wireworms are larvae of beetles of the family Elateridae. In central Russia, the most common species are Agriotes obscurus, A. lineatus, A. sputator and Athous niger (Akhatov et al., 2013). The larvae got their name for their hard, shiny yellowish-brown body, resembling a piece of wire. Their length is from 10 to 30 mm, they have three pairs of short legs and tough integuments.

Life cycle. Wireworm development lasts 3–4 years. Larvae and beetles overwinter in the soil at a depth of 10–30 cm. In spring, when the soil warms up, beetles emerge, mate and lay eggs in the soil (May–July). After 15–20 days, larvae appear, which in the first year feed on humus, and from the second year switch to living plant tissues. Larvae of the last instar pupate in July–August, and after 2–3 weeks young beetles emerge, which remain to overwinter in the soil (Akhatov et al., 2013).

How to recognise damage. Wireworms gnaw narrow, straight, deep tunnels in roots, often reaching the core. Entry holes are rounded, without a necrotic border (unlike carrot fly tunnels). They can also gnaw through seedlings and young plants at the root collar. Damaged roots are easily infected by fungal and bacterial rots (Autko et al., 2012).

Where it is more common. Wireworm prefers moist, heavy soils, especially after perennial grasses, turf layers, and areas overgrown with couch grass. In dry hot weather, larvae go down to 1 m deep, and with high humidity they rise to the surface.

3.2. Common mole cricket (Gryllotalpa gryllotalpa)

What it is. The mole cricket is a large insect (35–50 mm) of dark brown colour, with powerful digging front legs adapted for tunnelling. It leads an underground lifestyle, emerging to the surface mainly at night. It is a polyphage – damages almost all vegetable crops, including carrots (Akhatov et al., 2013).

Life cycle. Larvae and adults overwinter in the soil at a depth of 7 to 25 cm, sometimes up to 1–2 m. In spring, when the soil warms to 12…15 °C, mole crickets become active. Females lay eggs in clusters (up to 300–400) in a special nest which they dig at a depth of 10–20 cm. Eggs develop in 10–40 days depending on temperature. Larvae (nymphs) go through 8–11 moults and develop for 13–14 months. Thus, in central Russia, the generation lasts about two years.

How to recognise damage. The mole cricket eats large, ragged cavities of irregular shape in roots. It bites through young plants at the base, and they wilt and are easily pulled out of the ground. On the soil surface, winding loose earthen ridges – the so‑called “tunnels” of the mole cricket – are noticeable. The pest is especially active on moist, humus-rich soils, in lowlands, and on irrigated areas.

3.3. Chafer larvae (cockchafers)

May beetles (Melolontha melolontha, M. hippocastani) can also damage carrot roots, but to a lesser extent. Their thick white C‑shaped larvae eat lateral roots and gnaw pits on the root surface. However, mass reproduction of these pests occurs once every 3–5 years, and they usually prefer perennial grasses and root crops rather than carrots. Deep digging, manual collection of larvae, and birds (starlings, rooks) that actively destroy them help in control (Autko et al., 2012).

3.4. Slugs and their role in root damage

Although slugs are not purely “soil” pests, they often damage root crops, especially in wet weather. The most dangerous species are Deroceras reticulatum and Arion hortensis (Geoffriau & Simon, 2021). Slugs gouge large irregular cavities on the root surface, leaving a slimy trail behind. Damage serves as an entry point for rot pathogens.

Control measures:

• Reduce humidity (drainage, infrequent watering, ventilation).
• Remove plant debris and weeds where slugs hide during the day.
• Set traps (boards, pieces of slate) – slugs accumulate under them, then collect and destroy them.
• Use the biopreparation Phasmarhabditis hermaphrodita (nematode parasitic on slugs) – available as a finished product in some countries (Geoffriau & Simon, 2021).
• Chemical agents – granules with metaldehyde (Slug Eater, Groza) are scattered between rows. They are effective but toxic, so on small plots it is better to use safer products (iron phosphate – preparations like “Slug Eater-Bio”).

Brief summary on soil pests

For reliable protection, it is important to combine prevention (crop rotation, soil cultivation) with mechanical and biological methods, and resort to chemicals only when pest numbers are high.

4.1. Aphids – the main virus vectors

More than 20 species of aphids occur on carrots (Blackman & Eastop, 2006). The greatest damage in temperate climates is caused by the willow-carrot aphid (Cavariella aegopodii). Also encountered are the plantain aphid (Dysaphis crataegi) and the carrot aphid (Semiaphis dauci) (Akhatov et al., 2013).

Life cycle. Aphids are dioecious insects. Eggs overwinter on willow branches (goat willow, osier). In spring, larvae hatch from them, feed on willow, and then winged female dispersers appear. They fly to carrots, dill, parsley and other umbellifers, where they produce several generations (in Belarus and central Russia – 2–3 generations per summer). In August, winged individuals return to willow, where they lay overwintering eggs (Akhatov et al., 2013; Geoffriau & Simon, 2021).

How to recognise. Aphids settle on the underside of leaves, at the root collar and on petioles. Signs of infestation:

• Leaves curl into balls and become deformed.
• A sticky sugary coating (honeydew) appears on the leaves, on which sooty mould often develops (black coating).
• Colonies of aphids are clearly visible to the naked eye – these are small green, yellowish-green or dark green insects (Akhatov et al., 2013).

Why they are dangerous. Aphids themselves are not as harmful as the carrot fly, but they are vectors of dangerous viruses: carrot mosaic virus (CMV), carrot red leaf virus (CRLV), parsnip yellow fleck virus (PYFV) and others (Geoffriau & Simon, 2021). Viral infection leads to stunting, root deformation, and yield reduction of 30–50%. It is impossible to chemically control viruses, so the main task is to prevent mass colonisation by aphids.

4.2. Carrot psyllid – the cause of top curling

Carrot psyllid (Trioza apicalis) is a dangerous pest in Northern and Eastern Europe, Belarus, the Baltic region, and also in Siberia (Akhatov et al., 2013). In southern regions, a related species Bactericera trigonica occurs (Geoffriau & Simon, 2021).

Appearance and development. The adult insect is about 3 mm long, pale green, with reddish eyes, wings folded roof-like, hind legs jumping. Adults overwinter on coniferous trees (pine, spruce). In May, they fly to carrots. Females lay eggs on leaves, from which larvae appear after 20 days. Larvae are flat, oval, greenish-yellow, sedentary, with a waxy fringe along the edges. Development from egg to adult takes about 40 days. It gives one generation per season (Akhatov et al., 2013).

How to recognise. A characteristic symptom is leaf curling: the leaf blade becomes concave, edges curl inward, the rosette becomes “shaggy”. Chlorosis and leaf dieback usually do not occur (unlike viral diseases). On the underside of leaves, larvae and their waxy secretions can be seen. With severe infestation, the plant is stunted, the root becomes smaller, harder and loses taste (Akhatov et al., 2013).

Additional danger: the psyllid is a vector of the bacterium Candidatus Liberibacter solanacearum, causing a disease similar to “green stunting” (Geoffriau & Simon, 2021). In Europe, this disease causes serious damage.

4.3. Umbrella moth – a pest of seed plants

Umbrella moth (anise, carrot) – Depressaria depressana (syn. D. marcella) – is dangerous mainly on seed crops, where it damages inflorescences, but sometimes occurs on commercial carrots, eating leaves and buds if the crop has flowered (Akhatov et al., 2013).

Signs: caterpillars (up to 13 mm long, black-green with white tubercles) entangle umbels with webbing, eat buds, flowers and immature seeds. Leaves do not curl but are covered with webbing.

Control measures: mainly agrotechnical – timely harvesting and destruction of plant residues, mowing wild umbellifers (hogweed, cow parsley). With high numbers, biological preparations (Bitoxibacillin, Lepidocid) are used – they are safe for pollinators (bees, flies, beetles) that pollinate carrots. Chemical insecticides are used only with mass reproduction, taking into account harm to beneficial insects (Akhatov et al., 2013).

4.4. Leafhoppers – vectors of phytoplasmas

Leafhoppers (Macrosteles spp., Euscelis spp.) do not cause much damage themselves, but they are vectors of phytoplasma – the causative agent of aster yellows (Aster yellows) and stolbur. These diseases lead to stunting, reddening of leaves, proliferation of lateral roots (so‑called “witches’ broom”), roots become small, woody and lose marketable quality (Akhatov et al., 2013; Geoffriau & Simon, 2021).

How to recognise: on infected plants, leaves first turn yellow at the edges, then acquire a reddish-purple tint. Numerous thin roots begin to grow from the top of the root – this is the so‑called “stolbur”. On seed plants, flowers turn green, petals become smaller.

Protection measures: the main focus is on controlling the vectors – the same measures as for aphids and psyllids (nets, insecticide treatments). It is important to remove weeds that serve as phytoplasma reservoirs. Hybrids of carrots with some resistance to stolbur are also known – e.g., `Siroko`, `Excelso` (Akhatov et al., 2013).

4.5. Cutworm caterpillars and leaf-eating moths

In addition to cutworms (which mainly damage in the soil), carrot leaves can be eaten by caterpillars of the exclamation cutworm (Agrotis exclamationis), gamma moth (Autographa gamma), and in southern regions – the cotton bollworm (Helicoverpa armigera) (Geoffriau & Simon, 2021). These caterpillars (green, grey or brown) feed on leaves, eating large holes, sometimes completely skeletonising the plant.

Signs: ragged edges appear on leaves, eaten areas, often caterpillar excrement can be seen on the plant. With severe damage, the tops lose photosynthetic surface, yield decreases.

Control measures:

• Manual collection of caterpillars (on small plots).
• Biological preparations (Bitoxibacillin, Lepidocid, Fitoverm) – effective against young caterpillars and safe for the environment.
• Chemical insecticides – with mass appearance, strictly according to instructions.

Brief summary on foliar pests

Important note: foliar pests often appear after the use of broad-spectrum insecticides that destroy their natural enemies. Therefore, in private gardens it is better to start with biopreparations and agrotechnical measures, and resort to chemicals only in extreme cases, choosing products with the least toxicity to beneficial insects (e.g., based on pyrethrins, which degrade quickly).

5.1. Why prevention is the foundation of success

Experienced gardeners know: preventing pest outbreaks is much easier than eliminating their consequences. Pests are not random guests but part of the ecosystem. If you create conditions in which carrots grow quickly and healthily, and natural enemies of pests feel comfortable, then chemical treatments become only a backup, not the main tool.

Key principles of prevention:

• Healthy soil → strong plant → less attractiveness to pests.
• Crop diversity → disruption of life cycles of specialised pests.
• Preservation of beneficial organisms → natural population control.

Let us consider them in order.

5.2. Agronomic prevention: where protection begins

5.3. Biological protection: using natural enemies

Biological control is the use of living organisms (predators, parasites, pathogens) to reduce pest numbers. In the garden and vegetable plot, natural enemies work for free and around the clock. Your task is to create conditions for them to live.

5.4. Physical barriers – reliable chemical‑free protection

• Fine‑mesh insect netting or non‑woven cover material – the most effective protection method on small plots. Cover the beds immediately after sowing and keep until harvest. A net with a cell size of 0.8–1.0 mm completely prevents the penetration of carrot fly, psyllids, aphids and other flying pests. It also protects against wind and frost.
• Vertical barriers – up to 2 m high around the field – reduce infestation by carrot fly but do not completely eliminate it. For amateur plots, high mesh fences are sufficient (Siekmann & Hommes, 2007, cited in Geoffriau & Simon, 2021).

5.5. Use of resistant varieties

Although fully resistant varieties to the pest complex do not exist, breeding has already produced results:

• Varieties with partial resistance to carrot fly – e.g., `Flyaway` and `Resistafly` (UK). They contain less chlorogenic acid – a substance attracting flies – and more sugars and carotene, making the root less suitable for larval feeding (Ellis, 1993, cited in Geoffriau & Simon, 2021). Unfortunately, they do not always have good taste qualities, but in an integrated protection system they can be useful.
• Hybrids tolerant to stolbur and viruses – e.g., `Siroko`, `Excelso`, `Tempo`, `Bolero` (Akhatov et al., 2013). They tolerate infection without a sharp loss of yield.

When choosing a variety, always consider your regional conditions and the main problems in your area.

5.6. Integrated protection system: a step‑by‑step season plan

To ensure that all of the above does not remain theory, here is a specific action plan for the year for an amateur gardener (central Russia, 2 generations of carrot fly):

Autumn:

1. Deep digging of the plot with turnover of the layer.

2. Application of lime (if soil is acidic) or dolomite flour.

3. Remove and burn all plant residues.

4. Plan crop rotation for the next year – do not return carrots to this place for 3–4 years.

Early spring (before sowing):

1. If the plot is heavily infested with wireworms – 2–3 weeks before sowing, place traps (potato halves) and collect pests.

2. Prepare insect netting for covering beds.

Sowing (April–May):

1. Choose the optimal date – either early (end of April) or late (beginning of June) depending on your region.

2. Sow seeds on well‑prepared, loose soil. Seeding depth 2.5–3 cm.

3. Immediately after sowing, cover the bed with netting or agrofabric.

During the growing season:

1. May–June – set up yellow sticky traps. Monitor the appearance of the first flies.

2. At mass fly emergence (5–10 flies per trap per day) – if you are not using netting, carry out a treatment with an approved insecticide (e.g., based on cypermethrin). Repeat after 10–14 days.

3. Regularly weed and loosen between rows to destroy weeds and disrupt pest cycles.

4. When aphids or psyllids appear – use biopreparations or plant‑based infusions. In case of heavy infestation – use approved insecticides, but only before large roots form (taking into account waiting periods).

5. In dry weather – water, but moderately, avoiding waterlogging.

6. Inspect plants for leaf curling – if it appears, treat against psyllid.

Harvest (August–October):

1. Harvest roots before frost, not allowing them to over‑mature in the soil.

2. Cull damaged roots – they do not store well.

3. Immediately after harvest, destroy the tops.

4. If you noticed signs of carrot fly infestation, it is advisable to treat the second half of the crop intended for storage against rots (e.g., with Fitosporin) and store at a temperature of 0…2 °C and humidity of 90–95%.

Throughout the season – observe the plantings, record when and which pests appeared. This will help adjust treatment timing and choose the best varieties next year.

5.7. Main conclusions

1. The main method of protecting carrots from pests is prevention. Crop rotation, deep digging, optimal sowing dates, destruction of weeds and residues – these are the foundation of a healthy harvest.

2. Regular monitoring (inspections, traps) allows you to notice the threat in time and apply low‑toxicity agents, rather than “drench” plantings with chemicals.

3. Preserve beneficial insects – they are your main allies. Avoid broad‑spectrum insecticides unless absolutely necessary.

4. Biopreparations and physical barriers are a real alternative to chemicals that work in amateur and even commercial farming.

5. Integrate all methods – only an integrated approach gives a stable result and safe products.

By applying this knowledge in practice, you can minimise losses from pests and obtain an environmentally friendly, tasty and healthy carrot harvest year after year.