Pests

What does it look like and when to expect it?

The onion fly resembles a common housefly but has a grayish-yellow coloration and measures about 6-8 mm. Mass flights of flies begin during the blooming period of lilacs and dandelions. Females lay eggs in groups of 30-40 on the lower part of leaves or in soil cracks near the plant (Kemble, 2022). After 3-8 days, white, legless larvae up to 1 cm long emerge and burrow into the bulb base or the root collar of the stem.

Main signs of infestation

1. Yellowing and wilting of leaves: Begins at the tips and then spreads to the entire leaf. This is often the first noticeable sign.

2. Rotting of the bulb neck: Larvae eat tissues from the inside, causing softening and rot. In severe infestations, the plant can be easily pulled from the soil (Brewster, 2008).

3. Characteristic odor: A distinct putrid smell appears at the site of infestation.

4. Detection of larvae: If you cut open the bulb or stem, you can see white, worm-like larvae inside.

Why is it dangerous?

Larvae not only destroy storage tissues and the root system but also open the door to bacterial and fungal infections, such as soft rot, leading to complete plant death (Kemble, 2022).

Control and prevention measures

1. Crop rotation: The golden rule. Do not plant garlic and onions in the same place more than once every 3-4 years to interrupt the pest's life cycle (Engeland, 1991).

2. Deep soil tillage: Dig over the beds in autumn to the depth of a spade. This helps destroy wintering fly pupae, which are found at a depth of 5-10 cm (Kemble, 2022).

3. Remove infested plants: When you find a plant showing signs of wilting, remove it along with its roots and burn it. This prevents the pest from spreading.

4. Use traps: Place yellow sticky traps between rows during the fly's flight period. This helps monitor the start of activity and reduce the number of females.

5. Biological methods: Apply entomopathogenic nematodes (e.g., Steinernema feltiae) during the larval emergence period when they are most vulnerable (Engeland, 1991).

6. Chemical protection: For those who prefer chemical options, insecticides containing cyromazine can be applied when the first egg-laying sites are detected.

Remember: The onion fly is particularly active during wet seasons. Timely loosening of the soil between rows can help destroy some pupae at the pupation stage.

What does it look like and when to expect it?

Onion thrips are very small insects, only 1-1.2 mm long, with a narrow elongated body of light yellow or brown color. Adults have two pairs of narrow, fringed wings and can fly over long distances. Larvae look like small whitish or yellowish worms. Up to 8-10 generations can develop per season, but in colder regions, no more than 3-4. Thrips overwinter in plant debris, in the topsoil, and under the scales of bulbs left for storage (Engeland, 1991; Kemble, 2022).

Main signs of infestation

1. Silvery-white spots (etiolation): Thrips suck out cell sap, and chlorophyll is destroyed at the puncture sites. The leaf becomes covered with many small light dots that eventually merge into large silvery or whitish areas (Engeland, 1991).

2. Deformation and curling of leaves: In severe infestations, leaves begin to curl, turn yellow, and dry out, starting from the tips. Visually, the field may appear "gray" or "silvery."

3. Black dots of excrement: Small dark droplets—waste products of thrips—can be seen on the leaves.

4. Location: Pests prefer hidden places, so they are easiest to find at the base of leaves or in the axils (Brewster, 2008). To check for thrips, simply run a white sheet of paper over the garlic leaves—moving tiny dots will be visible on it.

Why is it dangerous?

Damaged leaves lose their ability to photosynthesize normally. This directly affects bulb formation: the bulbs become small and underdeveloped. Furthermore, plants weakened by thrips become easy targets for viral diseases. For example, thrips are vectors of the yellow dwarf virus, which can cause severe yellowing, deformation, and stunting of plants (Kemble, 2022).

Control and prevention measures

1. Destroy plant debris: After harvesting, burn or deeply incorporate all plant tops into the soil. This deprives pests of overwintering sites (Engeland, 1991).

2. Proper watering: Thrips do not tolerate high humidity. If the weather is dry and hot, increase watering—this creates uncomfortable conditions for them.

3. Use of entomophages: Use the predatory mite Amblyseius cucumeris, which is a natural enemy of thrips. However, its effectiveness is higher in high humidity conditions, for example, in greenhouses (Kemble, 2022).

4. Use of insecticides: In cases of high pest numbers, treatments with insecticides based on spinosad or acetamiprid can help (Kemble, 2022). Important: Treatments should be directed at the lower part of the plant, to the leaf bases where thrips hide. Repeat treatments according to instructions, observing pre-harvest intervals.

5. Barrier methods: Use fine-mesh netting to protect young plantings from the migration of adults from neighboring fields (Kemble, 2022).

Remember: Onion thrips are most active in hot, dry weather. One of the simplest and safest ways to reduce their numbers is to sprinkle the plantings during hot periods, which washes away the pests and creates a humid microclimate. In small areas, treatments with soapy water or insecticidal soap are effective.

What does it look like and when to expect it?

The stem nematode is a thread-like worm only 1-1.5 mm long. Adults are nearly transparent and can only be seen under a microscope. The most dangerous period is the growing season when humidity and temperature favor their active reproduction. In hot and dry weather, nematodes can enter a state of dormancy (anhydrobiosis) and remain viable in dry plant debris or soil for several years (Engeland, 1991). It is this ability that allows them to survive unfavorable conditions and makes them so resilient.

Main signs of infestation

The first signs may appear in spring, but they often become noticeable only in the middle of the season. Pay attention to the following symptoms (Engeland, 1991; Kemble, 2022):

1. Curving and deformation of leaves: Young leaves grow curved, thickened, and sometimes twisted. This happens because nematodes damage the tissues of the stem and leaves, disrupting their normal development.

2. Yellowing and dieback: Leaves begin to yellow and dry out, starting from the tips or lower tiers. Plants appear stunted and lag in growth.

3. Thickening and cracking of the bulb neck: The most characteristic sign! The lower part of the false stem and the bulb neck become swollen, soft, and crack. On a cut, softened, spongy tissue ("wateriness") is visible. This is where the main mass of pests is concentrated (Engeland, 1991).

4. Formation of a "rotten base": The bulb base (the old root plate) may easily detach and remain in the soil when the plant is pulled out. This signals that nematodes have destroyed the connecting tissues.

5. Absence of external signs: In the early stages of infection, affected plants may outwardly appear no different from healthy ones, making diagnosis particularly difficult.

Why is it dangerous?

The stem nematode feeds on plant sap by penetrating tissues. It destroys cells, creating tunnels into which bacteria and fungi then enter, causing rot. Plants not only lose yield but often die. Losses from nematodes can reach 100% in infested areas. Moreover, infected bulbs are unsuitable for storage, as rot spreads quickly in storage (Kemble, 2022).

Control and prevention measures

The main strategy in combating stem nematode is preventing its appearance. Fighting it once it has appeared is extremely difficult, and sometimes impossible.

1. Buy only healthy planting material: This is the most important rule. Purchase seed garlic only from reliable suppliers who undergo phytosanitary control. Carefully inspect each bulb before planting. Any suspicious specimens—with soft spots, cracks, brown spots—should be discarded and destroyed (Engeland, 1991).

2. Strict crop rotation: Do not return garlic and other Allium species (Allium) to the same place earlier than after 3-5 years. The nematode can persist in the soil for a very long time, and even a long break does not guarantee complete elimination (Kemble, 2022).

3. Destruction of infected plants: When diseased plants are found, they must be immediately dug up with their roots and burned. Never put them in compost! Nematodes can remain viable in compost.

4. Weed control: Some weeds (e.g., from the Asteraceae family) can also host the nematode. Keep the area clean.

5. Heat treatment (for planting material): There is a method of warming bulbs in hot water (about 45°C) before planting, which can kill nematodes. However, this process requires caution as it can damage the planting material itself (Engeland, 1991). This method is more suitable for small volumes of seed material.

6. Quarantine: In regions where the nematode is widespread, quarantine measures are in place. Do not import planting material from affected areas without a phytosanitary certificate (Kemble, 2022).

Remember: Recognizing stem nematode at an early stage is very difficult. The only reliable protection is prevention and vigilance. Invest in quality planting material, and you will significantly reduce the risk of this dangerous pest appearing in your garden.

What does it look like and when to expect it?

The bulb mite is a microscopic arthropod, only 0.5-1 mm in size. Its body is oval, translucent, whitish-glass or yellowish in color, with short legs and powerful chelicerae (mouthparts) with which it gnaws through tissues. It is practically impossible to see with the naked eye. Mites are most active at high humidity (over 70%) and temperatures around 25°C. They are easily carried with infested bulbs, soil particles, tools, and even by wind. In storage facilities, they can develop year-round, feeding on weakened or damaged bulbs (Engeland, 1991).

Main signs of infestation

The mite settles mainly on the bulb base and between scales. Infestation symptoms are often confused with other diseases, so it is important to know the exact signs (Engeland, 1991; Kemble, 2022):

1. Brownish dust on the base: The first and most characteristic sign is darkening and peeling of the bulb base. It becomes loose, crumbly, and covered with a brownish coating—this is a cluster of mites and their waste products.

2. Brown spots and depressions on cloves: Mites gnaw into cloves, leaving depressed brown spots and grooves on them. In severe infestations, cloves turn into a rotting mass.

3. Slow spring growth: If an infected bulb is planted, the mites continue to feed on young roots and the base. As a result, plants lag in growth in spring, leaves turn yellow, and plants are easily pulled from the ground.

4. Rot during storage: In storage, mites are a major cause of so-called "base rot" and mold. They damage the protective tissues, opening the door for fungi and bacteria. Infested bulbs gradually dry out and become hollow inside.

Why is it dangerous?

The bulb mite is a pest that works from the shadows. In the field, it rarely kills plants but significantly reduces their vigor and yield. However, the real disaster happens in storage, where mites rapidly multiply in warmth and humidity, turning the stored harvest into dust. Infested bulbs not only lose marketable appearance and weight but also become unsuitable for planting in the next season, as mites destroy the growing point and root system (Brewster, 2008; Engeland, 1991).

Control and prevention measures

Controlling bulb mites is primarily about prevention, especially at the preparation stage for storage and planting.

1. Thorough culling: When storing and especially when preparing planting material, inspect every bulb. Discard all specimens with damaged bases, brown spots, softness, or signs of rot. Never use infected bulbs for planting! (Engeland, 1991).

2. Optimal storage conditions: A key factor! Mites actively multiply at high humidity (above 70%). Therefore, store garlic in a dry, well-ventilated area with humidity no higher than 60-70% and a temperature of about 0°C for culinary garlic or 18-20°C for seed garlic (Brewster, 2008; Kemble, 2022). Maintaining low humidity is your main defense.

3. Proper drying and cleaning: Dry garlic thoroughly after harvest. Remove all dry outer scales, old roots, and soil, as mites and their eggs may hide under them.

4. Sanitize storage: Before storing the new harvest, be sure to disinfect the storage facility. Treat walls and floors with a bleach solution (1-2 kg per 10 L of water), fumigate with sulfur (30-60 g/m³), or use sulfur candles.

5. Heat treatment of planting material: Warm the bulbs before planting for 5-7 days at a temperature of 35-40°C. This helps destroy most mites and their eggs.

6. Biological method: Use predatory mites—for example, Hypoaspis aculeifer, which feed on bulb mites. This method is especially effective in protected cultivation and storages (Brewster, 2008).

7. Crop rotation and green manures: As with other pests, observe crop rotation. Planting marigolds, calendula, or mustard has a good preventive effect, as they release substances that repel mites.

Remember: The bulb mite is not as dangerous in the field as in storage. The most effective way to protect the harvest is to create unbearable conditions for the pest—namely, a dry and cool environment. And, of course, do not spare time for careful selection of planting material before planting.

What does it look like and when to expect it?

The wireworm is the larva of a beetle (click beetle). It resembles a piece of stiff wire, hence the name: the body is long (up to 15-25 mm), narrow, cylindrical, covered with a hard chitinous shell of yellow-brown or orange color (Engeland, 1991). The larva has three pairs of short thoracic legs and a dark head. Wireworm development lasts 2-5 years, and during all this time it lives in the soil, feeding on underground parts of plants (Kemble, 2022). Larvae are most active in spring and early summer, when the soil warms to 10-15°C, and also in autumn.

Adult click beetles are small (up to 15 mm), elongated beetles of dark brown or black color. A characteristic feature is the ability to flip over with a sharp click, throwing the body into the air. Beetle flight occurs in May-June, after which females lay eggs in the soil, mainly in areas overgrown with grassy weeds or in sod.

Main signs of infestation

Wireworms lead a hidden lifestyle, and their presence is often detected only during harvest. However, there are several signals that can help suspect their activity (Engeland, 1991; Kemble, 2022):

1. Wilting and yellowing of leaves: Young plants may suddenly start to wilt, especially in hot weather. This happens because the wireworm gnaws through the roots and the base of the stem, depriving the plant of nutrients and moisture.

2. Stunted growth and development: Affected plants lag in growth, look stunted, and their leaves become pale.

3. Tunnels and damage on bulbs: This is the main and most obvious sign! During harvest, you will find deep, narrow passageways or grooves penetrating the bulb tissue. Sometimes damage looks like dark, sunken spots. The pest itself can be seen inside the tunnels (Engeland, 1991).

4. Root damage: The roots of damaged plants have torn, chewed edges.

5. Location: The pest prefers moist, shaded places with dense soil. Wireworms are most often found in areas previously occupied by cereal crops, lawns, or fallow land.

Why is it dangerous?

The wireworm is one of the most dangerous soil pests for root crops and bulbous plants. It not only reduces yields but also makes bulbs unsuitable for storage. Bulbs damaged by tunnels quickly rot and are infected by fungal and bacterial infections (Brewster, 2008). In addition, wireworms can completely destroy seedlings by gnawing through the root collar.

Control and prevention measures

Controlling wireworms is a difficult task that requires a comprehensive approach. It is difficult to get rid of them completely, but their numbers can be significantly reduced and damage minimized.

1. Crop rotation and proper preceding crops: Do not plant garlic after cereal crops (wheat, rye, oats, corn) or in areas long occupied by turf. The best preceding crops are legumes (peas, beans), cucurbits, and nightshades (Kemble, 2022).

2. Deep digging and soil cultivation: Dig the area in autumn and spring to a depth of 25-30 cm. This helps destroy some larvae and pupae and makes the soil less favorable for their habitat. Wireworms prefer dense, poorly aerated soil.

3. Use traps: This is a fairly effective method. 1-2 weeks before planting, place baits in the soil: pieces of raw potato, carrot, or beet, threaded on sticks and buried to a depth of 5-10 cm. After 2-3 days, collect the traps with the pests and destroy them. Repeat the procedure until planting (Engeland, 1991).

4. Biological method: Use entomopathogenic nematodes Steinernema feltiae. These microscopic worms penetrate the wireworm and kill it. Nematodes are best applied to the soil at temperatures not below 10°C and with sufficient moisture (Engeland, 1991).

5. Soil acidity: Wireworms prefer acidic soils (pH below 5.5). Liming (with dolomite flour, chalk) not only reduces acidity but also creates unfavorable conditions for the pest. The recommended pH for garlic is 6.0-7.0 (Brewster, 2008).

6. Barrier methods: When planting garlic, individual protective "cocoons" made of thick paper or cardboard can be placed in the hole around the bulb. This physically prevents wireworms from accessing the roots.

7. Insecticides: In case of very high numbers and large planting areas, chemical preparations applied to the soil before planting (e.g., based on diazinon or bifenthrin) can be used. However, for home gardening, this is an extreme measure and requires strict adherence to the instructions.

Remember: Wireworm is a pest that is difficult to combat but can be successfully managed. A combination of agronomic methods (crop rotation, liming, deep tillage) and traps gives good results and allows you to grow a healthy garlic harvest without the use of pesticides.

What does it look like and when to expect it?

The mole cricket is a large insect (up to 5-8 cm long) with a powerful, elongated body of dark brown color. Its front legs are modified into digging "paws" resembling spades, with which it digs tunnels in the soil. Adults have short elytra and well-developed wings, but rarely fly. The mole cricket is most active in spring when the soil warms up and in early summer. During this period, females build nests at a depth of 10-15 cm and lay up to 500 eggs. Larvae hatched from the eggs resemble adults in appearance but are smaller and wingless. The full development cycle takes 1-3 years. The mole cricket overwinters at a depth of 1-2 m, in soil or manure heaps (Engeland, 1991; Kemble, 2022).

Main signs of infestation

The mole cricket leads a hidden lifestyle, but its presence can be guessed by characteristic signs that are hard to miss (Engeland, 1991; Kemble, 2022):

1. Wilting plants: Young garlic plants suddenly wilt, turn yellow, and die. This happens because the mole cricket gnaws through the root collar, depriving the plant of nutrition. Wilting may not be isolated but massive if the mole cricket is actively moving around the plot.

2. Damaged bulbs: During harvest, bulbs show deep torn wounds, gnawed cavities, and sometimes the bulb is completely eaten. The mole cricket leaves characteristic traces—torn edges of damage (Engeland, 1991).

3. Loose mounds of earth and tunnels: This is the most obvious and recognizable sign. In spring and early summer, loose earthen ridges appear on the soil surface—these are traces of the mole cricket's underground tunnels. If you rake such a mound, you can find the entrance to a vertical tunnel. Also, along the beds, you can see long winding furrows, as if someone crawled underground.

4. Nocturnal activity: The mole cricket is nocturnal. On warm, humid evenings, you can hear characteristic chirping, which it makes while sitting at the entrance to its burrow. This helps detect its presence on the plot.

Why is it dangerous?

The mole cricket is an omnivorous pest that damages not only garlic but also many other vegetable and flower crops. It causes damage throughout the season: destroys seedlings, gnaws through the roots of adult plants, and, most unpleasantly, spoils the marketable appearance of bulbs, making them unsuitable for storage and consumption. In particularly favorable years (wet and warm), mole crickets can destroy up to 50-70% of the harvest on an infested plot (Brewster, 2008).

Control and prevention measures

Controlling mole crickets is a constant and labor-intensive process that requires a systematic approach. Getting rid of them completely is difficult, but their numbers can be significantly reduced and the harvest protected.

1. Traps: This is one of the most effective methods. In early spring, before planting garlic, place fresh manure (horse or cow) in small piles (up to 30-40 cm) in different places on the plot. Mole crickets like to settle in manure, as it is warm and moist. After 2-3 weeks, check the traps and destroy the pests that have gathered there (Engeland, 1991). Similarly, you can use jar traps: bury containers (glass jars or cut plastic bottles) in the ground up to the neck, pour a little water with vegetable oil into them. Mole crickets moving through the tunnels fall into the water and cannot get out.

2. Deep digging: In autumn and spring, dig the plot to a depth of 25-30 cm. This destroys tunnels, eliminates some individuals and egg-laying sites, and makes the soil less attractive to mole crickets.

3. Repellent plants: Plant around the perimeter of the plot and between rows plants with a strong odor that the mole cricket cannot tolerate. Such plants include: marigolds, chrysanthemums, calendula, garlic (which, ironically, is its victim, but the smell of other alliums may repel it), as well as some types of mint and wormwood.

4. Biological method: Use entomopathogenic nematodes (Steinernema feltiae), which can penetrate the mole cricket and cause its death. Nematodes are best applied to the soil at temperatures not below 12°C and with sufficient moisture (Engeland, 1991). There is also a biological product "Metarizin" based on the entomopathogenic fungus Metarhizium anisopliae, which actively multiplies in the soil and affects mole crickets.

5. Chemical method: Apply insecticides in granular form, incorporated into the soil immediately before planting, for example, based on diazinon. However, for home gardening, this is an extreme measure requiring caution. Strictly follow the instructions on the package and use personal protective equipment (Kemble, 2022).

Remember: The mole cricket is a serious pest, but with systematic application of preventive measures and traps, you can significantly reduce its numbers and protect your garlic harvest. Do not forget the importance of crop rotation and sanitary cleaning of the plot—this is the basis for successful control of most soil pests.

Note: In the provided sources (Brewster, 2008; Engeland, 1991; Kemble, 2022), information on the mole cricket is not covered, as these works mainly focus on pests typical of North America and Europe, where the mole cricket is widespread but not as critical a pest as in more southern regions. However, the recommendations for combating it are based on generally accepted agronomic methods.

1. Agronomy—The Foundation of Plant Health

A strong, healthy plant grown in good conditions is much better able to resist pests and diseases. Therefore, the foundation of protection is proper agronomy.

Crop rotation (3-5 years): This is the most important rule. Never plant garlic (and other Alliums) in the same place more than once every 3-4 years, and preferably once every 5 years. This interrupts the life cycles of most soil pests and pathogens that accumulate in the soil under monoculture (Kemble, 2022; Engeland, 1991). The best preceding crops are legumes, cucurbits, nightshades (tomatoes, peppers), and brassicas. The worst are any Allium species and cereals (after which wireworms spread heavily).

Healthy planting material: This is your primary investment. Buy seed garlic only from reliable suppliers who undergo phytosanitary control. Carefully inspect each bulb before planting: discard all specimens with soft spots, stains, cracks, damaged bases, or signs of rot. One diseased bulb can infect the entire plot (Engeland, 1991).

Soil preparation: Deep autumn digging (to 25-30 cm) helps destroy the wintering stages of many pests (onion fly, wireworm, mole cricket). Regular loosening between rows during the season destroys tunnels and egg-laying sites and promotes better soil aeration.

Optimal conditions: Maintain the recommended pH level (6.0-7.0) through liming—this creates unfavorable conditions for wireworms. Ensure good drainage—many pests (e.g., bulb mites) actively multiply in conditions of high humidity. Use mulching with clean straw to maintain a stable microclimate (Brewster, 2008).

2. Prevention—Your Main Tool

Preventive measures significantly reduce the risk of pests appearing and reduce their numbers.

Destruction of plant residues: After harvesting, burn or deeply incorporate all tops and roots into the soil. This deprives many pests (thrips, nematodes, mites) of overwintering sites.

Timely watering: In hot, dry weather, increase watering—this creates uncomfortable conditions for onion thrips. At the same time, avoid overwatering, which provokes the development of mites and rots. Water garlic in the morning hours so that the plants dry out by evening.

Use of traps: This is an effective and environmentally friendly method of control, especially against mole crickets and wireworms:

• For mole crickets: In early spring, lay out piles of fresh manure (attracts mole crickets for overwintering and breeding); use jar traps buried in the ground with a small amount of water and vegetable oil (Engeland, 1991).
• For wireworms: 1-2 weeks before planting, bury pieces of raw potato or carrot on sticks to a depth of 5-10 cm; after 2-3 days, collect the traps with the pests and destroy them (Engeland, 1991).

Repellent plants: Plant marigolds, calendula, chrysanthemums, mint, and wormwood around the perimeter of the plot and between rows. Their smell repels many pests, including mole crickets and onion flies.

3. Monitoring—How to Notice the Threat in Time

Regular inspection of plantings helps detect pests at an early stage when control is most effective.

Visual inspection: Inspect at least once a week. Pay attention to leaf color (yellowing, silvery coating), deformations (curling, twisting), the presence of tunnels, dust, swellings on stems and bulbs.

Diagnostic traps: Use yellow sticky traps during the flight period of onion flies and thrips—this helps track the start of activity and take timely measures.

Timely response: When the first signs of infestation are detected, immediately remove and burn diseased plants to prevent the pest from spreading.

4. Biological Protection—Safe Weapons

Biological methods are based on using the natural enemies of pests and are safe for humans and the environment.

Entomopathogenic nematodes (Steinernema feltiae)—effective against wireworms, mole crickets, and onion fly larvae. Applied to the soil as an aqueous suspension at temperatures not below 10-12°C and with sufficient moisture (Engeland, 1991).

Predatory mites (Amblyseius cucumeris, Hypoaspis aculeifer)—help control onion thrips and bulb mites. Particularly effective in high humidity conditions, such as in greenhouses or under covers (Brewster, 2008; Kemble, 2022).

Biopreparation "Metarizin" —based on the entomopathogenic fungus Metarhizium anisopliae, effective against mole crickets and wireworms. The product is applied to the soil, where the fungus actively multiplies and affects pests.

5. Chemical Protection—A Last Resort

Chemical insecticides should be used only in cases of high pest numbers when other methods do not yield results. When using, observe the following rules:

• Choose low-toxicity products (e.g., based on diazinon, bifenthrin, spinosad, or acetamiprid). For thrips control, products based on spinosad or acetamiprid are effective (Kemble, 2022).
• Strictly follow the instructions for dosage, timing, and method of application.
• Observe pre-harvest intervals (indicated on the packaging)—this is the time during which the product breaks down to safe concentrations.
• Apply only in dry, calm weather, in the morning or evening, to avoid plant burns and the death of beneficial insects.
• Avoid applying insecticides to the soil before planting unless absolutely necessary, as this disrupts the soil microbiome.