Garlic

Garlic aspiezio

Introduction

Garlic (Allium sativum) is in the onion family. For thousands of years, it has been grown for culinary and medicinal uses. Garlic grows in a wide range of conditions. While most production is in mild areas, such as California, some varieties grow well and often develop better flavor in cold climates. 

Types and Varieties

There are two main types of garlic: hardneck and softneck. Hardneck (or topset) garlic produces false flower stalks called scapes, which are also edible. It typically has about 6 cloves per bulb. Softneck garlic typically has more than twice as many cloves and generally has a longer storage life than hardneck varieties. Softneck garlic dominates commodity production, but many growers in New England prefer hardneck types for retail sales due to their flavor and appearance. Hardneck varieties often have a reddish-purple clove covering versus the white color common in softneck types. Elephant, or great headed garlic (A. ampeloprasum) is grown like other garlic but has a milder flavor and is not widely grown in New England.

After centuries of cultivation, garlic has lost the ability to produce seeds. Therefore, it is vegetatively propagated by saving bulbs and planting individual cloves from which new bulbs form. The small bulbils produced on hardneck scapes can be used for propagation, but it takes several years of planting and selection to achieve marketable size bulbs.

Although many different variety names are used in garlic commerce, recent genetic research suggests there are only about 10 major varieties of garlic. These express different characteristics from one location to another, complicating variety identification. Since there is no standardization of varieties, as with potatoes, one must take garlic variety names with a grain of salt. As with other vegetatively propagated crop plants, diseases and mites can be carried over from one generation to the next. It's a good idea to start out with several different varieties and/or seed-sources produced by reputable producers in your area, selecting and saving seed from varieties and individual plants that perform best and appear to be free of pests.

Soil Fertility

A well-drained soil with good tilth and plenty of organic matter is ideal for garlic. Garlic has a shallow root system; excess moisture, compaction, or droughty conditions will reduce yields. The optimum soil pH is between 6 and 6.8. Since garlic commences growth very early in the season, it is important to have soil nutrients available at that time. The table below gives timing guidelines for use of quick-release sources, particularly for nitrogen. Adjust timing if using a slower release material. Since garlic has such an early start, avoid fields that are slow to drain in the spring. Sidedressing with 20-40 pounds of N every 3 weeks until 4-6 weeks before harvest will produce optimal yields.

Plant Nutrient Recommendations According to Soil Test Results for Garlic

  NITROGEN (N) - LBS PER ACRE PHOSPHORUS (P) -
BS P2O5 PER ACRE		 POTASSIUM (K) -
LBS K2O PER ACRE
SOIL TEST RESULTS   VERY LOW LOW OPTIMUM ABOVE OPTIMUM VERY LOW LOW OPTIMUM ABOVE OPTIMUM
Broadcast and incorporate in fall 40 150 100 25-50 0 150 100 50 0
Sidedress in spring when shoots are 6" high 40 0 0 0 0 0 0 0 0

Sidedress 3-4 weeks later 

40

0

0

0

0

0

0 

0 

 0
TOTAL RECOMMENDED 120 150 100 25-50 0 150 100 50 0

Planting

Garlic is planted in the fall since it requires cold temperatures to induce bulb formation. Planting typically occurs from October in northern New England to early November in southern New England. The goal is to time planting for good development of roots, but not enough time for the shoots to emerge from soil before winter (6-8 weeks before the ground freezes). Many different planting arrangements are used by growers depending on irrigation, mulching, and weed control systems. Planting cloves too densely can reduce bulb size, while spacing too far apart reduces yield per acre. Common planting arrangements include 2-row beds 30" apart on center with 6" spacing in- and between-rows, 3- or 4-row beds with 6-8" in- and between-rows, single rows spaced 24-30" with 6" in-row spacing. Wide row spacing between rows allows for easy mechanical cultivation for weed control; planting multiple rows per bed allows for use of plastic mulch to control weeds.

Garlic varieties differ in size and weight of cloves; generally, there are about 50 cloves in a pound. Large cloves tend to produce the most vigorous plants and largest bulbs; therefore, small cloves are often not planted. Bulbs should be separated no more than a day or two before planting so they do not dry out. Cloves should always be planted with the root side down, 3-4" deep, and so the top of the clove is 1" below the soil surface. Plant only healthy-looking cloves to avoid disease and pest problems.

Field Culture 

A layer of clean straw mulch is typically applied to garlic at planting to avoid drastic soil temperature fluctuations and heaving in the winter and early spring. The garlic will grow through the mulch in the spring. Alternatively, garlic can be planted into plastic mulch. Either will conserve soil moisture and suppress weeds. It may be advisable to remove straw mulches in very wet springs to allow soil to dry out and thus reduce the threat of soilborne diseases. In very cold growing areas, removing mulch can also speed soil warming and garlic growth in the spring. Because garlic is shallow-rooted, irrigation is very beneficial during dry periods. 

Clipping scapes from hardneck garlic once fully curled, just below the curl, has been found to improve bulb size. Scapes are edible, and can be sold and used as a garlic-flavored fresh vegetable similar to scallions.

Harvest and Storage

Although variable depending on variety and growing conditions, 1 lb of garlic 'seed' bulbs will usually yield 4-8 lb at harvest. Garlic may be ready to harvest over several weeks during July. When the lower third of leaves turn brown, it is advisable to pull several bulbs to check for maturity. Cut the bulbs in half width-wise, and check whether cloves have fully filled out within the skins or if there are gaps indicating they still have some room to grow. When no gaps remain and the cloves have filled their skins, they are ready to harvest. Gently pull, dig, and/or undercut the bulbs to remove them. Unless a lot of soil is adhered to the bulbs, they do not need to be washed at harvest (although some markets may demand it). Place the harvested plants on wire racks or tie in bundles for hanging and cure for several weeks in a dry area with good ventilation. Curing takes 10-14 days. Stems may be cut before or after curing. Curing is complete when the outer skins are dry and crispy, the neck is constricted, and the center of the cut stem is hard. After curing, tops can be cut to leave about 1" remaining, and roots should be trimmed closely. If necessary, bulbs may be brushed or the outer skin gently rubbed off to clean them.

For long-term storage, garlic is best maintained at temperatures of 30-32°F with relative humidity of 60-70%. Good airflow throughout storage containers is necessary to prevent any moisture accumulation. Under these conditions, well-cured garlic can be stored for 6-7 months. Storage at higher temperatures (60°F) may be adequate for the short term, but it is important to select a place with low relative humidity and good air flow. As with onions, relative humidity needs to be lower than for most vegetables because high humidity causes root and mold growth; on the other hand, if it is too dry the bulbs will dry out.

Seed. Garlic bulbs that are to be used as seed for fall planting of next years’ crop should be stored at 5°F and at relative humidity of 65-70%. Garlic cloves break dormancy most rapidly between 40 and 50°F; hence, prolonged storage at this temperature range should be avoided. Storage of planting stock at temperatures below 40°F results in rough bulbs, side-shoot sprouting (witches brooms) and early maturity, while storage above 65°F results in delayed sprouting and late maturity.

Garlic cloves used for seed should be of the highest quality, with no disease infections, as these can be spread to new fields and to next years’ crop. Be on the lookout for garlic bloat nematode which may have been distributed around New England on infested seed garlic. This nematode, which is also known as a bulb and stem nematode, causes bloated, twisted, swollen leaves, and distorted and cracked bulbs with dark rings. Infestation with this nematode can weaken plants, causing them to be susceptible to secondary infections.

Garlic Disease Control

Garlic Disease Control otank

NOTE: For the disease control products listed below, one product trade name and formulation is provided for each active ingredient (common name) as an example of rates, preharvest interval (PHI), restricted entry interval (REI), and special instructions. In many cases, there are other products available with the same active ingredient. Please see Table 26 and Fungicides and Bactericides Alphabetically Listed by Trade Name for more information on products with the same active ingredients.

The symbol OG indicates a product is listed by the Organic Materials Review Institute (OMRI) as approved for use in organic production. See Organic Certification section for more detail.

The most common controls for garlic diseases include the use of disease-resistant cultivars and pathogen-free seed and bulbs, as well as cultural practices including crop rotation and crop residue management that restrict the pathogens. 

Blue Mold (Penicillium spp.)

Blue mold is typically most problematic as a storage disease, although it can infect seed cloves as well, and cause poor stands. Several Penicillium species cause blue mold, and these species are common in soil, on plant and animal debris, and in senescing plant tissues. Some species may be carried on infected cloves or seed. The mold presents as a mass of blue-gray fungal growth on the bulb, and in the field, yellowed and stunted plants may be observed. These pathogens typically invade bulbs through wounds, mechanical bruises, or freezing injury. Control other diseases and pests in the field to prevent avenues for infection. Harvest bulbs with a minimum of bruising and wounding, and dry promptly. Store bulbs at 40°F with low relative humidity. Some countries recommend treating with fungicides before storage.

  • thiophanate methyl (Topsin M 70WP): 1.0 lb/100 gal; REI 72h, Group 1. Pre-plant treatment by immersion of garlic cloves in suspension for at least 5 minutes.

Damping-off and Seed Rot (Pythium and Rhizoctonia spp.)

Damping- off and seed rot are commonly caused by Pythium spp. from poor soil draining conditions. Seeds and roots of infected seedlings will appear water- soaked, then will decompose. Symptoms of plants infected after the seedling stage will show foliar damage, leaves yellowing from tip to base. Avoid excessive soil moisture by improving soil drainage or planting on raised beds. Seed and soil treatments with fungicides are a recommended practice.

  • mefenoxam (Apron XL): 0.085 to 0.64 fl oz/100 lbs seed; REI 48h, Group 4. Not effective for Rhizoctonia.
  • fludioxonil (Maxim 4FS): 0.08 to 0.16 oz/100 lb seed; REI 12h, Group 12. For protection against seedborne and soilborne fungi. Does not control Pythium or Phytophthora.

Downy Mildew (Peronospora destructor)

During extended periods of cool, humid weather, this disease can be highly destructive, causing losses in both yield and bulb quality. Symptoms can be seen as a grayish violet furry growth on the surface of the leaf or seed stem. Affected leaves will become pale-green to yellow. Practice a 3- to 4-year rotation. Plant on well-drained soil and orient rows in the same direction as prevailing winds. Avoid overhead irrigation. A regular program of fungicide spraying based on climatic conditions and disease forecasts should be followed.

  • ametoctradin plus dimethomorph (Zampro): 14.0 fl oz/A; PHI 0d, REI 12h, Groups 45 & 40.
  • azoxystrobin (Quadris F): 9.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11. Do not make more than 1 application before alternating to a non-Group 11 fungicide.
  • azoxystrobin plus chlorothalonil (Quadris Opti): 2.4 to 3.6 pt/A; PHI 7d, REI 12h, Groups 11 & M. See label for tank mix precautions. 
  • azoxystrobin plus propiconazole (Quilt Xcel): 17.5 to 21 fl oz/A; PHI 14d, REI 12h, Groups 11 & 3.
  • Bacillus amyloliquefaciens strain D747 (DoubleNickel LCOG): 0.25 to 3.0 lb/A; PHI 0d, REI 4 h, Group 44. Disease suppression only. For improved control, mix or rotate with a chemical fungicide.
  • copper hydroxide (Kocide 3000): 0.75 to 1.5 lb/A; PHI 0d, REI 48h, Group M1. Can cause phytotoxicity to leaves.
  • dimethomorph (Forum): 6.0 fl oz/A; PHI 0d, REI 12h, Group 40. Forum must be applied as a tank mix with another fungicide from a different FRAC Group. Apply in adequate water.
  • famoxadone plus cymoxanil (Tanos): 8.0 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Must be tank mixed with an appropriate contact fungicide from a different FRAC Group. Do not alternate or tank mix with other Group 11 fungicides.
  • fenamidone (Reason 500 SC): 5.5 fl oz/A; PHI 7d, REI 12h, Group 11. Do not make more than 1 application before alternating to a fungicide from a different FRAC Group.
  • fluazinam (Omega 500F): 16 fl oz/A; PHI 7d, REI 12h, Group 29. Use sufficient water for thorough coverage, but not less than 5 gal/A. 
  • mancozeb (Dithane F45): 2.4 qt/A; PHI 7d, REI 24h, Group M3.
  • mandipropamid (Revus): 8.0 fl oz/A; PHI 7d, REI 4h, Group 40.
  • mefenoxam plus chlorothalonil (Ridomil Gold Bravo SC): 2.5 pt/A; PHI 7d, REI 48h, Groups 4 & M5.
  • mefenoxam and mancozeb (Ridomil Gold MZ): 2.5 lbs/A; PHI 7d, REI 48h, Groups 4 & M3. Use sufficient water to obtain thorough coverage. Do not apply more than 4 times per season.
  • oxathiapiprolin & mandipropamid (Orondis Ultra): 5.5 to 8.0 fl oz/A; PHI 7d, REI 4h, Groups 49 & 40.
  • phosphorous acid (Fosphite): 1.0 to 3.0 qt/in a minimum of 20 gal/A; PHI 0d, REI 4h, Group 33. Do not apply to plants that heat- or moisture-stressed. Do not apply directly to copper-treated plants within 20-day interval to avoid plant injury.
  • pyraclostrobin (Cabrio EG): 12.0 oz/A; PHI 7d, REI 12h, Group 11. Do not rotate with other Group 11 fungicides.

Bulb and Basal Plate Rot (Fusarium spp.)

Bulb and basal plate rot of garlic is caused by Fusarium culmorum and F. roseum. Symptoms include pre-emergence decay of cloves and seedlings, decay of the stem plate and storage leaves during the growing season, and postharvest decay of cloves in stored bulbs. Infected cloves will have sunken, circular brown lesions on their outer surface and/or basal plate. Foliar symptoms include curving, yellowing and necrosis of leaves beginning at tips, and wilt. Infection occurs mainly from the soil through the stem plate. Incidence of the disease increases with injury by onion maggot or other insects. Cloves may remain infected but non-symptomatic. The pathogen is disseminated in seed, soil, infected debris, and irrigation water. Hot water seed treatment has reduced garlic clove infection by 50%, but is not enough to provide commercially-acceptable control when clove infection is severe and is a logistically difficult process. Excess soil N favors Fusarium infection; take care to account for soil organic matter and cover crop N credits and not to over-fertilize. Long (4-year) rotations to non-susceptible crops may minimize losses. Storage at 40°F also helps.

Purple Blotch (Alternaria porri)

Alternaria porri is most likely to become problematic when temperatures are warm (77-85°F) with high humidity. Small lesions will form on stems or leaves, eventually enlarging and becoming tan or purple. Purple blotch is easily confused with Stemphylium leaf blight, which tends to produce darker lesions. While laboratory diagnoses are needed for proper identification, these two pathogens can be managed in the same way. Practice long rotations with non-Allium crops, and use practices that reduce hours of leaf wetness, e.g. increased plant spacing and good air movement. Plow under crop residues promptly after harvest. Rotate fungicides throughout the growing season.

  • azoxystrobin (Quadris): 6.0 to 12.0 fl oz/A; PHI 0d, REI 4h, Group 11. Do not rotate with other Group 11 fungicides.
  • azoxystrobin plus chlorothalonil (Quadris Opti): 1.6 to 3.2 pt/A; PHI 7d, REI 12h, Groups 11 & M. See label for tank mix precautions. 
  • azoxystrobin plus difenoconazole (Quadris Top): 8 to 14 fl oz/A; PHI 7d, REI 12h, Groups 11 & 3. 
  • azoxystrobin plus propiconazole (Quilt): 14.0 to 27.5 fl oz/A; PHI 14d, REI 12h, Groups 11 & 3.
  • Bacillus amyloliquefaciens strain D747 (DoubleNickel LCOG): 0.25 to 3.0 lb/A; PHI 0d, REI 4 h, Group 44. Disease suppression only. For improved control, mix or rotate with a chemical fungicide.
  • boscalid (Endura): 6.8 oz/A; PHI 7d, REI 12h, Group 7. Do not make more than 2 consecutive applications before rotating to a fungicide from a different FRAC Group.
  • chlorothalonil (Bravo Weather Stik): 1.0 to 3.0 pt/A; PHI 7d, REI 12h, Group M5. When disease is present, use the higher rate.
  • chlorothalonil plus oxathiapiprolin (Orondis Opti): 1.75 to 2.5 pt/A; PHI 7d, REI 12h, Groups 49 & M05.
  • chlorothalonil plus zoxamide (Zing): 30.0 fl oz/A; PHI 7d, REI 12h, Groups 22 & M05. Do not apply to exposed bulbs.
  • copper hydroxide (Kocide 3000): 0.75 to 1.5 lb/A; PHI 0d, REI 48h, Group M1. Do not apply in a spray solution having a pH less than 6.5 or tank mix with Aliette.
  • cyprodinil plus fludioxonil (Switch 62.5 WG): 11.0 to 14.0 oz/A; PHI 7d, REI 12h, Groups 9 & 12. Do not make more than 2 consecutive applications before rotating to a fungicide from a different FRAC Group. 
  • difenoconazole plus cyprodinil (Inspire Super): 16.0 to 20.0 fl oz/A; PHI 7d, REI 12h, Group 3 & 9. Apply in sufficient volume to achieve thorough coverage.
  • difenoconazole plus fluopyram (Luna Flex): 10.0 to 13.6 fl oz/A; PHI 7d, REI 12h, Groups 3 & 7.
  • famoxadone plus cymoxanil (Tanos): 8.0 oz/A; PHI 3d, REI 12h, Groups 11 plus 27. Must be tank mixed with an appropriate contact fungicide from a different FRAC Group. Do not alternate or tank mix with other Group 11 fungicides. 
  • fenamidone (Reason 500 SC): 5.5 fl oz/A; PHI 7d, REI 12h, Group 11. Do not rotate with other Group 11 fungicides. 
  • fluazinam (Omega 500DF): 16.0 fl oz/A; PHI 7d, REI 12h, Group 29. Do not make more than 6 applications per acre per year. Do not use an adjuvant.
  • fluopyram (Velum Prime): 6.5 to 6.84 fl oz/A; PHI 30d, REI 12h, Group 7. Note longer PHI. 
  • penthiopyrad (Fontelis): 16.0 to 24.0 oz/A; PHI 3d, REI 12h, Group 7. 
  • mancozeb (Dithane F45): 2.4 qt/A; PHI 7d, REI 24h, Group M3.
  • polyoxin D (OSO 5%SC): 3.75 to13.0 fl oz/A; PHI 0d, REI 4h, Group 19.
  • propiconazole (Tilt): 4.0 to 8.0 fl oz/A; PHI 14d, REI 24h, Group 3.
  • Pseudomonas chlororaphis strain AFS009 (Howler EVOOG): 40.0 to 120.0 oz/A; PHI 0d, REI 4h, Group BM02.
  • pydiflumetofen plus fludioxonil (Miravis Prime): 11.4 fl oz/A; PHI 7d, REI 12h, Groups 12 & 7. Apply in sufficient volume to achieve thorough coverage.
  • pyraclostrobin (Cabrio EG): 8.0 to 12.0 oz/A; PHI 7d, REI 12h, Group 11. Do not rotate with other Group 11 fungicides.
  • pyraclostrobin plus boscalid (Pristine): 10.5 to 18.5 oz/A; PHI 7d, REI 12h, Groups 11 & 7. Do not make more than 2 applications before alternating with a fungicide from a different FRAC Group.
  • pyrimethanil (Scala SC): 18.0 fl oz/A; PHI 7d, REI 12h, Group 9.
  • pyrimethanil plus fluopyram (Luna Tranquility): 16.0 to 27.0 fl oz/A; PHI 7d, REI 12h, Groups 9 & 7.

Bloat Nematode (Ditylenchus dipsaci)

Ditylenchus dipsaci is a nematode species that infects germinating garlic seed and is primarily borne in seed cloves. The nematode itself has limited mobility, but can be easily spread in infested soil, on equipment, and in infected seed and plant material. D. dipsaci is common in all temperate regions. It is an obligate parasite of plants; populations of the nematode exhibit marked host preferences. The nematodes aggregate into a mass called nematode wool and with slow drying can persist in infested fields for long periods. Symptoms of infection include leaf yellowing, erratic stands, stunting, looping and bending of leaves, twisting, and growth deformities. Bulb damage can be mistaken for Fusarium basal plate rot with decay occurring both at the neck and the basal plate. Infected bulbs will lack roots. D. dipsaci can be controlled with long crop rotations including the elimination of volunteer onions, garlic, and host weeds. The primary method of controlling nematodes is hot water treatment of seed cloves but this process is difficult to do on-farm because of the large volume of water needed to be held at a specific temperature for treatment. The standard regime is 30-45 minutes at 100ºF, 20 minutes at 120ºF, and then 10-20 minutes at 64-72ºF. Hot water treatment must be performed carefully to prevent damage to cloves. Chemical, physical, and cultural methods have been used to restrict damage, but most chemical treatments are no longer registered for use.

White Rot (Sclerotium cepivorum)

White rot is caused by Sclerotium cepivorum, which persists for a long time in soil. It is “activated” by root exudates produced by allium crops. Affected plants will show yellowing older leaves and stunting, and small black sclerotia can be seen on the bulb. Disease development is favored by cool, moist soil conditions. There is little to be done once a field is infested with S. cepviorum, and crops should be rotated out of alliums for as long as possible. Some fungicides (Iprodione) provide protection for the establishment of garlic, but fungicide control is marginal for full-season crops. Soil fumigation may provide partial control. In general, neither fungicides nor fumigation have provided consistent, reliable, full-season control of white rot. Hot water treatment of garlic seed can reduce the potential to spread white rot sclerotia. Winter flooding and soil solarization can reduce the number of sclerotia.

  • azoxystrobin plus propiconazole (Quilt Xcel): 17.5 to 21 fl oz/A; PHI 14d, REI 12h, Groups 11 & 3.
  • Bacillus amyloliquefaciens strain D747 (DoubleNickel 55OG): 0.12 to 1.0 lb/A soil drench; PHI 0d, REI 4 h, Group 44.
  • boscalid (Endura): 6.8 oz/A; PHI 7d, REI 12h, Group 7. Apply in-furrow at planting.
  • cyprodinil plus fludioxonil (Switch 62.5 WG): 7 to 14 oz/A; PHI 7d, REI 12h, Groups 9 & 12.
  • fludioxonil (Cannonball WG): 0.5 oz/1000 ft.; PHI 7d, REI 12h, Group 12. Apply in-furrow at planting.
  • iprodione (Rovral): 4.0 pt/A; REI 24h, Group 2. Apply in-furrow at planting. Do not make more than 1 application per year.
  • tebuconazole (Orius 3.6F): 20.5 fl oz/A; PHI 7d, REI 12h, Group 3. Apply in-furrow at planting or over the top in a 4-6" band.
  • thiophanate methyl (Topsin M 70WP): 2.0 lb/A; REI 72h, Group 1. Apply in furrow.

Botrytis Neck Rot (Botrytis spp.)

Botrytis neck rot is limited to the allium family and also causes neck rot of onion, leeks, and shallots. The pathogen is soil- and seed-borne and is readily spread through planting of infected gloves or seed. Botrytis rot primarily appears after harvest in garlic that is not cured or stored correctly. Under moist conditions, a gray mold may develop on the surface of or between garlic scales and later distinct black sclerotia (overwintering, dense masses of fungal mycelia) appear around the rotting neck. These sclerotia germinate in spring and release thousands of spores, which can be wind-carried to susceptible host plants, starting new disease cycles. Initial symptoms of the disease may appear near the soil line on garlic necks as the pathogen penetrates the tissue directly or via a wound, it then moves along the neck causing water soaked lesions. Under warm and wet conditions, the disease progresses quickly. Plant disease-free cloves and minimize bruising or mechanical injury, especially during harvest and topping. Avoid excessive nitrogen application, which delays crop maturity and curing. Inspect plants for symptoms and signs of disease during the season as well as at harvest since plants may become infected in the field but will remain symptomless until they are in storage. Practice crop rotation and destroy and remove crop residue after harvest.

  • azoxystrobin plus difenoconazole (Quadris Top): 12.0 to 14.0 fl oz/A; PHI 1d, REI 12h, Groups 11 & 3. 
  • Bacillus amyloliquefaciens strain D747 (Double Nickel 55OG): 0.25 to 3.0 lb/A; PHI 7d, REI 4h, Group BM02.
  • chlorothalonil (Echo 720): 1.0 to 3.0 pt/A; PHI 14d, REI 12h, Group M05. 
  • chlorothalonil & oxathiapiprolin (Orondis Opti): 1.75 to 2.5 pt/A; PHI 7d, REI 12h, Groups 49 & M05.
  • chlorothalonil & zoxamide (Zing): 30.0 fl oz/A; PHI 7d, REI 12h, Groups 22 & M05. Do not apply to exposed bulbs.
  • copper octanoate (Cueva): 38.0 gal/A, 112 fl oz/1000 sq ft; PHI 0d, REI 4h, Group M01. 
  • cyprodinil (Vangard WG): 10.0 oz/A; PHI 7d, REI 12h, Group 9. Thorough plant coverage is essential.
  • cyprodinil plus fludioxonil (Switch 62.5 WG): 11.0 to 14.0 oz/A; PHI 0d, REI 12h, Groups 9 & 12. Suppression only.
  • difenoconazole plus cyprodinil (Inspire Super): 16.0 to 20.0 fl oz/A; PHI 7d, REI 12h, Groups 3 & 9. Apply in sufficient volume to achieve thorough coverage. 
  • difenoconazole plus fluopyram (Luna Flex): 10.0 to 13.6 fl oz/A; PHI 7d, REI 12h, Groups 3 & 7. 
  • fluazinam (Omega 500DF): 16.0 fl oz/A; PHI 7d, REI 12h, Group 29. Do not make more than 6 applications per acre per year. Do not use an adjuvant.
  • hydrogen peroxide plus peroxyacetic acid (Oxidate 2.0OG): See label for rates; PHI 0d, REI 1h, Group NC. 
  • laminarin (Vacciplant): 14.0 to 22.0 fl oz/A; PHI 0d, REI 4h, Group P04.
  • penthiopyrad (Fontelis): 16.0 to 24.0 oz/A; PHI 3d, REI 12h, Group 7. 
  • Pseudomonas chlororaphis strain AFS009 (Howler EVOOG): 40.0 to 120.0 oz/A; PHI 0d, REI 4h, Group BM02.
  • pydiflumetofen plus fludioxonil (Miravis Prime): 11.4 fl oz/A; PHI 7d, REI 12h, Groups 12 & 7. Apply in sufficient volume to achieve thorough coverage.
  • pyraclostrobin (Cabrio EG): 12.0 oz/A; PHI 7d, REI 12h, Group 11. Suppression only.
  • pyraclostrobin plus fluxapyroxad (Merivon Xemium): 8.0 to 11.0 fl oz/A; PHI 7d, REI 12h, Groups 11 & 7. Do not apply more than 2 consecutive applications before switching to a non-Group 7 or 11 fungicide.
  • pyrimethanil plus fluopyram (Luna Tranquility): 16.0 to 27.0 fl oz/A; PHI 7d, REI 12h, Groups 9 & 7.
  • Streptomyces lydicus strain WYEC 108 (ActinovateOG): 3.0 to 12.0 oz/A; PHI 0d, REI 4h, Group BM02.
  • tebuconazole plus fluopyram (Luna Experience): 8.0 to 12.8 fl oz/A; PHI 7d, REI 12h, Groups 3 & 7.

Stemphylium Leaf Blight (Stemphylium spp.)

The disease has a broad host range including garlic, leek, onion, shallot, asparagus, tomato, radish, sunflower, parsley, alfalfa, and soybean. Symptoms appear as small, tan to brown lesions on the leaves which rapidly progress to defoliate plants. A decrease in photosynthetic leaf area results in smaller and reduced quality of bulbs, and indirectly, poor shelf and storage life. The recent emergence of the pathogen has been associated with the development of resistance to single-site mode-of-action fungicides, including strobilurins (Group 11). Crop rotation to a non-host for at least one year may significantly reduce inoculum density. Additionally, post-harvest residue removal is an important means to promote degradation and overwintering of inoculum between seasons. Weed control and disease-free seed cloves for field establishment are essential.

  • azoxystrobin plus difenoconazole (Quadris Top): 12.0 to 14.0 fl oz/A; PHI 1d, REI 12h, Groups 11 & 3. 
  • cyprodinil plus fludioxonil (Switch 62.5 WG): 11.0 to 14.0 oz/A; PHI 0d, REI 12h, Groups 9 & 12. 
  • difenoconazole plus benzovindiflupyr (Aprovia Top): 10.5 fl oz/A; PHI 7d, REI 12h, Groups 7 & 3. Do not make more than 2 consecutive applications before switching to a non-Group 7 fungicide.
  • difenoconazole plus cyprodinil (Inspire Super): 16.0 to 20.0 fl oz/A; PHI 7d, REI 12h, Groups 3 & 9. Apply in sufficient volume to achieve thorough coverage. 
  • difenoconazole plus fluopyram (Luna Flex): 10.0 to 13.6 fl oz/A; PHI 7d, REI 12h, Groups 3 & 7. 
  • laminarin (Vacciplant): 14.0 to 22.0 fl oz/A; PHI 0d, REI 4h, Group P04. 
  • penthiopyrad (Fontelis): 16.0 to 24.0 oz/A; PHI 3d, REI 12h, Group 7. 
  • Pseudomonas chlororaphis strain AFS009 (Howler EVOOG): 40.0 to 120.0 oz/A; PHI 0d, REI 4h, Group BM02.
  • pydiflumetofen plus fludioxonil (Miravis Prime): 10.3 to 11.4 fl oz/A; PHI 7d, REI 12h, Groups 12 & 7. Apply preventatively in sufficient volume to ensure good coverage.
  • pyraclostrobin plus fluxapyroxad (Merivon Xemium): 5.5 to 11.0 fl oz/A; PHI 7d, REI 12h, Groups 11 & 7. Do not apply more than 2 consecutive applications before switching to a non-Group 7 or 11 fungicide.
  • pyrimethanil plus fluopyram (Luna Tranquility): 16.0 to 27.0 fl oz/A; PHI 7d, REI 12h, Groups 9 & 7.
  • tebuconazole plus fluopyram (Luna Experience): 12.8 fl oz/A; PHI 7d, REI 12h, Groups 3 & 7.
  • thyme oil (Guarda): See label for rates; PHI 0d, REI 0h, Group NC.
Disease Control

Garlic Insect Control

Garlic Insect Control otank

NOTES: For the insecticides listed below, one product trade name and formulation is provided for each active ingredient (AI) as an example of rates, preharvest interval (PHI), restricted entry interval (REI), and special instructions. In many cases, there are other products available with the same AI. Please see Table 27 and Insecticides Alphabetically Listed by Trade Name for more information on these insecticides.

The designation (Bee: L, M, or H) indicates a bee toxicity rating of low, moderate, or high. See the Protecting Honeybees and Native Pollinators section for more details.

The symbol * indicates a product is a restricted use pesticide. See Pesticide Safety and Use for more details.

The symbol OG indicates a product is listed by the Organic Materials Review Institute (OMRI) as approved for use in organic production. See Organic Certification section for more details.

Allium Leafminer (Phytomyza gymnostoma)

For more information on this pest and for cultural and chemical controls, see Allium Leafminer in the Leek section.

  • abamectin (Agri-Mek* SC): 1.75 to 3.5 fl oz/A; PHI 30d, REI 12h, Bee: H, Group 6. Make 2 consecutive applications then rotate to a different mode of action. Make at least 2 consecutive applications of another mode of action before making additional Agri-Mek SC applications. Insect control can be reduced if used with a sticker or binder type product.
  • azadirachtin (Azatin OOG): 4 to 16 oz/A foliar or drench, 4 to 16 oz/100 gal in greenhouses; PHI 0d, REI 4h, Bee: L, Group UN. When using lower rates, combine with adjuvant for improved spray coverage and translaminar uptake.
  • cyantraniliprole (Exirel): 13.5 to 20.5 fl oz/A; PHI 1d, REI 12h, Bee: H, Group 28. Use with an adjuvant to maximize efficacy. Spreading and penetrating adjuvants can cause negative crop response.
  • cyromazine (Trigard): 2.66 oz/A; PHI 7d, REI 12h, Bee: H, Group 17. Apply when leafminers first appear. Do not apply more than 6 times or 1 lb/A per calendar year.
  • dinotefuran (Scorpion 35SL): 5.25 to 7 fl oz/A foliar, 8.75 to 10.5 fl oz/A soil; PHI 1d, REI 12h, Bee: H, Group 4A. Do not apply more than a total of 10.5 fl oz/A per season.
  • gamma-cyhalothrin (Declare*): 0.77 to 1.28 fl oz/A; PHI 14 days, REI 24h, Bee: H, Group 3A.
  • Isaria fumosorosea Apopka Strain 97 (PFR-97 20% WDGOG): 1 to 2 lbs/A; PHI 0d, REI 4h, Bee: M, Group M.
  • lambda-cyhalothrin (Warrior* II): 0.96 to 1.6 fl oz/A; PHI 14d, REI 24h, Bee: H, Group 3A.
  • permethrin (Pounce* 25WP): 6.4 to 12.8 fl oz/A; PHI 1d, REI 12h, Bee: H, Group 3A.
  • pyrethrins (Pyganic EC5.0IIOG): 4.5 to 17 oz/A; 0.25 to 0.50 oz/gal, 3 gal/1000 sq ft in greenhouse for backpack sprayers; PHI 0d, REI 12h, Bee: M, Group 3A.
  • spinetoram (Radiant SC): 6 to 10 oz/A; PHI 1d, REI 4h, Bee: M, Group 5. Efficacy improves with the addition of an adjuvant. Do not make more than 2 consecutive applications of Group 5 insecticides. Do not make more than 5 applications per year per crop.

Bulb Mites (Aceria tulipae and Rhizoglyphus spp.)

Two types of mites are known to infect Allium species: a dry bulb mite, Aceria tulipae, and species in the genus Rhizoglyphus. Mites can survive in soil on decaying vegetation. Infected seeds may fail to germinate. Plants grown from infected seeds may lack vigor and produce stunted, deformed leaves. Plants may outgrow the damage if the infestation is not heavy, but mites may increase in number over the growing season and will remain in the harvested garlic. They are particularly troublesome in storage, causing desiccation and creating wounds that allow for entry of secondary pathogens.

Bulb mites are favored by mechanical injury, disease, cool soil temperatures, and soils with high organic matter content. Avoid adding manure and use fallow periods to eliminate crop residue. Removing culls from the field immediately after harvest in smaller plantings will reduce overwintering populations. Dark plastic mulch will increase soil temperatures and control mites. Plant clean seed and rotate out of alliums for at least 4years after an infestation. Avoid planting allium crops directly after brassicas, corn, grain, or grass cover crops.

Leek Moth (Acrolepiosis assectella)

For more information on this pest and for cultural and chemical controls, see Leek Moth in the Leek section.

Onion Maggot (Delia antiqua)

For more information on this pest and cultural and biological controls, see onion maggot in the Onion section.

  • diazinon (Diazinon* AG500): 2 to 4 qt/A; REI 3d, Bee: H, Group 1B. Broadcast and incorporate just before planting. Will not control organophosphate-resistant onion maggots. Do not make more than 1 application per year.

Onion Thrips (Thrips tabaci)

Thrips are favored by hot, dry weather. Thrips typically feed under leaf folds and in protected inner leaves, although they may feed on exposed leaf surfaces when populations are high. Feeding causes white scars on leaves that can reduce plant growth when severe, as well as provide entry points for foliar diseases. In severe infestations, the field may appear silvery in color. Both adults and nymphs cause damage. 

Heavy rain or overhead irrigation can lower populations quickly. Lacewing larvae, pirate bugs, and predatory thrips are important natural enemies. Reduce populations by cleaning up crop residue after harvest to limit overwintering sites. Do not plant garlic near other allium crops or alfalfa, clover, cucurbits, or brassicas, as these can harbor large thrips migrating to garlic when these crops are cut or harvested. Incorporate crop residues promptly after harvest and practice crop rotations out of allium crops.

Begin applications when damage is first noticed. Repeat applications at 7- to 10-day intervals. Use a shorter interval in hot, dry weather. Use spreader-sticker for better coverage. Apply in the early evening, using high pressure and 100 gal water/A for best results. See onion thrips in the Onion section for more information.

  • abamectin (Agri-Mek* SC): 1.75 to 3.5 oz/A; PHI 30d, REI 12h, Bee: H, Group 6. Must be mixed with a non-ionic wetting, spreading and/or penetrating spray adjuvant. Do not use binder or sticker type adjuvant. 
  • abamectin plus cyantraniliprole (Minecto* Pro): 7 to 10 oz/A; PHI 7d, REI 12h, Bee: H, Groups 6 & 28. Begin making applications when populations are low (1-3 thrips/plant). Repeat application as needed. If populations are high, use an effective thrips knockdown product before spraying Minecto Pro. For best control, use high rate. 
  • acetamiprid (Assail 30 SG): 5 to 8 oz/A; PHI 7d, REI 12h, Bee: M, Group 4A.
  • Beauveria bassiana (Mycotrol ESOOG): 0.25 qt to 1 qt/A; PHI 0d, REI 4h, Bee: L, Group UN. Treat when populations are low and thoroughly cover foliage. Takes 7-10 days after the first spray to see control. Repeat applications may be needed.
  • Burkholderia spp. strain A396 cells (Venerate XCOG): 2 to 4 qt/A; PHI 0d, REI 4h, Bee: M, Group UN. Suppression only.
  • Chenopodium extract (Requiem EC): 1.5 to 4 qt/A; PHI 0d, REI 4h, Bee: L, Group UN. Begin application as soon as thrips are seen. Thoroughly cover foliage.
  • Chromobacterium subtsugae strain PRAA4-1 (GrandevoOG): 2 to 3 lb/A; PHI 0d, REI 4h, Bee: M, Group UN.
  • cyantraniliprole (Exirel): 13.5 to 20.5 oz/A; PHI 1d, REI 12h, Bee: H, Group 28. Suppression only. For best performance, use with an effective adjuvant. 
  • deltamethrin (Delta Gold*): 1.5 to 2.4 oz/A; PHI 1d, REI 12h, Bee: H, Group 3A.
  • dinotefuran (Venom): 3 to 4 fl oz/A foliar, 5 to 6 fl oz/A soil; PHI 1d foliar, 21d soil, REI 4h, Bee: H, Group 4A.
  • gamma-cyhalothrin (Declare*): 1.02 to 1.54 oz/A; PHI 14d, REI 24h, Bee: H, Group 3A.
  • imidacloprid (Admire Pro): 14 oz/A; PHI 21d, REI 12h, Bee: H, Group 4A. Soil applications only.
  • kaolin (Surround WPOG): 25 to 50 lb/A or 0.25 to 0.5 lb/gal; PHI 0d, REI 4h, Bee: L. Suppression/repellence only. Good coverage into plant crown is essential. Generally compatible as a tank mix with other insecticides.
  • lambda-cyhalothrin (Warrior* II): 1.28 to 1.92 oz/A; PHI 14d, REI 24h, Bee: H, Group 3A.
  • malathion (Malathion 57 EC): 1.5 to 2 pt/A; PHI 3d, REI 24h, Bee: H, Group 1B.
  • permethrin (Pounce* 25WP): 9.6 to 12.8 oz/A; PHI 1d, REI 12h, Bee: H, Group 3A.
  • pyrethrin (PyGanic EC5.0OG): 4.5 to 17 oz/A; 0.25 to 0.50 oz/gal, 3 gal/1000 sq ft in greenhouse for backpack sprayers; PHI 0d, REI 12h, Bee: M, Group 3A.
  • sodium tetraborohydrate decahydrate (Prev-AM): 100 oz/100 gal; REI 12h, Bee: L, Group 25. Do not apply in midday sun or mix with copper, sulfur or oils.
  • spinetoram (Radiant SC): 6 to 10 oz/A; PHI 1d, REI 4h, Bee: M, Group 5. Thorough coverage is essential. Efficacy improves with the addition of an adjuvant.
  • spinosad (Entrust SCOG): 4 to 8 oz/A; PHI 1d, REI 4h, Bee: M, Group 5. Suppression only. Use adjuvant for better control.
  • spirotetramat (Movento): 5 oz/A; PHI 3d, REI 24h, Bee: M, Group 23. Must be tank-mixed with a spray adjuvant with spreading and penetrating properties to maximize leaf uptake and systemicity. Don't use sticker adjuvants. Controls immature stages; may also reduce adult fertility.
  • tolfenpyrad (Torac): 24 oz/A; PHI 7d, REI 12h, Bee: H, Group 21A. 
  • zeta-cypermethrin (Mustang*): 2.88 to 4 oz/A; PHI 7d, REI 12h, Bee: H, Group 3A.
Insect Control

Garlic Weed Control

Garlic Weed Control otank

NOTES: For the herbicides listed below, one product trade name and formulation is provided for each active ingredient along with preharvest interval (PHI), restricted entry interval (REI), resistance management group number, and example of rates and special instructions. In many cases, there are other products available with the same active ingredient. However, not all products with the same active ingredient are registered for use in a crop. Always check the product label to be sure that the crop is listed before using. 

Garlic is not very competitive, so good weed control is critical. Mulch will control weeds and conserve moisture. If the mulch is removed, cultivation will likely be needed. Cultivation should be shallow so as not to damage roots. 

Stale Seedbed

See Stale Seedbed Technique for information on the use of these herbicides or flaming.

Preemergent Herbicides (before weeds germinate)

  • bensulide (Prefar 4E): REI 12h, Group 0. Apply 5-6 qt/A per application, only 1 application allowed per year. Can be applied before planting or after planting before crop has emerged. Incorporate 1-2” into the soil within 36 hours by shallow cultivation or with water through irrigation or rainfall. Grass control only; should be supplemented with cultivation or another registered herbicide for broadleaf control.
  • dimethenamid (Outlook): PHI 30d, REI 12h, Group 15. Apply 8-21 oz/A, up to 2 applications allowed per year, a minimum of 14 days apart. Do not exceed 21 oz/A per year. If applying as a split application, apply 1/2 to 2/3 the rate at the first application and the remaining at the second application. Application rate depends on soil texture and organic matter content. Apply to garlic that have 2 fully expanded true leaves. Temporary leaf damage may occur and applying before the 2-leaf stage may cause significant crop injury.
  • flumioxazin (Chateau EZ): REI 12h, Group 14. Apply up to 6 oz/A per application, only 1 application per year. Apply within 3 days of planting garlic and before garlic has emerged. Incorporate into the soil with 0.5-0.75” of water through irrigation or rainfall.
  • s-metolachlor (Dual Magnum): REI 1d, Group 15. MA and NH only. Make sure the label for your state is available for download before using this product. This is a restricted label available only to growers who apply through the website www.syngenta-us.com/labels/indemnified-label-login and agree to a waiver of liability. Main target weeds for this registration are galinsoga and yellow nutsedge. All label instructions will be supplied after the application for use is completed.
  • pendimethalin (Prowl H2O): PHI 45d, REI 24h, Group 3. Apply 1.5-3.2 pt/A per application. Do not exceed 3.2 pt/A. Rate based on soil texture. Can be applied after planting but before crop emergence, after crop emergence when garlic is in the 1- to 5-true leaf stage, or at both timings. If applying before emergence, do not irrigate more than 0.5” of water until after loop stage.

Postemergent Herbicides (after weeds germinate)

  • bromoxynil (Broclean): PHI 112d, REI 24h or 48h, Group 24. Apply 1.5-2 pts/A per application. Apply to garlic after emergence before it is 12” tall and before susceptible weeds are at the 4-leaf stage, 2” tall, or 1” wide.
  • carfentrazone (Aim EC): REI 12h, Group 14. Apply 0.5-2 oz/A per application, multiple applications allowed per year. Do not exceed 6.1 oz/A per season. Can be applied as a preplant burndown no later than 30 days before planting by seed. Can also be applied to row middles of emerged crops with hooded sprayers to control emerged weeds. Prevent any spray from contacting the crop, or injury will occur. For best results, make application to actively growing weeds up to 4” tall and rosettes less than 3” across.
  • clethodim (Select Max): PHI 45d, REI 1d, Group 1. Apply 6-32 oz/A per application, up to 4 applications per year (2 if using 32 oz/A), a minimum of 14 days apart. Do not exceed 64 oz/A per year. Apply to actively growing grasses. Add 0.25% v:v nonionic surfactant (1 qt/100 gal of spray). Can also be applied as a spot-spray by mixing 0.33-0.66% (0.44-0.85 oz/gal) Select Max and 0.25% v:v nonionic surfactant (0.33 oz/gal). Spray to wet, but do not allow runoff of spray solution.
  • fluazifop (Fusilade DX): PHI 45d, REI 12h, Group 1. Apply up to 24 oz/A per application, up to 2 applications allowed per year, a minimum of 14 days apart. Do not exceed 48 oz/A per year. Apply to actively growing grasses. Add either crop oil concentrate (0.5-1%, 0.5-1 gal/100 gal of spray) or nonionic surfactant (0.25-0.5%, 1-2 qt/100 gal of spray).
  • glyphosate (Roundup PowerMax): PHI 14d, REI 4h, Group 9. Apply 10 oz-3.1 qts/A per application but do not exceed 5 qts/A per year. Rate is dependent on target weed species. Avoid any contact of herbicide with foliage, green shoots, stems, or exposed roots or crop death could result. Could cause injury when applied prior to planting into plastic mulch. Remove residual product from plastic mulch with a 0.5’’ of water through irrigation or rainfall prior to planting. Can be applied during fallow intervals, prior to planting, at planting, or before crop has emerged. For any crop not listed on the label, any application must be at least 30 days prior to planting.
  • oxyfluorfen (Goal 2 XL): PHI 60d, REI 48h, Group 14. Apply 2-4 oz/A to garlic that has at least 3 fully developed true leaves. Multiple applications allowed per year. Do not exceed 32 oz/A per year. For optimum control, apply when susceptible weeds are in the 2- to 4-leaf stage and actively growing. Application to weeds at later than 4-leaf stage may result in reduced weed control. Adjust nozzles for minimum spray contact with garlic plants, directing the spray to the soil at the base of garlic plants and adjacent bed top and furrow area. May cause chlorotic leaf banding, especially in cool wet conditions, but garlic will typically outgrow this damage.
  • paraquat (Gramoxone SL 3.0*): PHI 60d, REI 12h or 24h, Group 22. Apply 1.7–2.7 pts/A per application, only 1 application per year. Do not exceed 2.7 pts/A per year. Apply before crop has emerged as a broadcast application in a minimum of 10 gal/A of spray. May be fatal if swallowed or inhaled. *Restricted use: Applicators must complete an EPA-approved paraquat training every 3 years: https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training-certified-applicators.
  • pelargonic acid (Scythe): PHI 1d, REI 12h, Group 17. Apply a 3-10% solution (3-10 gal/100 gal of spray). Rate based on target weed species. Apply in 75-200 gal/A of spray or with a spot sprayer until foliage is wet but not to the point of runoff. Repeat applications as necessary. Can apply for vegetative burndown during site preparation, prior to crop emergence from soil, as a directed and shielded spray during crop growth taking care to avoid contact with foliage and green tissue of crops, or after harvest.
  • sethoxydim (Poast): PHI 30d, REI 12h, Group 1. Apply up to 1.5 pt/A per application, multiple applications allowed per year, a minimum of 14 days apart. Do not exceed 4.5 pts/A per year. Apply to actively growing grasses. Use with crop oil concentrate (2 pt/A) or methylated seed oil (1.5 pt/A). Can also be applied as a spot-spray by mixing 1-1.5% (1.3-1.9 oz/gal) Poast and 1% v:v crop oil concentrate (1.3 oz/gal). Spray to wet, but do not allow runoff of spray solution.
Weed Control