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Publication #ENY-467

Insect Management for Onions, Leek, and Garlic1

S. E. Webb2

Sweet varieties of bulbing onions, which make bulbs under short day conditions and do not store well, are by far the most common onions grown in Florida. They are generally grown on small acreages in the winter for local and farmers markets. In Hillsborough County and in the Suwannee Valley, strawberry growers are the major producers of onions, many of which are harvested green.

Because it is grown in the winter and early spring, the onion crop in Florida suffers from relatively few insect pests, with thrips and seedcorn maggot being the most commonly found. Armyworms and cutworms can occasionally damage seedlings. Cultural controls, such as growing thrips-tolerant varieties and preparing seedbeds early, should be used and insecticides avoided as much as possible to limit the development of insecticide resistance and favor the survival of insect predators and parasites.

Several species of thrips feed on onions. In north Florida, onion thrips (Thrips tabaci) and tobacco thrips (Frankliniella fusca) are the most commonly found. Onion thrips can transmit Iris yellow spot virus and tobacco thrips transmits Tomato spotted wilt virus to onions. Other thrips that have been reported to attack onions include western flower thrips (F. occidentalis) and melon thrips (T. palmi). Thrips can become resistant to insecticides very quickly. Because they feed deep down at the base of emerging leaves, they can also avoid both insecticides and natural enemies, such as the insidious pirate bug. There are relatively few insecticides labeled for use on onions. The most commonly used are the pyrethroids and methomyl, a carbamate, but they may be only moderately effective. A threshold of 5-10 thrips per plant has been suggested for winter-grown sweet onions in the South.

Seedcorn maggot (Delia platura), which feeds on many different plants, can be a problem when there are high levels of decaying organic matter in the soil and when the weather is cool and wet. Soil applications of chlorpyrifos or diazinon at planting may be useful if there is a history of seedcorn maggot problems. Early preparation of the field to allow the breakdown of organic matter before planting is essential.

Tables

Table 1. 

Selected insecticides for use on insects attacking onions and allies.

Trade Name

(Common Name)

Rate

(Product/acre)

REI (hours)

Days to Harvest

Insects

MOA Code1

Notes

Admire Pro

(imidacloprid)

14.0 fl oz

12

21

foliage-feeding thrips

4A

See supplemental label for application methods.

Agree WG

(Bacillus thuringiensis subspecies aizawai)

1.0-2.0 lb

4

0

lepidopteran larvae (caterpillar pests)

11A

Apply when larvae are small for best control. OMRI-listed2.

*Agri-Mek SC

(abamectin)

1.75-3.5 fl oz

12

30

Liriomyza leafminers, thrips

6

Must be used with a non-ionic activator type wetting, spreading and/or penetrating adjuvant., not a binder sticker type adjuvant. Maximum of 10.25 fl oz per acre per season.

*Ambush 25W

(permethrin)

6.4-19.2 oz

12

1

armyworms, cutworms, leafminers, onion maggot (adults), onion thrips, stink bugs

3A

Dry bulb and garlic only.

Maximum of 2 lb ai/acre per season.

Assail 30SG (acetamiprid)

5.0-8.0 oz

12

7

thrips

4A

No more than 4 applications or 32 oz of product per acre per season.

Aza-Direct

(azadirachtin)

1-2 pts, up to 3.5, if needed

4

0

aphids, beetles, caterpillars, leafhoppers, leafminers, mites, stink bugs, thrips, weevils, whiteflies

un

Antifeedant, repellant, insect growth regulator. OMRI-listed2.

Azatin XL

(azadirachtin)

5-21 fl oz

4

0

aphids, beetles, caterpillars, leafhoppers, leafminers, thrips, weevils, whiteflies

un

Antifeedant, repellant, insect growth regulator.

Biobit HP

(Bacillus thuringiensis subspecies kurstaki)

0.5-2.0 lb

4

0

caterpillars (will not control large armyworms)

11A

Treat when larvae are young. Good coverage is essential. Can be used in the greenhouse. For organic production.

BotaniGard 22 WP, ES

(Beauveria bassiana)

WP: 0.5-2 lb/100 gal

ES: 0.5-2 qt/100 gal

4

0

aphids, thrips, whiteflies

--

May be used in greenhouses. Contact dealer for recommendations if an adjuvant must be used. Not compatible in tank mix with fungicides.

Coragen

(chlorantraniliprole)

3.5-5.0 fl oz

4

1

beet armyworm

28

No more than 4 applications or 15.4 fl oz of product per acre per crop. For entire Bulb Vegetable Group.

Crymax WDG

(Bacillus thuringiensis subspecies kurstaki)

0.5-2.0 lb

4

0

caterpillars

11A

Use high rate for armyworms. Treat when larvae are young.

Deliver

(Bacillus thuringiensis subspecies kurstaki)

0.25-1.5 lb

4

0

caterpillars

11A

Use higher rates for armyworms. OMRI-listed2.

*Diazinon AG500, *Diazinon 50W

(diazinon)

AG500: 2-4 qt

50W: 4-8 lb

72

preplant

onion maggots, wireworms

1B

Do not make more than one soil application per year. For onions, bulb and green, leeks, garlic shallots.

DiPel DF

(Bacillus thuringiensis subspecies kurstaki)

0.25-2.0 lb

4

0

caterpillars

11A

Treat when larvae are young. Good coverage is essential. OMRI-listed2.

Entrust SC

(spinosad)

3-8 fl oz

4

1

armyworms, dipteran leafminers, flea beetle, loopers, suppression of thrips

5

No more than 5 applications per year (29 fl oz product). OMRI-listed2.

Esteem Ant Bait

(pyriproxyfen)

1.5-2.0 lb

12

1

red imported fire ant

7C

Dry bulb only.

Extinguish

((S)-methoprene)

1-1.5 lb

4

0

fire ants

7A

Slow‑acting IGR (insect growth regulator). Best applied early spring and fall where crop will be grown. Colonies will be reduced after three weeks and eliminated after 8 to 10 weeks. May be applied by ground equipment or aerially.

Grandevo

(Chromobacterium subtsugae strain PRAA4-1)

1-3 lb

4

0

aphids, armyworms, cutworms, leek moth, loopers, omnivorous leafroller, saltmarsh caterpillar, thrips, webworms

Leek, garlic, onion (bulb and green), shallot

Intrepid 2F

(methoxyfenozide)

4-12 fl oz

4

1

lepidopteran larvae, including armyworms and loopers

18

Green onion subgroup only. Do not apply more than 64 fl oz per acre per year.

Javelin WG

(Bacillus thuringiensis subspecies kurstaki)

0.12-1.5 lb

4

0

most caterpillars, but not Spodoptera species (armyworms)

11A

Treat when larvae are young. Thorough coverage is essential. OMRI-listed2.

Knack IGR

(pyriproxyfen)

8 fl oz

12

3

onion thrips, western flower thrips

7C

Maximum of 2 applications, at least 14 days apart. No activity against adult insects. Onion (dry bulb only).

*Lannate LV; *SP

(methomyl)

LV: 1.5-3.0 pt

SP: 0.5-1.0 lb

48

7

beet armyworm, black cutworm, thrips, variegated cutworm

1A

Dry bulb, green onions, only. Add a wetting agent to improve coverage.

*Lannate LV; *SP

(methomyl)

LV: 1.5 pt

SP: 0.5 lb

48

7

beet armyworm

1A

Garlic only.

Lorsban 15G; 75WG; *Advanced

(chlorpyrifos)

15G: 3.7 oz/1000 ft of row

75WG: 1.33 lb

Advanced: see label

24

at planting

onion maggot, seedcorn maggot

1B

Dry bulb only. One application per year.

Malathion 8F

(malathion)

1-1.56 pt

onions: 12, leeks, shallots, garlic: 24

3

onion maggot, thrips on onions, aphids and thrips on garlic, leeks, shallots

1B

Onions, bulb and green, leeks, shallots, garlic

M-Pede 49% EC

Soap, insecticidal

1-2% V/V

12

0

aphids, leafhoppers, mites, plant bugs, thrips, whiteflies

--

OMRI-listed2.

*Mustang

(zeta-cypermethrin)

2. 4-4.3 oz

12

7

aphids, armyworms, cutworms, leafminer adults, onion maggot adults, onion thrips, stink bugs

3A

Do not apply more than 21.5 oz per acre per season.

Neemix 4.5 EC

(azadirachtin)

4-16 fl oz

12

0

aphids, armyworms, cabbage looper, cutworms, leafminers, onion maggot, whiteflies

un

OMRI-listed2.

*Penncap-M

(methyl parathion)

2 pt

13 days

15

thrips

1B

Do not apply when onions are blooming and bees are foraging. Onions only.

*Pounce 25 WP

(permethrin)

6.4-19.2 oz—onions

6.4-12.8 oz—garlic

12

1

armyworms, cutworms, leafminer adults, onion maggot adults, onion thrips, , stink bugs

3A

Bulb onions and garlic

*Proaxis Insecticide

(gamma-cyhalothrin)

1.92-3.84 oz

24

14

armyworms (1st and 2nd instar), cutworms, leafminer adults, onion and seedcorn maggot adults, onion thrips, plant bugs, stink bugs, tobacco thrips, suppression of aphids, flower thrips, western flower thrips

3A

Bulb onions and garlic

Radiant SC

(spinetoram)

5-10 fl oz

4

1

armyworms, dipterous leafminers, loopers, thrips

5

Use with an adjuvant.

Requiem 25EC

(extract of Chenopodium ambrosioides)

1.5-3.0 qt

4

0

onion thrips, western flower thrips

un

Begin as soon as thrips are seen.

Trigard

(cyromazine)

2.66 oz

12

7

leafminers

17

Maximum of 6 applications per crop.

Trilogy

(extract of neem oil)

0.5-2.0% V/V

4

0

aphids, mites, suppression of thrips and whiteflies

un

Apply morning or evening to reduce potential for leaf burn. Toxic to bees exposed to direct treatment. OMRI-listed2.

*Warrior II

(lambda-cyhalothrin)

0.96-1.92 fl oz

24

14

aphids, armyworms, cutworms, onion maggot adults, onion thrips, plant bugs, stink bugs, tobacco thrips, suppression of flower thrips, western flower thrips

3A

For bulb crops only (onions and garlic), not green onions. Do not apply more than 0.24 lb ai/acre per season.

Xentari DF

(Bacillus thuringiensis subspecies aizawai)

0.5-2.0 lb

4

0

caterpillars

11A

Treat when larvae are young. Thorough coverage is essential. May be used in the greenhouse. Can be used in organic production.

The pesticide information presented in this table was current with federal and state regulations at the time of revision. The user is responsible for determining the intended use is consistent with the label of the product being used. Use pesticides safely. Read and follow label instructions.

1Mode of Action codes for vegetable pest insecticides from the Insecticide Resistance Action Committee (IRAC) Mode of Action Classification v.7.2 February 2012. http://www.irac-online.org/wp-content/uploads/MoA-classification.pdf

1A. Acetylcholinesterase inhibitors, Carbamates (nerve action)

1B. Acetylcholinesterase inhibitors, Organophosphates (nerve action)

2A. GABA-gated chloride channel antagonists (nerve action)

3A. Sodium channel modulators—pyrethroids

4A. Nicotinic acetylcholine receptor agonists (nerve action)

5. Nicotinic acetylcholine receptor allosteric activators—spinosins (nerve action)

6. Chloride channel activators (nerve and muscle action)

7A. Juvenile hormone mimics (growth regulation)

7C. Juvenile hormone mimics (growth regulation)

9B & 9C. Selective homopteran feeding blockers

10B. Mite growth inhibitors (growth regulation)

11A. Microbial disruptors of insect midgut membranes

12B. Inhibitors of mitochondrial ATP synthase (energy metabolism)

15. Inhibitors of chitin biosynthesis, type 0, lepidopteran (growth regulation)

16. Inhibitors of chitin biosynthesis, type 1, homopteran (growth regulation)

17. Molting disruptor, dipteran (growth regulation)

18. Ecdysone receptor agonists (growth regulation)

20B. Mitochondrial complex III electron transport inhibitors (energy metabolism)

21A. Mitochondrial complex I electron transport inhibitors (energy metabolism)

22. Voltage-dependent sodium channel blockers (nerve action)

23. Inhibitors of acetyl Co-A carboxylase (lipid synthesis, growth regulation)

28. Ryanodine receptor modulators (nerve and muscle action)

un. Compounds of unknown or uncertain mode of action

2OMRI listed: Listed by the Organic Materials Review Institute for use in organic production.

*Restricted Use Only.

Footnotes

1.

This document is ENY-467 (IG153), one of a series of the Entomology & Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published August 2002. Revised March 2010 and June 2013. For more publications related to horticulture/agriculture, please visit the EDIS website at http://edis.ifas.ufl.edu/.

2.

S. E. Webb, associate professor, Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611-0640.

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label. Use pesticides safely. Read and follow directions on the manufacturer's label.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.