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
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
|
Agree WG (Bacillus thuringiensis subspecies aizawai) |
1.0-2.0 lb |
4 |
0 |
lepidopteran larvae (caterpillar pests) |
11 |
Apply when larvae are small for best control. OMRI-listed2. |
*Ambush 25W (permethrin) |
6.4-19.2 oz |
12
|
1
|
armyworms, cutworms, leafminers, onion maggot (adults), onion thrips, stink bugs |
3 |
Dry bulb and garlic only. Maximum of 2 lb ai/acre per season. |
*Ammo 2.5 EC (cypermethrin) |
2.0-5.0 fl oz |
12
|
7
|
aphids, armyworms, cutworms, leafminers, onion maggot adults, stink bugs |
3 |
Maximum of 25 oz product/acre per season. |
Assail 30SG Assail 70WP |
5.0-8.0 oz 2.1-3.4 oz |
12 |
7 |
thrips |
4A |
No more than 32 oz 30SG or 13.7 oz 70WP 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) |
11 |
Treat when larvae are young. Good coverage is essential. Can be used in the greenhouse. OMRI-listed2. |
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. |
Crymax WDG (Bacillus thuringiensis subspecies kurstaki) |
0.5-2.0 lb |
4 |
0 |
caterpillars |
11 |
Use high rate for armyworms. Treat when larvae are young. |
Deliver (Bacillus thuringiensis subspecies kurstaki) |
0.25-1.5 lb |
4 |
0 |
caterpillars |
11 |
Use higher rates for armyworms. OMRI-listed2. |
*Diazinon AG500, *Diazinon 50W (diazinon) |
preplant - AG500: 2-4 qt 50W: 4-8 lb |
72 |
preplant |
onion maggots, wireworms |
1B |
Do not make more than one soil application per year. |
DiPel DF (Bacillus thuringiensis subspecies kurstaki) |
0.5-2.0 lb |
4 |
0 |
caterpillars |
11B2 |
Treat when larvae are young. Good coverage is essential. OMRI-listed2. |
Entrust (spinosad) |
1-2.5 oz |
4 |
1 |
armyworms, dipteran leafminers, flea beetle, loopers, suppression of thrips |
5 |
No more than 5 applications per year (9 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. |
Javelin WG (Bacillus thuringiensis subspecies kurstaki) |
0.12-1.5 lb |
4 |
0 |
most caterpillars, but not Spodoptera species (armyworms) |
11 |
Treat when larvae are young. Thorough coverage is essential. OMRI-listed2. |
Knack IGR (pyriproxyfen) |
8 fl oz |
12 |
3 |
onion thrips |
7C |
Maximum of 2 applications, at least 14 days apart. 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 and green onions only. Add a wetting agent to improve coverage.
|
Lorsban 15G; 75WG (chlorpyrifos) |
15G: 3.7 oz/1000 ft of row 75WG: 1.33 lb |
24
|
at planting |
onion maggot |
1B |
Dry bulb only. |
Malathion 8F (malathion) |
1-2 pt |
12
|
3, 7 for shallots
|
onion maggot, thrips on onions, aphids and thrips on garlic, leeks, shallots |
1B |
|
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 |
3 |
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, thrips, 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 |
3 |
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 |
3 |
Bulb onions and garlic |
Pyrellin EC (pyrethrin + rotenone) |
1-2 pt |
12
|
12 hours
|
aphids, leafhoppers, loopers, mites, plant bugs, stink bugs, thrips, whiteflies |
3, 21 |
|
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 |
western flower thrips |
un |
Begin as soon as thrips are seen. |
SpinTor 2SC (spinosad) |
3.0-8.0 fl oz |
4 |
1 |
armyworms, dipteran leafminers, flea beetle, loopers, suppression of thrips at high rate |
5 |
Do not apply more than 29 oz per acre per crop or make more than 5 applications per year. |
*Telone C-35 (dichloropropene + chloropicrin) |
See label |
5 days See label
|
preplant
|
symphylans, wireworms |
-- |
See supplemental label for use restrictions in south and central Florida. |
*Telone II (dichloropropene) |
||||||
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 |
3 |
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 |
11 |
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. |
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1Mode of Action codes for vegetable pest insecticides from the Insecticide Resistance Action Committee (IRAC) Mode of Action Classification v. 6.1 August 2008. 1A. Acetyl cholinesterase inhibitors, Carbamates (nerve action) 1B. Acetyl cholinesterase inhibitors, Organophosphates (nerve action) 2A. GABA-gated chloride channel antagonists (nerve action) 3. Sodium channel modulators (nerve action) 4A. Nicotinic acetylcholine receptor agonists (nerve action) 5. Nicotinic acetylcholine receptor allosteric activators (nerve action) 6. Chloride channel activators (nerve and muscle action) 7A. Juvenile hormone mimics (growth regulation) 7C. Juvenile hormone mimics (growth regulation) 9B and 9C. Selective homopteran feeding blockers 10. Mite growth inhibitors (growth regulation) 11. 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) 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 2 OMRI listed: Listed by the Organic Materials Review Institute for use in organic production. |
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* Restricted Use Only. |
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Footnotes
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. For more publications related to horticulture/agriculture, please visit the EDIS Website at http://edis.ifas.ufl.edu/.
S. E. Webb, associate professor, Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 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.
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Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place,
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