Bulbing onion, scallion, and shallot, along with garlic and leek, are members of the genus Allium. The characteristic flavors of Allium family members come from sulfur-containing compounds produced by these plants.
The bulbing onion, Allium cepa, appears to have originated near the intersection of Europe and Asia, whereas the bunching onion or scallion, Allium fistulosum may have originated in China.
Bulbing onions form bulbs in response to day length. Only long-day and intermediate-day types are recommended for summer harvest in New England since these types require at least 13 hours of daylight. Short-day onions begin forming bulbs when days are 10-12 hours long and are typically grown in southern regions of the U.S. where they are planted in the winter. Recently, some researchers and farmers in New England have been planting onions in low tunnels in the fall for spring harvest. The University of New Hampshire research report on overwintering onions includes planting details and trialed varieties (see https://bit.ly/overwinteronions). Shallots form clusters of bulbs. While shallots have traditionally been propagated vegetatively, hybrid cultivars that can be grown from seed are now available. Scallions a member of the Allium genus that do not form a fully developed bulb. They are planted from seed and commonly sold in bunches.
| Onion, SHallot, and Scallion Varieties | |
|---|---|
| Scallion/Bunching Onion | Onion - Yellow Storage |
| Evergreen Hardy White | Northstar (80) |
| Ishikura Improved | Bridger (90) |
| Southport White Bunching | New York Early (98) |
| Patterson (104) | |
| Shallot | Cortland (105) |
| Ambition | Crocket (114) |
| Conservor | |
| Onion - Red Storage | |
| Onion - Sets | Red Bull (104) |
| Ebenezer | Red Carpet (114) |
| Stuttgart | Redwing (114) |
| Onion - Sweet, non-storing | Onion - Overwintering |
| Ailsa Craig (110) | Bridger |
| Candy (85) | Gatekeeper |
| Hi-Keeper | |
| Onion - Sweet Spanish | Electric (red) |
| Super Star (100) | Desert Sunrise (red) |
| Yellow Sweet Spanish (120) | Red Rock (red) |
| The number in parentheses is the approximate number of days to maturity from seeding. | |
Apply lime according to soil test results to maintain soil pH at 6.5-6.8. Onions and leeks do not tolerate acid soil, especially in early growth stages. If the magnesium level is high, a lime high in calcium (calcitic lime) should be used to maintain a high calcium level.
Less nitrogen fertilizer will be needed if legume sod was plowed down or if manure was applied (see Table 1 and Table 7). These sources may also result in high soil nitrogen levels late in the season. Excessive nitrogen late in the season from any source can delay maturity and reduce storability of onions.
Onion flavor is determined by cultivar type, temperature and irrigation, and sulfur fertility. Growers wishing to produce mild-flavored onions for retail sale should choose mild cultivar types, irrigate regularly up to harvest, and maintain soil sulfur levels between 35 and 55 lb/A. Excessive sulfur levels in soils or fertilizers will increase pungency.
| PLANT NUTRIENT RECOMMENDATION ACCORDING TO SOIL TEST RESULTS FOR ONION, Scallion, and Shallot | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| ONION, Scallion, and Shallot | NITROGEN (N) LBS PER ACRE | PHOSPHORUS (P) LBS 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 | 80-100 | 150 | 100 | 25-50 | 0 | 175 | 150 | 50 | 0 |
| Sidedress 4-5 Weeks after Planting | 50 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| TOTAL RECOMMENDED | 130-150 | 150 | 100 | 25-50 | 0 | 175 | 150 | 50 | 0 |
Bulbing onion and shallot. Sow transplants in late February or early March, 10-12 weeks before setting in field. Direct seed onions in spring as soon as soil can be worked. Seeding should be completed by late April or mid-May at the very latest to allow time for adequate plant growth before bulb initiation occurs. Plant 2-4 rows per bed, 9-18" between rows and 3-4" apart within rows for transplants. Spacing will affect bulb size. For direct seeding, aim for a stand of 6-9 plants per foot. This can be increased to 9-12 plants per foot if double shoe precision seeders are used. This requires 5-6 lb of seed per acre (about 0.5 oz per 100 feet of row). Instead of transplants, some growers use sets to plant all or some of their crop. Sets are small bulbs (about 1/2") raised the prior year and stored over the winter. This provides for an early harvest (mid-summer), but larger sets can be prone to bolting (premature flowering). Sets should be planted as soon as the soil has dried and can be worked. Spacing is the same as for transplants. Some growers are finding success using black or white-on-black plastic mulch on raised beds for sets or transplants.
Scallion. In addition to early spring planting, mid-summer plantings can be used to produce fall harvests. Even moisture must be maintained throughout germination for direct-sown scallions. Seed in rows 2-3” wide, spaced 4” apart.
Bulbing onion and shallot: Late, hard, pungent varieties with good skin retention are preferable for winter storage. Undercutting several days before harvesting can improve keeping quality. It is best to undercut when most of the plants have 2 leaves that are still partially green. Allowing leaves to completely dry down before undercutting can result in excessive loss of skin during harvest. To develop best skin color, onions should be cured for 2 weeks at 75-80ºF and 70-80% relative humidity. After curing, lower temperature gradually to as near to 32ºF as practical without freezing. Cooling too rapidly, followed by a few warm days, can cause moisture condensation, resulting in bulb staining, sprouting and decay. Maintain storage relative humidity at 65-70%, and maintain sufficient air flow to keep cool air moving around bulbs.
Scallion. Scallions, or fresh bunching onions, can be harvested anytime after they are pencil-sized. To maintain good post-harvest quality, they should be cooled to 39ºF within 4-6 hours of harvest. Scallions can be stored for 7-10 days at 32ºF.
For long-term storage of bulbing onions or shallots, select storage varieties. Pungent dry onions can be stored for 6-9 months at 32ºF. For very long-term storage, a sprouting inihibitor, maleic hydrazide (2 gal of Royal MH-30/A in a minimum of 30 gal/A), may be applied when about 50% of the tops are down, the bulbs are mature, the necks are soft and five to seven of the leaves are still green. See the label for details.
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 25 and Fungicides and Bactericides Alphabetical Listing 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.
Avoid close planting and orient rows in the direction of prevailing winds. Do not plant on poorly-drained areas. Plow under crop debris after harvest. Remove cull piles and practice crop rotation. Avoid excessive nitrogen fertilization as this increases canopies and susceptibility. Plant less susceptible cultivars. Irrigate early in the day to reduce leaf wetness periods. Incorporate crop residues after harvest. Apply fungicides based on a disease forecast system (e.g., BOTCAST). Disease development, based on weather conditions near your farm, can be monitored on-line (www.newa.cornell.edu).
azoxystrobin (Quadris): 9.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11.
azoxystrobin plus chlorothalonil (Quadris Opti): 1.6 to 3.2 pt/A; PHI 7d, REI 12h, Groups 11 & M5.
azoxystrobin plus difenoconazole (Quadris Top): 12.0 to 14.0 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.
boscalid (Endura): 6.8 oz/A; PHI 7d, REI 12h, Group 7.
chlorothalonil (Bravo Weather Stik): 1.0 to 3.0 pt/A; PHI 7d, REI 12h, Group M5. To suppress Botrytis neck rot in storage, a minimum of 3 weekly applications prior to lifting using 1.25 to 1.8 lb/A is recommended.
cyprodinil (Vanguard): 10.0 oz/A; PHI 7d, REI 12h, Group 9.
cyprodinil plus fludioxonil (Switch 62.5 WG): 11.0 to 14.0 oz/A; PHI 7d, REI 12h, Groups 9 & 12.
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.
fluazinam (Omega 500F): 1.0 pt/A; PHI 7d, REI 12h to 24h (24h for hand weeding), Group 29.
fluopyram plus pyrimethanil (Luna Tranquility): 16 to 27 fl oz/A; PHI 7d, REI 12h, Groups 7 & 9. Do not make more than 2 sequential applications before alternating to a non group 7 or 9 fungicide.
fluxapyroxad plus pyraclostrobin (Merivon): 8.0 to 11.0 fl oz/A; PHI 7d, REI 12, Groups 7 & 11. For best results, begin applications before disease onset.
iprodione (Rovral 4F): 1.5 pt/A or 1.0 pt/A (if tank-mixed); PHI 7d, REI 24h, Group 2.
mancozeb (Dithane F45): 2.4 qt/A; PHI 7d, REI 24h, Group M3.
penthiopyrad (Fontelis): 16 to 24 oz/A; PHI 3d, REI 12h, Group NC.
polyoxin D (OSO 5%SC): 3.75 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.
potassium phosphite plus chlorothalonil (Catamaran): 4.0 to 7.0 pt/A; PHI 7d, REI 12, Groups 33 & M5.
propiconazole (Tilt): 4.0 to 8.0 oz/A; PHI 14d, REI 12, Group 3.
pyraclostrobin plus boscalid (Pristine): 14.5 to 18.5 oz/A; PHI 7d, REI 12h, Groups 11 & 7. Do not make more than 2 sequential applications of Pristine before alternating with a fungicide with a different mode of action.
pyrimethanil (Scala SC Fungicide): 18.0 fl oz/A; PHI 7d, REI 12h, Group 9.
azoxystrobin (Quadris): 9.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11.
azoxystrobin plus chlorothalonil (Quadris Opti): 1.6 to 3.2 pt/A; PHI 14d, REI 12h, Groups 11 & M5. See label for tank mix precautions.
azoxystrobin plus difenoconazole (Quadris Top): 12.0 to 14.0 fl oz/A; PHI 1d, REI 12h, Groups 11 & 3.
azoxystrobin plus propiconazole (Quilt): 14.0 to 27.5 fl oz/A; PHI 0d, REI 12h, Groups 11 & 3.
boscalid (Endura): 6.8 oz/A; PHI 7d, REI 12h, Group 7. Use higher rate and shorter interval when disease pressure is high. Do not make more than 1 application of Endura before alternating with a fungicide with a different mode of action (FRAC group).
chlorothalonil (Bravo Weather Stik): 1.5 to 3.0 pt/A; PHI 14d, REI 12h, Group M5. When disease is present, use the higher rate.
cyprodinil (Vanguard): 10.0 oz/A; PHI 7d, REI 12h, Group 9.
cyprodinil plus fludioxonil (Switch 62.5 WDG): 11.0 to 14.0 oz/A; PHI 7d, REI 12h, Groups 9 & 12.
difenoconazole plus cyprodinil (Inspire Super): 16.0 to 20.0 fl oz/A; PHI 14d, REI 12h, Group 3 & 9.
fluopyram plus pyrimethanil (Luna Tranquility): 16 to 27 fl oz/A; PHI 7d, REI 12h, Groups 7 & 9. Do not make more than 2 sequential applications before alternating to a non group 7 or 9 fungicide.
fluxapyroxad plus pyraclostrobin (Merivon): 8.0 to 11.0 fl oz/A; PHI 7d, REI 12, Groups 7 & 11. For best results, begin applications before disease onset.
penthiopyrad (Fontelis): 16.0 to 24.0 oz/A; PHI 3d, REI 12h, Group NC.
polyoxin D (OSO 5%SC): 3.75 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.
potassium phosphite plus chlorothalonil (Catamaran): 4-7 pt/A; PHI 14d, REI 12, Groups 33 & M5.
propiconazole (Tilt): 4.0 to 8.0 oz/A; PHI 0d, REI 12, Group 3.
pyraclostrobin plus boscalid (Pristine): 14.5 to 18.5 oz/A; PHI 7d, REI 12h, Groups 11 & 7. Do not make more than 2 sequential applications of Pristine before alternating with a fungicide with a different mode of action.
pyrimethanil (Scala SC Fungicide): 18.0 fl oz/A; PHI 7d, REI 12h, Group 9.
Primarily a storage disease. Do not apply nitrogen late in the season and avoid high-density planting. Undercut bulbs to promote drying. Allow the tops to dry completely and have tight necks before topping. Avoid condensation on bulbs during storage. Maintain storage environment at 32-33°F and 70-75% relative humidity. Fungicides applied to control Botrytis blight may also decrease neck rot.
azoxystrobin plus chlorothalonil (Quadris Opti): 1.6 to 3.2 pt/A; PHI 14d, REI 14h, Groups 11 & M5. Suppression only. See label for tank mix precautions.
cyprodinil plus fludioxonil (Switch 6.25 WG): 11.0 to 14.0 oz/A; PHI 7d, REI 12h, Groups 9 & 12. Suppression only.
fluazinam (Omega 500F): 1.0 pt/A; PHI 7d, REI 48h, Group 29.
fluxapyroxad + pyraclostrobin (Merivon): 8.0 to 11.0 fl oz/A; PHI 7d, REI 12, Groups 7 & 11. For best results, begin applications before disease onset.
iprodione (Rovral 4F): 1.5 pt/A or 1.0 pt/A (if tank-mixed); PHI 7d, REI 24h, Group 2.
mancozeb (Dithane M45): 2.4 qt/A; PHI 7d, REI 24h, Group M3.
polyoxin D (OSO 5%SC): 3.75 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.
pyraclostrobin plus boscalid (Pristine): 14.5 to 18.5 oz/A; PHI 7d, REI 12h, Groups 11 & 7.
pyrimethanil (Scala SC Fungicide): 18.0 fl oz/A; PHI 7d, REI 12h, Group 9.
The fungus overwinters in infected bulbs or sets and on other host plants, in cull piles, and in fall-seeded onion. Only a few spores are needed to initiate an epidemic. Eliminate cull piles, volunteer onion plants, and wild Allium species. Practice a 3- to 4-year rotation. Plant only on well-drained land. Apply fungicides when mildew is present in the area and weather favors disease increase based upon a disease forecasting system (i.e., DOWNCAST). Disease development, based on weather conditions near your farm, can be monitored online (www.newa.cornell.edu).
acibenzolar-s-methyl (Actigard 50 WG): 0.75 to 1.0 oz/A; PHI 7d, REI 12h, Group 21. Actigard acts as a plant activator and should be applied preventatively.
ametoctradin plus dimethomorph (Zampro): 14.0 fl oz/A; PHI 0d, REI 12h, Groups 45 and 40.
azoxystrobin (Quadris): 9.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11.
azoxystrobin plus chlorothalonil (Quadris Opti): 2.4 to 3.7 pt/A; PHI 7d, REI 12h, Groups 11 & M5. See label for tank mix precautions.
copper hydroxide (Kocide 3000): 0.75 to 1.5 lb/A; PHI 0d, REI 48h, Group M1. Can cause phytotoxicity to leaves. Do not apply in a spray solution having a pH less than 6.5 or tank mix with Aliette.
cyazofamid (Ranman 400 SC): 2.75 to 3.0 fl oz/A; PHI 0d, REI 12h, Group 21.
dimethomorph (Forum): 6.0 fl oz/A; PHI 0d, REI 12h, Group 40. Forum must be applied as a tank mix with another fungicide with a different mode of action.
famoxadone plus cymoxanil (Tanos): 8.0 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Must be tank mixed with an appropriate contact fungicide with a different mode of action. 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 of Reason before alternating to a non-Group 11 fungicide.
fluazinam (Omega 500F): 1.0 pt/A; PHI 7d, REI 48h, Group 29.
fluxapyroxad plus pyraclostrobin (Merivon): 8.0 to 11.0 fl oz/A; PHI 7d, REI 12, Groups 7 & 11. For best results, begin applications before disease onset. For supression only.
mancozeb (Dithane M45): 2.4 qt/A; PHI 7d, REI 24h, Group M3.
mancozeb plus copper hydroxide (ManKocide): 2.5 lb/A; PHI 7d, REI 48h, Groups M3 & M1.
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 plus copper hydroxide (Ridomil Gold Copper): 2.0 lb/A; PHI 10d, REI 48h, Groups M3 & M1.
mefenoxam plus mancozeb (Ridomil Gold MZ): 2.5 lb/A; PHI 7d, REI 48h, Groups 4 & M3.
oxathiapiprolin plus chlorothalonil (Orondis Opti): 1.75 to 2.5 pt/A; PHI 7d, REI 12h, Groups 49 & M5.
oxathiapiprolin plus 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/100 gal; PHI 0d, REI 4h, Group 33. Do not apply to heat or moisture stressed plants or to plants recently treated with copper.
potassium phosphite plus chlorothalonil (Catamaran): 4.0 to 7.0 pt/A; PHI 7d, REI 12, Groups 33 & M5.
pyraclostrobin (Cabrio EG): 12.0 oz/A; PHI 7d, REI 12h, Group 11.
pyraclostrobin plus boscalid (Pristine): 18.5 oz/A; PHI 7d, REI 12h, Groups 7 & 11. For suppression only. Rotate with a downy mildew fungicide with a different mode of action.
zoxamide plus chlorothalonil (Zing!): 30.0 fl oz/A; PHI 7d, REI 12h, Groups 22 & M3.
zoxamide plus mancozeb (Gavel 75 DF): 1.5 to 2 lb/A; PHI 7d, REI 48h, Groups 22 & M3.
ametoctradin plus dimethomorph (Zampro): 14.0 fl oz/A; PHI 0d, REI 12h, Groups 45 and 40.
azoxystrobin (Quadris): 9.0 to 15.5 fl oz/A; PHI 0d, REI 4h, Group 11.
azoxystrobin plus chlorothalonil (Quadris Opti): 2.4 to 3.7 pt/A; PHI 14d, REI 12h, Groups 11 & M5. See label for tank mix precautions.
copper hydroxide (Kocide 3000): 0.75 to 1.5 lb/A; PHI 0d, REI 48h, Group M1. Can cause phytotoxicity to leaves. Do not apply in a spray solution having a pH less than 6.5 or tank mix with Aliette.
cyazofamid (Ranman 400 SC): 2.75 to 3.0 fl oz/A; PHI 0d, REI 12h, Group 21.
dimethomorph (Forum): 6.0 fl oz/A; PHI 0d, REI 12h, Group 40. Forum must be applied as a tank mix with another fungicide with a different mode of action.
famoxadone plus cymoxanil (Tanos): 8.0 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Must be tank mixed with an appropriate contact fungicide with a different mode of action. Do not alternate or tank mix with other Group 11 fungicides.
fluxapyroxad plus pyraclostrobin (Merivon): 8.0 to 11.0 fl oz/A; PHI 7d, REI 12, Groups 7 & 11. For best results, begin applications before disease onset. For supression only.
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 14d, REI 48h, Groups 4 & M5.
mefenoxam plus copper hydroxide (Ridomil Gold Copper): 2.0 lb/A; PHI 7d, REI 48h, Groups M3 & M1.
oxathiapiprolin plus chlorothalonil (Orondis Opti): 1.75 to 2.5 pt/A; PHI 14d, REI 12h, Groups 49 & M5.
oxathiapiprolin plus mandipropamid (Orondis Ultra): 5.5 to 8.0 fl oz/A; PHI 7d, REI 4h, Groups 49 & 40.
potassium phosphite + chlorothalonil (Catamaran): 4.0 to 7.0 pt/A; PHI 14d, REI 12, Groups 33 & M5.
pyraclostrobin (Cabrio EG): 12.0 oz/A; PHI 7d, REI 12h, Group 11.
pyraclostrobin plus boscalid (Pristine): 18.5 oz/A; PHI 7d, REI 12h, Groups 7 & 11. For suppression only. Rotate with a downy mildew fungicide with a different mode of action.
zoxamide plus chlorothalonil (Zing!): 30.0 fl oz/A; PHI 7d, REI 12h, Groups 22 & M3.
zoxamide plus mancozeb (Gavel 75 DF): 1.5 to 2 lb/A; PHI 7d, REI 48h, Groups 22 & M3.
The pathogen overwinters in plant residue from onions and onion-related plants. Disease development is favored by warm, moist conditions. Avoid Sweet Spanish onions because they are extremely susceptible. Plow under crop residues after harvest. Rotate with non-hosts. Select sites and practice irrigation to enhance rapid drying of foliage. Apply fungicides as canopy becomes denser and leaf-wetness periods increase. Purple blotch disease development, based on weather conditions near your farm, can be monitored on-line (www.newa.cornell.edu).
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 (dry) and 14d (green), REI 12h, Groups 11 & M5. See label for tank mix precautions.
azoxystrobin plus difenoconazole (Quadris Top): 12.0 to 14.0 fl oz/A; PHI 7d, REI 12h, Groups 11 & 3.
azoxystrobin plus propiconazole (Quilt): 14.0 to 27.5 fl oz/A; PHI 14d (dry) and 0d (green), REI 12h, Groups 11, 7 & 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.
chlorothalonil (Bravo Weather Stik): 1.0 to 3.0 pt/A; PHI 7d (dry) and 14d (green), REI 12h, Group M5.
copper hydroxide (Kocide 3000): 0.75-1.5 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 (Vanguard): 10.0 oz/A; PHI 7d, REI 12h, Group 9.
cyprodinil plus fludioxonil (Switch 62.5 WDG): 11.0 to 14.0 oz/A; PHI 7d, REI 12h, Groups 9 & 12.
difenoconazole plus benzovindiflupyr (Aprovia Top): 10.5 fl oz/A; PHI 7d, REI 12h, Groups 3 & 7. No more than 2 sequential applications before alternating to a non-Group 7 fungicide.
difenoconazole plus cyprodinil (Inspire Super): 16.0 to 20.0 fl oz/A; PHI 7d (dry bulb); PHI 14d (green), REI 12h, Group 3 & 9. Apply in sufficient volume to achieve thorough coverage.
famoxadone plus cymoxanil (Tanos): 8.0 oz/A; PHI 3d, REI 12h, Groups 11 & 27. Must be tank mixed with an appropriate contact fungicide with a different mode of action. 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 500F): 1.0 pt/A (dry bulb only); PHI 7d, REI 12-24h, Group 29.
fluopyram plus pyrimethanil (Luna Tranquility): 16.0 to 27.0 fl oz/A; PHI 7d, REI 12h, Groups 7 & 9. Do not make more than 2 sequential applications before alternating to a non group 7 or 9 fungicide.
fluxapyroxad plus pyraclostrobin (Merivon): 5.5 to 11 fl oz/A; PHI 7d, REI 12, Groups 7 & 11. For best results, begin applications before disease onset.
iprodione (Rovral 4F): 1.5 pt/A (dry bulb only); PHI 7d, REI 24h, Group 2. Do not make more than 5 applications per season. If tank-mixing with another chemical registered for purple blotch, reduce iprodione rate to 1 pt/A.
mancozeb (Dithane F45): 2.4 qt/A (dry bulb only); PHI 7d, REI 24h, Group M3.
mancozeb plus copper hydroxide (ManKocide): 2.5 lb/A (dry bulb only); PHI 7d, REI 48h, Groups M3 & M1.
penthiopyrad (Fontelis): 16.0 to 24.0 oz/A; PHI 3d, REI 12h, Group NC.
polyoxin D (OSO 5%SC): 3.75 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.
potassium phosphite plus chlorothalonil (Catamaran): 4.0 to 7.0 pt/A; PHI 14d, REI 12, Groups 33 & M5.
propiconazole (PropiMax EC): 4.0 to 8.0 fl oz/A; PHI 14d bulb; PHI 0d green, REI 12h, Group 3.
pyraclostrobin (Cabrio EG): 8.0 to 12.0 oz/A; PHI 7d, REI 12h, Group 11. Do not exceed 6 applications per season or 72 oz/A. Do not rotate with other Group 11 fungicides.
pyraclostrobin plus boscalid (Pristine): 10.5 to 18.5 oz/A; PHI 7d, REI 12h, Groups 7 & 11. Do not rotate with another Group 11 fungicide.
pyrimethanil (Scala SC): 18.0 fl oz (alone) 9.0 fl oz (tank mixed)/A ; PHI 7d, REI 12h, Group 9.
tebuconazole (Orius 3.6F): 4.0 to 6.0 fl oz/A (for dry onion); PHI 7d, REI 12h, Group 7.
Symptoms appear as target-like brown lesions, lacking the purple margins seen with purple blotch. The pathogen overwinters in plant residues from onions and onion-related plants. Disease development is favored by warm, moist conditions. Plow under crop residues after harvest. Rotate with non-hosts. Select sites and practice irrigation to enhance rapid drying of foliage. Apply fungicides as canopy becomes denser and leaf-wetness periods increase.
difenoconazole plus benzovindiflupyr (Aprovia Top): 10.5 fl oz/A; PHI 7d, REI 12h, Groups 3 & 7. No more than 2 sequential applications before alternating to a non-Group 7 fungicide.
difenoconazole plus cyprodinil (Inspire Super): 16.0 to 20.0 fl oz/A; PHI 7d (dry bulb); PHI 14d (green), REI 12h, Group 3 & 9. Apply in sufficient volume to achieve thorough coverage.
fluopyram plus pyrimethanil (Luna Tranquility): 16 to 27 fl oz/A; PHI 7d, REI 12h, Groups 7 & 9. Do not make more than 2 sequential applications before alternating to a non group 7 or 9 fungicide.
fluxapyroxad plus pyraclostrobin (Merivon): 5.5 to 11 fl oz/A; PHI 7d, REI 12, Groups 7 & 11. For best results, begin applications before disease onset.
iprodione (Rovral 4F): 1.5 pt/A (dry bulb only); PHI 7d, REI 24h, Group 2. Do not make more than 5 applications per season. If tank-mixing with another chemical registered for purple blotch, reduce iprodione rate to 1 pt/A.
pyraclostrobin (Cabrio EG): 8.0 to 12.0 oz/A; PHI 7d, REI 12h, Group 11. Do not exceed 6 applications per season or 72 oz/A. Do not rotate with other Group 11 fungicides.
pyraclostrobin plus boscalid (Pristine): 10.5 to 18.5 oz/A; PHI 7d, REI 12h, Groups 7 & 11. Do not rotate with another Group 11 fungicide.
White rot is associated with soil-borne inoculum; repeated cropping of Allium species results in increased disease over time. The sclerotia can persist in the soil for up to 20 years in the absence of a host. Select fields with no history of this disease. Use only disease-free transplants. Soil fumigation may be useful. Stimulating the sclerotia to germinate with onion exudate mimics (diallyl disulphide) can reduce soil inoculum.
azoxystrobin plus propiconazole (Quilt Xcel): 17.5 to 26 fl oz/A; PHI 14d, REI 12h, Group 11 & 3.
Bacillus amyloliquefaciens strain D747 (DoubleNickel LCOG): 0.12 to 1.0 lb/A as 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.
cyprodinil plus fludioxonil (Switch 6.25 WG): 7.0 to 14.0 oz/A; PHI 7d, REI 12h, Groups 9 & 12. Apply at planting as in-furrow spray.
fludioxonil (Cannonball WG): 7.0 oz/A (0.5 oz/1,000 ft row); PHI 7d, REI 12h, Group 12.
penthiopyrad (Fontelis): 16.0 to 24.0 oz/A; PHI 3d, REI 12h, Group NC.
tebuconazole (Orius 3.6F): 20.5 fl oz/A (dry onion); PHI 7d, REI 12h, Group 7. Apply in a 4-6 inch band into/over each furrow. May also be applied by chemigation.
thiophanate methyl (Topsin M 70WP): 2.0 lb/A; REI 72h, Group 1. Apply in furrow.
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 26 and Insecticides Alphabetical Listing by Trade Name for more information on these insecticides.
All tolerances for chlorpyrifos in food crops were revoked in 2022, therefore products containing chlorpyrifos (e.g. Lorsban) cannot be applied to any food crop and growers CANNOT use up existing stock.
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.
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 7d for fresh or green onions and shallot leaves, 30d for onion and shallot bulbs, 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. Bulb onion only.
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. Onion only.
mineral oil (SuffOil XOG): 1 to 2 gal/100 gal water; PHI 14d, REI 4h, Bee: L, Group M. Onion only.
permethrin (Pounce* 25WP): 16.4 to 19.2 fl oz/A; PHI 1d, REI 12h, Bee: H, Group 3A. Onion only.
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.
spinosad (Entrust SCOG): 4 to 8 oz/A; PHI 1d, REI 4h, Bee: M, Group 5. Use adjuvant for better control. Do not make more than 2 consecutive applications of Group 5 insecticides. Do not make more than 5 applications per year per crop.
thiamethoxam (Cruiser 70 WS): 0.05 to 0.2 mg/seed; Bee: H, Group 4A. Dry bulb onions only.
zeta-cypermethrin (Mustang*): 2.4 to 4.3 fl oz/A; PHI 7d, REI 12h, Bee: H, Group 3A.
Two genera of mites are known to infect species of Allium. The dry bulb mite (Aceria tulipae) is an eriophyid mite that survives on cultivated Allium species. Bulb mite species in the genus Rhizoglyphus can also be troublesome on alliums. Bulb mites overwinter in soil on debris, stored onions and garlic, and in garlic seed pieces. They are moved from field to field with soil on equipment, boots, etc., and planting infested garlic They are particularly troublesome in storage, causing desiccation and creating wounds that allow for entry of 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. In smaller plantings, removing culls from the field immediately after harvest 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 four years after an infestation. Avoid planting alliums directly after brassicas, corn, grain, or grass cover crops.
Caterpillars hide under the soil surface adjacent to the plant during the day and feed on leaves after dark. For best results, make application between midnight and dawn while cutworms are feeding aboveground. Synthetic pyrethroids may work best during cool spring weather. All synthetic pyrethroid restricted use (*) insecticides listed to control thrips on onions are also registered to control cutworm on this crop. See cutworms in the Pepper and Tomato (Outdoor) sections for more information on the black and variegated cutworms.
Bacillus thuringiensis aizawai (XenTariOG): 0.5 to 1.5 lb/A; PHI 0d, REI 4h, Bee: L, Group 11. Must be ingested; apply in evening or early morning, before larvae are actively feeding. Adherence and weather-fastness will improve with use of an approved spreader-sticker. Use high rate at cool temperatures. For resistance management, may be rotated with Bt kurstaki products (Dipel).
Bacillus thuringiensis kurstaki (Dipel DFOG): 0.5 to 2 lb/A; PHI 0d, REI 4h, Bee: L, Group 11. Must be ingested; apply in evening or early morning, before larvae are actively feeding. Adherence and weather-fastness will improve with use of an approved spreader-sticker. Use high rate at cool temperatures. For resistance management, may be rotated with Bt aizawai products (XenTari).
Burkholderia spp. strain A396 (Venerate XCOG): 1 to 8 qt/A; PHI 0d, REI 4h, Bee: M, Group UN.
Chromobacterium subtsugae strain PRAA4-1 (GrandevoOG): 1 to 3 lb/A; PHI 0d, REI 4h, Bee: M, Group UN.
gamma-cyhalothrin (Declare*): .077 to 1.28 oz/A; PHI 1d, REI 24h, Bee: H, Group 3A.
lambda-cyhalothrin (Warrior* II): 0.96 to 1.60 oz/A; PHI 14d, REI 24h, Bee: H, Group 3A.
methomyl (Lannate* LV): 3 pt/A; PHI 7d, REI 48h, Bee: H, Group 1A. For green and dry onions. Add wetting agent to improve coverage. For black and variegated cutworm only.
spinosad (SeduceOG): 20 to 44 lb/A or 0.5 to1 lb/1000 sq ft.; PHI 1d, REI 4h, Bee: M, Group 5. Spread bait on soil around plants.
zeta-cypermethrin (Mustang*): 2.4 to 4.3 oz/A; PHI 7d, REI 12h, Bee: H, Group 3A.
For more information on this pest and for cultural and chemical controls, see Leek Moth in the leek section.
Infestations may reduce young plant stands, cause plants to wilt and yellow, or damage bulbs. There are 3 generations each year. Effective control of the first generation (mid-May to June), which causes the most destruction, and minimizing mechanical and chemical damage to onions throughout the season, will reduce or eliminate damage by later generations. Rotate crops to keep maggot populations low; greater distances are more effective. Cumulative growing degree days (GDD) can be used to monitor the activity of onion maggot fly in your area: peak flight for the first generation is at 735 GDD, base 40°F. Delay planting until after first flight is finished and soil temperatures are high enough to kill eggs (95°F). Planting in late-May is more likely to be safer than the first half of May. Cover recently seeded or transplanted crops with floating row covers as a barrier against onion maggot flies, placing the cover as soon as the transplants are set. Gathering culls into deep piles will limit reproduction to surface layers and reduce populations more than deep plowing or harrowing after harvest. Biological controls, including naturally-occurring fungal diseases, predaceous ground beetles, and soil applications of the entomopathogenic nematode Steinernema feltiae can all reduce onion maggot numbers. Nematodes can be applied to transplants, in transplant water, or as a post-transplant drench. Rates of 100,000 to 125,000 infective juveniles per transplant have been shown to be needed to achieve reduction in damage. Nematodes need a moist soil environment to survive. If using an insecticide, soil drench applications targeting the seed furrow or base of transplants, using at least 100-200 gal of water per acre to help the insecticide penetrate the root zone are the most effective.
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. For bulb and green onions. DO NOT make more than one application per year.
Onion thrips range in color from yellow to black and are only 1/16" in length. They spend the winter as adults in crop remnants, alfalfa, wheat, greenhouses and weeds along the border of crop fields. Thrips have rasping mouth parts which they use to tear open plant cells and feed on inner juices. Feeding occurs in protected areas between leaves. Damage may appear as silver lines, white patches, tip dieback and curling, slowed growth, reduced bulb size and yields, or result in plant death. Populations are favored by hot, dry weather. Plants are most sensitive when bulbs are forming and still small. 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 overwinter sites. Do not plant onions near alfalfa, clover, cucurbits or brassica crops that can harbor large populations of thrips, which may migrate to onions when these crops are cut or harvested.
Reflective mulch will repel colonizing thrips by confusing invading insects and preventing them from finding their host plants.
Scout plants along field margins where infestations build early. Begin applications when damage is first noticed or when there are 3 or more thrips per leaf. Repeat applications at 7- to 10-day intervals. From 3 to 6 applications may be necessary, but rotate between insecticide groups after 2 applications to help prevent resistance. Use a shorter interval in hot weather. Use spreader-sticker for better coverage. Apply in early evening, using high pressure and 100 gal water/A for best results.
acetamiprid (Assail 30SG): 5 to 8 oz/A; PHI 7d, REI 12h, Bee: M, Group 4A.
azadirachtin (Azatin OOG): 4 to 16 oz/A foliar or drench, 4 to 16 oz/100 gal in greenhouses. When using lower rates, combine with adjuvant for improved spray coverage and translaminar uptake; PHI 0d, REI 4h, Bee: L, Group un.
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 to 10 days after the first spray to see control. Repeat applications may be needed.
Burkholderia spp. strain A396 (Venerate XCOG): 1 to 8 qt/A; PHI 0d, REI 4h, Bee: M, Group UN. Suppression only.
Chenopodium extract (Requiem EC): 1.5 to 3 qts/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.
deltamethrin (Delta Gold*): 1.5 to 2.4 oz/A; PHI 1d, REI 12h, Bee: H, Group 3A.
gamma-cyhalothrin (Declare*): .1.02 to 1.54 oz/A; PHI 1d, 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 57EC): 1.5 pt/A; PHI 3d, REI 12h, Bee: H, Group 1B.
Metarhizium anisopliae Strain F52 (Met 52 EC): 40 to 80 oz/100 gal (drench), 8 to 64 oz/A (foliar); PHI 0d, REI 0h, Bee: L, Group UN.
methomyl (Lannate* LV): 3 pt/A; PHI 7d, REI 48h, Bee: H, Group 1A. For green and dry onions. Add wetting agent to improve coverage. Begin application before populations reach 3 to 5 thrips per plant.
permethrin (Pounce* 25WP): 9.6 to 19.2 oz/A; PHI 1d, REI 12h, Bee: H, Group 3A. For dry bulb onions only
petroleum oil (Suffoil XOG): 1 to 2 gal/100 gal water; PHI 0d, REI 4h, Bee: L. Apply as needed.
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.
pyriproxyfen (Esteem 0.86EC): 8 oz/A; PHI 3d, REI 12h, Bee: L, Group 7D. Dry bulb onions only. Suppression only.
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.
spinosad (Entrust SCOG): 4 to 8 oz/A; PHI 1d, REI 4h, Bee: M, Group 5. Suppression only. Use adjuvant for better control.
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.
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 sytemicity; don't use sticker adjuvants. Controls immature stages; may also reduce adult fertility.
zeta-cypermethrin (Mustang*): 3.2 to 4.3 oz/A; PHI 7d, REI 12h, Bee: H, Group 3A.
NOTE: 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.
See Stale Seedbed Technique in the Weed Management section. In place of herbicides, flaming can also be used.
glyphosate (Roundup Power Max): REI 12h, Group 9.
paraquat (Gramoxone SL 2.0*): restricted use. Dry bulb onion only. REI 12h, Group 22. Use 2 – 4 pts/A. Include a nonionic surfactant at 0.25% v/v, or crop oil concentrate/methylated seed oil at 1.0% v/v (1 gal/100 gal) of the finished spray volume for maximum efficacy. May be fatal if swallowed or inhaled. Applicators must complete an EPA-approved paraquat training listed on the following website https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training.... The training must be completed a minimum of every three years.
pelargonic acid (Scythe): PHI 1d, REI 12h, Group 17. Use a 3 -10% solution (3 to 10 gallons per 100 gallons).
bensulide (Prefar 4E): REI 12h, Group 0. Dry bulb onion and dry bulb shallot only. Apply 5 to 6 qt/A. Can be preplant incorporated by shallow cultivation (1-2”) or incorporated by irrigation within 36 hours of application. Grass control only; should be supplemented with cultivation or another registered herbicide for broadleaf control. See label for rotation restrictions.
dimethenamid (Outlook): PHI 30d, REI 12h, Group 15. Can be used for dry bulb onion and shallot, and also for green onion (leeks, spring onions or scallions, Japanese bunching onions, green shallots or eschalots). If applications are made to transplanted green onions, DO NOT apply until transplants are in the ground and soil has settled around transplants with several days to recover. This herbicide is a root and shoot growth inhibitor that controls susceptible germinating seedlings before or soon after they emerge from the soil. Do not apply until onion has reached the 2 true-leaf stage or significant crop injury can occur. May be applied as a single application (up to 21 oz/A) or used in split applications. For split applications do not exceed a total of 21 oz/A per season. An initial application of 10 to 14 oz/A can be followed by another application of the remaining 7 to 11 oz/A. Applications must be a minimum of 14 days apart. Application rates are influenced by soil organic matter content. See label for info on application rates depending on soil type and organic matter content. See label for info on tank mixing with other herbicides.
DCPA (Dacthal W-75): REI 12h, Group 3. Select rate for preemergence use based on soil type and weeds targeted for preemergence control. Good control of most annual grasses; fair on redroot pigweed, lambsquarter, and purslane. Apply to weed-free soil; will not control existing weeds. Can be applied at seeding or transplanting and/or at layby. Can be sprayed directly over transplants without injury. A layby application can be made on onions either alone or in addition to a Dacthal preemergence treatment up to 14 weeks after planting at rates up to 14 lb/A on any soil type. If weeds emerge prior to layby, the onions should be cultivated or weeded prior to application. Preplant incorporation not recommended.
s-metolachlor (Dual Magnum): REI 12h, Group 15. MASSACHUSETTS, MAINE, and NEW HAMPSHIRE ONLY. Dry bulb and green onion. 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 (PHI 30d for green onions), REI 24h, Group 3. Emerged weeds will not be controlled by Prowl. Dry bulb onion and dry bulb shallot: Apply 1.5 to 3.2 pt/A. Select rate based on soil texture. See label for details. Can be used preemergence after planting but before crop emergence, after crop emergence when onions/shallots are in the 1 to 5 true leaf stage, or at both timings. For green onions, use 2 pt/A as preemergence spray or as a postemergence spray to the crop at the 2 to 3 true-leaf stage. If applied sequentially as both a preemergence and postemergence spray, applications must be separated by at least 30 days. Do not exceed 4 pt/A per year on green onions.
carfentrazone (Aim EC): REI 12h, Group 14. For use between rows after crop establishment. Aim is a burndown herbicide and will injure any foliage it comes into contact with. Apply Aim to row middles of emerged crops with hooded sprayers to control emerged weeds, including crops grown on mulch or plastic. Prevent any spray from contacting the crop, or injury will occur. For best results, make application to actively growing weeds up to 4 inches tall and rosettes less than 3 inches across. Good coverage is essential for good control. Apply up to 2 oz/A per application, and do not exceed a total of 6.1 oz/ per season.
clethodim (Select Max): PHI 45d, 24hr REI, Group 1. Dry bulb onions and dry bulb shallots only. Will control grass weeds only. Apply to actively growing grasses. See label for rate selection. Multiple applications permitted of 9 to 32 oz/A per application, minimum 14-days between applications, not to exceed 64 oz/A per year. Add 0.25% v:v nonionic surfactant (1 qt per 100 gal of spray). Can also be used as a spot-spray by mixing 1/3-2/3% (0.44 to 0.85 oz per gallon) Select Max and 0.25% v:v nonionic surfactant (0.33 oz per gallon). Spray to wet, but do not allow runoff of spray solution.
fluazifop (Fusilade DX): PHI varies (45d dry bulb, 14d green onion), REI 12h, Group 1. Dry bulb and green onion only. For grass weed control only. See label to select rate based on grasses targeted for control. Apply up tp 24 fl oz/A. Can make up to 2 applications per year. Allow for minimum 14 days between applications, and not to exceed 48 oz/A per year. Apply to actively growing grasses (see product label for susceptible stage). Add either crop oil concentrate (0.5-1%, 0.5-1 gallon per 100 gallons of spray) or nonionic surfactant (0.25-0.5%, 1-2 qt per 100 gal of spray).
oxyfluorfen (Goal 2 XL): REI 48h, Group 14. Provides early postemergence and residual control of many broadleaf weed species. For direct seeded onions, apply 2 to 4 oz/A to onions that has at least 3 fully developed true leaves. For transplanted onions, an application of up to 2 pt/A acre may be made within two days after transplanting. If less than 2 pt/A acre is applied, a second application can be made two weeks or more after transplanting. Do not exceed the maximum use rate of 2 pt/A per season.
pelargonic acid (Scythe): PHI 1d, REI 12h, Group 17. Use a 3 -10% solution (3 to 10 gallons per 100 gallons). Use a 3 to 5% solution for annual weeds, a 5 to 7% solution for biennial and perennial weeds, and 7 to 10% solution for maximum burndown. Delivery rate for boom applications should be 75 to 200 gals of spray solution per acre; complete coverage of weed foliage is essential. Use a DIRECTED/ SHIELDED SPRAY; contact with crop will cause injury. For hand-held equipment, spray to completely wet all weed foliage but not to the point of runoff. Repeat applications as necessary. Tank mixes are allowed with this product. See label for complete details.
sethoxydim (Poast): PHI 30d, REI 12h, Group 1. Controls grass weeds only. Apply to actively growing grasses (see product label for susceptible stage). Maximum 1.5 pt/A per application, minimum 14-days between applications. Do not exceed 4.5 pt/A per year. Use with crop oil concentrate (2.0 pt/A) or methylated seed oil (1.5 pt/A). Note that crop oil can cause injury under hot and humid conditions. Can also be used as a spot-spray by mixing 1-1.5% (1.3 to 1.9 oz per gallon) Poast and 1% v:v crop oil concentrate (1.3 oz per gallon). Spray to wet, but do not allow runoff of spray solution.