Download the IPM Onion Scouting Form (188K pdf).

Link to New York Onion Crop Profile

New York IPM Elements for onions

Link to Resource Guide for Organic Insect and Disease Management

Recommended Varieties

Transplants	Seeded, main season
Mars (red)(F1)	Listed in approximate order of maturity.
Renegade (F1)	Early Yellow Globe strains
Redwing (F1)	Benny's Red (red)
Corona (F1)	Precedent (F1)
Viceroy (F1)	Gazette (F1)
Sweet Spanish types	Mars (red) (F1)
Candy (F1)	Ricochet (F1)
Sets	Mambo (red) (F1)
Ebenezer	Pennant (F1)
Stuttgart	Festiva (F1)
Green or Bunching	Millennium (F1)
Beltsville Bunching	Duration (F1)
Southport White Globe	Bradley (F1)
White Portugal	Endurance (F1)
White Sweet Spanish	Crusader (F1)
Seeded, early	Criterion (F1)
Early Yellow Globe strains
Norstar (F1)
Arsena (F1)
Hustler (F1)
F1 = hybrid

Many additional varieties are suitable for production, and new ones are being developed each year. Growers should test new varieties routinely to determine which perform best on their farms, choosing those with tolerance or resistance to diseases such as pink root and Fusarium basal rot if their fields have a history of these diseases.

Planting Methods

Onions are a cool-season crop that requires a long growing season to produce good bulb yields of high quality. In New York, most dry bulb onions for commercial production are grown on muck soils because of the advantages offered by these soils. These include a uniform water supply, early crop establishment, and ease of mechanical harvesting. Most mineral soils require irrigation to produce a good yield.

Because onion plants begin to bulb in early summer when days reach sufficient length, it is important to establish the crop early to assure that plants are large enough to develop a large bulb. The crop also must mature early enough to allow curing of the bulb before cool, wet weather arrives in the fall. Onions may be grown from seeds, sets, or transplants, but because of economics direct seeding is the usual practice in New York. Row spacing varies considerably depending upon weed and foliar disease management, seeder capability, and harvesting equipment. In-row spacing also varies depending upon variety, desired bulb size, row spacing, soil type, and other management considerations. To ensure good quality bulbs for storage and to produce acceptable yields, plants must not be spaced too far apart in the row.

Onion yields in New York vary considerably from year to year and from field to field. Average yields are around 300 to 350 cwt per acre but can reach 500 cwt or more per acre when growing conditions are good and proper management is practiced.

Crop rotation and disease management article

Fertility

Maintain a pH of 6.0 to 6.8 on mineral soils. Consider liming muck soils when pH is 5.2 or below. See Table 21.1 and Table 21.2 for the recommended rates of nitrogen, phosphorus, and potassium.

Cornell cover crop decision tool

See Cornell article on nutrient deficiency symptoms

Go to the Cornell Nutrient Analysis Lab website to find out how to get soil samples tested.

Cornell Soil Health website and manual

SARE Publication: "Building Soils for Better Crops"

SARE publication: "Managing Cover Crops Profitably"

Table 21.1 Recommended nutrients based on soil tests for onions grown in mineral soils.
N pounds/acre	P2O5 pounds/acre				K2O pounds/acre			Comments
	Soil Phosphorus Level				Soil Potassium Level
	low	med.	high		low	med.	high
90-120	150	100	50		150	100	50	Total recommended.
30-40	100	50	0		100	50	0	Broadcast after plowing
30-40	50	50	50		50	50	50	Apply in band at seeding or transplanting.
30-40	0	0	0		0	0	0	Apply at 4 to 5 week stage.

 

Table 21.2 Recommended nutrients based on soil tests for onions grown in muck soils.
N pounds/acre	P2O5 pounds/acre				K2O pounds/acre			Comments
	Soil Phosphorus Level				Soil Potassium Level
	low	med.	high		low	med.	high
100-1251	150	100	50		150	100	50	Total recommended.
30-40	150	100	50		150	100	50	Broadcast after plowing
1: On deep well-drained mucks, 50 pounds per acre may be sufficient for best yields, but higher rates may accelerate seedling growth and maturity of later hybrids. Muck onions have not responded to nitrogen sidedressings except in rainy seasons.

See UC Davis post harvest guide for dry bulb onions

See UC Davis post harvest guide for green bunching onions

See North Carolina post harvest guide for onions

See Cornell Report: Food Safety Begins on the Farm

See Cornell "Smart Marketing" series.

See USDA grade standards for fresh vegetables and processed vegetables

See USDA Marketing site

See current wholesale prices from US markets

SARE Publication: "Marketing Strategies for Farmers and Ranchers"

SARE Publication: "Direct Marketing Resource Guide"

Table 21.3 Sprout inhibitor compound.
Comparing Environmental Risks of Pesticides In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
Common Name Trade name	Rate/A Product	PHI (days)	REI (hours)	Field Use EIQ	Comments
maleic
Royal MH-30 1.5 lb/gal	1.33 gal	-	12	36	Temperatures should be below 85°F at application or below 80°F if temperatures are expected to exceed 85°F later in the day. Compatible with most insecticides and fungicides, but separate application is recommended.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

Disease Management

| Bacterial soft rot | Slippery skin | Bacterial canker | Sour skin |Fusarium basal rot |
|Botrytis leaf blight | Botrytis neck rot |
| Damping-off | Downy mildew | Flower blight | Nematodes |
| Pink root | Purple blotch | Smut | Stemphylium leaf blight |
| Onion yellow dwarf virus | Iris yellow spot virus |

SARE Publication: "A Whole-Farm Approach to Managing Pests"

Ontario, Canada fact sheet on onion diseases

Time for concern: Any time after bulbing, in storage and transit

Key characteristics: Bacteria can spread by splashing rain and enter through natural openings and mechanical injuries. The affected tissue becomes soft, spongy, and watery, and may cause interior breakdown in the bulb. B. cepacia a versatile bacterium found in soil and water, is the most important disease of onions. B cepacia strains comprise a heterogeneousgroup. Thus, copper-based bactericides can vary in their ability to reduce bacterial populations as shown in recent tests conducted in plate cultures. See Reference 1.

Management Option	Recommendation
Resistant varieties	Avoid planting susceptible varieties such as Spanish onions.
Harvest	Minimize injuries to maturing and harvested bulbs. Undercuting, lifting and wind rowing of bulbs is an important practice.
Postharvest	Dry onions thoroughly before storing at a temperature of 32 to 33°F and less than 70 percent relative humidity with good ventilation.
Crop rotation,	B. cepacia populations can be reduced with rotations, although the specific crop(s) to be used remains under investigation.Crop rotation and disease management article Cornell Forage Species Selection Tool
Scouting/thresholds, Site selection, Seed selection/treatment, and Sanitation	These are not currently viable management options.

Compound(s)
Comparing Environmental Risks of Pesticides In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
Common name Trade Name	Rate/A Product	PHI (days)	REI (hours)	Field Use EIQ	Comments
copper compounds
Champ F   or OLF Copper comparison article	0.66-1 pt	0	12/24(see label)	9-14	Label varies with manufacturer and formulation.
* Other labeled formulations.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

Fusarium basal rot, Fusarium oxysporum f. sp. cepae

Ontario, Canada fact sheet on onion diseases

Time for concern: Later stages of the growing season and in storage
Key characteristics: Roots of plants infected early in the growing season can decay and die; plants turn yellow and wilt. The bulbs of plants infected later in the season may appear normal, but inner neck tissue may feel soft. Portions or all of the basal plate develop a firm dry rot, turn brown, and die. Under moist conditions, the diseased scales can develop white mold. See Reference 1.

Management Option	Recommendation
Resistant varieties	Plant resistant varieties such as Eskimo, Frontier, Benchmark, Millenium, Condor, Prince, Copra, Duration, and Celtic.
Crop rotation	The disease persists as spores in the soil. Minimum three year rotation with crops other than onions. Crop rotation and disease management article Cornell Forage Species Selection Tool
Harvest	Avoid mechanical damage to bulbs during spray applications and harvest.
Postharvest	Keep onion storage areas dry and well ventilated.
Scouting/thresholds, Site selection, Seed selection/treatment, and Sanitation	These are not currently viable management options.
Compound(s)	No pesticides are available to manage Fusarium basal rot.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

Table 21.4  Thresholds for Botrytis leaf blight.
Number of plants	Cumulative number of lesions on 3 oldest leaves of each plant
	Lower limit	Upper limit
15	17	73
20	28	92
25	39	111
30	50	130
35	62	148
40	74	166
45	86	184
50	99	201

Key characteristics: Infection is favored by cool, wet conditions and poor drying and curing of harvested onions. The neck tissue of infected bulbs may shrivel; bulb scales may become soft and brown, and a superficial gray mold may develop. This disease often affects injured onions in storage. See Reference 1.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

Key characteristics: Seeds may rot and fail to germinate or newly emerged seedlings may rot at the soil line and wilt or collapse. The roots and shoots of surviving seedlings may have a brown rot and fail to thrive. See Reference 1.

Management Option	Recommendation
Scouting/thresholds	Record the occurrence and severity of damping-off. No thresholds have been established. Download the IPM Onion Scouting Form (188K pdf).
Resistant varieties	Avoid susceptible varieties such as Spanish onions.
Seed selection/treatment	Plant disease-free seed treated with an appropriate fungicide.
Transplants	Grow transplants in steam-treated soil or soilless mix to ensure freedom from disease.
Crop rotation, Site selection, Postharvest, and Sanitation	These are not currently viable management options.

Compound(s)
Comparing Environmental Risks of Pesticides In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
Common name Trade Name	Rate/A Product	PHI (days)	REI (hours)	Field Use EIQ	Comments
mefenoxam
Ridomil Gold EC or OLF	0.5-1 pt	-	48	7-14	Application may be made PPI or as a soil surface spray after planting.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

See Cornell fact sheet on DM

Ontario, Canada fact sheet on onion diseases

Time for concern: Mid- to late July through the end of the season

Key characteristics: Effects include heavily blighted onion leaves, reduced bulb growth, destroyed seed stalks, and spongy neck. Pale greenish yellow to brown elongated areas of varying sizes develop on infected leaves and seed stalks. Symptoms first appear on older leaves. If weather conditions are moist, masses of gray to violet fungal spores will envelop the infected leaves. Leaves become girdled and collapse. Cool temperatures of less than 72°F and the presence of rain or dew providing relative humidities greater than 95% are required to initiate infection. Sporulation occurs at night and spores are easily windborne considerable distances during the early morning hours. Spores are very susceptible to drying, but can survive on host tissue 1-3 days. See References 1 and 3.

Management Option	Recommendation
Scouting/thresholds	Look for downy mildew while scouting for other pests. If you suspect downy mildew, remove the infected leaves, place them in a plastic bag, and mark the location. Send the sample to an IPM specialist to confirm your diagnosis. Once diagnosed, a fungicide treatment is required. A forecasting system called Downcast, developed by Canadian researchers, can be used to determine fungicide application timing. See Reference 1 for a more detailed description of Downcast. NEWA makes daily Downcast forecasts. Download the IPM Onion Scouting Form (188K pdf).
Resistant varieties	No resistant varieties are available.
Crop rotation	Minimum two year rotation away from onions to break the disease cycle. Crop rotation and disease management article Cornell Forage Species Selection Tool
Site selection	Do not grow perennial onion species in the vicinity of commercial onion fields.
Transplants	Transplants should be mildew-free.
Seed selection/treatment and Postharvest	These are not currently viable management options.
Sanitation	Practice good sanitation. The fungus overwinters in volunteer onions as oospores and as mycelium on infected bulbs in cull piles. Remove and destroy cull and volunteer onions.

Compound(s)
Comparing Environmental Risks of Pesticides In the "Field Use EIQ" column is the range of EIQ (Environmental Impact Quotient) values for the rate range recommended for each pesticide (lower EIQ = lower environmental impact). Other pesticide risk models are useful for specific purposes. WIN-PST is required for some USDA NRCS conservation plans.
Common name Trade Name	Rate/A Product	PHI (days)	REI (hours)	Field Use EIQ	Comments
azoxystrobin (dry bulb and green bunching)
Quadris F	9.2-15.4 fl oz	0	4	2-4	Do not apply more than 1 application of Amistar, Quadris or Quadris Opti (Group 11) before alternating with a fungicide that has a different mode of action. See comments below for maneb/mancozeb program. Do not spray these products where spray drift may reach apple trees or use same sprayer to apply sprays to apple trees.
Amistar	3-5 oz	0	4	3-4
azoxystrobin+chlorothalonil(dry bulb and green bunching)
Quadris Opti	2.4-3.6 pt (dry) 2.4-3.7 (green)	7 (dry) 14 (green)	12		Do not apply more than 1 application of Amistar, Quadris or Quadris Opti (Group 11) before alternating with a fungicide that has a different mode of action. See comments below for maneb/mancozeb program. Do not spray t