Land preparation• Utilize the stale seed

bed technique to reduce weeds

• Plow or chisel if necessary (depth: 30 cm)

• Rotary harrow with horizontal axis before hilling (depth: 15 cm)

• If necessary to dry the soil: tooth harrow

Fertilization• Apply 60 lbs/acre of

phosphorus fertilizer• Apply 50 lbs/acre of

nitrogen fertilizer• Apply 55 lbs/acre of

potassium fertilizerPests

Flies • Install traps

Planting• Optimal sowing dates

vary with locality, soil type and variety: follow production guidelines

• Onions may be direct sown or transplanted.Where direct sown:• Sow at 25 mm

depth• 30 to 40 cm

between rowsPests

• Apply preventative pest spray for ants, cut worms and nematodes

Onion fly• Create a buffer zone

‘Green Banner’ on the edgeofthefields

Seedling fly• Foliar treatments as

recommendedDiseases

• Fungi and bacteria are predominant

• Use clean water and good crop moisture control

• Sow on warm soil

Weeding• Apply a herbicide if

necessary• Hand weeding best al-

ternative to herbicide application

Diseases Botrytis

• Install spore sensorsInsects Gray worm

• Begin to screen for presence

Onion and seedling fly:• Begin to screen for

damage

Weeding• 1st mechanical

weeding when the onion has 2 leaves

Fertilization• Apply fertilizer: 20

lbs./acre of phospho-rus; 70 lbs./acre of nitrogen; 80 lbs./acre of potassium

• Apply sulphur in the form of ammonium sulphate

• Apply a foliar spray with B, Mg, Mn, & Zn

Diseases• Apply fungicides &

herbicides Botrytis• Continue screening• Start preventive

treatmentfromfirstspot appearance

Insects Gray worm

• Continue screening; if necessary, treat in the evening

Onion and seedling fly:• If damage > 5 to 10

%, apply required foliar insecticides

• Mow the edges of fields

FertilizationStage 3 leaves:• Apply 20 lbs./acre of

nitrogen fertilizer• Apply 25 lbs./acre of

potassium fertilizer• Add calcium (Ca),

sulfur (S) and manga-nese (Mg) as needed (ifdeficientinthesecompounds) via foliar spraying

Weeding• 2nd mechanical

or hand weeding between rows if necessary

Insects • Apply herbicides,

fungicides, and surfactant at recom-mended rates

Thrips• Start screening• If treatment needed,

use nozzles with brush jet or double brush - volume of water > 500 L/ha

• Take advantage of the dew

Disease• Continue screening

Weeding• Weed control is vital,

especially in early growth stages

• Manual weeding as required

Irrigation• Irrigate as needed

Insects• Continue daily

screeningDisease

• Continue daily screening

Irrigation• Increase irrigation (peak

water demand at this stage of the crop)

Weeding• Weeding as required

InsectsThrips, Leaf Minors and Beet Army worms• Scout, use pheromone

traps, hand picking• Integrated Pest Man-

agement (IPM)• Pesticides as last resort

Disease• Screenfielddailyfor

pest and diseaseBotrytis• Screening; the thresh-

old: 3 lesions on old leaves and 1 on young leaves

• Adjust the amount of slurry at the culture stage

• If prolonged rain, use systemic fungicides

Downy mildew• Interveneinfieldand

neighboringfieldsiffirstsymptoms appear

Bacterial rot• Limit sprinkler irrigation• Apply preventative pest

sprays as required

• Avoid activities that may damage bulbs

• DO NOT mold up bulbs

Irrigation• Reduce irrigation; only

irrigate as neededFertilization

• Application at this stage to the discretion of the producer

• Avoid applying nitrogen fertilizers as it affects bulb quality at storage

Weeding• Weed control not

necessary at this stage and onwards as emerging weeds will not affect yield

• Continuefieldsanita-tion as needed

Insects• Continue daily

screeningDisease

• Continue daily screening

Irrigation• Cease irrigation 7

days prior to harvestHarvest screening

• Mature onion tops begin to fall and dry (> 50%); When more than 50% of the sheaves fall (“break-neck is observed”), the crop can be harvested

• Maximum yield is attained when tops are completely down and dry

• Yields may increase 25 to 30% between the stage when tops begin to go down, and the leaves are fully down and dry

• Optimum time for harvest must be a balance between highest yields and reduced bulb storage quality, if there is any intent to store rather than immediately sell the onions

Harvest • Lift onions carefully

by hand• Cut the leaves at + 2

cm from the neckDrying

• Leaveinfieldfor3-7days to be dried by the sun (minimum 2 days if weather allows)

• Once dry, attach in packs of 6 to 8 or windrow onion in thefield

• Alternatively, onions can be placed in a commercial dryer for at least 3 days

Curing• Cure onions for 1-2

weeks in a shaded, well-ventilated place before storage

Field management • Abandonedfields

must be harvested and immediately buried. Caution: if Frontier Herbicide has been applied, do not revert to onion, green onion, celery or carrot

Sorting and Grading• Sort harvested crop

for quality, removing diseased or damaged pieces

• Grade onions in view of different market needs prior to storage (e.g. high value market, export, agroprocessing, etc)

Storage• Store onions in a cool,

dry area• Onions can be stored

up to 4 months under the appropriate conditions

Diseases• Onions should be

inspected periodically for deteriorated bulbs

ONIONSSite Selection

• Flat terrain, good drainage, resistant to erosion, not prone to weed infestation

• While all types of soil are suitable, sandy loam soil types yield best results

Soil Type• SoilpHshouldnotbeacidic(lessthanpH6);fine,

loose soil tilth; free from stones, trash and weeds• If the soil is compact, use excavator at 45°

Choice of cultivar• Consider market demand, soil type, climate con-

ditions (e.g. photoperiodicity: short-day onions recommended in Caribbean), equipment, irrigation capacity

• Choosenew,certifiedseed• Saturn, 10210, and Mikado are recommended va-

rietiesRotation

• A 3 to 5 year rotation recommended to reduce the buildup of pathogens

• Avoid same family plants as previous crops (e.g. escallion)

• Consider onion companion planting (group of crops growntogether)forbeneficialplantinteraction

• Foe crops: asparagus, beans, peas, sage• Friendly crops: beets, brassica family, carrot, cham-

omile, cucumber, dill, leeks, pepper, potato, roses, spinach, squash, strawberry, summer savory, to-mato

Planting Schedule• Best results are observed by planting September to

January so as to avoid harvesting in the wet season (June to October)

Irrigation Requirements• Approx. 18,000 gallons/acre at germination (weeks

1-2); 30,000 gallons/acre per week during vegeta-tive development (weeks 3-11); 42,000/acre gallons per week at bulb initiation (weeks 12-13); 35,000 gallons per week (weeks 14-16) during bulbing

• Irrigation should be discontinued 1 week before harvesting

Fertilization & Other Inputs• Should be based on the results of a soil test, the

needs of the crop, the soil type, climate conditions,

and available fertilizers (NPK)• Important secondary and micro-nutrients include S,

Mn, Cu, Mo• Avoid applying nitrogen fertilizers after bulbing to

ensure good shelf-life of produce• Do consider the 4R’s of nutrient management: right

source, right rate, right time, and right place• Input list should include seeds, pesticides,

fungicides, herbicides, and fertilizers. Read product instructions carefully; products should be applied at the recommended rates

TECHNICAL ITINERARY

LAND PREPARATION PLANTING GERMINATION 1-3 LEAVES 3-5 LEAVES 5-7 LEAVES BULB INITIATION BULBING BULB MATURATION HARVEST/CURING POST-HARVEST

LEGENDSPESTS

WEEDS

DISEASE

TOOLS

SCREENING

Consult your local Extension Officer for further details on crop

production.

GENERAL GUIDELINES