Tractor fertilizing an onion field using liquid nitrogen placement beneath onion beds.

Spraying of herbicide onto an onion field

Using a backpack sprayer to apply pesticide to a field of onions.

Puncturevine (Tribulus terrestris) growing among onion plants.

Onion plants infested with black nightshade, Solanum nigrum.

A harvested yellow onion bulb.

A harvested yellow onion bulb.

A harvested white onion bulb.

A harvested white onion bulb.

A harvested red onion bulb.

Harvested white, yellow and red onion bulbs.

Harvested white, yellow and red onion bulbs

Onion bulbs cut open to reveal damage created by bruising during handling.

Damage to onion plant caused by the herbicide, Prowl.

Prowl herbicide damage to an onion plant.

Prowl herbicide damage to an onion plant.

Damage to onion caused by the use of Prowl herbicide.

Damage to onion caused by the use of Prowl herbicide.

Defoliation of onions due to storm damage.

Bruising of an onion leaf caused by a rainstorm.

Close-up view of herbicide damage on an onion plant.

Close-up view of herbicide damage on an onion plant.

Herbicide (Prowl) and crop oil damage to an onion field.

Close-up view of herbicide (Prowl) and crop oil damage to an onion.

Close-up view of herbicide (Prowl) and crop oil damage to an onion.

Severe damage to onion plants from a hailstorm.

Wind and temperature damage on onion seedlings.

Onion, field day, people, drip irrigation

Graph showing growth curve of the onion variety "Colorado 6."

Onion research and demonstration plots, Colorado State University Extension.

Harvesters used for field harvesting of onions.

Drip system just beginning to irrigate a field of onions.

Equipment used as part of a drip irrigation system for onions.

Field carts for sorting or bagging of onions at harvest.

Vacuum planter in use, planting onions.

Iris Yellow Spot Virus, onion, field preparation, equipment, tractor, roller harrow

Iris Yellow Spot Virus, onion, field preparation, equipment, tractor, roller harrow

Equipment used in a drip irrigation system for onions in western Colorado.

An onion transplanter in use on a field at Colorado, USA.

A cultivator in operation on an onion field in Colorado, USA.

A cultivator in operation on an onion field at Colorado, USA

A cultivator in operation on an onion field at Colorado, USA

A cultivator in operation on an onion field at Colorado, USA

A cultivator in operation on an onion field at Colorado, USA

Cardy nitrate meter for measuring soil fertility levels.

Equipment for use in setting up drip irrigation in an onion field.

Cultivator used in setting up a drip irrigation system in an onion field.

COAGMET and Spectrum weather stations in field plots for research on bacterial diseases of onions, Yuma, CO, 2004.

COAGMET and Spectrum weather stations in field plots for research on bacterial diseases of onions, Yuma, CO, 2004.

Closer view of tractor fertilizing an onion field using liquid nitrogen placement beneath onion beds.

Close-up view of tractor used for placing liquid nitrogen fertilizer beneath onion beds.

Herbicide application to an onion field prior to planting.

Equipment used to sort pearl onions.

A center-pivot irrigation system in use on an onion field.

A weather station equipment on an onion field.

A weather station equipment on an onion field.

A weather station equipment on an onion field.

A weather station equipment on an onion field.

A weather station equipment on an onion field.

A weather station equipment on an onion field.

A weather station equipment on an onion field at Rocky Ford.

A weather station equipment on an onion field at Kersey.

A weather station equipment on an onion field.

A weather station equipment on an onion field.

A weather station equipment on an onion field.

Sprinkler irrigation of onions.

Spectrum weather station set up in a research plot to model parameters in a study on diseases of onions.

Remote electronic weather station used for research on dry beans and onions - Ault, Colorado

Onion planter (tractor) in use.

Onion processing shed at Montrose, Colorado.

A truck used for the installation of a weather station equipment in an onion field.

An onion top-roller attached to a tractor in the field.

A tractor used for undercutting onion transplants in the field.

A tractor cultivating an onion field in Colorado.

A tractor cultivating an onion field in Colorado.

Truck loaded with onions at a processing shed in Montrose, Colorado.

Onions growing in pots in a research greenhouse.

Potted onions growing in a research greenhouse facility.

Scenic view of an onion field.

Onion production field.

A drip irrigation system in use on an onion field near Rocky Ford in Colorado.

View of a field of newly transplanted onions.

Onion fields in the Tenerife Valley, Colombia.

Furrow irrigation of onion beds.

Onions maturing in a field irrigated with a center pivot system, prior to harvest.

Field trial during research on onion thrips and Iris Yellow Spot Virus in Delta, Colorado, 2004.

Onion harvest, rolled tops

Onion harvest, rolled tops

A field of young onion plants under a center pivot irrigation system.

A furrow irrigated onion field.

A field of onion plants under a furrow irrigation system.

Drip irrigation of onions in California.

Field trial of the "El Charro" variety of onion, ready for harvest.

Field of onion transplants, showing proper spacing of plants.

Field of transplanted onions, demonstrating proper spacing of plants.

Onion breeding cages, Genetic research, Flowering, Screenhouse, Equipment, Seed quality

Field of flowering onions for seed production.

Onion flower buds emerging from the "bud" at the top of a stalk.

Onion leaf with dew on it, a factor in research modeling onion diseases.

A collection of some vegetables including white, yellow and red onions.

A collection of some vegetables including white, yellow and red onions.

A collection of some vegetables including white, yellow and red onions.

A collection of some vegetables including white, yellow and red onions.

Bags of onions awaiting shipment to market in Tenerife, Colombia.

Onions bagged and curing in a field that had been irrigated with a center pivot system

A tractor with an attached undercutter used for onion harvesting in the field.

A tractor with an attached undercutter used for onion harvesting in the field.

dehydrator onions

Bagged onions curing in the field, Rocky Ford, Colorado.

Truck harvesting onions.

A tractor undercutting onion transplants in the field during a harvesting operation.

Undercut onions on the field during a harvesting operation.

Onions curing in bags.

A scenic view of onion harvesting in the field.

Using a tractor to top onions in preparation for harvest.

Harvesting onions using a mechanical harvester.

Bagged onions curing in the field, post harvest.

equipment, harvest, rolling, undercutting onions, equipment, tractor, cutter 

rolling, undercutting onions, harvest

Onion culls piled and spread in a field could result in unwanted volunteer plants the next season. Sheep in the background.

Onion culls left lying in the field after harvest.

Culls left in the field can sprout ("volunteer") and promote diseases in onion fields.

Onion culls piled in a heap following harvest and sorting.

A pile of culled red onions discarded in the field.

Scouting onions, Larry Duell, Diesease, Insect, Pest, Crop consulting

Spinkler irrigating onion seedlings.

Drip irrigation in an onion field.

Drip irrigation in an onion field.

Close-up view (between rows) of drip irrigation in an onion field.

Drip irrigation in a California onion field.

Onions being shipped to market in a bus - Tenerife, Colombia.

Onions being shipped to market via bus in Tenerife, Colombia.

Vegetative chimera - an abiotic condition in onions.

Disked onion plants on a field in Colorado.

Yellow onions at the bulbing stage of development

Onion transplants with soil excavated to show root development.

A bundle of red onion transplants, ready for planting.

Morphology of an onion plant at the bulb initiation stage.

Newly transplanted onion plants on a field at Colorado, USA.

Workers transplanting onions on a field at Colorado, USA.

Workers transplanting onions on a field at Colorado, USA.

Workers transplanting onions on a field at Colorado, USA.

Workers transplanting onions on a field at Colorado, USA.

Workers transplanting onions on a field at Colorado, USA.

Onion transplants being set out in the field.

Field worker planting onion transplants.

Field workers planting onion transplants.

Preparing onions for the storage shed

Market class onions from variety trials: PSR93088, El Charro, and Mambo.

Bulb of a yellow onion

Yellow onion bulbs

Yellow onions

A grader being used to sort yellow onions.

Experimental plots in an onion/weed trial.

A volunteer onion plant in a cabbage field as a weed.

Onion seedlings with flag leaf symptoms on the field.

Red onion bulbs on the field after harvesting.

Cropped yellow onions at maturity in the field.

Garden onion pelleted seeds during seed quality inspection.

Straw mulch applied onto an onion field as part of onion thrips management research at Colorado, USA.

Straw mulch applied onto an onion field as part of onion thrips management research at Colorado, USA.

Straw mulch applied onto an onion field as part of onion thrips management research at Colorado, USA.

Straw mulch applied onto an onion field as part of onion thrips management research at Colorado, USA.

Straw mulch applied onto an onion field as part of onion thrips management research at Colorado, USA.

Straw mulch applied on to onion plots as part of an onion thrips management research on a field at Colorado, USA.

Straw mulch applied on to onion plots as part of an onion thrips management research on a field at Colorado, USA.

Straw mulch applied on to onion plots as part of an onion thrips management research on a field at Colorado, USA.

Straw mulch applied on to onion plots as part of an onion thrips management research on a field at Colorado, USA.

Straw mulch applied on to onion plots as part of an onion thrips management research on a field at Colorado, USA.

Computer set up for entering data in an onion storage shed.

Onion research plots at ARDEC in 1999.

Onion research plots at Rocky Ford in 1999.

A field of matured onions involved in an onion variety trial.

Harvested yellow onions involved in an onion variety trial

Harvested red onions involved in an onion variety trial.

Harvested white onions involved in an onion variety trial.

A scenic view of harvested onions topped and bagged in a field near Kersey.

A mid-season onion field showing a Pivot 39 access.

Field plots for research on bacterial diseases of onions, Yuma, CO, 2004.

Volunteer onion plants in a winter wheat field

An onion seedling with probable abiotic disease symptoms in the field.

A management process of pesticide and fertiliser application during onion cultivation.

Pesticide application on an onion field.

Pesticide application on an onion field.

A micro-climate weather station on an onion field.

A micro-climate weather station on an onion field.

Cages used to maintain seed quality while studying the genetics and breeding of onions.

An onion field with a split bulb showing symptoms of oil damage.

Strips of onions in a variety trial on the field.

An onion plant at the pre-bulbing stage of development in the field.

Onion plants at the pre-bulbing stage of development in the field.

Onion plants grown from large-sized seedsets in bolts.

Onion plants grown from large-sized seedsets in bolts.

Leaf color differences of different onion varieties in the field.

Leaf color differences of different onion varieties in the field.

Onion plants at near-maturity in the field.

Experimental research into the use of a non-registered defoliant as a pre-harvest treatment of onions.

Experimental research into the use of a (non-registered) defoliant as a pre-harvest treatment of onions - closer view of plants.

Experimental research into the use of a (non-registered) defoliant as a pre-harvest treatment of onions - closer view of affected plants.

Experimental research into the use of a (non-registered) defoliant as a pre-harvest treatment of onions.

Unloading of harvested onions to a storage shed.

An Air/Humidity control unit at the onion storage shed.

Matured onions on the field during a harvesting operation.

A windrow harvestor in operation during onion harvesting in the field.

A windrow harvestor in operation during onion harvesting in the field.

Micro-pipetter in use in research into bacteria of onions.

A scenic view of transplanted onion curing in bags on a field at Montrose.

A field of onion plants at maturity showing different varietal plant morphologies.

The damage to the basal plates of onion transplants due to high temperature stress.

The damage to the basal plate of an onion transplant due to high temperature stress.

Strips of onion plants on a study field.

Onion plants at maturity on a variety trial field.

Chimera of an onion plant in the field.

Experiment in topping onions by cutting the plants by hand, to similate the effects of storm damage.

Experiment in similating the effects of storm damage to onions: control plot, 0% of plants topped by clipping.

Experiment in similating the effects of storm damage to onions: control plot, 50% of plants topped by clipping.

Experiment similating the effects of storm damage to onions. Plants were topped by clipping.

Experiment similating the effects of storm damage to onions. Plants were topped by clipping.

Scott Fichtner taking onion biomass measurements in the field.

Raw garden onion seeds during a seed quality inspection exercise.

Close-up view of an onion seedling at the loop stage, showing the "knee" at the apex of the loop.

A onion seedling on a crusted field at Colorado, USA.

A post-emergence death of an onion seedling due to soil crusting.

A post-emergence death of an onion seedling due to soil crusting.

A post-emergence death of an onion seedling due to soil crusting.

A post-emergence death of an onion seedling due to soil crusting.

Onion seedlings

Onions being irrigated from a ditch system.

Water and soil erosion in an onion furrow.

Field, disked and plowed in preparation for planting onions and conducting research on Iris Yellow Spot Virus.

A field has been disked and plowed in preparation for planting onions and conducting research on Iris Yellow Spot Virus.

Field, disked and plowed in preparation for planting onions and conducting research on Iris Yellow Spot Virus.

Poor emergence of onion seedlings due to high soil salinity and crusting.

Poor emergence of onion seedlings due to high soil salinity and crusting.

Poor emergence of onion seedlings due to high soil salinity and crusting.

Drip irrigation of onions in a California field.

Sprinkler irrigation in operation in an onion field.

Gas well in an onion field.