Crop profile for asparagus in Canada, 2024

Asparagus (Asparagus officinalis) is a member of the Asparagaceae family. It is a perennial, monocotyledonous plant grown for its tender green shoots (spears) that are harvested in the spring. This crop is highly prized for its delicate flavour and tender texture.

The cultivation of this crop dates back to 200 BC in the Mediterranean region. It was brought to North America by European settlers in the 1800’s, and is now grown in most temperate regions of the world.

Asparagus breeding in Canada has progressed to the point where all cultivars grown in Ontario are male hybrids. These hybrids have replaced many open-pollinated varieties planted in Canada. The University of Guelph has developed and registered hybrids including: ‘Guelph Millennium’, registered in 2003; ‘Guelph Evolution’, ‘Guelph Equinox’ and ‘Guelph Eclipse’, registered in 2017; and ‘Guelph Galaxy’, registered in 2024. The new hybrids have an improved cold tolerance.

Preface

National crop profiles are developed by the Pest Management Centre of Agriculture and Agri-Food Canada (AAFC). The crop profiles provide baseline information on production and pest management practices and document growers’ needs to address pest management gaps and issues for specific crops grown in Canada. This information is developed through extensive consultation with stakeholders and data collected from reporting provinces. Reporting provinces are selected based on their acreage of the target crop (>10 % of the national production) and provide qualitative data on pest occurrence and integrated pest management practices used by growers in those provinces. For asparagus production, the reporting provinces are Ontario and Quebec.

Information on pest issues and management practices is provided for information purposes only. For detailed information on growing asparagus, the reader is referred to provincial crop production guides and provincial ministry websites listed in the Resources Section at the end of this document. For guidance about crop protection products registered for pests on asparagus, the reader is referred to provincial crop production guides and Health Canada’s Pesticide label database.

Every effort has been made to ensure that the information in this publication is complete and accurate. Agriculture and Agri-Food Canada does not assume liability for errors, omissions, or representations, expressed or implied, contained in any written or oral communication associated with this publication. Errors brought to the attention of the authors will be corrected in subsequent updates.

Agriculture and Agri-Food Canada gratefully acknowledges the contributions of provincial crop specialists, industry specialists and growers in the gathering of information for this publication.

Crop production

Industry overview

Asparagus is best known as a fresh vegetable in the marketplace; however, this crop is also canned, frozen and pickled. A small amount of white asparagus is also produced for specialty markets; white asparagus is grown underground, either covered by a thick layer of soil or plastic, and does not produce chlorophyll.

In 2024, the total acreage of asparagus production in Canada was 2,494 hectares with a production of 10,747 metric tonnes and a farm gate value of $53.9 million (Table 1). Asparagus exports in 2024 were valued at $19.9 million while imports totalled $99.3 million (Table 1).

Table 1. General production information for asparagus in Canada, 2024

Production regions

The largest producing provinces of asparagus in Canada are Ontario and Quebec, with 1,792 hectares (72% of national production) and 470 hectares (19% of national production), respectively (Table 2).

Cultural practices

Asparagus is best suited to soils that are deep, well-drained, porous and friable, such as a deep sandy-loam or muck soil in some provinces. An organic matter content of at least 3% is ideal. Heavy soils and stony ground are not suitable for growing asparagus as they can cause malformed spears. In addition, heavy soils usually lack sufficient porosity for good aeration and optimal water drainage; asparagus plants do not like ‘wet feet’ because excess moisture around the roots can exacerbate disease. Asparagus is very deep-rooted, with roots reaching depths of up to three metres. For this reason, it is important that planting sites not have a hard-pan or a plough layer that will interfere with root development. As asparagus is an early season crop, sites with good air circulation that are less prone to frost are preferable for planting. Producers can choose to plant asparagus seeds, transplants or one-year old crowns, although the planting of seedlings or crowns is more conducive to obtaining a uniform stand. Seedlings may be started in the greenhouse in the early spring and transplanted after 10 to 14 weeks of growth. Crowns are grown from seed sown into a nursery bed. Often, crowns are produced by asparagus growers who specialize in crown production. Planting is done as soon as possible in the spring after soil temperatures have reached 10 °C. Asparagus crowns are planted in furrows 15 to 30 cm deep. These furrows are gradually filled in as the asparagus plant becomes established. Asparagus plantations started with crowns may be harvested in the second year after planting in Ontario or in the third year in Quebec. Harvesting lasts up to 10 days in the second year and for six to eight weeks in the years following, depending on seasonal stressors (that is, temperature, rainfall, irrigation, etc.). Plantations that are started with transplants will require an extra year to produce harvestable spears.

Both male and female clones of asparagus are available. Recent asparagus cultivars introduced from the University of Guelph Asparagus Breeding Program and from Rutgers University in New Jersey, USA, are male hybrid cultivars. Since male hybrids cannot produce seeds, there is no chance for ‘volunteer’ asparagus seedlings to develop and become weeds, later competing for space, water and fertilizer. Male hybrids have been shown to be more productive than female hybrids, producing a higher percentage of #1 grade spears.

Asparagus plantings can be productive for 15 to 20 years, so considerable care is taken in site preparation. Troublesome perennial weeds are eliminated prior to planting. Additions of significant amounts of organic matter are also important in preparing the site. Based on soil testing, fertility adjustments are done at this time and soil pH is adjusted through lime applications if necessary. The ideal pH range for asparagus is 6.5 to 6.8. Windbreaks can be established near new plantings to prevent soil erosion and sand blasting damage to the crop resulting from strong winds.

A schedule for cultural and pest management practices for growing asparagus in Canada is presented in Table 3.

Table 3. General asparagus production and pest management schedule in Canada

April

May

June

July

August

September

October

November to December

Abiotic factors limiting production

Frost injury

Late spring frosts can damage early emerging spears resulting in yield loss. Affected spears develop a water-soaked appearance and become limp and furrowed as they thaw. The largest and most vigorous spears are the first to appear and if those are damaged by frost, a disproportionate amount of the yield can be lost. In addition, the development of new shoots by frost-injured crowns is often delayed. The removal of frost injured spears may reduce this delay but is an additional expense. An early fall frost can kill or severely injure the asparagus fern before the natural senescence process takes place. This reduces the movement of carbohydrates down to the crown. These carbohydrates are important for the overall survival of the plant and are especially critical for spear production the next season.

Excessive heat

Extreme or unseasonably warm temperatures can bring on the asparagus growth too quickly for the usual harvest practices to keep pace. High temperatures in the spring may also shorten the harvest season, and can also reduce yield.

Wind damage

Strong winds can cause newly emerged asparagus stems to curve. Asparagus spears will curve into the prevailing wind because of reduced cell growth on the exposed side. Severely affected spears are usually culled while other, less injured spears are sold as ‘seconds’ at a reduced price. Strong winds can also cause sand blasting, which creates wounds on the tender asparagus shoots that serve as points of entry for disease.

Hollow stem

Hollow stem can be a problem under growing conditions that promote rapid spear growth, typically being more prevalent in younger plantings. It is recognized as a problem during the harvest season, as it impacts the quality and potentially the marketability of the asparagus spears.

Diseases

In this section

• Key issues
  • Asparagus rust (puccinia asparagi)
  • Fusarium crown and root rot (fusarium oxysporum f. Sp. Asparagi and other fusarium spp.)
  • Gray mold / botrytis blight (botrytis cinerea)
  • Phytophthora spear rot (phytophthora megasperma f. Sp. Glycinea and p. Cryptogea)
  • Purple spot or stemphylium blight (pleospora herbarum, anamorph stemphylium vesicarium)
  • Virus diseases: asparagus virus 1 (AV-1) and asparagus virus 2 (AV-2), cucumber mosaic virus (CMV), tobacco streak virus (TSV)

Key issues

• The continued harmonization of pesticide registrations between Canada and the United States is very important to ensure Canadian growers remain competitive.
• There is a need for new conventional fungicides (with different modes of action than those currently registered) and non-conventional fungicides (for example, biopesticides) for the control of a number of diseases of asparagus.
• There is a need for the development of diseases resistant/tolerant varieties through plant breeding.
• For provincial ratings of key disease occurrence, see Table 4.

Asparagus rust (Puccinia asparagi)

Pest information

Damage

The first symptoms of rust infections are slightly raised, light green spots on stems and foliage in early summer. The spots develop into spore-containing pustules that range from cream-coloured to reddish brown. Heavily infected plants die back prematurely in the fall, lose vigour and produce fewer spears the following spring. Spears are not directly affected as they are usually harvested before symptoms appear.

Life cycle

Asparagus rust has a complex life cycle involving the production of multiple types of spores. The disease overwinters as teliospores in asparagus crop residues. The teliospores germinate in the spring and are wind-blown onto emerging shoots where they cause infection, typically on the lower portion of the fern stalks. The resulting lesions are cream-coloured pustules called aecia, which produce and release aeciospores. Aeciospores re-infect the asparagus fern under suitable moisture conditions. Later in the season, uredia blisters appear on asparagus stalks and on foliage. When the uredia blisters break open, they release rust- coloured urediospores that can repeatedly re-infect asparagus under suitable weather conditions. Late in the summer, black lesions form in the foliage that contain the overwintering teliospores.

Pest management

Cultural controls

Spacing plants and rows to facilitate drying of the foliage will reduce the duration of foliar wetness and rust infectivity periods. Monitoring for rust after spears are harvested in the spring will enable timely treatments that prevent the build-up of the disease in the field. The removal of crop debris by light disking of fields early in spring will help reduce the disease carry-over between seasons. Refer to Table 5 for practices used by growers in Canada to manage asparagus rust.

Resistant cultivars: Although currently available varieties have variable tolerance to rust, none are completely resistant.

Issues for asparagus rust

• Work towards the harmonization of pesticide registrations between Canada and the United States is very important to ensure Canadian growers remain competitive.
• There is a need for new fungicides, including biofungicides, in new chemical families that are effective against asparagus rust and will help to prevent the development of pathogen resistance.
• There is a need for the development of new monitoring methods, including the use of spore traps, to monitor rust in asparagus.
• There is a need for the development of new bioclimatic models to forecast rusting.

Fusarium crown and root rot (Fusarium oxysporum f. sp. asparagi and other Fusarium spp.)

Pest information

Damage

Fusarium crown and root rot affects plants scattered randomly throughout a field. The disease causes a brown, soft rot of the roots, reddish elliptical lesions on stems at or below the soil surface and rot of crowns. Ferns may become stunted and wilted and develop yellow to brown discoloration. Affected plants produce fewer spears, and thereby have reduced yields, and eventually may die. The presence of the disease shortens the productive life of an asparagus field. New asparagus crowns planted into fields with a history of Fusarium may become stunted, yellowish and die.

Life cycle

Fusarium crown and root rot is a soil-borne disease. Fusarium invades asparagus roots and crowns directly through root tips or wounds caused by tillage, harvesting knives, insect feeding or sand blasting. Fusarium oxysporum f. sp. asparagi can persist in the soil as chlamydospores (resting spores). Stresses caused by drought, high weed competition and over-harvesting can weaken a plant and predispose it to Fusarium crown and root rot infections.

Pest management

Cultural controls

Since Fusarium spp. are present in most soils, crown rot is almost impossible to avoid. However, maintaining vigorous plants through careful management, including the appropriate use of fertilizer and irrigation, preventing the over-harvesting of spears and generally avoiding stress on the crop, can minimize infection early in the life of asparagus crowns. Other disease management practices include minimizing stress by planting on appropriate sites, avoiding wounding by reducing tillage and avoiding soil compaction. As Fusarium can build-up in soils, fields that have not previously been planted to asparagus are best for new asparagus plantings and replanting asparagus in the same field for many years is not recommended. Refer to Table 5 for practices used by growers in Canada to manage Fusarium crown and root rot.

Resistant cultivars: None available.

Issues for fusarium crown and root rot

• Research is needed to establish management practices (including fumigation) to reduce Fusarium levels and minimize the chances of Fusarium diseases “rebounding” once asparagus is replanted.
• There is a need to develop integrated pest management approaches for the control of Fusarium crown and root rot.
• There is a need for fungicides, including biofungicides, that provide effective control of Fusarium crown rot.

Gray mold / botrytis blight (Botrytis cinerea)

Pest information

Damage

Botrytis infections result in tan lesions with dark borders and yellow halos on asparagus foliage. Under warm, humid conditions and extended periods of foliar wetness, extensive blighting can develop. Crops with dense canopies and poor air circulation are more likely to develop severe disease symptoms. Newly emerged spears may become completely blighted, turning brown to black.

Life cycle

Botrytis has a broad host range and is a common invader of weakened or senescent plant tissues. Masses of grey-brown spores are produced in infected tissues and crop residue, and are carried on air currents to susceptible tissues where they cause new infections. Botrytis also produces resting bodies called sclerotia that enable the long-term survival of the fungus and give rise to conidia that perpetuate the disease.

Pest management

Cultural controls

The elimination of infected crop residue will reduce a source of the fungus in the spring. Minimizing stresses and injuries caused by other diseases and pests will help reduce the development of botrytis blight.

Resistant cultivars: None identified.

Issues for gray mold / botrytis blight

• None identified.

Phytophthora spear rot (Phytophthora megasperma f. sp. glycinea and P. cryptogea)

Pest information

Damage

Spears affected by Phytophthora develop light brown lesions near the soil line. Affected spears become “hooked” as infected tissues cease to grow. Crown vigour and the productivity of an asparagus plant can be significantly reduced by Phytophthora infection.

Life cycle

This disease is soil-borne and is more likely to develop under excessively wet conditions and in areas with heavy soils and poor drainage. The fungus persists in soil as oospores (thick-walled sexual spores). The oospores germinate to produce sporangia and motile zoospores which can infect root and crown tissues. Infection occurs through wounds such as those caused by sand blasting, insect damage and other physical injuries.

Pest management

Cultural controls

Avoid sites with poor drainage and heavy soils when establishing new plantings to reduce the potential for the development of Phytophthora spear rot. Minimizing stresses such as the depletion of carbohydrate reserves of the crown through over-harvesting, will help reduce the impact of the disease on the asparagus. Refer to Table 5 for practices used by growers in Canada to manage Phytophthora spear rot.

Resistant cultivars: None identified.

Issues for phytophthora spear rot

• Phytophthora spear rot is difficult to diagnose in the field and may cause more yield reduction than currently recognized. Improved approaches to field diagnosis of Phytophthora spear rot are required.
• There is a need for harmonized fungicide registrations between the United States and Canada for the control of Phytophthora spear rot to ensure Canadian growers have access to the same pest management options as their competitors.
• There is a need for the development of practices to prevent phytophthora spear rot.

Purple Spot or Stemphylium Blight (Pleospora herbarum, anamorph Stemphylium vesicarium)

Pest information

Damage

Purple spot can infect spears, stems and foliage of asparagus. When infected, small purple lesions one to two millimetres in diameter develop on the spear. If numerous, the spears will not be marketable. Light brown lesions with purple margins develop on the fern and if severe can cause defoliation and dieback. Severe defoliation can result in a weakening of the plant and reduce yield in the following season.

Life cycle

This disease overwinters as pseudothecia (spore producing structures) on fern residue. Ascospores (sexual spores) are released during cool, moist weather during early spring and are dispersed by wind, often landing on the windward side of asparagus spears where they cause primary infections. Wounds caused by sand blasting are common infection sites, but infections may also occur through stomata and directly through the epidermis. The resulting lesions give rise to conidia (asexual spores) that cause new infections throughout the summer.

Pest management

Cultural controls

The removal or burying of crop residue will help reduce disease carry-over between seasons. The use of cover crops such as rye will help to reduce wounds due to sand-blasting, which are important infection sites. Reduced tillage systems are less prone to sand blasting so asparagus produced under these systems can have a lower incidence of Stemphylium blight. Refer to Table 5 for practices used by growers in Canada to manage purple spot.

Resistant cultivars: None identified. More recent male hybrid cultivars may have less tolerance to Stemphylium blight.

Issues for purple spot

• Studies are required to determine the impact of fungicides used for rust control on overall plant health and the development of purple spot.
• Studies are required to establish an integrated approach to the control of purple spot.
• There is the need for additional fungicides, including biofungicides, from new families to prevent and/or delay the development of resistance.
• Monitoring methods, including the use of spore traps need to be developed to aid in the control of purple spot.
• There is a need for harmonized fungicide registrations between the United States and Canada for the control of purple spot to ensure Canadian growers remain competitive.

Virus diseases: Asparagus virus 1 (AV-1) and asparagus virus 2 (AV-2), cucumber mosaic virus (CMV), tobacco streak virus (TSV)

Pest information

Damage

Viral infections in asparagus typically show minimal to no symptoms and require lab testing to verify. The AV-1 has little effect on growth, yield or longevity on its own, but it may increase asparagus susceptibility to other biotic and abiotic stresses. The AV-2 can cause decreased yield and reductions in spear diameter and number of spears in years following infection, ultimately shortening the productive life of asparagus. It also increases the susceptibility of asparagus to infection by Fusarium. Thus AV-2 is a major virus in asparagus and one of the main causes of asparagus decline. Combined infection by AV-1 and AV-2 is of greater concern than each on their own as these viruses have an additive effect on asparagus vigor and yield. The CMV does not produce any obvious symptoms in asparagus and TSV can cause minor stunting, chlorotic or brown streaks on spears and browning of needles but does not affect yield or spear quality. The CMV and TSV are not major concerns in asparagus on their own but can co-occur with AV-1 and/or AV-2 to cause greater reductions in vigor and yield. In some cases, it is unclear whether reported symptoms from viral infections are the cause of the virus itself or the result of increased susceptibility to other stressors or diseases.

Life cycle

Asparagus is the only natural host of AV-1 and AV-2. The AV-1 is spread rapidly through non-persistent transmission by some aphid species and is not found in seed or pollen. Conversely, AV-2 is not spread by insects or nematodes, but rather from contamination of cutting knives and machinery by infected plants. The AV-2 can also be seed- and pollen-borne. The CMV infects over 1200 different plant species and is spread from infected to uninfected asparagus plants through non-persistent transmission by over 80 aphid species. There is no evidence of CMV being seed- or pollen-borne in asparagus but it is in some other plant hosts. Both AV-1 and CMV are considered non-persistent viruses, because they are not retained by leaf-feeding insects who transmit them. The TSV infects over 80 different plant species. It spreads from infected to uninfected asparagus plants via thrips-mediated pollen transfer but is not seed-borne.

Pest management

Cultural controls

Chemical control of aphid populations will not necessarily control the transmission of non-persistent viruses such as AV-1 or CMV. Planting virus-free seeds, transplants or crowns are good practices. Scouting for the presence of aphids in association with changes in plant vigour can be an indication of the presence of a viral infection. Harvest and mulch younger and virus-free fields first and clean knives and machinery between fields. Avoid planting in fields near older asparagus crops which may harbor infection. Refer to Table 5 for practices used by growers in Canada to manage virus diseases.

Issues for virus diseases

A better understanding of virus vectors and their life cycles is needed.

Insects and mites

In this section

• Key issues
  • Alfalfa plant bug (Adelphocoris lineolatus)
  • Aphids: Asparagus aphid (Brachycorynella asparagi) and other species
  • Asparagus beetles: common asparagus beetle (Crioceris asparagi) and spotted asparagus beetle (Crioceris duodecimpunctata)
  • Asparagus miner (Ophiomyia simplex)
  • Cutworms: dark-sided cutworm (Euxoa messoria), sandhill cutworm (E. detersa), variegated cutworm (Peridroma saucia), white cutworm (E. scandens)
  • Japanese beetle (Popillia japonica)
  • Tarnished plant bug (Lygus lineolaris)

Key issues

• There is a need for lower-risk conventional and non-conventional insecticides, including biopesticides, to control a range of insect pests, such as common asparagus beetle, spotted asparagus beetle, asparagus leafminer and aphids.
• There is a need for additional products approved for organic production for the control of insects in asparagus.
• There is a need for conventional and non-conventional pesticides with short pre-harvest intervals for asparagus beetle, and pest control product that are pollinator-friendly (that is, honey bees during asparagus flowering).
• Registration of additional modes of action for insecticides are required for increased control and/or suppression of all insect and mite pests, especially common asparagus beetle and aphids.
• There is a need for harmonization of pesticide registrations between Canada and the US to help Canadian asparagus growers remain competitive.
• For provincial ratings of key insect and mite pest occurrence, see Table 6.

Table 6. Level of pest concern based on occurrence data for insect and mite pests in asparagus production in Canada

Alfalfa plant bug (Adelphocoris lineolatus)

Pest information

Damage

Plant bugs have piercing and sucking mouth parts through which they suck plant juices. The alfalfa plant bug injects toxins into the plant while feeding, resulting in wrinkling and growth distortion of spears and even plant death under severe feeding pressure. Yield losses as high as 10% have been reported. Alfalfa plant bugs present in nearby alfalfa fields may migrate into asparagus plantings when the alfalfa fields are cut.

Life cycle

Adult alfalfa plant bugs overwinter in plant debris. They emerge in mid-April to late-May and feed on asparagus spears. Eggs are laid on host plants including many weed species. Nymphs emerge 10 days later. There are two generations per year.

Pest management

Cultural controls

Good weed control in and around the asparagus planting will make the asparagus planting less attractive to plant bugs. Eliminating crop residue will reduce overwintering sites.

Resistant cultivars: None identified.

Issues for alfalfa plant bug

• There is a need to develop an integrated approach, including new conventional and non-conventional pest control products to control alfalfa plant bug.

Aphids: asparagus aphid (Brachycorynella asparagi) and other species

Pest information

Damage

Asparagus aphids are sap-sucking insects that feed on asparagus ferns. During feeding, they inject a toxin, causing the ferns to develop bushy, distorted growth called “witches brooms”. Feeding weakens the plants resulting in the production of numerous thin spears, yield losses the following season and eventual death of the plant under heavy infestations. Seedlings and newly established fields are more susceptible to injury. Some aphids may also be vectors of virus diseases.

Life cycle

The asparagus aphid overwinters as eggs on asparagus residue. Females hatch from the eggs and produce female nymphs which mature and give rise to subsequent generations of female aphids. Aphid populations build up quickly as aphids give birth to live young. The build-up of aphid populations is favoured by hot and dry weather. A generation of winged males is produced in the late summer and early fall. Following mating, females lay overwintering eggs, completing the cycle.

Pest management

Cultural controls

Lady bird beetles and other natural predators normally control aphid populations; however, they may not provide complete control under hot, dry conditions that favour aphid population build-up. It is important to scout fields regularly throughout the growing season as aphid numbers can increase rapidly. To monitor for aphids, which are difficult to detect visually on the plant, ferns may be shaken over a light-coloured surface. Burning old ferns will destroy overwintering eggs. The elimination of crop residue in the fall will reduce the overwintering aphid population. Refer to Table 7 for practices used by growers to manage asparagus aphid.

Resistant cultivars: None identified.

Issues for aphids

• There is a need for conventional and non-conventional insecticides, including biopesticides, for the control of aphids.

Asparagus beetles: common asparagus beetle (Crioceris asparagi) and spotted asparagus beetle (Crioceris duodecimpunctata)

Pest information

Damage

Adults of both species and the larvae of the common asparagus beetle cause feeding injury on both ferns and spears. Feeding on spears can result in misshapen spears. Feeding on the ferns can reduce the vigour of the asparagus plant. Severe defoliation can occur and potentially cause reduced yields in subsequent crops. Eggs laid on the spears in the early spring are unsightly and can result in the spears being culled. Larvae of the spotted asparagus beetle feed only on berries, reducing seed production.

Life cycle

In the early spring, the adults begin to feed and lay eggs on newly emerged asparagus spears. The eggs hatch in one to two weeks and larvae feed for three to four weeks. Pupation occurs at, or just below the soil surface. New adults emerge in late July and give rise to a second generation, which matures by September and overwinters in crop residues.

Pest management

Cultural controls

Allowing a row of asparagus to produce ferns early in the season has been shown to function in an ‘attract and kill’ approach for asparagus beetles. With beetles concentrated on the row of more mature plants, the individual row can be sprayed, reducing numbers of beetles in the rest of the field during harvest. Natural predators can contribute to keeping the population of asparagus beetles in check. Refer to Table 7 for practices used by growers to manage asparagus beetles.

Resistant cultivars: None available.

Issues for asparagus beetles

• Additional information is required on the application method and timing of insecticides for effective control of asparagus beetles.
• Studies are needed to develop a degree day prediction model for common asparagus beetle.
• Biopesticides are needed for management of asparagus beetle.

Asparagus miner (Ophiomyia simplex)

Pest information

Damage

Asparagus miners feed just under the epidermis of asparagus stems. Feeding injury is apparent as twisting mines at stem bases. Plants less than five years old are preferred hosts. Although serious plant injury does not usually occur, the insect is known to spread Fusarium diseases.

Life cycle

In early June, adults lay eggs beneath the epidermis of asparagus stems. Adult flies are short-lived. The eggs hatch and the first generation larvae feed until mid-July. Following pupation (in crop residues or soil), adult flies emerge and lay the second generation of eggs in late July or August. Second generation pupae overwinter and adults emerge in the spring.

Pest management

Cultural controls

The removal of crop residues in the fall eliminates potential overwintering sites for asparagus miner. Refer to Table 7 for practices used by growers to manage asparagus miner.

Resistant cultivars: None available.

Issues for asparagus miner

• Asparagus miner occurrence continues to increase in Quebec. Studies are required to determine the impact of asparagus miner on crop growth and vigour, and to establish an economic threshold.

Cutworms: dark-sided cutworm (Euxoa messoria), sandhill cutworm (E. detersa), variegated cutworm (Peridroma saucia), white cutworm (E. scandens)

Pest information

Damage

Cutworms feed on the growing tips of asparagus spears. Damaged spears are culled, reducing yield. Damage is more severe in early spring when spear growth is slow and there are fewer spears.

Life cycle

Cutworms may overwinter as eggs, larvae or pupae (depending on species and location) or adult moths may be blown northward from the United States in the spring. The overwintered larvae resume feeding mostly at night in the spring and feed until early June before they pupate in the soil. Cutworm moths lay eggs from about late June until mid-August. The eggs hatch and the larvae feed on asparagus and a variety of weeds.

Pest management

Cultural controls

Control is needed if damage to spears by cutworms exceeds 5% as observed in field or on grading line. Controlling weeds in the fall or spring will make the asparagus planting less attractive as an egg-laying site. Refer to Table 7 for practices used by growers to manage cutworms.

Resistant cultivars: None identified.

Issues for cutworms

• There is a need to identify what species of cutworms are present in asparagus fields in Ontario and Quebec, and to learn more about their life cycle.

Japanese beetle (Popillia japonica)

Pest information

Damage

Japanese beetle adults are generalist feeders that attack over 300 different plant species. Feeding damage by the Japanese beetle is hard to distinguish from common asparagus beetle feeding. Adults aggregate on ferns to mate and feed. Feeding damage to ferns can reduce the vigour of the asparagus plant.

Life cycle

The Japanese beetle has a one-year life cycle. Adult beetles emerge from the soil in early summer, feed on plant foliage and mate and lay eggs in the soil. Following egg hatch, the larvae, known as white grubs, feed on plant roots in the upper 10 to 12 cm of soil. The larvae continue to feed on plant roots into the fall, overwinter and resume feeding the following spring.

Pest management

Cultural controls

Monitoring for adult Japanese beetles and beetle damage can be done by visual inspection of ferns in July through August. Pheromone traps can be used to help determine when adults begin flying but visual inspections are more practical for monitoring in-crop populations. There are no thresholds established and adults are very active, continuously on the move.

Resistant cultivars: None available.

Issues for Japanese beetle

• Japanese beetle prevalence continues to increase in Ontario and Quebec. Studies are required to determine the impact of Japanese beetles on crop growth and vigour and to establish an economic threshold.

Tarnished plant bug (Lygus lineolaris)

Pest information

Damage

Tarnished plant bugs feed on a wide variety of ornamental and vegetable plants by means of piercing and sucking mouth parts. Tarnished plant bugs cause tip dieback injury to the asparagus fern and to newly emerged spears. Injury is caused by the feeding of both adults and nymphs.

Life cycle

Tarnished plant bugs overwinter as adults in sheltered sites. Adults become active in mid to late April with the onset of warm weather and begin to feed and lay eggs on a variety of hosts. Following egg hatch, nymphs feed and develop through five instars, before becoming adults. There are at least two generations per year, with the 1st generation appearing about two months after the over-wintering adults become active.

Pest management

Cultural controls

Good weed control in and around the asparagus planting will make the asparagus planting less attractive to plant bugs. Eliminating crop debris will reduce overwintering sites. Refer to Table 7 for practices used by growers to manage plant bugs.

Resistant cultivars: None identified.

Issues for tarnished plant bug

• There is a need to develop an integrated approach, including new conventional and non-conventional pest control products to control tarnished plant bug.

Weeds

In this section

• Key issues
• All weeds

Key issues

• There is a need for herbicides with short pre-harvest intervals for the control of annual grasses, perennial broadleaf weeds and horsetail at harvest. An example of a specific product needed is dicamba for the management of horse nettle, fleabane and nightshade, etc.
• There is a need for herbicides for the control of both annual and perennial weeds during the growing season. As well as herbicides with residual activity to rotate with Dual.
• The residual effect of herbicides over several asparagus production seasons is unknown. More research is needed to determine the impact of repeated residual herbicide applications on crop growth.
• There is a need for organically accepted herbicides for use in organic asparagus production systems.
• There is a need for registered herbicides for fall applied long-lasting residual control post-fern mowing, or spring applied long-lasting residual control pre-emergence.
• Registration of additional modes of action for herbicides are required for increased control and/or suppression of all weed species.
• There is a need for harmonization of pesticide registrations between Canada and the US to help Canadian asparagus growers remain competitive.
• For provincial ratings of key weed occurrence, see Table 8.

All weeds

Pest information

Damage

Weeds compete with asparagus for light, water and nutrients. High weed populations during the establishment of a new asparagus field can result in weak and non-uniform stands. Weeds may also impact yields of future harvests. In established crops, competition from perennial weeds can reduce the vigour of the planting. Annual weed problems may develop during the spring and early summer in the absence of a crop canopy and interfere with harvest operations. High populations of persistent perennial weeds, particularly field bindweed (Convolvulus arvensis) may require the removal of the asparagus planting.

Life cycle

Annual weeds – Annual weeds complete their life cycle from seed germination through vegetative growth and flowering to seed production, in one year. Annual weeds produce large numbers of seeds that can remain viable in the soil for many years, germinating when conditions are suitable. Summer annuals germinate in the spring and die before the onset of winter. Winter annuals germinate in the fall and overwinter in a vegetative state, flower in the spring, form seeds and then die. Perennial weeds – Perennial weeds are plants that live for many years. They spread by means of seeds, vegetative structures and the expansion of various types of root systems.

Pest management

Cultural controls

Due to the perennial nature of asparagus, it is important to select planting sites with low populations of annual and perennial weeds or to implement weed management practices in the years prior to planting. Cultural practices that result in a uniform and vigorous stand of asparagus will minimize problems due to weeds. The introduction of seeds and perennial, vegetative reproductive structures carried on equipment or in planting materials must be avoided. In young crops, light cultivation between rows and hand removal help reduce annual weed problems. Weed populations are continually monitored throughout the lifespan of the crop. Perennial weeds tend to become more problematic as the crop ages and may require physical removal. Tillage early in the year may be used to remove stubble left from the previous year and to eliminate overwintering and newly germinating weeds. Hand hoeing may be used to control annual grasses. A rye cover crop seeded into the asparagus crop in the fall and “burned-off” with herbicide in the spring, will serve to kill winter annual weeds and reduce the germination of summer annual weeds. Tillage is not generally used where a rye cover crop is planted. In organic production, mechanical weed control, including hand hoeing, is the primary means of weed management. Refer to Table 9 for practices used by growers to manage weeds.

Issues for weeds

• There is a need for new herbicides for the control of annual grasses and annual broadleaf weeds during harvest.
• Problems due to herbicide-resistant annual weeds are increasing. There is a need for new herbicides with different modes of action to manage weeds in asparagus.
• Herbicides for the control of perennial grasses are needed.
• Herbicides for the control of bindweed are needed.
• Some perennial weeds are only suppressed by herbicides registered for asparagus (that is, coltsfoot, horsetail). There is a need for the development of effective controls for these weeds.

Resources

Integrated pest management / integrated crop management resources for asparagus production in Canada

• British Columbia Agriculture. Asparagus production guide.
• CABI. BioProtection Portal.
• Quebec Reference Centre for Agriculture and Agri-Food (in French only).
• Health Canada. Pesticides and Pest Management.
• Manitoba Agriculture. Vegetable Crops. Production Information on Vegetable Crops – Asparagus (PDF).
• Ontario Ministry of Agriculture, Food and Agribusiness. Publication 839: Guide to Vegetable Production in Ontario (PDF).
• Ontario Ministry of Agriculture, Food and Agribusiness. Ontario Crop Protection Hub.

Provincial contacts

Provincial and national vegetable grower organizations

• Asparagus Growers of Ontario
• Association des producteurs maraîchers du Québec (in French only)
• Fruit and Vegetable Growers of Canada
• Canadian Organic Growers
• Ontario Fruit and Vegetable Growers Association

Appendix

Definition of coding for pest occurrence tables

The coding for each pest is based on 3 pieces of information: pest distribution, frequency and pressure in each province.

References

• British Columbia Agriculture. Asparagus production guide. https://www2.gov.bc.ca/gov/content/industry/agriculture-seafood/agriservice-bc/production-guides/vegetables/asparagus
• Centre de référence en agriculture et agroalimentaire du Québec (CRAAQ). SAGE Pesticides. https://www.sagepesticides.qc.ca/
• Foster R. and Flood B. (1995). Vegetable Insect Management - With Emphasis on the Midwest. Meister Publishing Company, Willoughby, Ohio.
• Howard J.R., Garland J.A. and Seaman W.J. (1994). Diseases and Pests of Vegetable Crops in Canada. The Canadian Phytopathological Society and Entomological Society of Canada. https://phytopath.ca/wp-content/uploads/2025/03/DPVCC-Intro.pdf
• Ontario Ministry of Agriculture, Food and Agribusiness. Crop IPM: Asparagus. https://cropipm.omafra.gov.on.ca/en-ca/crops/asparagus
• Ontario Ministry of Agriculture, Food and Agribusiness. Publication 839: Guide to Vegetable Production in Ontario. https://www.ontario.ca/files/2024-02/omafra-guide-to-vegetable-production-in-ontario-en-2024-02-15.pdf
• Ontario Ministry of Agriculture, Food and Agribusiness. (2021). Publication75B: Guide to Weed Control: Horticulture Crops. https://www.publications.gov.on.ca/store/20170501121/Free_Download_Files/300649.pdf
• Robb A.R. (1984). Physiology of asparagus (Asparagus officinalis) as related to the production of the crop. New Zealand Journal of Experimental Agriculture Vol. 12(3): 251-260. cabidigitallibrary.org/doi/full/10.5555/19840325778
• Thornton R.E. (1982). Washington Asparagus Production Guide. Washington State University. First edition. Bulletin # EB0997. https://openlibrary.org/works/OL12215944W/Washington_asparagus_production_guide
• University of California. (2012). Asparagus Pest Management Guidelines – Integrated Weed Management. Agriculture and Natural Resources. https://ipm.ucanr.edu/agriculture/asparagus/integrated-weed-management/#gsc.tab=0
• University of Minnesota Extension. Commercial Fruit and Vegetable Production. Asparagus production guide. https://conservancy.umn.edu/items/a3fcdea0-bca0-4bdb-8708-bc301c80fb5b
• Werling B. (2013). Managing Japanese beetles in asparagus. Michigan State University Extension. https://www.canr.msu.edu/news/managing_japanese_beetles_in_asparagus