Crop profile for lowbush blueberry in Canada, 2023

The lowbush blueberry, also known as wild blueberry, is a perennial, native fruiting plant that grows in north-eastern North America. It is a member of the Ericaceae or Heath family. The crop is unique in that it is harvested from managed, wild stands, unlike the highbush blueberry that is planted and maintained in an orchard. Harvested lowbush blueberry species include Vaccinium angustifolium and V. myrtilloides. V. angustifloium comprises most of the harvested lowbush blueberry in Canada.

Lowbush blueberries were harvested by Indigenous peoples before European settlers arrived in North America. Early settlers in the Atlantic provinces harvested the fruit for their own use or for local distribution. Markets expanded following improvements in marketing and shipping, and the establishment of canneries in Maine and along Canada's border with the United States in the mid-1800s. Improved harvesting methods and management resulted in an expansion of production throughout the 20th century. Since the 1980s, production has increased dramatically because of advancements in management, including improved weed control and the increased use of bees for pollination.

Today, most of the lowbush blueberry crop is sent to processing plants to be frozen using "Individually Quick Freezing (IQF)" technology. The berries may then be sold frozen or further processed into products such as pies, yogurt, ice cream, jams, juices and syrup.

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 lowbush blueberry production, the reporting provinces are Quebec, New Brunswick, Nova Scotia and Prince Edward Island.

Information on pest issues and management practices is provided for information purposes only. For detailed information on growing lowbush blueberries the reader is referred to provincial crop production guides and provincial ministry websites listed in the Resources Section at the end of the profile. For guidance about crop protection products registered for pests on lowbush blueberry, 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.

For inquiries regarding the contents of the profile, please contact:

Crop Profiles Coordinator
Pest Management Centre
Agriculture and Agri-Food Canada
aafc.pmcinfo-clainfo.aac@agr.gc.ca

Crop production

Industry overview

Blueberries (highbush and lowbush) are one of Canada's largest fruit crops in terms of production volume and farm gate value, second to apple. Annual production of lowbush blueberry in Canada in 2023 was 106,692 metric tonnes with a farm gate value of $121.6 million. This is down 33% compared to 2022, which saw a record production year of $180.8 million (data not shown). Cultivated area of lowbush blueberry in Canada has remained steady over the last 5 years at 63,155 hectares in 2023 (Table 1).

Table 1. General production information for lowbush blueberries in Canada, 2023

Production regions

Lowbush blueberries are only commercially produced in the eastern provinces of Canada. Quebec has the greatest acreage of lowbush blueberry production with 31,306 hectares (50% of national production), followed by Nova Scotia with 15,153 hectares (24% of national production). Other regions with significant production include New Brunswick (18% of national production) and Prince Edward Island (8% of national production) (Table 2).

Cultural practices

Lowbush blueberries are a perennial, native crop that grows in wild stands. A stand that is managed for commercial production is considered a field. The plants grow in areas of sandy, gravelly, well-drained soils with an optimum soil acidity level of 4.3 to 5.0. The blueberry bush spreads vegetatively through slow-growing underground stems called rhizomes, which produce roots and shoots. An individual plant, along with its system of rhizomes, shoots and roots, is called a "clone". In managed fields, rhizomes can spread as much as 38 cm in one season.

Pollination is an important component of lowbush blueberry production. Managed pollinators (mostly honeybees) are brought into the field to improve fruit set and increase productivity. The presence of windbreaks in blueberry fields will improve the effectiveness of insect pollinators, resulting in improved fruit set. When needed, pesticide selection is done in such a way as to preserve native and managed pollinators, which are necessary for fruit production.

Lowbush blueberries grow best in undisturbed soil. Control of weeds, insect pests and diseases is achieved through chemical and cultural control methods such as pruning and fertilizing, rather than the use of cultivation. The crop is usually pruned after harvest, late in the fall or in the early spring, and then allowed to re-grow during the non-crop ("sprout") year. Pruning by mowing or burning encourages the growth of vigorous new stems from underground rhizomes and increases flower bud set. Generally, blueberry fields are completely pruned every 2 years. Blueberries have a competitive advantage during re-growth due to their extensive root system. Flower buds are set in the fall of the sprout year. The crop bears fruit the following year or "crop year". Generally, fields are managed so that only half of the acreage harvested annually.

Over the years, growers have levelled their fields, allowing more mechanical operations of the crop, including harvest. This innovation has revolutionized the lowbush blueberry industry. Now, most picking is done mechanically (up to 80% in some areas) except in fields which have not been levelled or are in forested areas, which are still harvested by hand-raking.

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

Table 3. Lowbush blueberry production and pest management schedule in Canada

April

May

June

July

August

September

October

November

Abiotic factors limiting production

Pollination

Pollination is critical for successful blueberry production. Poor pollination may be the result of low numbers of pollinators or adverse weather conditions. Many native bee species pollinate lowbush blueberries; however, during most years, growers use managed pollinators (for example, honeybees, alfalfa leaf cutter bees) to maximize pollination.

Temperature extremes

Frost and cold temperatures during bloom and prior to harvest later in the summer can cause yield losses. During winter and spring, upper parts of blueberry plants can become desiccated due to cold temperatures, drying winds and insufficient snow cover. Windbreaks can be planted, and snow fencing used, to reduce wind and keep snow from blowing off fields. Dry, hot conditions in the summer can affect fruit quality and reduce yields by as much as 50%.

Diseases

In this section

• Key issues
  • Botrytis blight and fruit rot (Botrytis cinerea)
  • Exobasidium fruit and leaf spot (Exobasidium spp.)
  • Godronia canker/fusicoccum canker (Godronia cassandrae)
  • Leaf rust (Thekospora minima)
  • Monilinia blight or mummy berry (Monilinia vaccinii-corymbosi)
  • Phomopsis canker (Phomopsis vaccinii)
  • Powdery mildew (Erysiphe vaccinii)
  • Red leaf (Exobasidium vaccinii)
  • Septoria leaf spot (Septoria spp.)
  • Valdensinia leaf spot (Valdensinia heterodoxa)
  • Witches' broom (Pucciniastrum goeppertianum)

Key issues

• There is a need for the development of pest control products suitable for use in organic production, including biopesticides, for the management of a number of diseases in lowbush blueberry.
• There is a need for greater understanding of the yield impact of foliar diseases and the mitigating effects of cultural practices, such as pruning and fertilization, on lowbush blueberry.
• It is critical that all new pest control product registrations have pre-harvest intervals that are compatible with maximum residue limits for export and ensure the marketability of the crop.
• There is a need to determine the effects of long-term fungicide use on beneficial soil microorganisms, particularly mycorrhizae, which play an important role in nutrient absorption in lowbush blueberry.
• Further development and strong encouragement of equipment sanitation and biosecurity protocols for plant pathogens is needed.
• There is a need for degree day modelling for crop stage susceptibility and pathogen presence to allow for accurate and field-specific timing of management practices.
• For provincial ratings of key disease occurrence, see Table 4.

Botrytis blight and fruit rot (Botrytis cinerea)

Pest information

Damage

Botrytis blight can be a serious problem during prolonged wet conditions. Blossoms, fruit and leaves may be affected. Affected leaves turn brown and entire flower clusters may become blighted. Under humid conditions, infected tissues can become covered with grey mold. Frost and herbicide damage increase the susceptibility of the blueberry bushes to the disease. Botrytis blight can also develop during storage if fruit is contaminated or mishandled at harvest. Post-harvest losses can result if diseased and injured berries are stored together.

Life cycle

The fungus overwinters on infected weeds. In the spring the pathogen produces spores that are blown by wind to blueberry blossoms. Following infection of blossoms, new spore production occurs, and these spores are blown by wind to other susceptible tissues. The number of disease cycles and the severity of infection is associated with the frequency of cool, wet periods during bloom and shortly thereafter. Early-blooming blueberry clones are the first to be infected and become the source of spores for later flowering clones.

Pest management

Cultural controls

Pruning by burning every second or third crop cycle may reduce some overwintering inoculum of Botrytis cinerea. The control of weeds in and around blueberry fields will eliminate overwintering sources of disease. Potential host weeds include bunchberry, sheep sorrel, goldenrod, pearly everlasting, Potentilla spp. and some grasses. Monitoring of early flowering clones for infections of B. cinerea helps to determine if fungicide sprays are necessary. Modified atmosphere packaging, following rapid removal of field heat from the fruit after harvest, can reduce the growth of Botrytis blight in storage. Additional management practices for Botrytis blight are listed in Table 5.

Issues for for Botrytis blight

• Conventional and non-conventional pesticides that are safe for pollinators are required for the management of Botrytis blight.
• There is a need for further investigation into the potential of novel application methods, such as bee vectoring of biological fungicides, for the management of Botrytis blight.
• The development of a forecasting model to improve timing of treatments for Botrytis blight would be of benefit to growers.

Exobasidium fruit and leaf spot (Exobasidium spp.)

Pest information

Damage

Exobasidium fruit and leaf spot is an emerging disease of lowbush blueberry with the potential to reduce yield and fruit quality. The pathogen causes round white to pale-green spots on the leaves and fruit. Infected berries become unmarketable.

Life cycle

Little is known about the life cycle of this pathogen in lowbush blueberry in Eastern Canada.

Pest management

Cultural controls

None identified

Issues for exobasidium leaf and fruit spot

Research to determine the life cycle of the pathogen, impact of the disease and control options in lowbush blueberry production is needed.

Godronia canker/fusicoccum canker (Godronia cassandrae)

Pest information

Damage

Godronia cassandrae only infects new wood. Infected branches are killed, reducing lowbush blueberry yields.

Life cycle

The fungus overwinters as mycelium in living stems and crowns. Pycnidia (fungal spore producing bodies) develop in cankers and release spores during rainy periods. Lesions develop at leaf scars and in the axils of buds, and eventually girdle stems, causing wilting and death. Most infections occur in spring and fall.

Pest management

Cultural controls

Practices for Godronia canker include pruning out and destroying infected branches. Pruning will also promote good air movement around plants and facilitate foliar drying.

Issues for Godronia canker

None identified.

Leaf rust (Thekospora minima)

Pest information

Damage

Severe outbreaks of leaf rust can cause extensive defoliation in sprout fields. Infected leaves develop small, reddish spots on the upper leaf surface that may coalesce into larger spots. Small water-soaked spots appear on the lower leaf surface, with yellow-orange pustules of spores appearing in these lesions. Premature defoliation from rust impacts fruit bud development and is of greatest concern when it occurs in sprout fields. Leaves begin to fall in response to rust infection in late summer and early fall.

Life cycle

Leaf rust produces a number of different spore types and requires 2 hosts to complete its life cycle. In the spring, aeciospores produced on eastern hemlock needles are wind-blown to lowbush blueberry fields where they infect new foliage. Rust pustules develop in leaf lesions by mid-season and release urediniospores that can re-infect blueberry leaves. The pathogen overwinters as teliospores (dormant spores) in leaf lesions on blueberry plants; these germinate in spring producing basidiospores that re-infect hemlock.

Pest management

Cultural controls

Burn pruning of blueberry fields is beneficial to reduce sources of inoculum. Removing nearby hemlock trees, the secondary host, is also a good practice to reduce disease pressure. Over-fertilization may increase leaves' susceptibility to leaf rust. Additional management practices for leaf rust are listed in Table 5.

Issues for leaf rust

• There is a need for improved understanding of the yield impact of leaf rust and the mitigating effects of cultural practices such as pruning and adjustment of fertilization.
• There is a need for the development of an integrated approach to the management of leaf rust. The development of a forecasting model based on rust levels on secondary hosts would allow growers to improve the timing of rust control treatments.

Monilinia blight or mummy berry (Monilinia vaccinii-corymbosi)

Pest information

Damage

The development of Monilinia blight or mummy berry disease is favoured by extended wet periods. The fungus infects blossoms, leaves and fruits, resulting in foliar wilting and shrivelling of flower clusters. Infected fruit shrivel and harden several weeks before harvest, becoming black fungal masses known as 'mummy berries'.

Life cycle

The fungus overwinters in mummy berries and can survive for many years. During bud break, mummy berries give rise to apothecia, structures that release ascospores. Under cool and wet conditions, these spores infect the vegetative and floral buds, with disease symptoms appearing in 10 to 20 days. Exposure to frost increases the susceptibility of buds to infection. Conidia are produced on diseased shoots that germinate and grow near flowers and infect maturing berries. Fruits developing from infected blossoms remain symptomless until they are almost mature, at which time they drop to the ground as mummy berries and the fungus completes its life cycle.

Pest management

Cultural controls

Pruning by intense burning helps destroy mummy berries. Measures to improve drainage and air circulation in a field can also help reduce the susceptibility of lowbush blueberry plants to Monilinia blight. Spreading a mulch of straw or wood chips can help to prevent the spread of Monilinia blight by covering the mummy berries. Additional management practices for Monilinia blight are listed in Table 5.

Issues for Monilinia blight

• Fine-tuning of existing monitoring models is needed to allow for field-specific forecasting.
• New fungicides from classes other than demethylation inhibitors (DMIs) are required for the management of Monilinia blight and as fungicide resistance management tools.
• There is a need for new registered products with maximum residue limits that are acceptable for key export markets (for example, European Union, Asia), as well as domestic markets.
• Research and registration of non-conventional alternatives to traditional fungicides needs to be accelerated, particularly for year of harvest applications.

Phomopsis canker (Phomopsis vaccinii)

Pest information

Damage

Phomopsis canker is found in sprout fields from late July until the end of September. Disease lesions appear as elongated flattened cankers on stem bases and cause the stems to drop off. Phomopsis canker can be devastating to bushes in low areas where winter injury and spring frosts are a problem. The disease is not as common in fruiting fields, where it might be confused with Godronia canker.

Life cycle

Conidia are spread by splashing rain throughout the growing season from bud break through September. Injuries from mechanical damage, winter stresses or spring frost are necessary for Phomopsis vaccinii infection because wounded tissues serve as entry points for conidia. Wounds from mechanical harvesting or pruning may also facilitate infections. Stems infected during the growing season often wilt during the summer months.

Pest management

Cultural controls

Monitoring of fields for Phomopsis canker is done in early September of the sprout year. Pruning by burning is assumed to reduce disease incidence. Careless pruning, cultivating and fertilization late in the summer should be avoided to minimize mechanical injury to the plants. Keeping plants well-watered through prolonged periods of dry weather in the summer helps to prevent the disease.

Issues for Phomopsis canker

None identified.

Powdery mildew (Erysiphe vaccinii)

Pest information

Damage

Powdery mildew may cause premature leaf drop in both fruiting and sprout fields. Some clones show irregular reddish patches on the leaves, while others show abundant white mycelial growth. Early leaf drop may cause poor fruit bud development in sprouts and reduced yields in crop fields.

Life cycle

The fungus overwinters in infected tissues. First symptoms appear in early July, resulting from infections that took place 2 to 3 weeks previously. Spores (conidia) are produced within the white mycelia on the leaf surfaces and are spread by wind to new tissues throughout the growing season. Powdery mildew tends to be more serious in fields on light sandy and gravelly soils, and during hot, dry summers. Phosphorous deficiency may increase powdery mildew severity.

Pest management

Cultural controls

Pruning by burning may reduce inoculum; however, the susceptibility of lowbush blueberry clones to powdery mildew may vary.

Issues for powdery mildew

None identified.

Red leaf (Exobasidium vaccinii)

Pest information

Damage

Plants infected with red leaf develop conspicuous red foliage in June and July. The pathogen grows systemically throughout the plant and reduces plant vigour and yield. Infected plants may fail to flower and do not produce much fruit. By mid-summer, infected leaves drop, and the disease becomes inconspicuous. Symptoms reappear on the same plants each year until the plants weaken and die.

Life cycle

The fungus overwinters in the shoots and rhizomes of blueberry plants, infecting new sprouts as they arise from the mother plant. Infected leaves turn red, and the fungus develops spore-bearing structures on their underside. The role of the spores in spreading the disease is unknown. It is assumed that spore-mediated field infections occur only under extended wet conditions.

Pest management

Cultural controls

The practice of burn pruning or burying mowed prunings does not control rhizome infections as plants are systemically infected by the pathogen. However, this practice may destroy new infections in the shoots that have not yet progressed into the rhizome.

Issues for red leaf

• The industry-wide impact of this disease is minor, but yield reduction does occur in some production regions. Further studies on the biology, yield impact and effective management, including potential benefits of improved soil nutrition, are required.
• Monitoring of this disease to track its severity and occurrence is required.
• More information is needed on the potential of fungicides to control red leaf.

Septoria leaf spot (Septoria spp.)

Pest information

Damage

Symptoms of Septoria leaf spot develop on the lower leaf surface and appear as small water-soaked lesions, similar to early rust symptoms. The lesions later coalesce to produce irregular, brown blotches. Septoria leaf spot may cause defoliation in both crop and sprout fields. This may affect fruit bud development in the sprout year and reduce yield in the crop year.

Life cycle

The fungus overwinters on infected leaves and twigs. In the spring and early summer, infected litter from the previous year can cause the development of lesions on lower stem portions. Spores are released from late spring to early summer, and rain splashing of spores contributes to the next infection cycle. Infected leaves drop prematurely in August and secondary infection can start on dead leaves. The severity of Septoria leaf spot depends on the number of wet periods in a growing season.

Pest management

Cultural controls

Pruning by intensive burning or mowing will reduce the inoculum source during the non-fruiting year of a biennial production cycle. Additional management practices for Septoria leaf spot are listed in Table 5.

Issues for Septoria leaf spot

• Further studies are required to establish the yield impact of Septoria leaf spot, and the efficacy and economic value of practices, including burning and chemical treatments, for the management of this disease.
• Research and registration of non-conventional pest control products, including biological alternatives, must be accelerated.
• The development of a reduced input management approach that includes non-conventional pest control products and alternatives is required for Septoria leaf spot control.

Valdensinia leaf spot (Valdensinia heterodoxa)

Pest information

Damage

Valdensinia heterodoxa causes the development of large reddish-brown circular spots on foliage. Infected leaves drop soon after symptom development. This disease may cause severe defoliation in both fruit and sprout fields during very wet years.

Life cycle

The fungus overwinters as sclerotia (resting bodies) in infected leaves. In the spring, large spores (conidia) are produced on the sclerotia. After 2 to 3 days of wet conditions, spores are released and infect leaves, causing large lesions. Another generation of spores is produced after another period (1 to 2 days) of wet conditions, and spread in the foliage canopy where they cause new infections. The fungus can spread easily from field to field on equipment and footwear. Other hosts of V. heterodoxa include wild raspberry, birch saplings, bunchberry, maple saplings and wild strawberry.

Pest management

Cultural controls

Cleaning equipment and boots between fields will help reduce spread of Valdensinia leaf spot. Cleaning and sanitizing boxes and bins used during harvest before re-use will also help to limit spread. Small-scale infections can be managed with a hand-held weed burner under dry conditions, as this pruning will reduce inoculum during a sprout year. Avoiding over fertilization will help to reduce the susceptibility of foliage to this pathogen. Additional management practices for Valdensinia leaf spot are listed in Table 5.

Issues for Valdensinia leaf spot

• Further studies are required on the impact of production practices such as fertilization and pruning by mowing on the incidence and spread of Valdensinia leaf spot.
• Pest control products that can be used in alternate years to burning (pruning) are required for the management of Valdensinia leaf spot.
• Growers need more information on how to identify and manage this disease.
• Research and registration of non-conventional pest control products must be accelerated, particularly for year of harvest applications.

Witches' broom (Pucciniastrum goeppertianum)

Pest information

Damage

Plants infected with witch's broom develop broom-like masses of shoots with few or no leaves, and do not produce fruit. Symptoms appear the year following infection and persist for many years.

Life cycle

Pucciniastrum goeppertianum has a complex life cycle with balsam fir as an alternate host. From mid-May to late June, rust spores develop on infected shoots and germinate to produce basidiospores. These spores are carried by wind to balsam fir where they attack young needles and aeciospores are produced. Aeciospores are carried by wind back to blueberry plants where they cause new infections, stimulating the production of lateral buds that develop into the characteristic broom-like swollen shoots. Finally, teliospores are formed on the swollen, broom-like shoots of blueberry plants and overwinter there. The brooms are perennial and produce new growth each spring, serving as sources of the fungus for many years.

Pest management

Cultural controls

Because infections are systemic and remain in the rhizomes, burning or flail mowing will not control this disease. Infected plants are removed to eliminate this source of infection.

Issues for witches' broom

None identified.

Insects and mites

In this section

• Key issues
  • Blueberry case beetle (Neochlamisus cribripennis)
  • Blueberry flea beetle (Altica sylvia)
  • Blueberry gall midge/cranberry tipworm/blueberry tip midge (Dasineura oxycoccana)
  • Blueberry leaftier (Croesia curvalana)
  • Blueberry maggot (Rhagoletis mendax)
  • Blueberry sawfly (Neopareophora litura)
  • Blueberry spanworm (Speranza argillacearia) and other spanworms
  • Blueberry stem gall wasp (Hemadas nubilipennis)
  • Blueberry thrips (Frankliniella vaccinii and Catinathrips kainos)
  • Chainspotted geometer (Cingilia catenaria)
  • Plant bugs: tarnished plant bug (Lygus lineolaris) and other Lygus spp.
  • Redstriped fireworm (Aroga trialbamaculella)
  • Spotted wing drosophila (Drosophila suzukii)
  • Whitemarked tussock moth (Orgyia leucostigma)

Key issues

• Given the high potential for damage, it is important to continue to monitor for the presence of spotted wing drosophila in lowbush blueberry. Improved monitoring approaches and treatment thresholds need to be developed, particularly as the climates in growing regions change.
• Grower education on monitoring, scouting and treatment thresholds of blueberry pests is needed to improve management.
• There is a need for the development of alternative pest control solutions and integrated approaches, including the availability and use of biopesticides, for blueberry maggot management. New programs must provide comparable levels of control to conventional approaches for the management of this insect. Monitoring for blueberry maggot is now critical in Quebec.
• There is a need for the development of an integrated approach to blueberry flea beetle management, including the development of a forecasting model that can be implemented in the sprout year.
• Protocols for equipment sanitization and field biosecurity are needed. Adoption of these protocols will help growers reduce the spread of insect pests among lowbush blueberry fields.
• It is critical that new pest control product registrations have pre-harvest intervals that meet maximum residue limits for export and ensure the marketability of the crop.
• There is a need for the registration of pest control products that are pollinator-friendly and that target common pests faced by lowbush blueberry producers.
• There is a need for degree day modelling for crop stage prediction and insect emergence to allow for accurate and field-specific timing of management practices.
• 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 highbush blueberry production in Canadanote ¹

Blueberry case beetle (Neochlamisus cribripennis)

Pest information

Damage

Both adults and larvae of the blueberry case beetle feed on leaves, causing severe defoliation if present in large numbers. Adult feeding on the bark of stems causes the most serious damage, resulting in drying and winter kill. Damage is most serious in sprout fields or second crop fields in a three-year production cycle, where a major portion of the crop can be lost during large outbreaks. Damage is not serious during the crop year in a 2-year rotation, as plants are pruned.

Life cycle

The pest overwinters as adults in leaf litter under blueberry plants. Adult beetles emerge in May and lay eggs in mid-June. The eggs hatch in about 10 days and emerging larvae feed mainly on the leaves of blueberries. Larvae go through 3 instars (stages) and pupate from late July to early August. The egg, larva and pupa are each enclosed in a bell-shaped case. The pupal stage lasts from 4 to 5 weeks, and emerging adults of the second generation remain active until November.

Pest management

Cultural controls

Pruning by burning may reduce populations. Pest populations are often managed by several species of parasitoid wasps and chemical sprays are not necessary. Weekly sweep net sampling is most important in sprout fields, where adult activity in the fall can cause severe damage.

Issues for blueberry case beetle

• Detection of blueberry case beetle in blueberry fields has increased. Monitoring is warranted.
• More information is needed on blueberry case beetle biology and potential crop damage in blueberry fields.

Blueberry flea beetle (Altica sylvia)

Pest information

Damage

The blueberry flea beetle can cause severe defoliation when present in large numbers. Both adults and larvae feed on blueberry foliage. Outbreaks develop in late May or early June and can occur in both the crop and sprout years. If not controlled, these outbreaks can cause severe losses in plant emergence and growth in the sprout year.

Life cycle

The eggs of the flea beetle overwinter in leaf litter and hatch in May when the leaves begin to unfold. The larvae develop through 3 instars (stages) before pupating in the soil. Adults emerge in late June, lay eggs in late July and are present until late August.

Pest management

Cultural controls

Fall or spring burning will help control the flea beetle population, as the eggs overwinter in the leaf litter. Most outbreaks occur in mechanically pruned fields. A sweep net can be used for weekly sampling. Additional management practices for blueberry flea beetle are listed in Table 7.

Issues for blueberry flea beetle

• Research on integrated management approaches for blueberry flea beetle, including control options in the sprout year, are needed. Although the industry-wide impact of this pest is minor, it can cause severe damage in specific areas.
• There is a need for non-conventional, pollinator-friendly insecticides, including Bacillus thuringiensis (Bt)-based products, for the control of blueberry flea beetle.
• There is a need for improved knowledge of the factors impacting population dynamics and a predictive model of emergence that is validated in field.

Blueberry gall midge/cranberry tipworm/blueberry tip midge (Dasineura oxycoccana)

Pest information

Damage

Blueberry gall midge larvae feed on the terminal growth of vegetative shoots causing deformed foliage, premature break of secondary buds and excessive branching. As a result of this shoot growth, the development of flower buds for the following season's crop may be delayed and rendered more susceptible to winter injury.

Life cycle

The blueberry gall midge overwinters in the soil as pupae and emerges as adult flies in the spring. First generation adults mate and females lay eggs in buds. Following egg hatch, larvae feed within buds for up to 10 days. Larvae develop through 3 instars (stages) and, when mature, drop to the ground to pupate. The next generation adults emerge soon after. There can be several generations per year.

Pest management

Cultural controls

It is important to apply balanced fertilizers that do not stimulate excessive plant growth, which is attractive to this insect. The presence of gall midge can be detected by visual examination of blackened shoot tips when leaf buds unfold in the spring. Monitoring through scouting and tracking can help to determine if economic threshold levels have been reached and controls are warranted. Pruning by intense burning is effective against this pest.

Issues for blueberry gall midge

• Additional research on the biology of the blueberry gall midge and its impact on growth and yield of lowbush blueberry is required.
• The development of an integrated approach that includes improved monitoring methods, the implementation of economic thresholds, and new conventional and non-conventional pest control products is required for effective management of the blueberry gall midge.

Blueberry leaftier (Croesia curvalana)

Pest information

Damage

Blueberry leaftier larvae can cause severe damage by feeding on developing flower buds. They also feed on leaves and flowers. Defoliation can be close to 100% if the outbreak is severe.

Life cycle

The pest overwinters as eggs in leaf litter around blueberry plants. Eggs hatch from April to May. Larvae feed on buds, young leaves and flowers, and form a protective shelter of leaves and silk when molting. Larvae pupate within these shelters during the month of June. Adult moths emerge from the pupae in early to late July and lay eggs on the leaf litter from late July to early August.

Pest management

Cultural controls

Burning in the sprout year can help reduce pest numbers for the following crop year. Additional management practices for blueberry leaftier are listed in Table 7.

Issues for blueberry leaftier

Growers need more information on scouting and monitoring to better understand the pest's frequency and to help establish the degree of damage caused by the blueberry leaftier.

Blueberry maggot (Rhagoletis mendax)

Pest information

Damage

The blueberry maggot is the most serious insect threat for the lowbush blueberry industry in Quebec. It is recognized as the most important insect pest of lowbush blueberry. The pest consumes the inner parts of the berry, resulting in shrivelling and premature fruit drop. Although direct losses of fruit are of minimal economic importance, there is zero tolerance for blueberry maggots in some export markets. The presence of larvae at low levels in harvested fruit greatly reduces the commercial value of the crop.

Life cycle

Most pupae spend one winter in the ground in a diapause state, a period of suspended development. Others can prolong their diapause for a second or third year. Adult flies emerge from soil between late June and early August, and live for approximately 30 days. Females lay eggs in fruit as it begins to ripen. Each female can lay up to 100 eggs, usually deposited under the epidermis of the fruit. Larvae develop inside the berries and when full grown, drop to the soil where they pupate and overwinter. There is one generation per year.

Pest management

Cultural controls

Since the majority of flies emerge during the sprout year in a 2-year cropping system, it is important that crop and sprout fields remain isolated from one another to reduce new infestations. Sanitation practices, such as destroying fallen fruits rather than composting them, and picking and removing infested berries, will help to reduce re-infestation. Controlling weeds that provide shelter for adult flies can also be helpful. Adult flies may be monitored using yellow sticky traps placed around the outer margin of the field. Phytosanitary requirements prohibit the domestic movement of crops infested with blueberry maggot under the Plant Protection Regulations of the Plant Protection Act to prevent the spread of this pest within Canada. These requirements are also part of the Blueberry Certification Program. Additional management practices for blueberry maggot are listed in maggot are listed in Table 7.

Issues for blueberry maggot

• Effective control of blueberry maggot is critical as the pest is becoming established in many lowbush blueberry growing regions. As well, the marketability of this crop is greatly implicated given that blueberry maggot is a regulated (zero tolerance) insect in some export markets and there is close to zero tolerance for the pest in fruit for direct-to-consumer sales.
• Improved monitoring (for example, emergence models) is required to prevent the introduction of blueberry maggot into non-infested areas and to limit fruit infestation.
• The use of insecticide sprays late in the production cycle for the management of blueberry maggot creates difficulties in exporting the crop to foreign markets which have specific residue import tolerances. It is important that maximum residue limits/export tolerances are considered during the registration of new insecticides.
• There is a need for the development of alternative integrated approaches, including non-conventional pesticides like biopesticides, which provide comparable control to conventional approaches, for the management of blueberry maggot.
• There is a need for control strategies that are safe on beneficial insects for the management of blueberry maggot to encourage natural predatory activity.
• There is a need for reinforced biosafety measures within Quebec.
• There is a need for intervention thresholds that are linked to market tolerance for larvae.

Blueberry sawfly (Neopareophora litura)

Pest information

Damage

Blueberry sawfly larvae feed on leaves and, under high pest pressure, can cause severe defoliation. Infestations are usually confined to isolated areas within a field.

Life cycle

Adult sawflies lay eggs in May inside developing leaf whorls. Larvae feed on foliage until late June when they move to the ground, spin cocoons and overwinter in leaf litter. Pupation takes place the next spring and adults emerge within 2 weeks.

Pest management

Cultural controls

Pruning by burning does not have a huge effect on sawfly populations as pupae are often deeper in the soil than other insect pests and are protected. Several parasitic wasps (family Ichneumonidae) are active in blueberry fields and help to keep populations of blueberry sawfly low. However, parasites may not control an outbreak early enough to prevent economic damage. It is important to monitor crop fields weekly using a sweep net. The blueberry sawfly is usually kept in check by treatments for other insects such as the blueberry flea beetle or spanworm.

Issues for blueberry sawfly

There is a need for new control products for the management of blueberry sawfly.

Blueberry spanworm (Speranza argillacearia) and other spanworms

Pest information

Damage

Caterpillars of several species of spanworm moths feed on the foliage of lowbush blueberry. Plants can be completely defoliated if the outbreak is severe. In sprout fields, the new shoots may be completely consumed. These insects are more problematic in fields that are pruned by mowing as opposed to burning.

Life cycle

Adult moths are present in mid-summer and lay overwintering eggs in litter at the base of plants. The eggs hatch when plant growth resumes in the spring. The larvae feed on leaves and buds at night, hiding in leaf litter on the ground during the day. Larvae complete their feeding by early summer, at which time they drop to the soil to pupate, with adults emerging in mid-summer.

Pest management

Cultural controls

Burning can reduce the number of spanworms in the field by destroying overwintering eggs. Several species of parasitic wasp attack the blueberry spanworm and help to control the population. The pest can be monitored once a week, starting from early May until June, using a sweep net. Remedial treatments can be applied when threshold levels have been reached. Additional management practices for blueberry spanworm are listed in Table 7.

Issues for blueberry spanworm

Improved monitoring methods and thresholds are required for more targeted treatments of blueberry spanworm.

Blueberry stem gall wasp (Hemadas nubilipennis)

Pest information

Damage

The blueberry stem gall wasp causes the formation of galls (irregular growths) on the stems of the plant in response to egg laying and larval feeding on blueberry. Tissue at the tip of the stem is destroyed, stopping the formation of fruit buds on affected stems. If this damage occurs during the vegetative year, yield can be reduced the following year. Galls can also break off from the stem during harvesting, pass through the processing line and end up as foreign objects in the finished product. Infestations can be high in fields that have been exclusively mechanically pruned for an extended number of years.

Life cycle

Adults are almost all females. They emerge from galls from May to June before the buds break and lay eggs in developing shoots. The process of egg laying induces abnormal tissue growth, resulting in a chamber being formed around each egg. Eggs hatch in 2 weeks and larvae feed inside the chamber, further stimulating the undifferentiated growth of the plant tissue. Eventually a gall is formed around several feeding larvae. The larvae overwinter inside the gall, pupate and emerge as adults the following spring.

Pest management

Cultural controls

Burn pruning of the plants may have some effect in decreasing gall wasp populations.

Issues for blueberry stem gall wasp

The development of a protocol for equipment sanitation is required to help growers to minimize the spread of the blueberry gall wasp.

Blueberry thrips (Frankliniella vaccinii and Catinathrips kainos)

Pest information

Damage

These 2 thrips species feed on leaves of lowbush blueberry plants, causing them to tightly curl and wrap around the stem. In sprout fields, damage is only visible in spring on leaves that remain attached to the plant. In crop fields, expanding leaves do not unfold normally and resemble enlarged buds. Most infestations are localized, but sometimes large infestations of several hectares can occur. Infested plants are more susceptible to winter injury and produce less fruit.

Life cycle

The 2 species attacking lowbush blueberries have a similar appearance and life cycle. Adult females overwinter in the soil and emerge from the ground in April and May. Females lay eggs in leaf tissues from May to June. Emerging larvae feed on blueberry leaves by sucking sap, causing the leaves to curl. Frankliniella vaccinii pupates within the curled leaves and Catinathrips kainos often drops to the soil to pupate and complete its development. Adults appear in late July.

Pest management

Cultural controls

Fields are inspected for the presence of thrips and associated damage beginning in early June. Infested areas can be treated the following spring, when the plants are small and the overwintered adults first appear. In some areas, delayed pruning by mowing or burning in mid-June, after thrips colonization during a sprout year, has been shown to be effective in controlling thrips populations.

Issues for thrips

• The true impact of blueberry thrips on lowbush blueberry needs to be determined.
• Work is needed on alternative management approaches due to the narrow window for use of pest control products.

Chainspotted geometer (Cingilia catenaria)

Pest information

Damage

The chainspotted geometer feeds on a wide variety of plants including blueberry and cranberry. Most of the damage is done by the later instar larvae, which consume both leaves and fruit. When larvae are numerous, large areas of plants may be completely defoliated. Outbreak levels are rare and tend to be quite patchy in distribution throughout the field.

Life cycle

The adult moths emerge in early September and are present until mid-October. They begin egg laying shortly after they emerge. The eggs are loosely attached to the underside of leaves of the host plant. A variety of shrubs may be suitable host plants, including lowbush blueberry, however, sweet fern (Comptonia peregrina) is the preferred host. The eggs overwinter and begin hatching in early June. The newly hatched larvae skeletonize the leaves, and as they become larger, the entire leaf is eaten. Pupation takes place in the leaf litter from August to early September.

Pest management

Cultural controls

Weed control in the field and field margins, especially of sweet fern, may help reduce the attractiveness of the site for egg laying. Several natural parasites have been recorded for the chainspotted geometer. These include flies of the family Tachindae, and wasps in families, Braconidae, Chalcididae and Ichneumonidae. The fungal disease, Entomophthora aulicae and multi-cupsid nuclear-polyhedrosis virus (MVPV) have also been noted as natural controls.

Issues for chainspotted geometer

None identified.

Plant bugs: tarnished plant bug (Lygus lineolaris) and other Lygus spp.

Pest information

Damage

Plant bugs feed and injure fruit and leaf buds. Late season damage may occur anywhere on the fruit. The tarnished plant bug has a wide range of hosts, feeding on weeds, vegetables, fruits, flowers and shrubs. It punctures the fruit skin and sucks the sap, resulting in fruit deformation. They prefer floral buds and immature fruits.

Life cycle

Adult tarnished plant bugs overwinter under leaf and weed litter. In late spring, they migrate to weeds and wildflowers where they lay their eggs into stems and stalks. There can be several overlapping generations per year.

Pest management

Cultural controls

Keeping neighbouring fields free of weeds and mowing field borders can help to reduce attractiveness of the area to plant bugs.

Issues for plant bugs

None identified.

Redstriped fireworm (Aroga trialbamaculella)

Pest information

Damage

The redstriped fireworm is most prevalent in sprout fields, but can also be found in crop fields. The larvae web stems and leaves together and feed within the webbed leaves. They may also web together fruit, which may affect fruit size and interfere with harvest. The caterpillars are considered to be harvest contaminants on field equipment and processing lines.

Life cycle

The redstriped fireworm overwinters as mature larvae in ground litter. Pupation occurs in the spring and adults begin to emerge in late June. Adults lay eggs under bark and in leaf axils of blueberry plants.

Pest management

Cultural controls

Due to the importance of this pest as a harvest contaminant, monitoring is essential.

Issues for Redstriped fireworm

• Studies are required to better understand the impact of redstriped fireworm feeding in the sprout year on yields in the following year.
• Continued work to determine ecological factors resulting in outbreak conditions and identification of behavioural attractants would be beneficial.
• Conventional and organic products are needed for the control of redstriped fireworm.

Spotted wing drosophila (Drosophila suzukii)

Pest information

Damage

The spotted wing drosophila (SWD) attacks wild and cultivated lowbush blueberry, other berry crops and stone fruit crops. Feeding by larvae within the fruit turns the flesh of the fruit brown and soft. Damage can provide entry sites for infection by secondary fungi and bacteria, causing further deterioration of the fruit. This injury results in unmarketable fruit and economic loss to growers.

Life cycle

The insect overwinters as an adult fly. In the spring, flies mate and lay eggs under the skin of ripening fruits. Larvae feed and develop within the fruit. Due to the short generation time and extended period of egg laying by adults, there can be several overlapping generations each year. This insect is spread short distances by wind and can be carried to new areas through the movement of infested fruit.

Pest management

Cultural controls

Sanitation practices such as the removal of over-ripe and fallen fruit, the elimination of old fruit in processing areas and in equipment, and the removal of nearby wild hosts, will help to reduce the SWD population. Fields and earlier fruiting hosts in the vicinity of the blueberry field are closely monitored through the use of apple cider vinegar baited traps for the presence of SWD. Treatments are initiated when the first male fly is detected. Additional management practices for SWD are listed in Table 7.

Issues for spotted wing drosophila

• Studies to understand the biology of this insect in Eastern Canada are required. The development of a growing degree day model for first emergence would be very helpful for the management of this pest.
• Continued monitoring approaches and treatment thresholds are required for SWD in lowbush blueberry.
• Effective pest control options are required. New insecticides must be "beneficial insect-friendly" and meet pre-harvest interval and maximum residue limit requirements of domestic and export markets to ensure crop marketability.
• Efficient harvest insecticide application methods during harvest need to be developed.

Whitemarked tussock moth (Orgyia leucostigma)

Pest information

Damage

The whitemarked tussock moth is primarily a forest pest, but is a general feeder and can attack lowbush blueberry. Larvae feed on the foliage of blueberry and can completely defoliate large portions of a field. The damage can take place at a critical time of development in the growth of both crop and sprout fields. Outbreaks are sporadic, with a history of outbreaks every 20 years that can last from 2 to 3 years at a time.

Life cycle

The pest overwinters in egg masses and hatches from late June to mid-July. First instars feed on the upper surface of leaves and can easily be dispersed by wind. After 6 weeks of feeding, the caterpillar pupates in a loosely spun cocoon on host plants with adults emerging from mid-August to September. Females lay egg masses, which are protected by a white foam coating.

Pest management

Cultural controls

Whitemarked tussock moth populations are normally kept in check by several parasites. Monitoring for first instars in both crop and sprout fields in early July is necessary to time spray applications. Workers in heavily infested fields must wear protective clothing and dust filters to avoid contact with hairs of the insect, which are easily dislodged from the caterpillars and can cause irritation and allergic reactions in humans.

Issues for whitemarked tussock moth

None identified.

Weeds

In this section

• Key issues
• All weeds

Key issues

• There is a need for new selective conventional and non-conventional pest control products, which are active against a targeted range of weeds to reduce reliance on applications of broad-spectrum, pre-emergence herbicides.
• There is a need for post-emergence herbicides active against grass weed species, specifically non-Group 1 herbicides, in order to facilitate resistance management within weed populations.
• It is critical that new pest control product registrations have pre-harvest intervals that meet maximum residue limits for export and to ensure the marketability of the crop.
• A protocol for equipment sanitization and field biosecurity is needed to help growers reduce the spread of weeds among blueberry fields.
• There is a need for research on the effect of soil nutrition and pH on the growth of perennial weeds.
• New weed control methods need to be explored to help organic production and reduce reliance on chemical weed control.
• For provincial rankings of key weed occurrence, see Table 8.

All weeds

Pest information

Damage

Weeds compete for space, moisture and nutrients, and can reduce blueberry plant vigour and yield. Weeds may shade the crop, resulting in poor bud formation and can act as alternate hosts for insects and diseases. The presence of weeds can also cause harvesting challenges.

Life cycle

Annual broadleaf and grass weeds: Annual weeds complete their life cycle in one year, from seed germination through vegetative growth and flowering to seed production. They produce large numbers of seeds that can remain viable in the soil for many years and germinate when conditions are suitable.

Perennial broadleaf and grass weeds: Perennial weeds are herbaceous or woody plants that live for many years. They can reproduce and spread by means of seed as well as through the expansion of various types of root systems and other vegetative mechanisms.

Pest management

Cultural controls

Equipment sanitation when moving between fields, the use of weed-free straw for prune-burning and controlling weeds along roadsides and at field perimeters, is important to prevent the introduction of weeds into blueberry fields. Weed pulling and cutting prior to seed set, can prevent seed dispersal. Avoiding excessive fertilizer applications and reducing soil pH can improve the competitiveness of the crop. Eliminating bare areas in a field by interplanting young blueberry plants will eliminate sites prone to weed establishment. Pruning by burning will destroy weed top-growth and seeds. However, pruning by burning or mowing may only suppress perennial weeds as these practices do not completely destroy the root systems, allowing these weeds to re-grow. Additional management practices for weeds are listed in Table 9.

Issues for annual broadleaf and grass weeds

• There is a need for improved understanding of the impact of fertilization and soil nutrient levels on the growth and vigour of annual broadleaf weeds.
• There is a need for the registration of post-emergence grass weed herbicides in groups other than Group 1 for resistance management.
• Witch grass (Panicum capillare) is an emerging annual grass problem and cow wheat (Melampyrum lineare) is an emerging annual broadleaf weed problem.
• Biological control options are required for weed control in lowbush blueberry.

Issues for perennial broadleaf and grass weeds

• Clearer understanding of the spectrum of weeds controlled by currently available herbicides is needed for improved treatment decisions.
• Additional information on the best timing of herbicide applications and the impacts of combining herbicide treatments for weed control is required.
• There is a need for new pest control products to manage a targeted range of weeds, to allow for more precise herbicide applications and reduce the need for broad-spectrum pre-emergence herbicides.
• St. John's wort (Hypericum perforatum), spreading dogbane (Apocynum androsaemifolium), barrenberry (Photinia spp.), spreading blackberry (Rubus spp.), vetch (Vicia spp.), sheep sorrel (Rumex acetosella), hawkweed (Hieracium spp.), bulrush (Scirpus spp.), sweet fern (Comptonia spp.), goldenrod (Solidago spp.) and wild sarsaparilla (Aralia nudicaulis) are perennial weed species that are particularly challenging to control.
• Protocols that outline equipment sanitation are required to help growers reduce the spread of weeds between fields. In addition, an effective approach to inform growers about sanitation protocols is required.
• Research on the effect of soil nutrition and pH on the growth of perennial weeds is needed.
• Perennial grasses, including poverty oat grass (Danthonia spicata) and fescues (Festuca spp.) are an increasing problem in lowbush blueberry. New conventional and non-conventional herbicides are needed for resistance management in these weeds.
• Alternative approaches to weed control including organic methods and different application timings that break weed cycles are required.

Resources

Integrated pest management/integrated crop management resources for production of lowbush blueberry in Canada

• Agri-Réseau, Québec (in French only)
• Canadian Food Inspection Agency. D-02-04: The Blueberry Certification Program and Domestic Phytosanitary Requirements to Prevent the Spread of Blueberry Maggot (Rhagoletis mendax) within Canada.
• Ontario Ministry of Agriculture, Food and Rural Affairs. 2021. Publication 360B, Crop Protection Guide for Berries.
• Ontario Ministry of Agriculture, Food and Rural Affairs. Berries.
• Perennia. Wild Blueberries.
• Quebec Reference Centre for Agriculture and Agri-Food.
• Wild Blueberry Network Information Centre.

Provincial contacts

Provincial and national grower organizations

• NB Blueberries
• Fruit and Vegetable Growers of Canada
• Ontario Berry Growers Association
• PEI Wild Blueberry Growers Association
• Syndicat des producteurs de bleuets du Québec (in French only)
• Wild Blueberry Producers Association of Nova Scotia

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

• Agriculture and Agri-Food Canada. 2016. Diseases of lowbush blueberry and their identification [Hildebrand, P.D., W.E. Renderos and R.W. Delbridge]. AAFC No. 12476E. ISBN 978-0-660-04183-4. Catalogue No. A59-37/2016E-PDF.
• Centre de référence en agriculture et agroalimentaire du Québec (CRAAQ). 2016. Wild Blueberry Production Guide… in a context of sustainable development. Pub. No. PAUT0108-PDF.
• Drummond, F., J. Smagula, S. Annis and D. Yarborough. 2009. The University of Maine. Cooperative Extension: Maine Wild Blueberries. Organic Management – Maine Agricultural and Forest Experiment Station Bulletin 852: Organic Wild Blueberry Production. ISSN: 1070-1494.
• Lambert, L., G.H. Laplante, O. Carisse and C. Vincent. 2013. Diseases, Pests and Beneficial Organisms of Strawberry, Raspberry and Blueberry. Centre de référence en agriculture et agroalimentaire du Québec. ISBN 978-2-7649-0230-1. 343 pp.
• New Brunswick Department of Agriculture, Aquaculture and Fisheries. 2017. Wild Blueberry IPM Weed Management Guide (PDF). Wild Blueberry Fact Sheet C.4.2.0
• New Brunswick. Agriculture, Aquaculture and Fisheries. Wild Blueberries.
• Reekie, M., K. McKenzie and B. Lees. The biology and pest potential of cranberry tipworm (Diptera Cecidomyiidae) in lowbush blueberry. 2009. Proceedings of the IX International Vaccinium Symposium, ISHS Acta Horticulture 810: 401-410.
• Wild Blueberry Producers Association of Nova Scotia. 2011. Wild Blueberry Fact Sheet: Blueberry Gall Midge (PDF).
• University of Maine. 2017. Cooperative Extension: Maine Wild Blueberries. Insects – 208-Blueberry Tip Midge. Fact Sheet No. 208.
• University of Maine. 1994. Cooperative Extension: Maine Wild Blueberries. Insects – 205-Red-Striped Fireworm (Aroga trialbamaculella Cham.). Fact Sheet No. 205.