Blueberry

Reading: Chapter 7 in Small Fruit Crop Management

Blueberries are native to North America (one of the few fruit crops native to NA).

Various species occur from Florida to Nova Scotia in the East, and westward to northern Indiana. Other species occur from the Rocky Mountains to the west coast.

Family: Ericaceae

Sub-family Vacciniaceae

Tribes: Gaylussacieae Huckleberry

Vaccinieae Blueberry, cranberry, whortleberry, bilberry

Genus: Vaccinium

Subgenera: Batodendron

Euvaccinium

Oxycoccus Cranberry

Cyanococcus Blueberry

Cultivated (Tame) Blueberries

1. Highbush: Grown from Mid-Atlantic to NE, and Mid-South, Midwest, and Northwest US.

V. corymbosum - Northern highbush

V. australe - Southern highbush

2. Rabbiteye grown mainly in SE US

V. ashei

3. Others: Half-high (highbush x lowbush) in Northern areas

Southern highbush (V. corymbosum x V. darrowi) in Southern areas

“Managed” Wild Blueberries

1. Lowbush Grown mainly in NE US and Canada

V. angustifolium - U.S. commercial production: Maine, New Hampshire, Massachusetts

V. myrtilloides - Native stands managed and harvested (esp. in eastern Canada)

Highbush Cultivar Development

Early work (pre-1900s) Selection of best types from the wild and propagating and transplanting studies. Done in Maine, Rhode Island, New York, and Michigan

Cultivar Improvement - Breeding

F.V. Coville - USDA, Beltsville, MD. Began in 1906 collecting the best wild selections and making crosses between them to compliment their characteristics.

Mrs. Elizabeth White - Farmer/land owner that provided the land and labor to maintain the breeding work of Coville.

Several cultivars were released: Pioneer, Katherine, Cabot, Rubel

This work was the foundation for a ‘new’ fruit industry that began in the 1920s.

Genetics of Blueberry

V. corymbosum (highbush) 4n n=12

V. australe (southern highbush) 4n

V. angustifolim (lowbush) 4n

V. ashei (rabbiteye) 6n

other species 2n

The major goals of modern breeding programs are:

1) large fruit size, lighter fruit color - to improve consumer appeal

2) fruit firmness, small stem scar - to improve post harvest shelf life

3) winter hardiness, drought resistance, disease resistance, late-bloom / early fruit maturity, high yield and adaptation to machine harvesting.

World Production of Cultivated (Tame) Blueberries

US - major leading producer 45,000 acres 169 mil lbs

1. Michigan 16,500 acres 70 mil lbs

2. New Jersey 7,400 acres 33 mil lbs

3. Georgia 3,800 acres 9 mil lbs

4. North Carolina 3,750 acres 8 mil lbs

5. Oregon 2,500 acres 20 mil lbs

6. Washington 1,300 acres 8 mil lbs

7. Mississippi 1,200 acres 3 mil lbs

8. Florida 1,150 acres 1.5 mil lbs

9. Indiana 800 acres 3.0 mil lbs

Other countries with blueberry production

Canada

British Columbia 22 mil lbs

Ontario 1 mil lbs

Europe, New Zealand, Australia, Chile

Total World Production: ~250 mil lbs worth about $150 mil

Botany / Anatomy of Blueberries

Topgrowth: Woody shrubs which produce new growth as succulent green canes from base of the plant, and as green shoots from 1 yr old wood in the top of the plant.

Canes can live 10-20 years, but are generally pruned out after 5-7 years.

Highbush blueberries can reach 4-10 ft tall, lowbush types generally are less than 3 ft tall, and half-high types are intermediate. Rabbiteye blueberries are the tallest, most vigorous species and can reach heights of 20 ft.

Root system:

Highbush Fine, fibrous roots that lack roothairs.

Often associated with endotrophic mycorhizza (VAM) which help the roots absorb water and nutrients. Roots can extend out about 6 ft from the base of the plant, but seldom penetrate more than 3 ft deep.

Lowbush Fine, fibrous roots lacking roothairs. Grow adventitiously from rhizomes so the plants have a spreading growth habit. Over time, a large ‘patch’ may result from a single plant.

Flower bud development:

Fruit buds develop in the late summer and fall.

Development occurs basipetally - from the tip of the new shoot towards the base.

The number of flower buds is dependent on the shoot diameter as well as the climate;

Flower differentiation within buds Acropetally - from the base to the tip. The flower type is a raceme.

Fruit development: Fruit size is dependent on several factors:

Shoot diameter - larger is better

Seed number - more is better - Pollination is critical in blueberries

Pollination: Blueberries have ‘entomophilous’ (insect loving) flowers that need pollinators.

Characteristics of blueberry flowers:

1. Fused petals - open only at end

2. Nectaries are at the base of the ovary and fragrant - they attract the insect deep into the flower

3. Pollen is heavy, sticky, and not wind blown

4. Stamens are shorter than the style, so pollen cannot fall on the stigma

5. Style is flanged to prevent self pollination

Highbush Blueberry Culture

Temperature:

Need at least 160 frost free days

2,000 + Growing Degree Days

Need 650-850 chilling hours (250 for Southern highbush and rabbiteye)

Cold hardiness:

Buds -15 to -20˚F

Stems -20 to -30˚F

Flowers 24 to 30˚F (more tolerant of cold than some small fruits)

Daylength:

Long days promote vegetative growth

Short days promote fruit bud development - occurs in late summer and fall

Moisture:

Because blueberries lack roothairs, they are very sensitive to changes in soil moisture status and require adequate levels during growth and fruiting which is about 1-2 inches per week (depending on vigor, variety, climate, etc).

Water quality is very important and should be low in salts, especially calcium.

Soils:

Ideal blueberry soils are well-drained, acid, and sandy.

Soil pH should be 4.5 to 5.2

Heavier soils are acceptable if they have a high organic mater content.

To be suitable for blueberries, upland mineral soils must be:

1) amended with peat moss or compost before plant establishment and

2) mulched with sawdust, bark, pine needles, etc.

Site Selection:

Good air and soil drainage are most important. Because blueberry flowers are fairly tolerant of light frosts, they don’t necessarily need to be on frost-free sites.

Land preparation:

Soil drainage improvement - tiling

Soil building with cover crops to increase organic mater content

pH adjustment - Addition of sulfur according to current pH and soil type

Addition of nutrients - add P, K, Ca, Mg, etc. as needed and cultivate into top 12 inches

Bedding or ridging of rows - especially on somewhat poorly drained soils

Planting:

Plant in spring or fall depending on severity of winter temperature, likelihood of frost heaving, etc.

Set as same depth in nursery (do not plant too deeply)

Mulch - after planting apply a 6 to 8 inch deep band of mulch 2 to 4 ft wide along the row

Fertilize with nitrogen after plant has begun growth. Split nitrogen applications

Spacing:

4 ft x 10 ft is the standard spacing, but can be extended to 5 between plants and 12 feet between rows. Rows should be no closer than 8-9 ft to allow room for pickers to walk through

Planting stock:

3 choices: 1 yr. old rooted cuttings

2-3 yr. old nursery grown plants bare-rooted

2-3 yr. old container grown plants

Pruning:

“Renewal” pruning

Annual removal of older and younger canes to achieve a balance of cane ages.

Procedure:

Remove weak or diseased canes

Remove some of the oldest, less productive canes each year.

Remove excess young canes to improve growth of the others.

Reduce density of branches in top of plant (detail pruning)

Bushes should end up with 15-25 canes with the same number in each of the age classes.

Pest Management:

Diseases

Fungi:

Blueberries have fewer fungal disease problems than some other small fruits.

Mummyberry – Monilinia vaccinii-corymbosi

Phomopsis Canker and Twig Blight – Phomopsis vacinnii

Phytophthora Root Rot – Phytophthora cinnamomi

Fruit rots:

Anthracnose – Colletotrichum gloesporioides

Alternaria – A. alternata

Viruses:

Viruses can be a problem in blueberries

Blueberry Scorch

Shoestring Disease

Blueberry Leaf Mottle

Necrotic Ringspot

Red Ringspot

Mycoplasma-like-organisms:

Blueberry Stunt

Insects:

Direct Pests (feed on fruit and cause “direct” loss of yield

Cranberry Fruitworm

Blueberry Maggot

Others: Cherry fruitworm, Plum curculio

Indirect Pests (feed on the foliage and reduce yields “indirectly” by weakening the plant, or by vectoring virus or MLO diseases.

Sharp-nosed leafhopper

Scale insects

Blueberry tip borer

Blueberry stem borer

Birds

Bird damage is a major problem in some regions. Growers use an integrated approach to managing bird damage.

Scare Tactics:

Noise makers

Recorded bird distress calls

Visual deterrents

Scare crows

Scare-eye balloons

Mylar tape

Exclusion:

Netting

Chemical deterrents:

Measurol – banned

Some insecticides

Sucrose