Cranberry

Description

Cranberry is the name given to a group of long-lived woody perennial shrubs or trailing vines in the genus Vaccinium, including Vaccinium macrocarpon, the most popular commercial species, grown for their edible berries. The cranberry bush possesses a slender, wiry stems with small elliptical waxy evergreen leaves 7–10 mm (0.28–0.45 in) in length. The plant produces distinctive dark pink flowers with reflexed petals that leave the style and stamens exposed. The fruit is produced on the new plant growth produced that season and are initially white and ripen to dark red, waxy berries measuring 9–14 mm (0.4–0.6 in) in diameter. The cranberry plant can reach 5–20 cm (2.0–7.9 in) in height, with the vines stretching up to 2 m (6.6 ft) long. The cranberry may also be referred to as bearberry and originates from North America.


Uses

Cranberries are usually processed into juice, sauce, jam and sweetened dried cranberries. They may also eaten raw. Cranberries have long been used as a remedy to prevent recurrent urinary tract infections, research has demonstrated the benefit to women, but the effect on other groups is less clear.


Propagation


Basic requirements
Cranberries are wetland plants which grow best in bogs, swamps and poorly draining soils. The plants grow best in acidic, organic or sandy soils with a pH between 4.0 and 5.5 where there is a plentiful water supply. The bed should have a base material which is impermeable to water such as clay or peat. Commercially grown cranberries are grown in large beds surrounded by dykes that hold water in the beds when flooded for harvest. Cranberry is very susceptible to frost and flooding is also used to protect the plants along with sprinkler irrigation. This means that it is the water that will freeze and the resultant heat produced by the change of liquid to solid (latent heat of fusion) protects the plants from freezing themselves. It is common for cranberry beds to be covered with up to 25 cm (9.8 in) of ice.

Propagation
Cranberries are usually propagated vegetatively by moving vines to a new bed. Cuttings are obtained as a by product of the practice of mowing the beds. Mowing helps to prevent the vines from becoming matted and leads to greater productivity by promoting new growth. Cuttings are pushed into a layer of fresh sand approximately 15 cm (5.9 in) deep and the sand is kept moist to allow the new vines to establish and produce new growth. Fruit will be produced on the new vine within 2–3 years and full productivity should be reached within 4 to 6 years of planting. Rooted plants are available for planting in home gardens and are less labor intensive option.

General care and maintenance
One of the most important aspects of caring for cranberry plants is to protect them from frosts. Growers use irrigation systems to help prevent damage and are able to flood the beds to protect the plants. In the home garden, cranberry plants can be protected by covering with plastic sheets or blankets in the event of a frost. Cranberry beds should be kept moist through irrigation. Cranberries benefit from the addition of fertilizers with nitrogen being the most common requirement. Cranberries utilize nitrogen in the ammonium form as the lack the ability to reduce the nitrogen to nitrate. Phosphorous may also be required but should not be applied to the soil in excess amounts as acid soils bind large quantities of the element and it is unavailable to the plants.

Harvest
Cranberries can be dry or wet harvested. Berries are dry harvested with the use of a machine which combs berries from the plants. Wet harvesting of berries occurs in many major cranberry growing regions and involves flooding the beds and using machinery to remove the berries from the vines. The beds are flooded with water sufficient to cover the vines and a piece of machine called a water reel, or “beater”, is driven through the bed to displace the berries from the plants. More water is then added to the beds to allow the berries to float free from the plants and they are then moved with the use of booms to one corner of the bed where they are removed by conveyor belts or pumps for transport and processing.


References

CABI Crop Protection Compendium. (2008). Vaccinium macrocarpon datasheet. Available at: http://www.cabi.org/cpc/datasheet/56008. [Accessed 18 November 14]. Paid subscription required.

Caruso, F. L., & Ramsdell, D. C. (Eds.) (1995). Compendium of Blueberry and Cranberry Diseases. American Phytopathological Society Press. Available at: http://www.apsnet.org/apsstore/shopap.... Available for purchase from APS Press.

D’Sa, E. M. (2003). Using and Preserving Cranberries. National Center for Home Food Preservation . Available at: http://nchfp.uga.edu/publications/nch.... [Accessed 18 November 14]. Free to use and share.


Common Pests and Diseases

Cottonball
Monilinia oxycocci

Symptoms
Tip blight on new shoots (shriveled tip resembles a shepherd's crook); masses of white powdery spores on tips just before plant bloom; brown V- or U-shaped lesions on leaf midveins
Cause
Fungus
Comments
Fungus overwinters in dried up remains of fruit
Management
Primary method of controlling cottonball is the application of appropriate fungicides if available; cultural practices that reduce incidence of the disease have not yet been investigated

Botryosphaeria fruit rot and berry speckle
Botryosphaeria vaccinii

Symptoms
Small, light colored lesions on skin of fruit; epidermis surrounding lesion turns red; on green fruit lesions appear as red ring spots; fruit may develop a watery rot postharvest
Cause
Fungus
Comments
Occurs in all major cranberry growing regions of the US but causes little economic damage
Management
No specific control measures; application of fungicides for other fruit rots usually sufficient to control this particular disease; removing plant debris from beds during flooding may reduce levels of inoculum

End rot
Godronia cassandrae

Symptoms
Soft watery rot which can start at either end of berry with clear boundaries between rotting area and unaffected tissue; rot progresses to affect entire berry which becomes soft to touch; upper surface of leaves may become infected and develop red-brown spots which develop tan or gray centers and black borders; areas of leaves outside black borders turn bright red; leaves may drop from plant
Cause
Fungus
Comments
Fungus overwinters in bark, dead leaves and rotting fruit; disease incidence is increased when raking is used during wet harvest of cranberries
Management
Disease usually manifests as a post harvest berry rot and only requires control if berries are for soft market; fungicides are available in some US states; end rot development can be slowed by refrigerating berries after harvest

Proventuria Early Leaf Spot
Proventuria barriae

Symptoms
Red circles or rings on upper surfaces if leaves which darken as the fungus multiplies; symptoms of early leaf spot can appear as early as March
Cause
Fungus
Comments
Management
No control measures currently recommended

Red leaf spot
Exobasidium rostrupii

Symptoms
Circular Albright red spots on upper leaf surfaces; spots may also be present on young berries
Cause
Fungus
Comments
Fungus overwinters on infected leaves and stems; disease emergence is favored by periods of high humidity such as rainfall and fogs
Management
Spraying with Bordeaux mixture after bud break protects new leaves from becoming infected; avoid over fertilizing vines; fungicide applications are ineffective if disease outbreak is severe

Cranberry fruitworm
Acrobasis vaccinii

Symptoms
Berries turning red prematurely; fruit shriveling and drying up; fruit is hollowed out and filled with insect frass; entry and exit holes may be visible on the berry - exit holes are significantly larger than entry holes; adult insect is a gray-brown moth which lays its eggs near the calyx end of the berry; newly hatched larvae are very small and are pale yellow in color; larvae are the damaging stage and they burrow into the berries to consume the pulp inside
Cause
Insect
Comments
One fruitworm larva can consume 3 to 8 berries prior to pupation; insect undergoes only one generation per year; insect is also a pest of blueberry
Management
Predation by natural enemies does occur but is not enough to keep the cranberry fruitworm under control; late flooding of the cranberry plantation (30 day reflood before the end of dormancy) has een shown to successfully reduce the activity of the fruitworm; chemical control option include several broad spectrum insecticides for commercial use but must be applied at the egg stage in order to be effective as larvae which have already entered the fruit are shielded from the chemical

Cranberry tipworm
Dasineura oxycoccana

Symptoms
Cupping and whitening of terminal leaves; death of growing tips of plants; plants will compensate by creating a new branch at a lateral bud, these new branches may produce only vegetative growth and no fruit, resulting in reduced yield the following year; adult insect is a tiny (2 mm) fly which only lives a few days; larvae are maggots which are initially clear but change to white and finally orange as they mature
Cause
Insect
Comments
Damage from the insect is most apparent the year following attack in the form of reduced yield; the fly can undergoe between 3 and 5 generations per year
Management
Because cranberry tipworm larvae and adults are so small, they are difficult to monitor; sanding the cranberry bushes is an effective method of controlling insect emergence as it prevent that adults emerging from pupae in the soil; sanding should be conducted on continuous blocks as there is potential for the insect to recolonize from unsanded areas; natural enemies include hoverflies and some species of parasitic wasp

Blackheaded fireworm
Rhopobota naevana

Symptoms
Several leaves webbed together at growing tips of fresh growth; insects feed on lower leaf surface, creating holes which remain covered by the upper leaf surface; upper leaf surface turns red-brown and dies; insect may also wound fruit and encourage secondary infections with fungi and/or bacteria; adult insect is a gray-brown moth; larvae are cream to gray-green caterpillars shiny dark brown or black head
Cause
Insect
Comments
Insect overwinters as eggs on the foliage; insect typically undergoes 2 generations per year but there may be a third generation in warmer years when there is an early spring; insect can cause substantial damage if populations are left unchecked
Management
Reflooding the beds for between 24 and 48 hours after eggs have hatched will kill off a high number of larvae; application of Bacillus thurengiensis may reduce the populations of larvae on the plants

Cranberry weevil
Anthonomus musculus

Symptoms
Flowers are orange instead of pink due to feeding damage and do not produce fruit; numerous holes in berries; feeding damage to underside of leaves results in small black crescent-shaped spots; damage to the base of runners by adult insect may cause damage similar to frost; adult insect is a reddish brown beetle with elongated snout; larvae are yellow-white grubs
Cause
Insect
Comments
Weevils overwinter as adults under the winter flooded beds; the insect undergoes only one generation per year
Management
Cranberry weevil populations usually remain low and little is known about their natural enemies and cultural control methods; chemicals registered for use in commercial plantations on the East coast of the US include azinphosmethyl and chlorpyrifos which should be applied if weevil population has reached the threshold (on average 4.5 weevils per 25 sweep net samples)

Cranberry blossomworm
Epiglaea apiata

Symptoms
Feeding damage to leaves; holes bored in buds; buds and blossoms dropping from plant; adult insect is a dark brown moth; young larvae are green caterpillars which turn reddish-brown sa they mature
Cause
Insect
Comments
Insect overwinters as eggs on crop debris in the soil; blossomworms undergo one generation per year
Management
Insectide application is recommended for commercial production if the number of blossomworm larvae reaches the threshold of 4.5 larvae per 25 sweep net samples (sweep netting must be done at night as the insect is nocturnal);

Gypsy moth
Lymantria dispar

Symptoms
Feeding damage to cranberry foliage and terminal buds and new growth; adult insect is a brown (male) or white (female) moth; larvae are black caterpillars which are covered in hair-like structures called setae; as the caterpillars mature they develop five pairs of raised blue spots and six pairs of raised red spots along their backs
Cause
Insect
Comments
Gypsy moths are serious forest pests and can find their way into cranberry plantations by dropping from nearby trees; outbreaks are cyclic in nature and serious outbreaks in the US have tended to occur every 9-10 years; eggs can overwinter on the bed of the bogs and cause a new infestation in spring
Management
Larvae are easily controlled with insecticides or by reflooding the beds for a period of 24 hours

Phytophthora root and runner rot
Phytophthora spp.

Symptoms
Discrete patches in a bed which are devoid of vines; other symptoms of disease include: weak and unproductive vines; stunted shoots; small leaves which turn red prematurely in the Fall; reduced flower and fruit production; olive green to dark brown discoloration of root tissue under periderm
Cause
Oomycete
Comments
Disease is most severe in water logged or poorly drained soils
Management
Control of the disease is most effective when an integrated management strategy is implemented, control strategies include: managing water to avoid water saturated soil; increasing soil drainage through digging of ditches or installing drains; stimulating root production and plant growth by fertilizing, particularly unproductive plants; application of appropriate fungicides if available