Archive for June, 2012

Blueberries: Organic Production

June 30, 2012

Blueberries are the most widely grown fruit crop in the United States. Blueberries are well-suited to organic culture, and good markets exist for organically grown blueberries. The production guide, Blueberries: Organic Production by the Natonal Sustainable Agriculture Information Service, addresses key aspects of organic blueberry production, including soils and fertility, cultural considerations, pests, and diseases, as well as marketing. Additional resources are provided for further investigation.

This publication focuses on organic blueberry production, specifically the highbush and rabbiteye species, and is most relevant to production conditions east of the Rocky Mountains. It does not go deeply into many of the basics of blueberry culture—variety choice, planting, pruning and training—which are largely the same under both organic and conventional management. Such general information is available from your state’s Cooperative Extension Service and many horticulture books, periodicals, and bulletins. Nor does this publication address organic production of lowbush blueberries. The Maine Organic Farmers and Gardeners Association (MOFGA) and K-Ag Laboratories International in Wisconsin both have information on organic culture of native, unimproved lowbush blueberries.

Information in the publication includes:

Choosing a Variety

Blueberries are members of the genus Vaccinium and belong to the Rhododendron family (Ericaceae). The Vaccinium genus contains several species of economic importance. The highbush blueberry (Vaccinium corymbosum) is the most widely cultivated, grown from the Mid-Atlantic to California, Oregon, and Washington, and from the Upper Midwest to the Mid-South. The lowbush (wild) blueberry (V. angustifolium) is adapted to the far North and is commercially important in Maine, Eastern Canada, and parts of New Hampshire, Massachusetts, Michigan, and Wisconsin. Rabbiteye (V. ashei) is a large bush well-adapted to the South, in the region roughly south of Interstate 40. Southern highbush (V. corymbosum x V. darrowi), a new hybrid, is adapted to the southern rabbiteye zone as well as the coastal South. It has a lower chilling-hours requirement, and it flowers and fruits earlier than highbush or rabbiteye varieties.

Soils and Fertility

The Importance of Soil pH

Blueberries are distinct among fruit crops in their soil and fertility requirements. As members of the Rhododendron family, blueberries require an acidic (low pH) soil, preferably in the 4.8 to 5.5 pH range. When soil pH is appreciably higher than 5.5, iron chlorosis often results; when soil pH drops below 4.8, the possibility of manganese toxicity arises. In either case, plants do not perform well.

Blueberry Fertilization Practices

Soil-building practices prior to establishment can go a long way toward providing the fertility necessary for a healthy blueberry planting. High levels of soil organic matter are especially important in blueberry culture, contributing to the soil’s ability to retain and supply moisture to the crop, buffering pH, and releasing nutrients through decay. Soils rich in organic matter are also a desirable environment for symbiotic mycorrhizal fungi that assist blueberry roots in absorbing water, nitrogen, phosphorus, and other minerals.(Yang et al., 2002) Green manures in advance of planting can play an important part in cycling organic matter into the soil system, as can applications of composts and livestock manures. ATTRA has several publications that can be useful in these areas, including Overview of Cover Crops and Green Manures, Manures for Organic Crop Production, and Farm-Scale Composting Resource List.

Cultural Considerations

Plant Spacing

Highbush blueberries are typically spaced 4 to 4½ feet in the row, with 8 to 12 feet between rows. As bushes can get quite large at maturity, many growers find that 10– to 12–foot row spacings—approximately 900 to 1090 plants per acre—are preferable for tractor operations (mowing, harvesting, and spraying). Rabbiteyes are typically spaced at 5 to 8 feet within a row, with 12 to 14 feet between the rows, or 388 to 726 plants per acre.

Inter-row Management

Blueberries do not have extensive root systems. As a result, clean cultivation of row middles to control weeds and to incorporate cover crops is less damaging to blueberries than it is to bramble fruits. Still, it is wise to till no deeper than 3 inches. Similarly, inter-row living mulches—also called sodded middles—generally are not competitive with the crop unless the inter-row species are aggressive and invade the rows. Fescue is commonly used in the Mid-South for sodded middles, as are several other grass species.

In-row Weed Management and Mulching

Weeds are considered by many growers to be the number one problem in organic blueberry culture. It is especially important to control aggressive perennial weeds such as johnsongrass, bermudagrass, and quackgrass prior to crop establishment. Sites with these grasses should generally be avoided for blueberry establishment. Details of pre-plant and post-plant weed management for all fruit plants are provided in ATTRA’s Overview of Organic Fruit Production. Some techniques, however, deserve additional elaboration.


Blueberries are insect-pollinated; thus, increasing the number of pollinators can be quite beneficial. Blueberry flowers vary greatly in size and shape, depending on species.(Lyrene, 1994) Therefore, having a variety of pollinators like horn-faced bees, mason bees, carpenter bees, bumblebees, orchard bees, and others is important for good fruit set.

The guide also addresses insect pests, diseases, bird and rodent control and economics.

Kuepper, George L. and Steve Diver. Blueberries: Organic Production. 2010. Retrieved 26 August 2010.




A Year in the Life of a Blueberry Bush

June 28, 2012

Have you ever wondered how blueberries grow? If so, Mark Longstroth of the Michigan State University Cooperative Extension Service reveals all in the article, A Year in the Life of a Blueberry Bush. Information in the articles includes:

Roots: Roots are organs, which absorb water. This is their primary function. Most of the water is taken up at the root tips. There is a zone of active cell division at the root tip where new cells are formed. Directly behind the tip is a region known as the zone of elongation where the new cells grow by increasing in length. This elongation pushes the root into the soil.

Water Movement in Plants: Water has to enter the plant cells to get into the roots, but plant cells do not actively take up water. The water moves into the cells because they are full of salts and sugars. Root cells receive sugars from the leaves and also actively absorb salts from the soil. This concentration of salts and sugars causes water from the soil to move into the cell. This water is then pulled to the xylem by the active movement of salt ions into the xylem and the water follows the salts. The stem of the plant is simply a plumbing system. The inner layer is the wood or xylem, which carries water from the roots up to the leaves.

Annual Cycle of Growth: In the early spring, as the ground begins to warm, the roots begin to grow. The roots use sugar, which was stored in the shoots and roots the previous year, for this growth. Many growers will put on fertilizer at this time so the roots can absorb it. But the roots take up very little because plants that have no leaves use very little water. As the buds begin to grow they use sugar that was stored in the buds. The new leaves do not have a waxy cuticle water is lost water fairly rapidly. Now the plant begins to take up water from the soil. The roots and shoots are growing at the same time. There is plenty of water and sugar to go around. The roots grow where the conditions are best. Most root growth takes place in the moist warm surface soil early in the year. If the soil is saturated with water, as in flooded fields, the roots may drown. As the soil dries, the roots grow deeper. If the soil remains wet, because of a wet spring, a high water table, or a low spot in the field, then the root system will remain shallow.

Read more at:

Monitoring Soil Quality for Blueberries

June 27, 2012

Monitoring Soil Quality involves tracking trends in quantitative indicators or the functional capacity of the soil in order to determine the success of management practices or the need for additional management changes. Monitoring involves the orderly collection, analysis, and interpretation of data from the same locations over time.

For more information visit:

Blueberries Are Easy to Grow

June 25, 2012

From a gardening standpoint, blueberries are fairly easy to grow. If you can grow azaleas, you can grow blueberries. Depending on who’s counting, there are about 450 species of Vaccinium in the world. Most of these different blueberries grow in the Northern hemisphere and a number of them grow in North America. Man has used blueberry as a food source since before recorded history. In fact a good portion of the annual production in some areas still comes from berries harvested in the wild.

Two species of lowbush blueberry, V. angustifolium and V. mytilloides are still harvested in the wild in the United States. These species are also cultivated in places like Maine and Michigan. The flavor of lowbush blueberries is said to be superb. The Northern highbush blueberry, V. corymbosum, is the most commonly cultivated type of blueberry in the United States. A good portion of the production comes from the Northeast and the Pacific Northwest. Northern highbush will grow and produce on elevated sites as far south as Alabama. The most commonly planted blueberry in the Southeast is the rabbiteye, V. ashei. Like a lot of other fruits that grow well in the Deep South, the rabbiteye is a true Southern native. Vast areas of the Southern woodlands are covered by wild rabbiteye blueberries.

Along the Gulf Coast, many acres are being planted to Southern highbush blueberries. This is a hybrid, primarily between Northern highbush and V. darrowi, as well as other species. The Southern highbush was bred to incorporate the superior fruit characteristics of the Northern highbush with the heat tolerance and low chilling requirement of the other species. The Southern highbush is a very temperamental plant and needs special care and attention to grow. Some growers actually plant them on raised beds of pure organic matter and irrigate them. This special attention results in a high quality berry that can be grown father south and harvested a little earlier than rabbiteye.

Regardless of the species, one thing all blueberries have in common is a love of organic matter. When planting blueberries, it is important to incorporate some organic matter into the planting hole. This can be peat moss, compost or fine pine bark. After planting, it is a good idea to mulch the plants. Container grown blueberries can be planted locally from October through March. Bare root blueberries have the best chance of living when planted from December through February.

Fertilizing blueberries is a little tricky. They can not tolerate the nitrate form of nitrogen, therefore many of the commonly available fertilizers are not suitable. Ammonium forms of nitrogen such as urea or ammonium sulfate are better. There is no substitute for a soil test for determining the other elements that are needed. Also, blueberries need to be grown on acidic soil. In reality, you are far more likely to kill blueberry plants with fertilizer than with anything else.

Once the plants are in the ground, it would be a good idea to prevent them from fruiting for the first couple of years by pulling the young fruit off. That way, all of the energy the plant makes goes into establishment rather than producing a fruit crop.

Another thing to be aware of is that blueberries usually bloom very early in the spring and are subject to late spring frosts. Newer cultivars of rabbiteye blueberry such as Alapaha, Ochlockonee, Vernon and DeSoto bloom a little later than older cultivars such as Tiftblue, Climax and Premier.


Scouting for Pests in Blueberry Fields

June 24, 2012

Regular scouting of pests and diseases in bluebeberry fields is the foundation for effective pest management, as well as ensures early detection of insect and disease problems before they reach damaging levels. Regular scouting also helps optimize proper timing of control measures.

Read more about scouting here:

Blueberry Knowledge: A Video Trilogy

June 23, 2012

In order to have a productive blueberry crop, there are some things you should know and do from the beginning. These videos will help you learn what and when to do certain tasks to ensure you have a bountiful blueberry crop.

Watch the videos here:

Fire Ants in Blueberries

June 22, 2012

Although fire ants may feed on ripe fruit, they have only an insignificant impact on crop yields.
They may even increase the amount of marketable fruit because they are natural enemies of other pests (e.g. cutworms, leafrollers, maggots, etc.) that live or pupate in the soil.
Fire ants are regarded as pests primarily because they attack pickers and other agricultural workers who tend the bushes.

There are several formulations of insecticides and growth regulators that are sold for controlling fire ants, but only carbaryl (Sevin) and diazinon are labelled for use in blueberry fields. Sevin can be applied as a foliar spray one day before harvest to kill foraging workers. This provides only short-term protection so pickers can harvest the fruit without being stung. For more long-lasting protection, diazinon is used as a mound drench to saturate the soil and kill the occupants of an entire nest site. Mix one pint of diazinon in 100 gallons of water and use one gallon of this solution for mound up to 8 inches in diameter and two gallons for larger mounds (Banks 1990). Contact your local Cooperative Extension Service for control recommendations in your region.
Drench treatments are most effective when applied on cool, sunny mornings while the ants, including queens and immatures, are concentrated near the soil surface. Later in the day and during hot, dry weather, the ants retreat deep into the mound where the insecticide is less likely to reach them

Learn more here:

Effects of Insects on Blueberry Plants (Video)

June 18, 2012

Rufus Isaacs of MSU Entomology explains his experiment to discover effects of insects on blueberry plants in this video:




Soil pH for Blueberry Plantings

June 17, 2012

Blueberries require a lower pH than many other fruit and vegetable crops. Before planting blueberries, test the soil to determine the pH level, as well as amounts of nitrogen, phosphorus, potassium and organic matter present. More information can be found in the Soil Testing secion of this article, Site Selection for Blueberry Production.

Blueberries require a soil pH of 4.0 to 5.3 for best growth. The primary material recommended for lowering soil pH is finely ground wettable sulfur. Because sulfur reacts slowly and must be converted by soil bacteria, the change in soil pH is brought about slowly; therefore, sulfur should be added to the soil and mixed thoroughly several months to a year prior to planting.

If the soil pH is in the range of 5.4 to 6.0, sulfur can be applied six months before planting to lower the pH. Sulfur also can be applied after planting to the soil surface but not mixed with the soil. Rates of up to 7/10 pound per 100 square feet can be used yearly, if needed. If the initial soil pH is above 6.0, growing blueberries will be difficult unless massive amounts of peat moss or milled pine bark are mixed with the soil. Use 1 pound (2.5 cups) per 100 square feet on sandy soils to lower pH by 1 unit (for instance, from 6.0 to 5.0). Apply 2 pounds per 100 square feet for the same amount of pH lowering on heavier soils containing silt, clay or more than 2 percent organic matter. Try to achieve a pH of around 4.8; too much reduction can be detrimental to bush growth.


Gu, Mengmeng and Keith Crouse. Soil pH and Fertilizers. Retrieved 16 March 2010.


Blueberry pest- Cranberry Fruitworm

June 16, 2012

The cranberry fruitworm is one of the most serious pests of blueberries in the Eastern United States. Some fields have suffered 50 percent to 75 percent losses of fruit. Infested berries may be harvested and packaged without detection, resulting in consumers finding larvae in packaged berries.

The eggs are very small and difficult to see without a hand lens. They look like flat white scales with small yellowish to reddish areas near the center. Hatched eggs appear brighter white; eggs that have been parasitized by a small wasp appear black and will not develop into larvae.
In the larval stage, the cranberry fruitworm is a smooth caterpillar that is mostly green with some brownish-red coloration on its top surface. It has three pairs of true legs on the thorax and five pairs of fleshy prolegs on the abdomen. Larvae are about 1/2 inch long when fully grown. The larvae attain a length of about 3/8 inch and are usually greenish, sometimes light brown along the back. Once larvae are fully grown, they drop to the ground and spin a hibernation chamber where they overwinter. There is only one generation per year.
The adults are brownish-gray moths with a wingspan of about 5/8 inch.
Overwinters as a fully grown larva within a cocoon made of silk and soil particles.
The cocoons are frequently made under weed and debris on the soil surface, but they may be deeper.
The larvae pupate in the spring and complete development, with the adult moths emerging after bloom and fruit set.
The eggs are deposited on the berries, almost always on or inside the calyx cup (blossom end) of unripe fruit.
Eggs hatch in about five days.

Young larvae move to the stem end of the fruit, enter, and feed on the flesh.
A single larva may feed on up to eight berries to complete its development.
The larvae move from one berry to another within a cluster and usually web the berries together with silk.
The inner flesh of developing and ripening berries is consumed entirely by fruitworm larvae. *Damaged berries are covered with brown sawdust-like frass and usually webbed together with silk.
The frass fills the tunnels in the berries that cling to the silk webbing, producing very messy feeding sites, which easily distinguish cranberry fruit worm damage from cherry fruitworm damage.

Monitoring the flight of adults with pheromone traps will greatly improve the timing of pesticide treatments for this pest.
Experienced scouts can also monitor the calyx ends for eggs to determine the amount of egg laying.

Cultural Control: Elimination of weeds and trash around plants helps by cutting down on overwintering protection for fruitworm cocoons.
Mechanical Control: Cranberry fruitworm was effectively controlled in the past by picking off infested berries, which are easily detected because of the webbing and their early ripening. *Control by Insecticides: Clean cultivation will reduce the population of cranberry fruitworm within a field significantly, but insecticide treatments may still be needed to achieve satisfactory control of this pest. In New Jersey, university recommendations suggest making the first application when larval entries are first seen on the fruit, with a second application 7 days to 12 days later in fields where the pest is a serious problem. Economic threshold levels have not been established.