           SUGGESTIONS FOR ESTABLISHING A BLUEBERRY
              PLANTING IN WESTERN NORTH CAROLINA1 
                      Charles M. Mainland  
              Extension Horticultural Specialists  
                  May 1989   Leaflet No. 201  
  


Site Selection  
  
a)  Well-drained, sandy or loamy soils  
b)  pH 4.0-5.0 -- high organic matter -- 3% greater  
c)  Level or rolling land -- elevated area with good air drainage 
    d)  Possibilities for irrigation.  
  

Preparation of Land  
  
a)  Soil test:  Bring to a medium level of P before planting  
b)  Eliminate problem weed species with herbicides or cultivation
    the year before planting.  
c)  Bark humus or sawdust worked into soil to bring organic
    matter to 3% or greater if needed in the row (2-4 foot strip)
    well prepared before planting  
d)  Set plants 5 feet apart in 9-10 foot rows in late winter or
    early spring (as soon as the soil can be worked).  
e)  Sawdust mulch (4-6 inches deep) placed over row immediately
    after setting plants.  
f)  Row middles should be in sod (fescue or bluegrass)  
=================================================================
               HARVEST SEASON             BERRY  
VARIETIES    BEGINS         ENDS          SIZE       COLOR       

*Weymouth    6-15 to 7-1   7-15 to 8-1    small      dark blue
FLAVOR:  poor  

*Earliblue   6-15 to 7-1   7-11 to 7-28   medium     med blue
FLAVOR:  good  

Spartan      6-21 to 7-6   7-21 to 8-7    large      light blue
FLAVOR:  excellent  

Collins      6-22 to 7-7   7-22 to 8-8    med-large  light blue
FLAVOR:  good  

Patriot      6-28 to 7-13  7-28 to 8-12   large      med. blue
FLAVOR:  excellent  

Bluejay      6-30 to 7-15  7-30 to 8-20   med-large  light blue
FLAVOR:  good, mild  

*Blueray     7-3  to 7-19  8-3  to 8-20   large      dark blue
FLAVOR:  good  
*Bluecrop    7-7  to 7-23  8-13 to 8-29   med-large  light blue
FLAVOR:  good  

*Berkeley    7-7  to 7-23  8-7  to 8-20   large      light blue
FLAVOR:  fair, mild  

*Jersey      7-14 to 7-30  8-18 to 9-3    small      light blue
FLAVOR:  good  

Coville      7-20 to 8-5   8-20 to 9-5    med-large  med blue
FLAVOR:  good, tart

Elliott      7-30 to 8-15  8-30 to 9-15   med        light blue
FLAVOR:  good 

*Varieties that have been grown successfully in the mountain
area.  The other varieties are suggested for trial planting.  


Availability of Plants.  Nurseries usually have ample supply of
plants priced from 50 cents to $2.00 per plant depending on
quantity, variety and size. Two-year-old plants are preferred.
Additional plants may be obtained in later years from locally
grown cuttings.


Cultivation.  Cultivate first year only to control weeds and
grass.  A 4-6 inch mulch of sawdust or bark helps control weeds
and grass.  Keep row middles mowed to conserved soil moisture and
to keep groundcover under control.  


Fertilization. (Caution: Blueberry plants are easily damaged by
too much fertilizer.)  Acid forming fertilizers that have little
limestone filler are desirable.  Special azalea or rhododendron
fertilizers meet this requirement, but the price maybe
prohibitive for more than a few bushes.  A standard 12-12-12,
10-10-10 or 8-8-8 can be used if a special blueberry fertilizer
is not available.  The high analysis fertilizers such as 12-12-12
generally have lower amounts of limestone filler than lower
anlaysis fertilizers like 8-8-8.  Ammonium nitrate (33.5-0-0) or
ammonium sulfate (20.5-0-0) are desirable sources of supplemental
nitrogen.  If the soil pH is below 5.0, use ammonium nitrate, but
use ammonium sulfate for more acid forming effect if the pH is
above 5.0.  Special attention should be given to leaf yellowing
(complete area of young and old leaves) caused by nitrogen
deficiency when sawdust or bark was combined with the planting
soil.  Organisms in the soil deplete the available nitrogen and
cause a deficiency for the blueberry plant as the sawdust or bark
decompose.  


First Year.  Uniformly distribute 16 pounds of nitrogen per acre
after the first flush of growth is complete (6-8 weeks after
planting) within a band 1 foot on each side of the plant.  The 16
pounds of nitrogen are supplied by 133, 160 or 200 pounds,
respectively, of 12-12-12, 10-10-10 or 8-8-8.  Fertilizer can
also be applied by hand around individual bushes.  Uniformly
distribute 1/2 oz (1 tablespoon) of 12-12-12 within a circle 1
foot from the plant.  Use proportionately more 10-10-10 or 8-8-8. 
Repeat applications using ammonium nitrate or ammonium sulfate
every 4-6 weeks until July 1.  Extend application intervals
during dry periods until rainfall has totaled 4 inches.  Use 50
pounds per acre of ammonium nitrate or 80 pounds per acre of
ammonium sulfate in a 2 foot band (1 foot on each side of the
bush).  This rate corresponds to about 1/4 oz (1/2 tablespoon)
ammonium nitrate or 3/8 oz (3/4 tablespoon) of ammonium sulfate
within the circle 1 foot from the plant.  


Second Year.  Double the first year rates, but increase the band
width to 3 feet or the circle around individual plants to 1 1/2
feet.  


Bearing Plants.  Apply 300-500 pounds per acre of 12-12-12 or an
equivalent amount of 10-10-10 or 8-8-8 in a 3-4 foot band.  For
individual bushes, apply the equivalent of 1/2 pound (1 cup) of
12-12-12 within a circle 3 feet from the plant.  Sidedress with
30 pounds of N (about 100 pounds of ammonium nitrate or 150
pounds of ammonium sulfate) per acre 4-6 weeks later.  For
individual bushes, this is 2 oz (1/4 cup) of ammonium nitrate or
3 oz (3/8 cup) of ammonium sulfate.


Early Fruiting (places stress on young plants). Plants should not
be allowed to fruit the first 2 years. Remove fruiting wood and
weak growth during the dormant season.  


Insect and Disease Control. 
Insects and diseases have not been serious problems; however,
check for damage periodically.  Wild blueberries are common in
western North Carolina; and, therefore, some pest problems may be
expected at one time or another.  

                                
1For more detailed information, refer to N.C. Extension Circular
AG-115, "Commercial Blueberry Production in N.C.".   

                            * * * * *
         BLUEBERRY FREEZE DAMAGE AND PROTECTION MEASURES
             Mike Mainland, Horticultural Specialist
          October 1992  (Revised)    LEAFLET NO. 201-E


Freeze Prone Sites.  Commercial blueberries are generally planted
in low areas with high organic-matter content. These sites
satisfy the cultural requirements of blueberries for a constant
and uniform moisture supply. However, on cold, still nights when
radiation frosts occur, heavy cold air from higher surrounding
areas "drains" into the low areas causing lower temperatures.
Also, the high organic content, especially if the soil is dry,
acts as an insulator to restrict heat in the soil from moving up
around the plants. The cultural requirement for a uniform soil
moisture make selecting higher sites that are less subject to
radiation frosts much less practical than with other fruit crops.
Although there is almost no wind during a radiation frost an
occasional gentle breeze will occur. Removal of trees and brush 
from  around the  field to improve air circulation will allow
these breezes to penetrate the field at bush level. The cold air
will be displaced or mixed with the warmer air from higher
locations and less temperature drop will occur.


Cold Susceptibility. Blueberry blossoms and small berries are
considered hardier than the blossoms of most fruits. Temperatures
must drop below 28 F for economic losses to occur on highbush
blueberry (Vaccinium corymbosum L.). The temperature at which
freeze injury begins to occur depends on the stage of development
from dormant flower buds through young fruit.

During the winter, dormant flower buds of highbush blueberries
will survive temperatures as low as -20 to -30 F while the  less
hardy  rabbiteye (V. Ashei Reade) have survived -10 F but are
often damaged below 0 F. As flower bud swell progresses, cold
tolerance decreases. By the time individual flowers begin to
protrude from the bud, temperatures below 20 F will begin
damaging the most exposed flowers. When corollas have reached
half of their full length, temperatures below 25  to 26 F will
kill the complete flowers. However, at this stage, blossoms on
rabbiteye blueberries may receive corolla damage at temperatures
as high as 30 F. The corolla withers, but usually remains
attached. The withered, unopened corolla prevents bee pollination
and otherwise undamaged flowers drop rather than developing into
fruit. Corolla damage to unopened highbush flowers that prevents
pollination is seldom a problem with highbush blueberries. When
the blossoms are open, a temperature of 27 F for more than a few
minutes causes damage. Immediately after corolla drop and before
the berry begins to swell is the most sensitive stage. A few
minutes below 28 F will result in damage. As the berry begins to
enlarge, susceptibility is similar to the critical temperature of
28 F for open blossoms.


Injury Symptoms. Cold damage is not always obvious. Following
temperatures well below the critical level, the complete flower
or small fruit will develop a water-soaked appearance, shrivel
and drop. However, a very brief time at the critical temperature
may damage only the pistil. All or a portion of the damaged
pistil will develop a brown appearance and prevent pollination
and fruit set. Ovules, which develop into the seeds within the
berry, can also be damaged without any exterior symptoms. Healthy
ovules are plump and white, but become black with cold injury. If
a large number of ovules or young seeds are black, the flower or
fruit will probably drop. If only a few are damaged, fruit
development usually continues, but the fruit will be later
ripening and of smaller size than berries with a larger numbers
of healthy seeds.


Monitoring Temperature. Reliable and accurate thermometers that
register current and minimum temperatures are essential if frost
control measures will be used and also to help predict the extent
of damage if no protection is provided. Most fields should have
at least 3 thermometers placed at bush height in high (warm), low
(cold) and average locations in the field. Hygrothermographs that
constantly measure temperature and relative humidity placed in a
weather shelter at bush height are also very helpful if frost
protection measures are available. The plot of temperature and
humidity as the night progresses on the hygrothermograph chart
aids in making the best possible management decisions. It is much
easier to determine the rate of temperature drop and predict the
minimum temperature before sunrise from the hygrothermograph
chart than from watching the thermometers and plotting
temperature change. Thermometers in warm, cold and average
locations in the field should be checked in addition to the
hygrothermograph to determine differences across the farm.
Relative humidity is usually 100% on radiation frost nights,
however, occasionally lower humidity occurs. With sprinkler
irrigation for frost control, the system must be started at a
higher temperature when humidity is low to compensate for the
evaporative cooling that will occur as the first water strikes
the bushes. A sling psychrometer that measures wet bulb and dry
bulb temperatures is a less expensive method for determining
relative humidity than the hygrothermograph, however, unlike the
hygrothermograph, there is no constant measurement or permanent
record.

Sources of temperature monitoring equipment are listed in Table
1. Commercially manufactured temperature alarms are available or
they can be assembled from a refrigeration thermostat and
transformer. The thermostat should be set at a temperature high
enough to awaken the irrigation manager in time to check field
thermometers before the temperature drops below 35 F.
Thermometers shielded from the open sky and placed at the height
of the upper 1/3 of the bush give air temperature readings that
can be related to the temperatures described in this leaflet.

Listening to weather reports is not a reliable method of
monitoring current temperatures or determining what the low
temperature will be in a blueberry field. Many of the official
temperatures reported on radio or television are taken at airport
locations. The large paved areas that hold heat and the aircraft
mixing of air at airports makes them much warmer than surrounding
areas on radiation frost nights. However, you may be able to
develop a reasonably reliable adjustment factor for how much
colder the blueberry field is than the local reporting station.
Blueberry fields will often be as much as 10 to 12 F colder on a
radiation frost night than warmer locations such as airports.


                         PRACTICES FOR 
                     REDUCING FREEZE DAMAGE

Pruning. Flower buds on short, small-diameter shoots will open
and become susceptible to freeze damage sooner than flower buds
on larger diameter shoots. Pruning to a balance of early blooming
and later blooming shoots will help insure a crop. If no frost or
freeze occurs, the early blossoms will develop into the early
ripening, high priced fruit. If a frost or freeze occurs, there
will still be some later fruit for a partial crop.

Avoid Cultivation. Cultivation in late winter and early spring
tends to increase freeze damage. Soil temperature on a
radiation-frost night will be much warmer than air temperature.
If the soil has been cultivated, the surface layer will contain
more air and less water. With less water, the surface layer will
hold less heat. Also, the increased soil air will cause the
surface layer to be a better insulator which will decrease the
amount of heat released from deeper in the soil. Bushes will
probably stay 1 to 2 F warmer on uncultivated soil than on
cultivated soil. To avoid spring cultivation, adequate drainage
should be established the previous fall, followed by herbicide
application in late winter.

Maintain Soil Moisture. Growers who have hose reel, hose pull, or
small portable irrigation systems can benefit from maintaining a
moist soil during the period when frosts are possible. By
increasing the amount of water in the soil, the soil will absorb
more heat during the day and conduct more heat to the surface for
plant protection. Maintaining a moist surface on peat and muck
soils is especially important. When these soils are dry, they
hold very little heat and a dry surface acts as an excellent
insulator to prevent beneficial heat release. Excess water for
extended periods must be avoided to prevent flooding or
phytophthora root rot damage.

Sprinkler Irrigation. Permanent or solid set irrigation has been
the most dependable frost control method. Depending on the design
of the system, damage can be prevented when temperatures drop as
low as 20 to 23 F. The system commonly used in blueberries is a
sprinkler spacing of 60 ft. x 60 ft. with nozzles that supply
about 5 to 6 gpm at 55 to 60 psi. This design requires 12
sprinklers/acre. The system is started when the temperature has
dropped into a range of 33  to 38 F and the grower expects the
temperature to reach a minimum below 28 F before warming begins
after sunrise. The temperature to begin sprinkling depends on
humidity. If the humidity is near 100% as it usually is on
radiation-frost nights in southeastern NC, 33  to 34 F is
satisfactory. However, at 40% relative humidity the system should
be started at about 37 F to avoid evaporative cooling below 30 F.
A psychrometer or hygrometer as previously mentioned is needed to
determine relative humidity.


Table 1. Sources of temperature and humidity measuring equipment

                                 Minimum    Hygro-    Temperature
Company          Thermometers thermographs  Alarms   Psychrometers
                                                                 

Cassco                 X
P. O. Box 3508
Montgomery, AL 36193
1-800-633-5888

Cole-Parmer                         X          X
7425 N. Oak Park Ave.
Chicago, IL 60648
1-800-323-4340

Forestry Supplies, Inc.             X          X           X
205 W. Rankin St.
P. O. Box 8397
Jackson, MS 39204
1-800-647-5368

Omega Engineering, Inc.                        X
1 Omega Dr.
Stamford, CT 06907
(203) 359-1660

Science Associates, Inc.            X          X           X
230 Nassau St.
Princeton, NJ 08540
(609) 924-4470

Weather Measure Corp.               X          X           X
P.O. Box 41257
Sacramento, CA
(916) 481-7565

                            * * * * *

BLUEBERRY

SYMPTOMS                POSSIBLE CAUSES          CONTROL AND COMMENTS

Plants stunted and      -Soil pH too high        -Blueberries require acid
discolored                                        pH; soil test
                        -Nutrient deficiency     -Soil test
                        -Virus disease (any      -Submit sample for labora-
                         of several)              tory diagnosis
                        -Poor quality water      -Water analysis

Berries turn reddish    -Mummy berry (fungal     -Use registered fungicide
or tan color as they     disease)                 
they ripen and become 
shriveled and hard; 
blossoms turn brown 
and wither; centers 
of new leaves are 
black

Branches die back;                               -Common in spring
cankers may be evident 
externally; internal 
discoloration not 
reddish brown

Ripening berries soft   -Blueberry maggot        -Use registered insecticide 
                                                  on a regular schedule
BLUEBERRIES FOR THE HOME GARDEN

Blueberries are popular with people and birds. They are attractive
fruit-bearing plants that can be used in the landscape or in the
garden. They are easy to grow, but usually must be covered with
netting to prevent the birds from eating the whole crop. Plants
bear more fruit when two or more varieties are grown together.

Site Preparation - Blueberries prefer light, well-drained, acid
soils that are high in organic matter. Since most garden don't have
these conditions, they must be created. You can add organic matter
to your soil by applying peat moss, sawdust, leaf mold, or similar
material before planting.

The pH should be kept between 4.5 and 5.2. If pH is below 4.4, add
a cup of ground limestone per plant. To lower the pH from 6.0 on
sandy soil, apply 12 lbs of finely ground sulfur per 1000 square
foot. To lower pH from 5.5, apply 8 lbs. If you have a loam soil,
use 35 lbs at a pH of 6, and 24 lbs at a pH of 5.5.

The plants should be mulched to help maintain a uniform soil
moisture content and to control weeds. Use any organic matter
source that won't pack. Pine bark, straw, or pine needles are
satisfactory. Mulch should be 6 inches deep.

Planting - Spring plantings work best for Delaware. Don't plant
blueberries deeper than they were grown in the nursery. Prune off
broken limbs or roots before planting.

Varieties - Bluetta, Jersey, Bluecrop, Blueray, and Herbert are
some of the better varieties for Delaware. Buy vigorous 2-year-old
plants that are free of disease. Rooted or unrooted cuttings can be
bought, but they need special care to keep them alive.

Fertilizer - A soil test will indicate what is needed. As a general
guide, apply 1/8 cup of 10-5-10 per plant 2 to 3 weeks after
transplanting. Spread it evenly in a band 6 to 12 inches from the
plant to avoid root damage. Repeat in late June if plants have been
watered regularly.

Each year after the initial planting, apply double the rate until
the total of two applications reaches 2 cups. This is the maximum
rate normally needed.

Watering-Blueberries are shallow-rooted plants that need about 2
inches of water per week during the growing season. Water is
necessary for fruit set, fruit size and plant vigor. Blueberries
need water, even after harvest, to set flower buds for next year's
crop.

Pruning - The first year, cut back the tips to remove the flower
buds. Remove any weak wood. The following year, leave some of the
tips uncut to allow some fruit to develop. Again, remove any weak
wood. In subsequent years, leave more and more fruit buds until the
plants reach 5 to 7 years old. The plants then will be mature and
should remain productive for 15 to 20 years. From that point on,
each year remove dead wood and diseased wood. Old and unthrifty
canes should be cut back to new and vigorous canes, or to within 3
inches of the ground, to encourage new shoots.

Canes that are 5 years or older are less productive and need to be
removed. A lack of new, vigorous shoots indicates under-
fertilization or overcrowding of old canes. After making major
pruning cuts, return later to remove the weakest lateral shoots
that develop.

Fall pruning will usually delay blooming in the spring. The normal
pruning time is late winter to early spring before the plants break
dormancy. For details on pruning, see Bulletin 197, "Pruning in the
Home Garden."

Pest Control - Birds love blueberries. Covering the plants with
netting before the berries ripen deters birds from eating the fruit
and is the only reliable method of control.

Some insect and disease problems may occur, but good fruit can be
produced without pesticides. Diseases can be controlled by raking
up and removing fallen leaves before April, and then lightly
cultivating the soil. Add two inches of fresh mulch to cover the
rotten berries before the plants bloom in the spring. However,
don't increase the depth of mulch that was originally applied. Too
much mulch will prevent air from reaching the roots and slowly kill
the plants. These practices will control the major fruit diseases.

Dormant sprays of liquid lime sulfur can help prevent phomopis
blight and blueberry die-back.

Compiled by:
S. Derby Walker, Jr., County Agricultural Agent
          PRINCIPLES OF PRUNING THE HIGHBUSH BLUEBERRY
    Pruning the Highbush Blueberry in Eastern North Carolina
            Charles M. Mainland and E. Barclay Poling
                    Horticultural Specialists
           October 1992 (Revised)   LEAFLET NO. 201-B



Effect on Plant Size and Crop Yield. Pruning of a fruit plant
reduces its ultimate adult size and the crop yield in at least
the following season. To compensate for this loss of bearing area
and yield, other factors, largely economic, must be considered in
planning a pruning program.


Effect on Fruit Size. By reducing the number of fruit buds (and
hence clusters) on the bush, pruning results in an increase in
the size of the individual berries. Up to a point, the more
severe the pruning, the larger the remaining berries are. Pruning
for increased size is a compromise between desired size and yield
of fruit.


Effect on Ripening Period. Moderate to heavy pruning tends to
shift the ripening period forward so that most of the remaining
fruit ripens together and early. Light pruning results in a
longer season of ripening. It may be more profitable in this area
to prune fairly heavily, even at the expense of some yield, to
realize the earliest possible maturity.


Effect on Plant Growth and Vigor. Pruning results in longer and
more vigorous (thicker) shoot growth in the next season. Heavy
pruning causes thicker and more leafy shoots than light pruning.
The thicker and later-developing shoots tend to produce fewer
fruit buds than those which stop growing earlier in the season.
Fruit of the blueberry is borne on wood produced in the previous
season (one-year-old wood). By pruning you are regulating the
fruiting potential of next season's crop. Pruning should be
severe enough to invigorate the plant so that sufficient new wood
is produced during the following season. You are actually
determining the fruiting potential of the crop of two seasons
hence by the number and type of cuts you make this winter.


Spacing the Crop on the Bush. By wise selection of canes and
lateral shoots on those canes which will bear the crop, the
grower can prune to have his fruit well-distributed on the plant.
Well-distributed clusters should have enough leaves around them
to provide adequate foodstuffs, but not enough to overshade the
fruit, or to reduce spray or dust coverage, or to make the
clusters hard to reach during harvest.


Bush Life and Productive Life. Blueberry bushes tend to overbear
which shortens their lives. By pruning to regulate crop load, the
grower can lengthen the life of his bushes and increase the
number of commercial crops.


Training Young Plants  (1 to 3 or 4 Years of Age).
If vigorous, well-rooted two-year plants are set, they do not
need cutting back the first year except to remove fruit buds
shortly after planting. Pruning should be moderately heavy in the
third year to stimulate strong new growth on selected canes. Do
not permit plants younger than three years of age to bear more
than a cluster or two of fruit, or the onset of the commercially
productive period will be delayed. A large bearing area should be
established in the shortest possible time.


Pruning Bearing Plants

1. Make large "shaping cuts" -- Remove all low spreading branches
   and the oldest canes if they are weak, particularly if in the
   center of the plant. "Head back" the upright "bull shoots" to
   the desired height to keep the bush from growing too tall.
   Essentially, you have then automatically selected the
   remaining, more upright canes to bear your crop next season
   and the following season.

2. On the remaining canes, systematically "thin out" the shorter,
   thinner shoots, leaving enough of the thick shoots to bear the
   crop and make new growth. Only experience can tell you how
   many shoots a particular variety of a particular age can carry
   and still perform well. It is probably better in most
   instances to prune too lightly than too heavily. Lighter
   pruning is usually practiced as the  plant  grows  older
   because it can carry more "wood" successfully due to a larger
   root system.

3. Finally, some varieties such as Murphy and Scammell should
   have their fruiting shoots cut back to three to five fruit
   buds per shoot. This is done principally to insure adequate
   fruit size.

Renewal Pruning. When blueberries are about 8 to 10 years old,
they are at their productive peak, but renewal growth has reached
a minimum, and production will then decline markedly from year to
year. Some provision must be made to revitalize the plant to
prolong its productive period. Weak or badly diseased canes
should be removed entirely. These canes can be identified by
generally poor vigor and low fruit bud production. However, in
this climate many varieties do not sprout new canes readily from
the crown. It may be necessary to either cut the cane back to a
strong lateral which is properly located, or to cut the cane
severely ("dehorn") back to within two to three feet of the
ground. By the latter method, it is hoped that new lateral
branches can be forced from below the cut.

Either method may result in a one- to three-year crop reduction,
but the plants should then bear several more good crops. However,
when rejuvenation becomes necessary, it is well to start
considering newer and better varieties to which your acreage may
be systematically replanted in the near future.

                            * * * * *

 
