Progress 10/01/03 to 09/30/08
Outputs
OUTPUTS: Pollination and fruit set- These studies have included possible techniques that could lead to better fruit set, berry sizing and associated increases in yield. The main cultivar investigated was 'Reveille' which has excellent firmness flavor and mechanical harvesting traits. However, yields have been inconsistent and often low. Domestic bumblebees, that became available for use in the field about 10 years ago, have been evaluated for improving set and yield. The benefit of bumblebees would be from there characteristic of pollinating in cooler weather, wetter and more windy conditions. These trials have also involved moving the bumblebees to another blueberry production area after pollination was complete in North Carolina in order to reduce the cost to growers in each state. The attractiveness of 'Reveille' to honeybees, domestic worker bumblebees, native queen bumblebees, southeastern blueberry bees was compared with cultivars that had better set and higher yields. The pollination trials were continued over the past five years. The growth regulators gibberellic acid and cytokinin as well as boron were tested at three locations in 2008 as possible treatments for increasing fruit set. Controlled release nitrogen- Heavy rains especially during the harvest season leach the soluble nitrogen and and cause poor growth after harvest is complete. Equipment damages too much fruit during harvest to apply additional soluble nitrogen after heavy leaching. A liquid controlled-release nitrogen source was tested on highbush blueberries and rabbiteye blueberries each at two sites in 2007 and 2008. Cultivars trials- Highbush cultivars O'Neal, Bladen, Reveille, New Hanover, NC 3104, Croatan, US 508, Duke, Biloxi, Jubilee, Legacy, Bluegold, Bluechip and Bluecrop were harvested for yield, fruit quality, and storage durability for the past three, four or five years. Lab measurements of soluble solids (sugars) and acids were also made. The same measurements were made for the rabbiteye cultivars Premier, Montgomery, Austin, Columbus, Ira and Powderblue. Although there was a report of some soft-fruit problem in a 2008 'New Hanover' shipment, there was no indication of any softening of fruit directly from the bush or after storage in these tests. Some stem tearing did occur again with 'New Hanover' but it was less than two per cent. Samples of the major cultivars developed in North Carolina were sent to Dr. Jim Hancock at Michigan State University where he is getting cultivars from other productionl areas for tast testing. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Pollination and fruit set- No treatments have completely overcome the problems of 'Reveille' set and yield. Domestic worker bumblebees did increase set by about 10 per cent over only honeybees in one trial although this was only an increase from about 50 per cent to 60 per cent which is still much below the desirable set of 85 to 95 per cent. The commercial bumblebee colonies were found to remain strong through the North Carolina pollination season and were of equal strength and value in another state. This reduced the cost to North Carolina growers by 50 per cent the past three years. Gibberellic acid also increased the set of 'Reveille' by about 10 per cent at two locations but more testing is needed and on a larger scale. Controlled-release nitrogen- Low amounts of rainfall in 2007 and 2008 kept the usual leaching from being a problem and there was little difference in plots receiving soluble and controlled-release nitrogen. Cultivar trials- The ratings from blind taste tests of North Carolina cultivars from best to poorest was 'Reveille', 'Bladen', 'New Hanover', 'O'Neal', 'Bluechip' and 'Croatan'. 'Reveille' was rated the firmest and 'Croatan' the softest. In our storage tests of fruit from the same harvest, marketable after 8 days at 70F was as follows: 'Reveille' 52%, 'Bladen' 43%, 'New Hanover' 72%, 'O'Neal' 28%, 'Bluechip' 56% and 'Croatan' 16%. Results of the cultivar trials has been of value for growers in making decisions on what cultivars to plant and possible problems. Results of the blueberry experiments have been presented at the North Carolina Blueberry Open Houses in 2004, 2005, 2006, and 2007 and documented in the proceedings.
Publications
- No publications reported this period
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Progress 10/01/06 to 09/30/07
Outputs
Fertilization- A controlled release nitrogen resin with a predicted 60 day release was applied at three farms in Bladen County, NC. Treatments 9 treatments were replicated four times each on two highbush and two rabbiteye plots. The controlled-release product containing 28% nitrogen was compared with the industry standard fertilizer,soluble 6-12-6. Applications were made in late March, early May and July. Rates of nitrogen were a total of 30 and 45 lbs./acre. The multiple applications were established to determine the best timing and length of activity. No heavy leaching rains occurred during the unusually dry 2997 season. As a result, soluble fertilizers remained available and there were no obvious differences. Of the 9 rate/timing treatments only bushes receiving no fertilization had less growth and some leaf yellowing. A nitrogen product with controlled-release properties was thought to have potential for maintaining adequate nitrogen in the root zone during the
harvest period. It has been observed that bush growth and vigor at the end of harvest have been much better if there have been no heavy, leaching rains that would remove soluble nitrogen. Cultivars- Trials in New Hanover and Pender Counties, NC established in 2006 were observed. These trials contained the cultivars Aurora, Berkeley, Biloxi, Bluecrop, Bluegold, Bluejay, Blueray, Brigitta, Chandler,Darrow, Draper, Elliott, Jewel, Liberty, Maru, Millenia, Misty, Olympia, Patriot, Reka, Sapphire, Southmoon, Spartan, Star and Toro. Evaluation was for survival, growth and small amounts of fruit. A trial 33 cultivars replicated three times was established at the Ideal Tract, Horticultural Crops Research Station, Castle Hayne, NC. Cultivars in this trial are the recent releases from North Carolina, Florida, Georgia, Mississippi and northern states. These cultivars and those in the 2006 plantings will be evaluated for growth, yield, and fruit characteristics. Pollination- Counts of honeybees,
queen bumblebees, worker bumblebees and southeastern blueberry bees visiting blueberry blossoms were counted on 8 cultivars. Honeybees and southeastern blueberry bee numbers were much higher than queen bumblebees or worker bumblebees from purchased colonies. Blossoms were counted and tagged on 'Reveille', 'O'Neal', 'Legacy', 'Premier' and 'Powderblue' at the Ideal Tract, Horticultural Crops Research Station, Castle Hayne, NC. These counts were intended to determine the percentage set on these cultivars. 'Reveille' has had poor set in previous evaluations and in commercial fields. However, temperatures dropped to 17-18 F on Easter morning, April 8th. About half of the blossoms were damaged and no meaningful results were obtained.
Impacts
Research on cultivar fruit quality and production has been a major factor in North Carolina growers planting improved cultivars and the increase in production. In a year without historic freeze damage, production now averages more than 25 million pounds. Ten years ago the averages were 10-15 million pounds. Cultivars with much better shipping quality are now being planted and growers are receiving better prices. Controlled-release fertilizers have the potential to also increase yields. Studies with domesticated bumblebees provide a cost savings to growers. These bees can be moved to another blueberry production area after pollination is complete in North Carolina and half of the cost can be recovered. It has been difficult to measure the direct benefit of the bees to improving fruit set
Publications
- Mainland, C.M. 2007. Experiences with bumblebees in the past three years. Proc. 41st Annu. Open House North Carolina Blueberry Council 41:29-31.
- Mainland, C.M. 2007. Highbush and rabbiteye blueberry cultivar evaluations for 2006. Proc. 41st Annu. Open House North Carolina Blueberry Council 41:32-35.
- Mainland, C.M. 2007. Fruit quality evaluations, bees and NC updates. pp. 51-55 In: Proc. Sunnyridge Annu. Meeting, Jan. 13-14, Amelia Island, FL.
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Progress 10/01/05 to 09/30/06
Outputs
Cultivars - Trials were established in New Hanover and Pender Counties that included the cultivars Aurora, Berkeley, Biloxi, Bluecrop, Bluegold, Bluejay, Blueray, Brigitta, Chandler, Darrow, Draper, Elliott, Jewel, Liberty, Maru, Millenia, Misty, Olympia, Patriot, Reka, Sapphire, Southmoon, Spartan, Star and Toro. These cultivars will be evaluated for growth, yield and fruit characteristics. Yield, weight/berry(g), % splits, % stems, % tears, color, firmness, pH, soluble solids, acids and storage quality at 4.4 and 21.1 degrees centigrade was measured for the cultivars O'Neal, Bladen, Reveille, New Hanover, NC 3104, Croatan, US 508, Lenoir, Star, Sun, Duke, Sampson, Biloxi, Jubilee, Legacy, Beaufort, Craven, Pamlico, Carteret, Roberson, Bluegold, and Bluecrop highbush/southern highbush. Rabbiteye cultivars evaluated were Premier, Montgomery, Austin, Brightwell, Columbus, Ira, Powderblue and Onslow. Of highbush/southern highbush, New Hanover, NC 3104 and US 508 had the
largest berries, all averaging over 2.0 grams/berry for the season. Bladen and US 508 had the best color, above 26.0 L*. Reveille was the firmest at 247 g/mm compression force followed by Bladen (218), Star (216) and US 508 (210). US 508 was the highest in acid content, had adequate sugar content and had among the best keeping quality. However the yield of US 508 was rated as light. Star and Biloxi had the best keeping quality at 21.1 degrees centigrade for 8 days. Among the rabbiteye cultivars, Columbus had the largest berries (1.85g), the best color (22.9 L*) and among the best keeping quality. Powderblue had the smallest berries (1.3g) but very good color (22.6 L*) storage quality and high yield. Pollination - In Bladen County, fruit set for cultivar Reveille was 53.0% where only honeybees were used for pollination. It increased to 62.1% with only bumblebees. Where both types of bees were present it was 51.7%. In New Hanover County, the cultivar Powderblue was most attractive to
honeybees with 38 visitations during 30-minute observations. Bumblebee visitations ranged from 10 to 14 for southern highbush cultivars Legacy and Bladen and the rabbiteye cultivars Premier, Tifblue and Powderblue. Activity from the bumblebee colonies moved to Indiana and Michigan, remained similar to what it had been in North Carolina. This supports previous observation that bumblebee colonies can be used in two production areas over an 8-week period. In 2006, about 1,000 colonies (250 quads) of bumblebees went to New Jersey, Indiana, or Michigan after pollination was complete in North Carolina. North Carolina growers received $25.00 per colony which was about 45% of the original cost. This was $25,000 in savings to North Carolina growers compared to having to pay the entire expense.
Impacts
Finding that bumblebees could be used in more than one production area reduced the cost to North Carolina growers by about 45%. As a result, this was a savings of approximately $25,000 that can be attributed directly to this project. Research on cultivar characteristics, cooling and fruit quality over many years and the acceptance of the technology by the industry has allowed the marketing of a good quality product. It is difficult to put a price on this improved handling, but undoubtedly price and demand reflect the better quality. The cultivar, Columbus, with excellent storage quality could extend the shipping season from North Carolina if fruit is held in storage.
Publications
- Mainland, C.M. 2006. ABCs of overhead irrigation for blueberry freeze protection. Proc. 40th Annu. Open House North Carolina Blueberry Council. 40:44-49.
- Mainland, C.M. 2006. Weed control in first-year blueberry plantings. pp.36-41 In: Proc. Sunnyridge Annu. Meeting, Jan. 14-15, Amelia Island, FL.
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Progress 10/01/04 to 09/30/05
Outputs
Bumblebees colonies are now available that have been reared to coincide with blossoming of blueberries and other crops. If bumblebee colonies could be used in two or more blueberry production areas, the grower cost could be shared. In 2004, 320 colonies that were delivered in NC NC were moved at least twice to distant locations. These colonies went into blueberries in NC in late March, were moved to Indiana and Michigan in early May and to cranberries in Michigan in mid June. Eight fresh colonies were delivered in Indiana. Representative colonies were evaluated after each move. After the first move, colonies were as strong or stronger than new colonies. After the second move, colonies were beginning to decline. Based on the 2004 findings, in 2005 approximately 600 colonies of bumblebees were delivered in NC for the pollination season and then moved to New Jersey, Michigan and Indiana. Growers received $22.50 to $25.00 per colony. This was 40 to 45% of the original
cost. This was a return of about $14,000 to North Carolina Growers. As in 2004, colonies remained strong in NC but became weaker after working in the second location, but some of these colonies were purchased by the supplier and used in a third location. Cultivar Fruit Evaluations - Fruit of 16 highbush/southern highbush cvs. and selections and 8 rabbiteye cvs. were evaluated for yield, berry size, splits, stems, color, sugar and acid content and storage characteristics. 'Lenoir' and `New Hanover' had the highest yields. Berry size based on average weight/berry in grams for the cvs. was US 508 3.89; NC 3104 2.49; Sampson 2.31; Bluegold 2.29; Summit 2.18; O'Neal 2.14; Bluecrop 2.01; New Hanover 1.92; Biloxi 1.91; Legacy 1.77; Jubilee 1.54; Duke 1.50; Croatan 1.42; Lenoir 1.30; Bladen 0.95 and Reveille 0.94. All of these cvs. had good to excellent color, L* values above 20.0, with the exception of `Croatan' 18.9 and `Lenoir' 18.3. Firmness as measured in g/mm of compression (largest
number being the firmest) ranged from `Croatan' 135 to 'Reveille', 197 and `Bladen' 206. The fruit was stored for one week at 70F and two weeks at 40F. After 8 days at 70F, the percentage marketable fruit ranged from 91.3 for `Legacy' to 35.5 for `New Hanover' and 34.7 for `Croatan'. In past years, New Hanover' remained in much better condition after this storage period, however, there was more rain during the ripening period in 2005. When the fruit was held for two weeks at 40F, percentage marketable remained above 80.0 for all cultivars except `Croatan' which was 78.6. 'NC 3104', `Reveille' `Biloxi' and `Legacy' had the highest sugar (soluble solids) levels at 13.8, 13.3 12.7 and 12.5 respectively. The rabbiteye were evaluated in the same way as the highbush/southern highbus. 'Columbus' again had good storage quality but more rain in the `Columbus' ripening season caused it to not keep as well as the later ripening `Rahi', `Powderblue' and `Onslow'. As in previous years, `Columbus'
was highest in acid and had excellent flavor. `Rahi' `Powderblue' and `Columbus' had the best color with L* values of 27.5, 26.3 and 25.2 respectively.
Impacts
Finding that bumblebees could be used in more than one production area reduced the cost to North Carolina growers by about 40-45 per cent. As a result, this was a savings of approximately $14,000 that can be attributed directly to this project. Research on cooling and fruit quality over many years and the acceptance of the technology by the industry has allowed the marketing of a good quality product. It is difficult to put a price on this improved handling, but undoubtedly price and demand reflect the better quality. The potential cultivar, Columbus, with excellent storage quality could extend the shipping season from North Carolina if fruit is held in storage.
Publications
- Mainland, C.M., 2005. Herbicide use. pp. 67-81 In: Proc. Sunnyridge Annu. Meeting , Jan. 16-19, Amelia Islamd, FL.
- Mainland, C.M., 2005. Growtin blueberries without mineral fertilizersand weed control without herbicides. pp. 124-136 In: Proc. 2nd Seminar Japan Blueberry Assn., Apr. 24, Tokyo, Japan.
- Mainland, C.M., 2005. Functionality of cultivated blueberries. pp. 37-46 Proc. 5th BlueberryFunctionality Sym., Apr. 28, Tokyo, Japan.
- Cline, W. O. and C.M. Mainland. 2005. Blueberry production recommendations and costs. Proc.39th Annu. Open House North Carolina Blueberry Council. 39:1-8.
- Cummings, G.A. and C.M. Mainland. 2005. Fertilizer recommendations. Proc.39th Annu. Open House North Carolina Blueberry Council. 39:37-39.
- Mainland, C.M., 2005. Land selection, preparation and planting. Proc.39th Annu. Open House North Carolina Blueberry Council. 39:9-14.
- Mainland, C.M., 2005. Pruning recommendations. Proc. 39th Annu. Open House North Carolina Blueberry Council. 39:9-14.
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Progress 10/01/03 to 09/30/04
Outputs
Extended Benefits from Commercial Bumblebees - Bumblebee colonies are now available that have been reared to coincide with blossoming of blueberries and other crops. Each colony consists of a queen and approximately 200 workers at a cost about double the rental of a hive of honeybees. Bumblebees are much more efficient pollinators than honeybees. If bumblebee colonies could be used in two or more blueberry production areas, the grower cost could be shared. In 2004, 320 colonies that were delivered in North Carolina were moved at least twice to distant locations. These colonies went into blueberries in North Carolina in late March, were moved to Indiana and Michigan in early May and to cranberries in Michigan in mid June. Eight fresh colonies were delivered in Indiana. Representative colonies were evaluated after each move. After the first move, colonies were as strong or stronger than new colonies. After the second move, colonies were beginning to decline. From these
preliminary observations, bumblebee colonies could be used in at least two states and would be of about equal value in each location. Rooting Media and Cultivar Responses - A new medium became available in 2004 for blueberry propagation. This medium is a screened pine bark that has had pieces removed that were larger than about 0.4 inches in diameter. This particle size allows both hardwood and softwood cuttings to be easily stuck. The standard horticultural bark has larger pieces that make sticking hardwood cuttings more difficult and softwood cuttings almost impossible. Hardwood cuttings of different diameters were stuck in April in one of five media. Hardwood rooting percentage in the new blueberry propagation bark for 8 cultivars was 46.4. When 25% sand or 25% perlite was added to the blueberry propagation bark, rooting was 54.6 and 56.1% respectively. Rooting in 100% horticultural bark was 39.3% and in sawdust, 36.8%. The new blueberry propagation bark appears to be an acceptable
replacement for the traditional pine sawdust, but rooting of the hard-to-root cultivars, 'Columbus' rabbiteye and 'Sampson' southern highbush remained very poor and poor respectively. Cultivar Fruit Evaluations - Fruit of 6 highbush/southern highbush cultivars and selections was evaluated for berry size, splits, stems, color, sugar and acid content. Berry size based on average weight/berry in grams was 'Reveille' 0.96; 'Sampson', 1.64; 'NC 3103', 2.07; 'Bounty', 1.65; 'Summit', 2.02; and 'Legacy', 1.54. Bushes were not all of the same age so yields could not be compared. Based on observation for the size bush, 'NC 3103' and 'Legacy' had the highest yields. All of these cultivars/selections had good to excellent color. The fruit was stored for one week at 70F and two weeks at 40F. After one week at 70F, the percentage marketable fruit was: 'Reveille', 64;'Sampson', 48; 'NC 3103', 41; 'Bounty', 39; 'Summit', 81; and 'Legacy', 80. Freeze damage and mummy berry infection took at least 75%
of the crop on other highbush/southern cultivars we expected to evaluate in 2004.
Impacts
Use of commercial bumblebees could increase the production of difficult to pollinate cultivars such as Croatan and Jersey by 30%. In years when weather is unfavorable for honeybee pollination, similar increases in yield and berry size could be expected from other cultivars. Use of the bumblebees in more than one production area lowers the price to about the same as for honeybees on a per colony basis. Pine bark that had been milled to a particle size less than 0.4 inches in diameter but with very few particles less than 1/16 inches is a replacement for old sawdust. Old pine sawdust that has been the standard medium in the past has now become scarce. This new medium, referred to as blueberry propagation mix, is less expensive and results in better rooting than most commercial mooting media. The cultivar Legacy and the selection NC 3103 had the highest yields of the highbush and southern highbush in the trial and offer potential for increasing North Carolina yields.
Both Legacy and NC 3103 have excellent flavor that will increase their demand by consumers.
Publications
- Mainland, C.M. 2004. Planning for fruit quality. Proc. Georgia Blueberry Conf., p.79-83, Jan. 9-11, Savannah, GA.
- Mainland, C.M. 2004. Propagation experiences in 2003--and the previous 35 years. Proc. 38th Annu. Open House North Carolina Blueberry Council. 38:1-8.
- Mainland, C.M. 2004. Fertilizer basics--what the plant needs. Proc. 38th Annu. Open House North Carolina Blueberry Council. 38:46-50.
- Rohrbach, R.P., Mainland, C.M. and Osborne, J.A. 2004. Effects of sunlight or shade on maturity and optical density in blueberries. Proc. 9th North American Blueberry Workers Conf. 9:409-421.
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