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2001 Fruit and Vegetable Crops Research Report
Introduction ! Tree Fruits ! Small Fruits ! Vegetables ! Greenhouse Production ! Diagnostic Laboratory ! Appendix

Small Fruits

Evaluation of Eastern European Wine Grape Varieties for Kentucky

Gerald R. Brown, Dwight Wolfe, John Strang, and April Satanek, Department of Horticulture

Introduction

There is increasing interest in producing grapes for wine in Kentucky. Grapes have a high income per acre potential on upland sites. One of the critical needs for the Kentucky grape producer is the identification of varieties that are well adapted to Kentucky and are capable of producing a sufficient quantity of high quality grapes.

Traditionally, there are four types of grapes grown in the United States for wine—American (Vitis labrusca), Muscadine (Vitis rotundifolia), European (Vitis vinifera), and American French hybrids (Vitus labrusca X V. vinifera). Generally, the Muscadine and European grapes are not adapted to Kentucky's environment. American grapes grow well, but fruit quality for wine is usually substandard. Many American French hybrids grow well, and fruit quality for wine is intermediate between the American and French parents. The majority of the wine from Europe and the West Coast of the United States is made from European grapes.

European grapes are not well adapted to northern Europe, and vines are buried to prevent winter injury, a very labor-intensive operation. Northern Europeans have crossed V. vinifera with different Vitis sp., including some species from China. The resulting advanced selections have shown improved hardiness as well as outstanding fruit quality when grown in Eastern Europe. The late Dr. Bob Goodman of the University of Missouri evaluated these selections in Eastern Europe and selected candidates based on winterhardiness, disease resistance, and fruit quality. After importation, these grapes were grown in Missouri under post-entry quarantine, and in 1998 the first cultivars were distributed to selected land-grant institutions in the United States, Kentucky being one of them.

The objective of the program is to evaluate these selections in different regions of the United States. It should be noted that to participate in this program, the University of Kentucky signed an agreement specifying that no one could collect bud wood from this planting.

Material and Methods

Eighteen advanced selections were released from post-entry quarantine in the spring of 1998 and planted at the University of Kentucky Research and Education Center at Princeton. The vines were planted 8 feet apart in rows 12 feet apart. The planting stock was small potted cuttings. These were trained to two leaders and tied to 5-foot bamboo canes during the first year. During the second year, vines were trained to a high bilateral cordon system. The planting was trickle irrigated, and a 4-foot-wide herbicide strip was maintained beneath the vines with mowed sod alleyways.

Beginning in 2000 and continuing in 2001, yield, cluster size (as weight in grams per cluster), berry size (as weight in grams per berry), pH, and Brix (as percent soluble solids) were recorded for each selection. The harvested grapes were distributed to cooperating wine makers, and the wine quality produced from some of these selections was evaluated.

Results and Discussion

Yield, fruit quality components, and the cooperators receiving fruit from particular grape varieties of grapes harvested in 2000 are listed in Table 1. Wine made from these grapes (listed in Table 1) was evaluated on June 23, 2001, and October 20, 2001, by members of the Kentucky Vineyard Society. Results from these evaluations are shown in Table 2. Yield, fruit quality components, and the cooperators receiving fruit from particular grape varieties of grapes harvested in 2001 are listed in Table 3. A notable difference between years was that fruit sugar content and pH were slightly lower in 2001 than in 2000. One variety, `Burmunk' has yet to be harvested. Less than 50 percent of the vines initially planted have survived; no fruit was produced in 2000; and in 2001 green June beetles destroyed the small amount of fruit. All data should be considered preliminary as it will take several years to fully evaluate these selections for wine quality and vine adaptation to Kentucky.

Table 1. Yield and fruit quality results for the year 2000 from the 1998 eastern European wine grape variety trial at UK Education and Research Center, Princeton, Ky.
Cultivar Harvest date Number of vines Yield T/A1 Cluster wt. (g) Berry wt. (g) Soluble solids % pH Wine makers2
Bianca (N3) 8-14 15 3.0 367 1.8 21.0 3.6 Dave, Eddie, & Thomas Walker
Bianca (S) 8-14 15 2.1 233 1.7 21.6 3.6 Dave, Eddie, & Thomas Walker
I 31/67 8-14 12 2.0 500 1.3 18.0 3.6 Eddie O'Daniel
Iskorka 8-14 14 3.9 400 1.5 21.0 - Dave Miller
Kozma 55 (N) 8-21 12 0.8 333 1.5 19.0 3.3 Chris Nelson
Kozma 55 (S) 8-21 13 0.4 233 1.8 19.6 3.6 Chris Nelson
Kozma 525 8-21 14 1.5 467 1.4 - 3.6 Chris Nelson
Laurot 8-21 15 1.8 367 1.0 18.2 3.3 Eric Durbin
Liza 8-21 14 1.2 333 1.1 19.0 3.1 Butch Meyer
M 39-9/74 8-21 14 2.4 600 2.3 19.2 3.5 Eric Durbin
Malverina 8-17 11 2.9 567 1.9 18.0 3.4 Dave and Butch
Petra 8-17 13 1.1 300 1.3 21.4 3.7 Gari Thompson
Rani Riesling 8-17 14 0.5 500 1.2 18.0 3.4 Butch Meyer
Rubin Tairovski 8-11 14 2.6 433 1.6 19.0 - Eddie O'Daniel
Toldi 8-17 14 2.4 500 3.2 19.0 3.5 Butch Meyer
XIV-1-86 8-17 13 4.7 533 2.0 16.4 3.3 Dave, Butch, & Gari Thompson
XIV-11-57 8-19 10 2.4 210 1.0 18.8 3.6 Eddie O'Daniel
XX-15-51 8-11 15 1.5 300 1.1 21.0 - Gari Thompson
34-4-49 8-21 15 1.2 467 1.2 19.0 3.2 Butch Meyer
1 Tons per acre. Vines in this planting are on an 8 x 12-foot spacing, or 454 vines per acre.
2 The authors wish to thank the participating wine makers for their contributions to this study.
3 An "N" or "S" indicates from north or south part of row, respectively.

Table 2. Wine tasting results 2000 season grapes--June 23 and October 20, 2001.
Cultivar Color Wine maker Average1 Range2 Comments
Bianca white T. Walker Wine was very harsh and not evaluated.
Bianca white D. Miller 9.7 5-16 Weak aftertaste, light appearance, reddish on skins.
I31/67 red E. O'Daniel 8.6 1-14 Good but would not buy, light appearance, young, chocolate aroma.
Iskorka white D. Miller 11.1 7-14 Good dessert wine, low tannin, smooth, reddish on skins.
Kozma 55 red C. Nelson 8.8 3-17 Thick appearance, no flavor, good tannins, slight haze, perfumey.
Kozma 525 red C. Nelson 11.2 8-17 Purple appearance, flat taste.
Laurot red E. Durbin 12.8 11-14 Needs aging, high tannin, would be very good with food, high acid, tastes very much like a good, rich Chancellor, light wine, fruit maybe shows some promise, lots of tannins, great deep color, this aroma tastes exactly that of Chancellor, barnyard aroma.
Liza white B. Meyer 15.0 14-17 Long aftertaste.
M39-9/74 red E. Durbin 11.5 6-15 Tastes like Chambourcin, somewhat astringent, tough one, aroma part perfume.
Malverina white B. Meyer 12.7 9-17 Some alcohol noticeable, spice, slight chemical taste.
Malverina white D. Miller 11.2 6-17 High alcohol.
Petra white G. Thompson 12.8 9-16 Chemical taste, slight off color, weak bouquet.
Rani Riesling white B. Meyer Wine did not turn out.
Rubin Tairovski red E. O'Daniel 11.2 8-14 New, no balance, dull, light red color, smoky, tobacco aroma.
Toldi white B. Meyer 10.8 5-14 Very earthy, young, light aroma.
XIV-1-86 white B. Meyer 15.2 12-17 Sweet, spicy, cleansing sweet.
XIV-1-86 white G. Thompson 9.4 6-14 Slight chemical taste, clean, clear, colorless, stuck fermentation.
XIV-1-86 white D. Miller 14.2 9-19 Good legs, pear, slight off color.
XIV-11-57 red E. O'Daniel 10.4 7-15 Long aftertaste, berry-like aroma.
XX-15-51 white G. Thompson 13.0 9-15 High alcohol, good balance, good legs, very slight straw color, short, pucker aroma.
34-4-49 white B. Meyer 11.6 9-14 This wine would really do well aged in oak, the flavor profile would match up very well with oak, light fruit, long, lingering aftertaste, off nose, stuck fermentation.
Cayuga White (std)3 white B. Wilson 8.8 6-11 The best white from this trial, good acid, crisp, very pleasant, good for the long haul.
Chambourcin (std) red B. Wilson 14.3 8-19 Chambourcin, bit light, good structure and tannins, still light on fruit but true taste, clean aftertaste, good balance, well made, nice pencil shaving tones, good color, varietal nose.
Vidal Blanc (std) white C. Nelson 14.8 11-17 Well made, great balance, this wine is a "ringer" for a nice Vidal Blanc.
1 Average rating: 0-5 = poor or objectionable, 6-8 = acceptable, 9-11 = pleasant, 12-14 = good, 15-17 = excellent, 18-20 = extraordinary. Each wine was evaluated by 9-10 tasters-Jim Bravard, Danny Buechele, Dave Miller, Bud Mirus, Mickey Mirus, Butch Meyer, Dr. Chris Nelson, Eddie O' Daniel, Jay Pruce, Gina Pruce, Gari Thompson, George Wessel.
2 Range 1st number = lowest score received, 2nd number = highest score received.
3 (std) Cayuga White, Chambourcin and Vidal Blanc were included in the trial as high quality French American standards for comparison.

Table 3. Yield and fruit quality results for the year 2001 from the 1998 eastern European wine grape variety trial at the UK Research and Education Center, Princeton, Ky.
Cultivar Wine makers1 Harvest date Number of vines T/A2 Cluster

wt. (g)

Berry wt. (g) Brix pH
Bianca Krasimir Georgiev 8-3 15 4.4 160 1.6 16.6 3.0
Bianca () Chris Voytek 8-6 15 4.6 181 1.7 18.6 3.4
I 31/67 Chris Nelson 8-13 12 2.0 238 1.4 18.2 3.5
Iskorka Mike Dudley 7-27 14 3.6 175 1.8 16.2 3.2
Kozma 55 Butch Meyer 8-22 26 2.5 188 0.8 19.2 3.4
Kozma 525 Eric Durbin 8-20 14 5.2 414 1.5 18.4 3.5
Laurot Gari Thompson 8-22 14 3.5 203 1.0 17.8 3.2
Liza Eric Durbin 8-14 14 3.7 134 0.9 20.8 3.2
M 39-9/74 Chris Nelson 9-12 14 3.1 289 2.4 17.9 3.3
Malverina Gari Thompson 8-6 11 7.6 260 2.0 17.8 3.3
Petra Eddie O'Daniel 8-3 11 1.9 157 1.1 15.0 3.2
Rani Riesling Butch Meyer 8-7 14 3.0 250 1.4 19.0 3.2
Rubin Tairovski3 Eddie O'Daniel 8-3 14 6.5 422 1.2 17.6 3.2
Toldi Chris Voytek 8-13 14 8.3 352 3.2 17.6 3.3
XIV-1-86 Butch Meyer 8-7 14 4.1 284 1.7 15.7 3.3
XIV-11-57 Eddie O'Daniel 8-3 10 6.4 224 1.0 13.1 3.1
XX-15-51 Mike Dudley 7-27 15 4.2 202 1.6 18.2 3.2
34-4-49 Gari Thompson 8-7 14 3.1 381 1.4 16.7 3.2
1 The authors wish to thank the participating wine makers for their cooperation in this study.
2 Tons per acre. Vines in this planting are on an 8 x 12-foot spacing, or 454 vines per acre.
3 20 pounds went to Krasimir and Vicky Georgiev.

Pierce's Disease, a New Disease of Grapes in Kentucky

John Hartman, Dominique Saffray, Diane Perkins, John Strang, and Julie Beale, Departments of Plant Pathology and Horticulture and Hancock County Extension Office

Introduction

Pierce's disease is a threat to grapes in California and in southern states from Florida to Texas. Disease symptoms vary with species and cultivar but are typified by marginal browning of leaves and death of vines. This disease is favored by the hot weather found in the southeastern United States.

Symptoms. Symptoms vary with the different species and cultivars. Symptoms in spring and early summer include delayed shoot growth, leaf mottling, and dwarfing of new shoots. Late summer and fall symptoms are more dramatic and include burning, scorching, or drying of leaves, wilting or premature coloring of fruit, and uneven cane maturity. Scorching begins near the margin of the leaf blade where tissues become completely desiccated and die. As summer progresses into fall, scorching progressively spreads inward in concentric zones until the entire leaf blade is affected. Leaf blades often fall from the vine at the point of attachment to the petiole, leaving the petiole still attached to the shoot.

The disease progresses along the grapevine with symptoms developing in adjacent leaves along the shoot both above and below the point of initial infection. Flower clusters on infected vines usually dry up. Late in the season, wood on affected canes fails to mature normally, leaving green "islands" of tissue that persist into the dormant season and can be seen on canes throughout the winter. Tips of shoots often die the first year the vine is infected. Initially, only one or a few canes on a vine show foliar and wood symptoms. Symptoms are more pronounced in vines that are stressed by high temperatures and drought conditions.

Grape susceptibility and disease spread. Some grape cultivars are very susceptible, usually dying within two years. Most French (vinifera) varieties die within two to five years, while American (labrusca) varieties often live longer than five years. French-American hybrids are intermediate in susceptibility. Pierce's disease is spread by several types of sharpshooter leafhoppers, by spittlebugs, and by grafting.

For many years, trees, especially oaks, in Kentucky landscapes have suffered from bacterial leaf scorch disease, also caused by Xylella fastidiosa (but a different strain from the one that causes Pierce's disease). Leaf scorching symptoms associated with this disease annually appear in late summer. Symptoms are quite striking on pin and red oaks with individual leaves turning one-third to two-thirds brown on the leaf ends and margins. The causal agent of bacterial leaf scorch is also vectored by leafhoppers or other xylem-feeding insects. As far as is known, the grape pathogen is similar, but not identical, to the tree leaf scorch pathogen. Thus, the disease would not be spread from trees to grapes.

Materials and Methods

Grape leaves showing symptoms of bacterial leaf scorch were collected from a vineyard in Hancock County and delivered to the UK Plant Disease Diagnostic Laboratory. Petioles from affected leaves were crushed using a mortar and pestle so that the extract could be tested for presence of the pathogen using a special laboratory test, an enzyme-linked immunosorbent assay (ELISA) developed for X. fastidiosa ("Pathoscreen-Xf," Agdia, Inc., Elkhart, IN). Color reactions for the ELISA test were evaluated visually and by using an ELISA plate reader. To overcome doubts due the possibility that the ELISA test might give a false positive reaction, specimens were sent to a laboratory in California that specializes in testing for Pierce's disease using a rapid-cycling real-time polymerase chain reaction (PCR) assay for presence of bacterial DNA (California Seed & Plant Lab., Inc., Elverta, CA).

Results and Discussion

In our laboratory, some of the samples reacted strongly positive in ELISA tests for X. fastidiosa, the Pierce's disease pathogen. The PCR assay done by the laboratory in California corroborated our ELISA test so the specimens again were positive. Thus, Pierce's disease of grapes caused by X. fastidiosa was discovered for the first time in Western Kentucky (1). This disease can be devastating to grape production, and much more Kentucky research is needed.

In other regions, X. fastidiosa is distributed in a wide range of monocot and dicot native plants that may be infected but not show symptoms. We do not know if the bacterium has become established in the wild and, if so, on which plants. We have preliminary evidence that X. fastidiosa can live in some grasses, weeds, and woody plants here in Kentucky. These plants do not show scorch symptoms but could be reservoirs of the bacteria. We do not know if these plants harbor the Pierce's disease strain, however. Pierce's disease could be carried from infected vegetation to grapes or from diseased grapes to healthy grapes by insect vectors; however, we know little about which vectors are involved in Kentucky. Where the disease is isolated, removal of infected vines should keep further spread to a minimum.

With an emerging grape industry developing in Kentucky, it is important that growers and County Extension Agents be on the lookout for this disease. Personnel in the UK Plant Disease Diagnostic Laboratory can run specialized tests to determine the presence of the Pierce's disease bacterium.

Literature Cited

  1. Bachi, P.R., J.W. Beale, J.R. Hartman, D.E. Hershman, W.C. Nesmith, and P.C. Vincelli. 2002. Plant Diseases in Kentucky— Plant Disease Diagnostic Laboratory Summary, 2001. UK Department of Plant Pathology. In press.

Eastern Kentucky Blueberry Cultivar Trial

R. Terry Jones, William Turner, Amanda Ferguson, and John C. Snyder, Department of Horticulture; David C. Ditsch, Department of Agronomy

Although blueberries are a native fruit crop, only limited commercial acreage has been established in Kentucky. Blueberries have an excellent potential for local sales and U-pick operations. Recent research into the health benefits of small fruits including blueberries may help further increase sales. Vaccinium is increasing in popularity in the world of pharmaceuticals. As consumers become more conscious of the foods they eat, they may find themselves eating more blueberries. Scientists attribute the blueberry's healing powers to the flavonoid anthocyanin that is responsible for the blue color found only in the berry's peel. Anthocyanins and other flavonoids could help fight the development of cancer, cardiovascular disease, as well as eye problems such as glaucoma and poor night vision.

The high initial startup costs for blueberries, approximately $4,000 per acre, is mainly due to land preparation, plant, and labor costs. However, after the plants reach maturity in approximately five years, the profits should steadily increase to as high as $6,000 per acre. Farmers must make the decision to grow blueberries based on their own land and facilities.

The longevity of a properly managed blueberry crop is similar to that of a well-managed apple orchard. Blueberries require acidic soils with a pH of 4.5 to 5.2, with good drainage and high organic matter. It is best to plant more than one cultivar to ensure good pollination and a continuous harvest of berries. Harvest usually begins in early June and lasts into July.

Materials and Methods

Two blueberry plantings were established in the fall (October) of 1996 at the University of Kentucky Robinson Station at Quicksand and the Laurel Fork Demonstration Site (Table 1). The Laurel Fork site is part of the UK Robinson Forest in the southeastern corner of Breathitt County. It is at a higher elevation (1,200 feet) than Quicksand (733 feet), and apple tree phenology at this site is seven to 10 days later than similar cultivars at Quicksand. Growth, yield, and survival of various blueberry cultivars were compared between a normal silt loam site at Quicksand and a disturbed mine site (Laurel Fork). The plantings consisted of eight to 12 rows of various cultivars1 in a randomized complete block design. Plants were spaced 4 feet apart in raised beds 14 feet apart. Drip irrigation with point source emitters (2 gph/plant) was installed shortly after planting. Plants were fertilized beginning in the spring of 1997. In 2001, one application of 5 pounds of 5-20-20 per 100 feet followed by two sidedressings of 2 pounds of ammonium sulfate per 100 feet of row (at bloom and again two weeks later) were applied. Netting was used at both sites to prevent loss due to birds.

Results

Twenty-one cultivars at Quicksand and 18 cultivars at Laurel Fork were tested, and results are shown in Tables 2 and 3, respectively. Late spring freezes (April 17-19, 26 ) during bud swell and bloom hurt the blueberry yields in 2001. It is believed that early maturing cultivars like Duke may have suffered greater losses. The Laurel Fork reclamation site is about 500 feet higher in elevation than Quicksand and has much better air drainage. Moreover, based on time of apple tree bloom, Laurel Fork plant development is about seven to 10 days behind that seen at Quicksand. As a result, the plants had thicker foliage, grew better, and were higher yielding in 2001 on the disturbed soil site at Laurel Fork (Table 2). This is in contrast to past years where Quicksand was the more productive site.

Briggitta was the highest yielding cultivar at Quicksand followed by Bluegold and Bluejay (Table 2). Briggitta's yield was significantly higher than 18 of the 21 cultivars tested at Quicksand and 11 of those tested at Laurel Fork. Briggitta is an attractive large-fruited cultivar that matures relatively late in Kentucky's growing season with only 51 percent of the fruit picked during the first four harvests. Ozark Blue is another attractive late-maturing berry. Even though the Ozark Blue plants were a year younger than the cultivars that were planted first, they produced the sixth highest yield. Several of the North Carolina numbered cultivars also appear to be late maturing. One North Carolina entry (NC-2675) also gave a relatively high yield at both locations and had large, very attractive berries. Late-maturing blueberries in Kentucky will require protective sprays to prevent damage by Japanese beetles.

Briggitta was the highest yielding blueberry variety at Laurel Fork (Table 3) followed by Patriot, Reka, Bluecrop, Toro, Bluegold, and Nelson. The largest berry sizes were those of NC-2675 and Toro followed by Briggitta and Sierra. Based on appearance, the most attractive blueberries at Quicksand were Briggitta, Ozark Blue, NC-2675, and Toro. At Laurel Fork, Briggitta, Bluecrop, Toro, Bluegold, Nelson, Sierra, and NC-2675 were judged to be the most attractive. At both locations berries of the cultivar Reka failed to color up properly (reddish-white instead of blue) and would have been difficult to sell.

These data represent only the second harvest response from the various cultivars after three and a half to four and a half years of growth. Additional harvests and observations will be needed to determine which cultivars are the best performing over time in Kentucky. For additional information and trial results see also:

1Some cultivars were furnished by Hartman's Plant Company, P.O. Box 100, Lacota, MI 49063 or were purchased from Fall Creek Farm & Nursery Inc., 39318 Jasper-Lowell Rd., Lowell, OR 97452. James R. Ballington at North Carolina State University and John Clark at University of Arkansas supplied other cultivars used in the trial.

Table 1. 1996 Laurel Fork and Quicksand soil test results.
Location pH Buf-pH P K Ca Mg Zn
Laurel Fork mine site1 5.9 7.2 46 206 1057 541 10.7
Quicksand 5.7 6.5 14 173 1497 126 5.1
1 Mine soil pH adjusted with granular sulfur at 2.5 lb/100 sq ft in late summer 1996, 2 months prior to planting. Both sites received 2.5 cubic ft of Canadian peat/50 sq ft of bed area prior to raised bed formation. Additional peat (0.13 cubic ft) was placed in each hole at planting. Granular elemental sulfur (0.75 lb./100 sq ft) was applied to the beds at Quicksand.

Table 2. Yield and quality of blueberry cultivars at Quicksand, Ky., 2001.
Cultivar1 Fruit yield lb/bush2 Berry size oz/berry2 Visual size rating3 Taste4 Appearance5 % total fruit first two harvests6 % total fruit first four harvests6
Briggitta 7.1 A 0.05 ABC VL ST A+ 2 51
Bluegold 5.6 AB 0.04 ABCD LM T A 27 61
Bluejay 5.0 ABC 0.03 BCD M SB A 37 87
Blueray 4.0 BCD 0.06 A VL ST A 26 82
Reka 3.9 BCD 0.03 CD SM T A- 42 81
Ozarkblue* 3.7 BCD 0.06 AB VL ST A+ 0.8 33
NC-2675* 3.7 BCD 0.06 A VL ST A+ 25 76
NC-2852* 3.5 BCD 0.03 D SM S A 10 46
Ornablue 3.3 BCD 0.02 D S BT A 38 73
NC-1852* 3.2 BCD 0.05 ABC M ST A 37 85
O'Neal 3.2 BCD 0.04 ABCD M SB A 53 97
Bluecrop 3.1 BCD 0.04 ABCD ML ST A 21 69
NC-1832* 3.0 BCD 0.04 BCD M SB A 0 4
NC-1827* 3.0 BCD 0.03 CD M T A 0 5
Sierra 2.9 BCD 0.04 ABCD L SB A 33 94
Toro 2.9 BCD 0.05 ABC L SB A+ 36 93
Patriot 2.8 BDC 0.04 ABCD LM ST A 45 91
Nelson 2.7 DC 0.05 ABCD M ST A 8 52
Duke 2.7 DC 0.05 ABCD LM ST A 84 100
Spartan 1.7 D 0.05 ABC VL S A 46 87
Jersey 1.7 D 0.03 CD M SB A 6 72
LSD2 1.98 0.02
* Cultivars followed by an * are one year younger than the other cultivars in the trial.
1 In descending order of yield.
2 Numbers followed by the same letter within columns are not significantly different (P = 0.05).
3 Visual size ratings: S = small, M = medium, L = large, VL = very large.
4 Informal taste ratings: S = sweet, T = tart, B = bland.
5 Appearance ratings: A- = below average, A = average, A+ = above average.
6 Harvest dates: 6/08, 6/15, 6/20, 6/29, 7/09, 7/16 (38 day harvest season).

Table 3. Yield and quality of blueberry cultivars at Laurel Fork mine site, 2001.
Cultivar1 Fruit yield lb/bush2 Berry size oz/fruit2 Visual size rating3 Taste4 Appearance5 % total fruit first two harvests6 % total fruit first four harvests6
Briggitta 8.4 A 0.05 BC VL ST A+ 7 56
Patriot 7.1 AB 0.04 CDEFG LM ST A 48 82
Reka 6.6 ABC 0.04 DEFG M ST A- 43 62
Bluecrop 6.5 ABCD 0.05 CDE L SB A+ 28 61
Toro 6.3 ABCD 0.06 AB VL S A+ 24 75
Bluegold 6.2 ABCD 0.04 CDEFG LM T A+ 25 63
Nelson 6.0 ABCD 0.05 CDEF L ST A+ 24 67
Ornablue 5.2 BCD 0.02 H S SB A 40 78
Sierra 5.0 BCD 0.05 BCD VL ST A+ 36 84
Blueray 4.2 CDE 0.04 FG M S A 42 83
Bluejay 4.0 DE 0.03 G M S A 60 93
Duke 4.0 DE 0.05 CDEF L S A 84 99
NC-2675* 2.0 EF 0.07 A VL S A+ 80 95
O'Neal* 1.9 EF 0.04 CDEFG M SB A 79 98
NC-1852* 0.9 F 0.05 CDE M S A 95 100
NC-1832* 0.7 F 0.01 H S ST A 0 39
NC-2852* 0.6 F 0.04 EFG SM ST A 58 92
NC-1827 0.4 F 0.01 H SM ST A 0 71
LSD2 2.3 0.01
* Cultivars followed by an * are one year younger than the other cultivars in the trial.
1 In descending order of yield.
2 Numbers followed by the same letter within columns are not significantly different (P = 0.05).
3 Visual size ratings: S = small, M = medium, L = large, VL = very large.
4 Informal taste ratings: S = sweet, T = tart, B = bland.
5 Appearance ratings: A- = below average, A = average, A+ = above average.
6 Harvest dates: 6/08, 6/15, 6/20, 6/29, 7/09, 7/16 (38 day harvest season).

Western Kentucky Blueberry Cultivar Trial

Dwight Wolfe and Gerald R. Brown, Department of Horticulture

Introduction

The blueberry is a fruit crop native to North America. At present, Kentucky blueberries have a small established commercial market and an excellent potential for local sales, U-pick, and home use. Blueberries have recently been touted for their health benefits because of their high levels of antioxidants. Also, highbush blueberries have been a good supplemental crop for some Kentucky growers. For these reasons, the goal of this study was to evaluate highbush blueberry varieties for adaptability to Kentucky.

Materials and Methods

This blueberry cultivar trial was established in the spring of 1993 at the UK College of Agriculture Research and Education Center at Princeton. The planting consisted of eight cultivars spaced 4 feet apart within rows spaced 14 feet apart. Prior to planting, the pH was reduced from above 6 to 5.4 with elemental sulfur. The planting has been mulched yearly with sawdust and is trickle irrigated using 1 gph vortex emitters. Plants were netted during the last week of May, and fruit was harvested from the first week of June through the first week of July.

Results and Discussion

Cumulative yield from 1995 through 2001, the 2001 yields, and average percentage of fruit ripe by the end of the first and third weeks of June are shown in Table 1. Yields in 2001 averaged about one-third lower than those reported in 2000 (3). This was probably the result of several freezes occurring throughout the month of March 2001. Duke and Sierra have produced the most fruit (cumulative yield) to date, although Nelson produced the most fruit in 2001.

Duke and Sunrise have been the earliest ripening cultivars in this planting, with 44 percent and 48 percent respectively of their fruit ripening during the first week of June this year. Nelson was the latest ripening cultivar again this year, with only half of its fruit being picked by the third week of July 2001.

These results should be useful to growers in choosing blueberry cultivars. The potential labor conflicts of blueberry harvest with the production and/or harvest of other crops may have to be evaluated, especially with regard to the highest yielding cultivar. Additional factors important for cultivar selection are discussed in other publications (1,2).

Literature Cited

  1. John Strang, Terry R. Jones, and G. R. Brown, 1989. Growing Highbush Blueberries in Kentucky. University of Kentucky College of Agriculture Cooperative Extension Service, Publication HO-60.
  2. Dwight Wolfe and Gerald R. Brown. 1999. Blueberry Cultivar Trial. Kentucky Fruit Facts. 1-99:2.
  3. Dwight Wolfe and Gerald R. Brown. 2001. Western Kentucky Blueberry Cultivar Trial. 2000 Fruit and Vegetable Crops Research Report, PR-436:20.

Table 1. Yields of blueberry cultivars in Western Kentucky.1
Cultivar2

Yield (lb/bush)

Average percent ripe fruit at end of week in June 2000

Cumulative 2001 1st 3rd
Sierra 50.7 8.7 0 85
Duke 50.1 6.3 44 100
Nelson 47.8 10.5 0 48
Toro 47.5 8.7 0 72
Bluecrop 45.0 9.1 0 79
Blue Gold 41.8 6.2 0 93
Sunrise 29.2 3.5 48 100
Patriot 26.6 4.1 0 100
LSD (0.05) 5.6 1.8 -- --
1 The planting was established in April 1993. Plant spacing is 4 feet between bushes in rows 14 feet apart. There are three bushes/cultivar/rep combination.
2 In descending order of cumulative yield (1995-2001).

Introduction ! Tree Fruits ! Small Fruits ! Vegetables ! Greenhouse Production ! Diagnostic Laboratory ! Appendix


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