Five year old 'Bluecrop' blueberry plants were subjected to five irrigation regimes over a two year period to determine the influence on yield, berry weight, and plant growth. The plants were in 140 liter open-ended barrels to isolate different rates of moisture application. Ten plants/treatments were utilized in this study, with each plant considered a rep. Total yields did not follow a predictable pattern. Plants receiving 12 and 16 liters of water 3x per week produced larger berries, and resulted in larger dry weights at termination of this study. Plants receiving 20 liters 1x per week produced smaller berries than other treatments, lower yields in year 2, and smallest dry weight at end of the study.
Angela K. Tedesco, Gail R. Nonnecke, Nick E. Christians, John J. Obrycki, and Mark L. Gleason
Field plots of four production systems of `Tristar' dayneutral and `Earliglow' June-bearing strawberry (Fragaria ×ananassa Duch.), established in 1993, included conventional practices (CONV), integrated crop management practices (ICM), organic practices using granulated corn gluten meal, a natural weed control product, (ORG-CGM), and organic practices using a natural turkey manure product (ORG-TM). `Earliglow' total yield from CONV plots in 1994 was similar to ICM and ORG-CGM, but greater than ORG-TM. Average berry weight and marketable yield were greater in the CONV system than both organic systems. CONV, ICM, and ORG-CGM plots had more runners and daughter plants than ORG-TM. Plots with CONV herbicide treatments were similar to ICM and ORG-CGM for percentage weed cover 1 month after renovation. `Tristar' crown number, crown and root dry weights, yield, and berry number were reduced when plants were grown under straw mulch in ORG-CGM and ORG-TM compared to CONV and ICM plots with polyethylene mulch.
Bruce P. Bordelon and J.N. Moore
Various plant growth regulators were used to stimulate endosperm and embryo development in four stenospermic grape cultivars. Five antigibberellins were applied to clusters at 1000 and 100 ppm two weeks prior to bloom. Two cytokinins were applied at 1000, 500, and 250 ppm 20 days after bloom. Combinations of the treatments were also made. Data collected included: 1) cluster weight, 2) berry weight, 3) number of `sinker' and `floater' seed traces, 4) `sinker' weight and 5) percent germination. Significant differences were found among treatments for some of the variables. Differences also occurred among cultivars. Percent germination was greater for cultivars with large seed traces. The technique appears to have promise as an alternative to ovule culture/embryo rescue for intercrossing stenospermic grapes.
Blair Sampson, Steve Noffsinger, Creighton Gupton, and James Magee
Fruit set in the muscadine grape (Vitis rotundifolia Michx.) depended on insect cross-pollination, although flowers were well adapted for selfing. Pollinizer cultivars produced about half of their optimal fruit set when selfed, but cross-pollination was needed to reach an optimal fruit set of 33.7%. Eighty-one percent of the overall fruit set in pistillate vines was attributed to insect cross-pollination; wind played only a small role. Diminished fruit set and fewer seeds per berry occurred in cultivars receiving no effective cross-pollination. Components of fruit quality were not profoundly affected by the pollination treatments, although seed set and berry weight in pistillate cultivars was lower in the absence of cross-pollination. Parthenocarpy was rare, except in `Fry Seedless'. Muscadine production throughout the southeastern United States depends on cross-pollination by indigenous insects, particularly bees. To ensure consistently high yields, bees must have safe access to flowers and their nesting sites must be preserved.
Joseph Naraguma and John R. Clark
Applications of N to blackberry plantings are a common practice in Arkansas, but fertilizer recommendations are largely based on those of other states. The need for information on fertility of a new blackberry from the Arkansas breeding program motivated this study. A three-year-old `Arapaho' blackberry planting at the University of Arkansas Fruit Substation was used for this study. Treatments which began in 1994 and continued through 1996 were: 1) control—no N applied, 2) 56 Kg N/ha applied in a single application in early spring, 3) 112 Kg N/ha applied in a single early spring application, and 4) 112 Kg/ha applied in a split application with one-half applied in the early spring and one-half applied immediately after harvest. Fruit was harvested from the plots in June and total yield and average berry weight determined. Foliar samples were collected in August and elemental analysis conducted. Primocanes in each plot were counted at the end of the growing season. Over the three years, there was no significant treatment effect on yield, berry weight, or primocane number. A trend toward higher primocane number where N was applied was seen, however. Foliar levels of N, P, K, Ca, S, and Mn were affected by either N rate or time of application. The foliar N levels were influenced by N rate and the split application gave the highest concentration. Calcium was higher when no N was applied, Mn was greater at higher N rates while the control had the lowest foliar N level in each year.
Manjula Carter, John R. Clark, and Mike Phillips
The southern highbush blueberry is a hybrid of Vaccinium corymbosum L. and one or more southern-adapted Vaccinium species. The southern highbush is advantageous to blueberry growers in the South since its fruit ripen 1 to 4 weeks in advance of traditional rabbiteye (V. ashei Reade) cultivars. Only limited research has been done on cultural aspects of southern highbush production. The objective of this study was to determine the optimum nitrogen rate for the southern highbush blueberry. A planting of pine straw-mulched `Cape Fear' blueberry was established in 1994 at the Southwest Research and Extension Center, Hope, Ark. Nitrogen rate treatments (0, 67, 134, 202, 269 kg·ha-1 N) were applied annually over a 3-year period (1997-99) with urea as the N source. Soil samples were taken prior to N fertilization to determine if N applied the previous year influenced current soil analysis values. Foliar elemental composition, fruit yield and individual berry weight were also determined for each treatment. Soil analysis indicated that the carryover effect of N applications from previous years was minimal. However, a possible decline in soil pH, Ca, and Mg over time at the higher N rates indicated that these variables should be closely monitored. No consistent relationship was evident between N application rate and soil nitrate. Nitrogen application rate did not have any consistent impact on yield, berry weight or foliar elemental composition. However, based on foliar N, the data indicate that N rates of 67-134 kg·ha-1 N are adequate for southern highbush in mulched culture.
D. Scott NeSmith
timing of CPPU application with respect to stage of plant development will likely govern its effectiveness. The objective of this research was to examine fruit set and berry weight of ‘Brightwell’, ‘Climax’, and ‘Tifblue’ rabbiteye blueberries under field
Marvin D. Butler and Robert E. Rush
Early maturity is of major importance to table grape producers in the Sonoran Desert. Prices are historically high at the beginning of the season, declining substantially over the first few days or weeks of harvest. Research was conducted in 1990 and 1991 at a commercial vineyard in southwest Arizona to determine the effect of bunch count per vine on yield and early maturity of fifth and sixth year flame seedless grapes. Vines were thinned to 15, 25 and 35 bunches in 1990, and 20, 30, 40, and 40 short bunches in 1991. The two-row, 0.2 acre plots were replicated four times using a randomized complete block design. Despite the large variation in crop load, there were no significant differences in total yield. There was an increase in percent soluble solids as bunch counts decreased. Berry weight followed the same trend. Small to moderate bunch counts produced a larger number of boxes and a greater percentage of the crop early in the season. By maintaining small to moderate bunch counts, early maturity is attainable without significantly reducing total yield.
David E. Yarborough
Improvements in the Bragg harvester and the introduction of a new Nimco harvester warranted a reevaluation of new technologies. Four technologies: the Bragg harvester, a modified Bragg harvester, the Nimco prototype, and hand-harvesting were evaluated at two locations: a land-leveled field (T-19) and a field without land leveling (Deblois). The experimental design was a randomized complete block with eight replications. A 150-ft strip was harvested with each technology, with strips directly adjacent to each other to minimize field variability. Time to harvest and berry weights were measured. Poor maintenance, adjustment and skill of the operator contributed to a 69% recovery relative to hand-harvest by both the Bragg and modified Bragg harvesters. The Nimco harvester has great potential, but only if it is properly mounted to allow it to cover the fields at a speed similar to the Bragg harvesters. The land-leveled field allowed for greater recovery for the Bragg and Nimco harvester, indicating that smoother fields are more efficient for machine-harvesting.
R.K. Striegler and G.T. Berg
Grape growers in the southern San Joaquin Valley of California are increasingly concerned about production costs. Reduced demand for wine grapes from this district has resulted in low prices and a decline in grower profitability in recent years. Minimal pruning is a low-cost production system that was developed in Australia more than 20 years ago. This system offers complete mechanization of pruning and harvesting. In general, there is little information available on the use of minimal pruning in California vineyards. The propose of the experiment was to compare the effects of hand and minimal pruning on growth, yield, and fruit composition of `Ruby Cabernet' grapevines. This experiment was conducted in a commercial vineyard near Huron, Calif., during the 1993 and 1994 seasons. Minimally pruned vines had more shoots and fewer mature nodes than hand-pruned vines. Yield and components of yield were also significantly altered by pruning method. Minimal pruning produced the highest yield and number of clusters, while hand-pruning resulted in larger berry weight, cluster weight, and number of berries per cluster. Pruning method did not significantly affect fruit composition.