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.
The competitive effects of bunchberry Cornus canadensis L. on native stands of blueberries Vaccinium angustifolium Ait. was assessed in 1986 and 1987, and in the greenhouse in 1987 with replacement series experiments. In the field, blueberry and bunchberry fruit were harvested in August and all aboveground growth was cut, the species were separated, and dry weight was determined. The relative yield total (RYT), defined as the dry weight (DW) of the combined aboveground portions of the blueberry and bunchberry divided by their respective DW at 100% cover, was >1 and showed an increase with increasing proportion of bunchberry. Blueberry relative yield, defined as the DW of the aboveground portion divided by the DW at 100% cover, was >1, but bunchberry relative yield DW was ≤1. Regression of individual on associate DW yield indicates blueberry is as aggressive as bunchberry. Blueberry fruit count and yield decreased with increasing bunchberry density. In the greenhouse study, plant count and cover were assessed weekly, and leaf area index (LAD and DW were obtained at the end of the study. RTY > 1, and combined DW increased with increasing proportion of bunchberry. The LAI of blueberry or bunchberry was higher in mixtures than in pure stands. Blueberries are competitive with bunchberry, but in native fields, open areas among clones allow faster growing bunchberry to spread without competition.
Hexazinone was applied preemergent, after pruning, at 1.1, 2.2, 4.5, or 9.0 kg/ha to a commercial lowbush blueberry (Vaccinium angustifolium Ait.) field. Visual ratings indicated a quadratic decline in grasses and a linear increase in blueberry injury associated with hexazinone application. Counts of weed populations showed a highly significant linear decline in meadowsweet (Spiraea latifolia Borkh.) and goldenrod (So-lidago sp.) with an increase in hexazinone rate. Hexazinone treatments did not affect the density of blueberry stems, but flower buds and yield followed a quadratic trend. Hexazinone provided excellent control of many common weed species accompanied by a significant increase in blueberry yield. Chemical name used: 3-cyclohexyl-6-(di-methylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione (hexazinone).
No differences in plant stand, stem length, growth habit, flower bud formation or yield were detected between fall vs. spring or between mechanical vs. thermal pruning (burning with oil) of lowbush blueberries Vaccinium angustifolium Ait. This suggests that close flail mowing may be an acceptable alternative to burning for pruning lowbush blueberries.
Experimental plots in a commercial lowbush blueberry (Vaccinium angustifolium Ait.) field deficient in N and P received preemergent 33.6 and 67.2 kg/ha rates of N (urea), P (23 % phosphoric acid), N+P (DAP), N+P+K (S-10-5) or N+P+K (fish hydrolysate, 2-4-2). A RCB design with eight replications of 12 treatments was used. Fertilizer containing N alone was as effective in raising N leaf concentrations, as those containing N and P. However, leaf phosphorus concentrations were raised more by fertilizer providing N and P than only P. Fish hydrolysate fertilizer was as effective as 5-10-5 in raising leaf N, P and K concentrations in prune and crop year leaf samples.
Three hundred, 1 m2 plots with either 0%, 25%, 50%, 75% or 100% dogbane or bracken fern weed cover were used in the study. The experimental design was completely randomized with two species, three treatments (mow, wipe and untreated), five densities and 10 replications. One half of each plot had weed cover and one half was kept weed free in order to compare the effect of weed density on yield. Plots were treated with either 10% v/v glyphosate in a hand held weed-wiper, mowed with a string trimmer or left untreated. Wiping was more effective than mowing for reducing weed numbers in the following year. However, wiping reduced yields compared to mowing at higher weed densities. Mowing proved more effective at increasing yields up to 50% weed cover compared to wiping or not treating. Averages from 1991 and 1992 study indicate mowing increases yields compared to wiping up to 50% then tend to decline, but yields remain greater than not treating.
One hundred lowbush blueberry (Vaccinium angustifolium Ait.) clones were randomly sampled from a commercial field to estimate potential productivity. Yield data exhibited a normal distribution ranging from 300 to 17,000 kg·ha-1 with a mean of 7726 kg·ha-1. Commercial use of selected clones or improved cultivars through new plantings, interplanting into existing clones, or replacement of low-yielding clones in native stands and increasing the intensity of field management would increase the yielding potential of native lowbush blueberry fields.
Blueberry production area in North American increased 30% from 1992 to 2003 to 239,818 acres (97,054 ha); most of this increase occurred in Canada. During this period, lowbush blueberry (Vaccinium angustifolium) area increased 33% and highbush 24%. In the United States, the area planted to highbush, which includes northern (V. corymbosum) and southern highbush (Vaccinium sp.) and rabbiteye (V. ashei) blueberries, increased from 48,790 acres (19,745 ha) to 55,898 acres (22,622 ha) from 1992 to 2003, a 15% increase. In 2003, the midwestern region of the U.S. accounted for 35% of the area of highbush blueberries planted. The southern, northeastern, and western regions accounted for 29%, 19%, and 13% of the planted area, respectively. Specific states in the U.S. that had considerable growth from 1992 to 2003 were California, Mississippi, North Carolina, Oregon, and Washington. In Canada, the area planted to highbush blueberries increased 105% to 11,010 acres (4456 ha). Commercial blueberry plantings in Mexico were estimated at 70 acres (28.3 ha) in 2003. In the U.S., total lowbush area increased 6% in 10 years, with Maine accounting for 97% of the area planted. In Canada, lowbush area increased 57% since 1992 with 37% and 34% of the total area present in Quebec and Nova Scotia, respectively. The blueberry industry is still projected to grow considerably in the next 5 to 10 years. Highbush blueberries in the U.S. are expected to increase in area planted by 14% and 31% in the next 5 and 10 years, respectively. In Canada, planted area of highbush blueberries is expected to increase by 22% in 5 years and 26% in 10 years. If projections are correct, planted area in Mexico will increase by almost 30-fold in 10 years. The managed area of lowbush blueberries is expected to increase by 5% to 10% over the next 10 years. Data on typical yields, types of cultivars grown, markets, proportion of machine harvest, major production problems, and changes in production practices are presented.
Effects of selective contact application of 2,4-dichlorophenoxyacetic acid (2,4-D) or N-phosphonomethylglycine (glyphosate) on a mixed stand of blueberry (Vaccinium angustifolium Ait.) and barrenberry (Aronia melanocarpa (Michx.) Ell.) were studied using a selective herbicide applicator. The greater height of barrenberry in its second year of growth provided the selectivity. Herbicide application on the burn year reduced both blueberry and barrenberry plant stands. Selective application of glyphosate or 2,4-D reduced the number of barrenberry plants without seriously affecting blueberry plant stem length or fruit bud number when applied to crop year plants after harvest. Higher rates of herbicides resulted in a greater reduction in barrenberry plant stand. Glyphosate or 2,4-D provided adequate control of regrowth of black barrenberry plants in lowbush blueberry fields.
N-(phosphonomethyl)glycine(glyphosate) or 2,4-D (2, 4 dichlorophenoxy)acetic acid (2, 4-D) was applied on 2 dates (October 28 or November 10) after leaf abscission of blueberry (Vaccinium angustifolium Ait.) in a commercial field containing lambkill (Kalmia angustifolia L.); plots were thermally pruned the following spring. Lambkill plant stand decreased with increasing rates of glyphosate or 2, 4-D. A late application of glyphosate was more effective than 2, 4-D in reducing lambkill plant stand. Increasing the rate of glyphosate resulted in a greater number of blueberry stems, more flower buds per stem, and a higher yield. Glyphosate applications reduced the length of reemerging lambkill stems but 2, 4-D did not. Glyphosate was as effective in reducing lambkill plant stand at 2.2 kg/ha as 2, 4-D was at 4.5 kg/ha.