Search Results

You are looking at 1 - 10 of 125 items for

  • Author or Editor: Bernadine Strik x
Clear All Modify Search

The effect of early cropping (no removal of fruit buds the first two years) and in-row spacing (0.45 or 1.2 m) on growth and yield of `Duke', `Bluecrop', and `Elliott' northern highbush blueberries (Vaccinium corymbosum L.) was studied. Plants were grown on raised beds for four years. No yield was produced on the control plants in the planting year (year 1) and year 2. Plant growth at the start of year 3 was adversely impacted by early cropping in years 1 and 2. Early cropping reduced the dry weight of the root system, crown, and 1- to 3-year-old wood in all cultivars. `Bluecrop' plants had less total dry weight than those of `Duke' or `Elliott'. Roots accounted for 30% to 45% of the total plant dry weight depending on cultivar. Early-cropped plants had a lower percentage of fruit buds than control plants. Early cropping reduced yield 44%, 24%, and 19% in year 3, compared to control plants, in `Elliott', `Duke', and `Bluecrop', respectively. Cumulative yield (years 1 through 4) was similar between control and early cropped plants in `Bluecrop' and `Duke', whereas early cropping reduced cumulative yield in `Elliott' 20% to 40%, depending on in-row spacing. Plants spaced at 0.45 m produced 62% to 140% more yield per hectare than those spaced at 1.2 m, depending on cultivar. `Elliott' plants seemed less suited to high density planting due to their large root system.

Free access

All life stages of grape phylloxera [Daktulosphaira vitifoliae (Fitch) (Homoptera: Phylloxeridae)] were eradicated with a hot-water treatment (dip) of 5 minutes at 43 °C (110 °F) to warm roots, followed by a 5-minute dip at 52 °C (125 °F). Neither grafted nor nongrafted dormant grape plants were damaged by the hot-water treatment.

Full access

Many growers in the Pacific Northwest are planting blueberry fields at higher densities to improve yields and increase the number of berries harvested per acre in the first few years after planting. The objective of this study was to determine the effect of high-density planting on blueberry water requirements. Although close spacing reduces individual plant size, we expected that plants spaced closer together would require more irrigation per unit land area than those spaced further apart due to increased canopy coverage within rows. The study utilized a 5-year-old planting of highbush blueberry, consisting of three cultivars, `Duke', `Bluecrop', and `Elliott', planted at 0.5- and 1.2-m in-row spacings. Plant water use was calculated from changes in soil water content measured using TDR probes for shallow depths and a neutron probe and access tubes for deeper depths. Stem water potentials were also measured periodically using a pressure chamber to determine how well irrigation was meeting crop water demands throughout the season. Surprisingly, plants spaced 0.5 m apart required only slightly more water than those spaced 1.2 m apart. They did, however, require more frequent irrigations due to their smaller root systems, especially during fruit filling. Water use by each cultivar increased during fruit filling and then rapidly decreased after harvest. `Duke' required the most water among cultivars, using 5–10 mm/day from mid-May to mid-August, while `Elliott' required the least, using 3–5 mm/day.

Free access

Primocane-fruiting blackberry (Rubus L. subgenus Rubus, Watson) cultivars, Prime-Jan® and Prime-Jim®, grown only for a primocane crop, were studied for 2 years to evaluate whether this type of blackberry should be sampled at a certain stage of development or time of season to best evaluate plant nutrient status. Leaves were sampled every 2 weeks from a primocane height of ≈0.75 m in spring through fruit harvest in autumn and were analyzed to determine concentration of macro- and micronutrients. Primocanes were summer pruned at 1.4 m, by hedging to a height of 1.0 m, to induce branching, a standard commercial practice. Leaf nutrient concentration was related to stage of primocane growth and development and whether the leaves originated on the main cane or on the branches that resulted from summer pruning. Nutrient concentration of leaves sampled on the main primocane from early growth in spring until early branch growth in summer was significantly affected by cultivar, year, and week for most nutrients. When leaf sampling occurred on the older leaves of the main cane (for 4 weeks after hedging), the concentration of Ca, Mg, B, Fe, Mn, and Al increased, likely a result of the relative immobility of most of these nutrients. When samples were taken on primocane branches, leaf N, Mg, S, B (2009 only), Fe, Mn, Cu (2009 only), Zn, and Al concentrations did not differ between samples taken 6–8 weeks after summer pruning or hedging. Leaf K and Ca were more stable when sampling was done from weeks 8 to 10 (early bloom to green/early red fruit). There was a significant difference in leaf P among all weeks sampled during this period. A sample date corresponding to early green fruit stage (week 8) would thus likely provide the best compromise for assessing plant nutrient status in this crop. During this stage of development the nutrient concentrations measured for both cultivars and years, were within the present recommended nutrient sufficiency levels for other blackberry and raspberry crops for all except leaf K and P which were below current standards. The results suggest leaf sampling primocane-fruiting blackberry at the early green fruit stage (about 8 weeks after summer pruning) rather than a particular calendar date. The present leaf sufficiency range for P and K may need to be lowered for this crop. In addition, sampling cultivars separately for tissue analysis would still be advised to better manage nutrient programs.

Free access

Timing and severity of pruning in a 30-year-old commercial `McFarlin' cranberry (Vaccinium macrocarpon Ait.) bed were studied. Treatments in 1989 and 1990 consisted of early or late pruning and heavy, moderate, light, or no pruning. Yield component data were collected in Fall 1989 and 1990, just before harvest. Time of pruning did not affect yield components. In 1989, the unpruned and lightly pruned vines had a higher total plant fresh weight, fewer berries, higher berry yield, longer and more fruiting uprights, and fewer nonfruiting uprights (U,) compared with moderately or heavily pruned vines. Average length of UN and anthocyanin content of berries in 1989 were not influenced by pruning. In 1990, the effects of pruning severity were similar to 1989. In 1990, unpruned vines had a lower percent fruit set and berries contained less anthocyanin than pruned vines. Annual pruning with conventional systems in use decreases yield.

Free access

`Meeker' red raspberry (Rubus idaeus L.) cane densities of 5, 10, or 15 canes/hill in a hill system, with canes topped at 2 m or the entire cane length retained and looped, were compared with a 15- or 30-cm-wide hedgerow with canes topped at 2 m from 1995 to 1997. Cane density among all treatments ranged from 2.2 to 9.9 canes/m2 during the study. Plots were harvested by machine every 2 days. Within the hill system, total yield increased with cane density in all years. Looped treatments produced a higher yield/plot than did topped ones in all years except 1996, when the yield difference was insignificant because looped canes had greater winter injury. Weight per fruit ranged from 5.4% to 9.7% less on looped than on topped canes. Hedgerow systems had a lower yield than hill systems in 1996, but a higher yield in 1997. Losses due to machine harvest were not affected by pruning (cane density or topping) or production system (hill system or hedgerow) and averaged 16.2% of total yield in 1997. Thirty-five percent of the loss due to machine harvest occurred between harvests.

Free access

The following pruning treatments were studied in mature `Bluecrop' (1996-2000) and `Berkeley' (1996-98) plants: 1) “conventional” pruning with removal of unproductive canes, thinning of 1-year-old shoots at the base of the bush, and removal of any unproductive wood or thinning of excessive fruiting wood near the top of the bush, as required; 2) “speed” pruning involving removal of one or two of the most unproductive canes at the base of the bush; and 3) “un-pruned” where no pruning was done for the length of this study. Conventional pruning took an average of 6.4 min/plot, while speed pruning saved 88.8% time. There was no pruning treatment effect on the percentage of fruit buds in `Berkeley' (42%) or `Bluecrop' (34%) or percent fruit set (70% to 90%, depending on cultivar and year) in any year. Un-pruned plants of both cultivars had significantly greater yield than conventionally pruned plants, depending on the year, while speed pruning generally resulted in intermediate yields. Un-pruned and speed-pruned plants produced berries that were 19% to 27% smaller than conventionally pruned plants, depending on year. The fruit harvest season of un-pruned plants began 3 to 5 days later and lasted a week longer than that of conventionally pruned plants. The harvest efficiency of un-pruned plants was reduced as much as 51% in the later years of this study and was most closely correlated with berry weight. Conventionally pruned plants had a significantly higher percentage of the above-ground dry weight allocated to 1-year-old wood and crown than un-pruned plants. In `Bluecrop', N concentration tended to be higher in the crown of conventionally pruned plants than in un-pruned or speed-pruned plants. Conventionally pruned `Bluecrop' plants had significantly higher concentrations of K and P and lower N than un-pruned plants and `Berkeley' had lower concentrations of N, than un-pruned plants. Results indicate that not pruning mature plants may be an option in the short-term, but may have undesirable effects for long-term sustainability.

Free access

Primocane-fruiting blackberries produce fruit on current-season canes (primocanes) and second-season canes (floricanes), if desired. Primocane-fruiting blackberries are likely adapted to a diverse range of climates, particularly because cold hardiness is not an issue when plants are grown for a primocane crop only. The floricane crop of ‘Prime-Jan’® and ‘Prime-Jim’® is from 3 June to 6 July in Arkansas and 30 June to 22 Aug. in Oregon, thus overlapping with other fresh market blackberries. However, although the primocane crop overlaps with the semierect cultivar Chester Thornless, the fruiting season of the primocane-fruiting types is longer. Harvest on primocanes began 17 July and mid-August in Arkansas and Oregon, respectively. The primocanes of ‘Prime-Jan’ and ‘Prime-Jim’ tend to branch naturally, producing a couple of branches near the base. However, soft-tipping primocanes at 1 m early in the season increased branch and flower number, resulting in a threefold yield increase compared with untipped canes. Yield and berry size in Oregon has been from 1.8 to 5.2 t·ha−1, depending on primocane management treatment, and 5.2 to 7.4 g, respectively. However, yield would have been much higher if all fruit could have been harvested as would be possible under protected culture. Our research to date indicates that primocane-fruiting blackberry can be easily manipulated to adjust harvest time. Remowing primocanes to create a delayed flush of growth will delay harvest. Rowcovers or tunnels that increase temperature will advance primocane growth and harvest. Soft-tipping height and frequency can affect cane architecture and season. Management techniques along with new genotypes of primocane-fruiting blackberry will have a great impact on blackberry production worldwide.

Free access

The effect of sand application to `Stevens' cranberry (Vaccinium macrocarpon Ait.) was studied for 3 years in a 24-year-old (site 1) and an 8-year-old (site 2) commercial planting. Treatments in Apr. 1991 consisted of a onetime sand application of 1.3 or 2.5 cm on the surface of the cranberry bed and a nonsanded control. Yield component data were collected in Fall 1991 through 1993. In 1991, 2.5 cm of sand reduced yield 50% at site 2 compared to the nonsanded control. At site 1, the 2.5-cm sand depth did not reduce yield, while the 1.3-cm-deep application improved yield 18% compared to the control. The year after sanding (1992), yields equalized across all treatments at both sites. In 1993, there was no significant difference in yield for treatments at site 1. At site 2, however, heavy sanding reduced yield 63% compared to 1.3 cm of sand. Our work suggests that heavy sanding is not recommended for `Stevens' cranberry beds in Oregon.

Free access