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On fl at ground it is generally better to plant rows oriented north–south rather than east–west as light interception by plant rows will be greater. Because the sun rises in the east and sets in the west, the entire canopy receives exposure to direct sunlight at some point during the day (as long as rows are not too close together). The only exception is if fall raspberries are being grown in a high tunnel for late season production. In this case, east–west rows intercept more sunlight when the sun is low in the western sky after the equinox.

The aspect of the slope is also an important consideration when the goal is to maximize light interception of the canopy. Steep, north-facing slopes at high latitudes may never receive direct sunlight and plants may not grow well under these conditions. In contrast, in the northern hemisphere during summer, plants on a south-facing slope will receive more direct sunlight than those facing other directions. Diff erences in light interception are small when the angle of the slope is small, but become signifi cant when the angle of the slope increases, especially at higher latitudes.

Raspberries are particularly sensitive to wind damage. Even though damage may not result in visible symptoms, raspberries grown under windy conditions generally have shorter canes and lower yields. Two strategies are used to mitigate wind damage. The fi rst is to use natural or artifi cial shelter belts to break the wind. Typically, if wind comes from the west, a north–south windbreak on the west end of the fi eld will help reduce wind damage. The windier the site, the more frequent these windbreaks should occur. Raspberry

Site Preparation, Soil Management and Planting 99

rows themselves may be less susceptible to wind damage if planted in the direction of the prevailing wind, but light interception must be considered as well. The taller the windbreak, the longer the distance that wind speed will be reduced.

A second strategy to mitigate wind damage is to use a trellis. All brambles benefi t from a trellis, even those grown for a fall-crop only. A trellis not only helps prevent canes from moving in wind and damaging their vascular connections with the root, but also holds canes erect, helps improve exposure of fruit, and improves effi ciency of harvest and fruit quality. Trellises for fall-fruiting types need not be elaborate, but simply need to hold canes erect. Trellises for fl oricane-fruiting plants need to be more rugged to hold primocanes and fruit-bearing canes erect throughout the year.

Materials for constructing trellises have traditionally consisted of 5 × 10 cm (2 × 4 in), or 10 × 10 cm (4 × 4 in), treated posts, with metal wires strung between posts. Posts are usually 8–10 m (25–30 ft) apart down the row, sometimes with metal stakes in between. Floricane-fruiting types benefi t from having the canes spread into a V-shape so that light interception and penetration, especially into the lower canopy, is improved. Newer, lighter-weight materials have been developed for trellises. Monofi lament plastic wire is as strong as steel wire, and is easier to work with as it does not conduct electricity in the event of a lightning strike. Fiberglass posts are easy to adjust and just as strong as steel.

PLANTING

Several choices of planting stock are available, depending on the nursery. The traditional and most common type of red raspberry are the bare root suckers taken from mother plants in a nursery. These have a short piece of cane attached to a rather large root and are dug dormant in fall. Bare-rooted plants are kept in a cooler until shipping in spring. They can be planted in spring as soon as the soil can be worked. Black raspberries can be propagated by root tips. They, too, are dug in the fall with roots attached to a shoot, so are best transplanted in early spring.

Tissue-cultured green plants are similar in size to a pepper or tomato transplant, and so are much smaller than bare-rooted plants. The plugs are easily handled by most mechanical transplanters. They should be planted only after the danger of heavy frost is over because the leaves are green and sensitive to extreme cold.

Green tissue-cultured plugs can be chilled in the nursery or subjected to conditions that encourage leaf drop and dormancy. These propagules are very small – just a root ball with a leafl ess shoot, a few centimeters tall. They can be planted while there is still a risk of frost. These dormant tissue-cultured plugs ship well because they have no leaves.

100 M. Pritts and E. Hanson

Studies have compared the performance of these three types of propagules.

By the time these plants reach maturity, the performance is about equal among the propagule types. Therefore, the choice of which to purchase is based primarily on characteristics other than yield. Green plugs might be the best choice if the planting date is after frost and irrigation water is readily available.

Dormant, bare-root plants might be the best choice if no irrigation is available.

Typically, raspberries are set in rows, with the distance between rows depending on the plant type and their tendency to produce laterals. Between-row spacing is a minimum of 3 m (10 ft), while the intra-Between-row spacing is from 30 cm to 1 m (1–3 ft), depending on the training system. Primocane-fruiting raspberries can be planted as close as 2.6 m (9 ft) between rows and 30 cm (1 ft) between plants within rows. In high tunnels and greenhouses where tractors are not used down rows, between-row spacing can be as close as 1.8–2 m (6–7 ft).

Studies have shown that shallow-rooted plugs are sensitive to herbicides and soil disturbance after planting (Neal et al., 1990). Therefore, planting through plastic mulch or mulching with straw or newspaper after planting helps suppress weeds while retaining soil moisture (Warmund et al., 1995;

Percival et al., 1998). Plants mulched their fi rst year tend to outperform unmulched plants because herbicide use and cultivation are avoided and moisture levels remain consistently high (Trinka and Pritts, 1992). Plants can also be set into killed rye or other cover crop, mimicking a no-till or strip-till situation. This strategy helps suppress weeds while the plants become established without a lot of soil disturbance.

Once plants are set, they should be irrigated. The shallow root system of plug plants cannot access much soil moisture; therefore, suffi cient water should be applied to maintain some moisture in the root zone of the plants.

Once plants are set, mulched and irrigated, they are well on their way to becoming established. If recommended procedures are followed, fertilizer should not be required because nutrients should have been incorporated into the soil during the pre-plant step, and suffi cient N will be provided from organic matter for several months after planting. The most important function for the grower after planting is to keep weeds under control. If the planting establishes well and weeds are kept under control the fi rst year, then it will be diffi cult for weeds to invade the planting later.

In many cases, a perennial grass is planted between rows of berries to help suppress weeds and provide a suitable surface for tolerating equipment and movement of foot traffi c, especially after it rains. Fescues and dwarf perennial ryes are good choices. Grass seed germination is best when soil is moist and temperatures are cool, so fall planting is often the best time to seed row middles.

An initial investment in the pre-plant site preparation and modifi cation can pay major dividends for growers in the ensuing years, but planning ahead is the key to success.

Site Preparation, Soil Management and Planting 101

REFERENCES

Belair, G. (1991) Eff ects of preplant soil fumigation on nematode population densities and on growth and yield of raspberry. Phytoprotection 72, 21–25.

Black, B.L., Swartz, H.J., Millner, P. and Steiner, P. (2003) Pre-plant crop rotation and compost amendments for improving establishment of red raspberry. Journal of the American Pomological Society 57, 149–156.

Forge, T.A., Walters, T.W., Koch, C.A. and Particka, M. (2009) Eff ects of compost and manure mulches on soil biological activity, population densities of Pratylenchus penetrans, root-associated fungi, and root biomass of ‘Meeker’ red raspberry.

Canadian Journal of Plant Pathology 31, 136.

Hargreaves, J., Adl, M.S., Warman, P.R. and Vasantha Rupasinghe, H.P. (2008) The eff ects of organic amendments on mineral element uptake and fruit quality of raspberries. Plant Soil 308, 213–226.

Maloney, K., Pritts, M., Wilcox, W. and Kelly, M. (2005) Suppression of Phytophthora root rot in red raspberries with cultural practices and soil amendments. HortScience 40, 1790–1795.

Neal, J.C., Pritts, M.P. and Senesac, A.F. (1990) Evaluations of preemergent herbicide phytotoxicity to tissue culture propagated ‘Heritage’ red raspberry. Journal of the American Society for Horticultural Science 115, 416–422.

Orhan, E., Esitken, A., Ercisli, S., Turan, M. and Sahin, F. (2006) Eff ects of plant growth promoting rhizobacteria (PGPR) on yield, growth and nutrient contents in organically growing raspberry. Scientia Horticulturae 111, 38–43.

Percival, D.C., Proctor, J.T.A. and Sullivan, J.A. (1998) Supplementary irrigation and mulch benefi t the establishment of ‘Heritage’ primocane-fruiting raspberry. Journal of the American Society for Horticultural Science 123, 518–523.

Pinkerton, J.N., Ivors, K.L., Reeser, P.W., Bristow, P.R. and Windom, G.E. (2002) The use of soil solarization for the management of soilborne plant pathogens in strawberry and red raspberry production. Plant Disease 86, 645–651.

Seigies, A.T., Pritts, M.P. and Kelly, M.J. (2006) Cover crop rotations alter soil microbiology and reduce replant disorders in strawberry. HortScience 41, 1303–1308.

Taylor, J. and Harrier, L. (2000) A comparison of nine species of arbuscular mycorrhizal fungi on the development and nutrition of micropropagated Rubus idaeus L. cv. Glen Prosen (Red Raspberry). Plant Soil 225, 53–61.

Toussaint, V., Valois, D., Dodier, M., Faucher, E., Dery, C., Brzezinski, R., Ruest, L. and Beaulieu, C. (1997) Characterization of actinomycetes antagonistic to Phytophthora fragariae var. rubi, the causal agent of raspberry root rot. Phytoprotection 78, 43–51.

Trinka, D.L. and Pritts, M.P. (1992) Micropropagated raspberry plant establishment as infl uenced by weed control practice, row cover use and fertilizer placement. Journal of the American Society for Horticultural Science 117, 874–880.

Warmund, M.R., Starbuck, C.J. and Finn, C.E. (1995) Micropropagated ‘Redwing’

raspberry plants mulched with recycled newspaper produce greater yields than those grown with black polyethylene. Journal of Small Fruit and Viticulture 3, 63–73.

Wilcox, W.F., Pritts, M.P. and Kelly, M.J. (1999) Integrated control of Phytophthora root rot of red raspberry. Plant Disease 83, 1149–1154.

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© CAB International 2013. Raspberries (eds R.C. Funt and H.K. Hall) 103