Bare-root Transplants Research Articles

Performance of Containerized and Bare-root Transplants with Soil Fumigants for Florida Strawberry Production

Field studies were conducted in three Florida locations (Bradenton, Gainesville, and Quincy) during 1998-99 and 1999-2000 to: 1) compare the performance of two transplant systems under diverse MBr alternative programs in `Chandler' strawberry (Fragaria ×ananassa), and 2) determine the efficacy of these treatments on soilborne pest control in strawberry. Fumigant treatments were: 1) nonfumigated control, 2) methyl bromide plus chloropicrin (MBr + Pic) at a rate of 350 lb/acre, 3) Pic at 300 lb/acre and napropamide at 4 lb/acre, 4) 1,3-dichloropropene (1,3-D) plus Pic at 35 gal/acre and napropamide at 4 lb/acre, 5) metam sodium (MNa) at 60 gal/acre and napropamide at 4 lb/acre, and 6) MNa followed by 1,3-D at 60 and 12 gal/acre and napropamide at 4 lb/acre, respectively. Strawberry transplants were either bare-root or containerized plugs. There were no significant fumigant by transplant type interactions for strawberry plant vigor and root weight per plant, whereas ring nematode (Criconema spp.) and nutsedge (Cyperus rotundus and C. esculentus) populations, and total marketable fruit weight were only infl uenced by fumigant application. The nonfumigated plots had the lowest strawberry plant vigor and root weight per plant in all three locations. In most cases, plant vigor and root biomass per plant increased as a response to any fumigant application. With regard to the transplant type, bare-root transplants had similar plant vigor as plugs in two of the three locations. Fumigation improved nutsedge and ring nematode control. All fumigants had higher early and total marketable yield than the nonfumigated control, whereas transplant type had no effect on total fruit weight.

Containerized Strawberry Transplants Reduce Establishment-period Water Use and Enhance Early Growth and Flowering Compared with Bare-root Plants

Experiments were conducted in two seasons in Dover, Fla. (central Florida), with bare-root and containerized (plug) strawberry (Fragaria ×ananassa) transplants to evaluate transplant establishment-period water use, plant growth, and flowering responses in the 3-week transplant establishment period. Strawberry plug plants were established with 290 gal/acre water applied only with the transplant at planting time, while 200,000 gal/acre from microjet or 1 million gal/acre of water from sprinkler irrigation were used to establish bare-root transplants. Root, shoot, and crown dry matter of plug plants rapidly increased during the establishment period, while there was a decline in leaf area and root and crown mass of bare-root plants, even with sprinkler or microjet irrigation. Water applied with the bare-root transplant only at planting was not enough to keep the plant alive during the establishment period. Large plug plants, but not irrigated bare-root plants, began flowering at 3 weeks after planting. Plug plants were used to successfully establish strawberry crops with low water inputs.

First Report of Meloidogyne partityla on Pecan in Florida.

Pecan (Carya illinoensis (Wagenh.) K. Koch) is an important tree in the southern United States for commercial nut production and residential use. Meloidogyne partityla (pecan root-knot nematode) is only known to parasitize trees in the Juglandaceae including pecan, walnut, and hickory. In the United States, it has been reported on pecan in Texas, New Mexico, and Georgia and internationally in South Africa. Portions of a large pecan nursery in Madison County, Florida were infested with an unknown species of root-knot nematode. The pecan trees at this nursery are grafted onto rootstock and grown in the field until the trees are large enough to sell as bare-root transplant stock in several states including and adjoining Florida. Trees infected by the root-knot nematodes were stunted, had extensive galling and rotting of the root system, and pulled from the ground relatively easily compared with noninfected trees. Attempts to rear these nematodes on tomato in the greenhouse were unsuccessful. Young egg-laying females were isolated directly from pecan roots for speciation. Enzymes extracted from females were resolved with polyacrylamide gel electrophoresis [4% stacking (pH 6.8) and 8% separating gel (pH 8.8) with Tris-glycine buffer]. The esterase (Est) and malate dehydrogenase (Mdh) phenotypes of the unknown Meloidogyne sp. were consistent with those reported for M. partityla. In addition, specimens of M. partityla maintained by the USDA Southeastern Fruit and Tree Nut Research Laboratory in Byron, GA were obtained and their Est and Mdh phenotypes compared with the unknown Meloidogyne sp. under identical electrophoretic and enzyme staining protocols. The Est and Mdh phenotypes of the two isolates were identical. Therefore, we conclude that the root-knot nematodes infesting the pecan nursery in Florida are M. partityla. To our knowledge, this is the first report of this nematode in Florida and also the first report of this nematode from infected nursery stock. It is unknown how long the field has been infested but clearly, there is potential for spread of M. partityla to locations around Florida and bordering states. This nematode may be widespread throughout pecan-growing regions of the United States.

Protected Culture Enhances Early Season Strawberry Fruit Yield and Quality in Southern California

Total and marketable yield, fruit size and fruit rot were evaluated for `Camarosa' and `Ventana' strawberries grown with or without protected culture in southern California in 2003 and 2004. In both years, bareroot transplants were established on 5 Oct. using standard “open field” production methods. Fifty-five days after transplanting, metal posts and arcs were positioned over portions of the field and covered with 0.0324-mm-thick clear polyethylene (Tufflite Thermal, Tyco Plastics, Inc., Minneapolis, Minn.) to create “tunnel” structures 5 m wide, 25 m long, and 2.5 m high. Each tunnel covered three contiguous strawberry beds, and experiment design was a randomized complete block with four replications, with individual plots consisting of 20 plants. In 2003, early season (Jan.–1 Apr.) marketable yields in tunnels were 90% and 84% greater than outdoor culture for `Ventana' and `Camarosa', respectively. In 2004, use of tunnels resulted in a 140% marketable yield increase for `Ventana' and 62% for `Camarosa' (Jan.–31 Mar.); however, unusually high temperatures (38 °C) in April resulted in reduced yields in tunnels thereafter. In both years, increased early production coincided with highest fresh market fruit prices, resulting in $5700–7700 greater returns per-acre compared to open field production. For both cultivars, tunnel production resulted in 37% to 63% fewer non-marketable fruit due to less rain damage, better fruit shape, and decreased incidence of gray mold. For all treatments, fruit size decreased as the season progressed and was more pronounced in tunnels after April. Overall, these studies indicate that tunnels have potential for enhancing early-season production and profitability of strawberries in southern California.

Leaf removal and prohexadione-calcium can modify Camarosa strawberry nursery plant morphology for plasticulture fruit production

Mowing and the application of a new gibberellin biosynthesis inhibitor, prohexadione-calcium (ProCa), were studied as methods to modify the bare-root transplant morphology of Camarosa strawberry (Fragaria × ananassa Duchesne) in a Nova Scotia nursery. The effect these nursery practices had on fruit production in annual hill plasticulture was also determined. In one experiment Camarosa plants were sprayed with ProCa at an active ingredient concentration of 62.5 mg L-1 on Aug. 22, Sep. 05, or Sep. 19, 2001 and 2002, corresponding, respectively, to growing degree days (10°C base) of 800, 894 and 965 in 2001 and 726, 821 and 908 in 2002. Application on Aug. 22 increased production of daughter plants, especially those of marketable size, by increasing the number of daughters per meter of runner and allocating more dry matter to marketable daughters. In a second experiment, field plots were mowed and/or treated with ProCa at an active ingredient concent ration of 62.5 mg L-1 on Sep. 05 or Sep. 19, 2001 and 2002. All plants were dug in early October, shipped to Dover, Florida, and transplanted into plasticulture for fruit production. At digging, plants that had been mowed or treated with ProCa on Sep. 05 were reduced in plant height and total leaf area compared with untreated plants. Plants that were treated both with ProCa and mowed were the shortest. Fruit yield was higher from treated than from untreated plants. In 2001, the treatments increased early fruit production. Key words: Fragaria × ananassa, mowing, gibberellin biosynthesis inhibitor, phenology, height control

Evaluation of Organic Strawberry Runner Production

System requirements for organic strawberry (Fragaria × ananassa) runner production under cover were determined during the 2001-02 and 2002-03 seasons. In the field, yield and fruit quality were assessed for organically produced runners (plug and bare-rooted transplant) in comparison with barerooted conventionally produced runners under organic, BioGro certified production conditions. The preferred organic production system was the enhanced suspended system, where mother plants grew on benches in the tunnel house and the first two runners were potted into growth substrate. This system produced approximately 50 plug transplants/mother plant or 200 plug transplants/m2. The least preferred system was the nursery bed, where mother plants were allowed to produce runners that yielded approximately 100 bare-rooted runners or 100 transplants/m2. Tunnel house production of runners (plug transplants and bare-rooted) allowed earlier planting (March vs. May) compared to field-produced bare-rooted runner plants. The earlier planting date increased yield by approximately 181 g/plant. Under organic production conditions, organically produced runners (plug and bare-rooted transplants) performed at least as well as bare-rooted conventionally produced runners. Our results show that indoor production of organic strawberry runners is possible. We also showed that organically produced runners (bare-rooted and plug transplants) perform similarly in the field compared to bare-rooted conventionally produced runners. Generally, there were no differences in yield or fruit quality among runner sources.

Uso de poliacrilamidas y el riego en el manejo hídrico de lechugas ( Lactuca sativa L.)

In San Ramon Farm, located 5 km south of Villarrica, Chile, a research was carried out between November 2002 and February 2003, with the purpose of studying the effect of different hydric treatments on lettuce production. A soil conditioner (hydrogel) was applied to: roots of seedlings at transplant time, to soil (prior to the transplant) and applied together to roots and soil, with bare root transplant as control. Irrigation and no irrigation was an additional factor, generating a total of eight treatments under study. Parameters measured were: percentage of established plants, plant diameter, number of leaves/plant, complete plant weight, leaves weight, root weight and days from transplant to harvest. All parameters were measured at harvest time. The experimental design was a complete block, with 3 random blocks with 8 treatments each. Results were subjected to Anova and Tukeys’s multiple comparison test. The analysis of percentage of established plants showed no significant differences. Largest diameters were obtained with hydrogel applied only to soil and to roots and soil. For number of leaves, the largest values were obtained with gel applied to soil and to roots and soil. Irrigation, increased significantly the number of leaves. In regard to weight of complete plant, leaves and roots weights, a significant difference was found in favor of gel, as the largest weights were associated to the application of this product to soil and to roots-soil. For roots weight, a significant interaction was found, and gel applied to soil without irrigation (T7) produced the highest weight. By applying gel to soil and to soil and roots, average value of plant vegetative cycle were shorter than with bare root transplant. Irrigation also shortened average cycles. An economic evaluation showed that soil application of hydrogel, without irrigation (T3) produced the higher profit, with a net present value of $ 18.489.426. The IRR´s were all higher than the discount rate used, so investment is attractive irrespective of the project option used.

Greenhouse-grown Transplants as an Alternative to Bare-root Transplants for Onion

Commercially produced bare-root onion (Allium cepa L.) transplants may not be uniform in size and require a period following planting in which to begin regrowth. There is little information on how, when established in the field, plants developed from greenhouse grown onion transplants differ from those that develop from bare-root transplants. Development and yield for onions grown from bare-root transplants were compared to plants produced from transplants grown in single cells with volumes of 36 or 58 cm3 in seedling production trays in a greenhouse. `Texas Grano 1015Y' and `Walla Walla' onions were established in the field with commercially available bare-root transplants or with greenhouse grown transplants produced in trays. Bare-root transplants were heavier than 8-week-old greenhouse grown transplants. Fresh weights of transplants produced in 58-cm3 cells were heavier than those from 36-cm3 cells, but dry weights were similar. From when about 20% of onion tops were broken over, onion bulb diameters did not increase sufficiently to justify delaying harvest until 50% of tops had broken over. Yields of `Walla Walla' were better than those of `Texas 1015 Y' and yields from plants developed from seedlings grown in 58-cm3 cells were similar to those from plants developed from bare-root transplants and better than those from plants developed from seedlings grown in 36-cm3 cells. Individual bulb weights of `Texas 1015 Y' were not affected by transplant type and averaged 162 g. Individual bulbs for `Walla Walla' from plants developed from bare-root transplants and those produced in 58-cm3 cells were similar in weight (averaged 300 g) and were heavier than those from plants developed from transplants grown in 36-cm3 cells (240 g). Greenhouse transplants produced in trays with the larger cells may provide an alternative to the use of bare-root transplants, if transplant production costs are comparable.

Effect of Prohexidione-Ca and IBA on Establishment and Yield of Green-Top Bare-root Strawberry Transplants

Bare-root transplants received from high latitude nurseries for Florida production have limited root systems, very long petioles and wilt soon after planting. Further dessication occurs when leaves come in contact with black plastic mulch used in the annual production system. Conventional irrigation practices for the establishment of bare-root transplants of strawberry consist of overhead water application for at least 8 hours/day for 10-14 days after planting. Plant growth regulators (PGRs) have been used to modify the growth characteristics of many plants species. A split-block experiment was implemented at the GCREC-Dover, Dover Fla., to determine the effect of the use Prohexidione-Ca (PC) and IBA [(indole-3) butyric acid] on growth, yield and establishment of strawberry. Main blocks consisted of over head establishment irrigation for 4, 8, and 12 days, and sub-plots consisted of treatments of PC applied in the nursery at a rate of 62.5 mg·L-1 2, 4, or 6 weeks before digging, PC applied in the nursery at 31.25 mg·L-1 2 weeks before digging, a root dip of transplants in 100 mg·L-1 IBA just prior to transplanting. The experiment was conducted for four growing seasons. Data were recorded for marketable yield, number of marketable berries (>10g), and disease incidence. Significant differences were detected for duration of establishment irrigation and growth regulator treatment. No interaction was shown between establishment irrigation and growth regulator treatment.

Effects of transplant type, plant growth-promoting rhizobacteria, and soil treatment on growth and yield of strawberry in Florida

The effects of transplant type and soil treatment on growth and yield of strawberries (Fragaria x ananassa Duch.) produced in annual hill culture were evaluated for three years in Florida field trials. `Sweet Charlie' and `Camarosa' strawberry transplants were propagated as bare root, plug, and plugs amended with a plant growth-promoting rhizobacterial (PGPR) treatment, LS213. The transplant treatments were evaluated in combination with methyl bromide, 1, 3-dichloropropene (Telone II), an unregistered iodine-based compound (Plantpro 45), and untreated soil. `Camarosa' plugs amended with LS213 had higher overall yields than bare root transplants in all three years. Both `Camarosa' and `Sweet Charlie' plug and LS213 plug plants produced yields approximately two weeks earlier than bare root transplants in all years. Regardless of transplant type, and in both consecutive years of Plantpro 45 and Telone application, treatment with Plantpro 45 resulted in smaller and less healthy root systems than other soil treatments, and treatment with Telone resulted in yields comparable to methyl bromide.

Reducing Mechanical Damage during Transplant Digging Increases Early Season Fruit Yield of Strawberry

Transplant quality can have a major effect on the productivity of many crops. Bare-root, green-top transplants for Florida winter strawberry (Fragaria ×ananassa) production are produced mainly in highlatitude (>42° N) nurseries. Mechanical digging machines are used to remove plants from the soil at these nurseries before transport to production fields in Florida. In the course of this operation, crowns, petioles, and leaves may be crushed and broken. Machine and hand-dug bare-root transplants of `Camarosa' and `Sweet Charlie' were obtained from a Nova Scotia, Canada nursery, planted at the Gulf Coast Research and Education Center, Dover, Fla. field facility on 2 Nov. 1999 and 10 Oct. 2000, and grown using standard annual-hill production practices. Plots were harvested twice weekly beginning 5 Jan. 2000 and 15 Dec. 2000. Hand-dug transplants produced significantly higher monetary returns both seasons. Therefore, fruit producers may consider paying the higher cost associated with changes in harvesting and packing operations needed to reduce damage to transplants.

Severe Root Pruning of Strawberry Bare Root Transplants Is Yield Neutral

In Florida annual hill strawberry (Fragaria ×ananassa Duch.) production, bare-rooted transplants are hand-planted for establishment. Northern latitude or high-elevation nurseries produce these transplants during the summer months and begin digging plants in September for winter production areas. The green-topped bare-root transplants arrive in Florida with varying amounts of root development and number of mature leaves. These plants are planted on raised, black polyethylene mulch beds. Commonly, the root mass exceeds the size of the planting hole, requiring a folding of the roots (J rooting). The objective of this study was to determine if mechanical root pruning has an effect on early or total season fruit yield of strawberry bare-root transplants in a winter production system.

Temperature Conditioning and Container Size Affect Early Season Fruit Yield of Strawberry Plug Plants in a Winter, Annual Hill Production System

The demand for plug transplants by the Florida winter strawberry (Fragaria ×ananassa Duch.) industry may increase as water conservation during plant establishment becomes more important and the loss of methyl bromide fumigant makes the production of bare-root transplants more problematic. A study was conducted during the 1995-96 and 1996-97 seasons to determine the effect of container size and temperature conditioning on the plant growth and early season fruit yield of `Sweet Charlie' strawberry plants. Plants in containers of three sizes (75, 150, and 300 cm3) were grown in one of two temperature-controlled greenhouses (35 °C day/25 °C night or 25 °C day/15 °C night) for the 2 weeks just prior to transplanting into a fruiting field at Dover, Fla. Plants exposed to the 25/15 °C treatment had significantly higher average root dry weights at planting in 1995 and 1996 than did plants exposed to the 35/25 °C treatment. Plants exposed to the 25/15 °C treatment also had higher average fruit yields than the plants exposed to the 35/25 °C treatment (48% and 18% higher in 1995-96 and 1996-97, respectively). The effect of container size on plant growth and yield was variable. Plants propagated in the 150- and 300-cm3 containers tended to be larger (at planting) than the plants propagated in the 75-cm3 containers, but the larger container sizes did not result in consistently higher yields.

Recent Advances in Strawberry Plug Transplant Technology

Plugs are rapidly replacing fresh-dug bare-root and cold-stored frigo plants as transplants for strawberry (Fragaria × ananassa) production worldwide. Plugs have many advantages over these other types of propagules. They are grown in controlled environments (greenhouses, tunnels) in less time than field produced bare-root transplants, and are not exposed to soilborne pathogens. Plugs afford greater grower control of transplanting dates, provide mechanical transplanting opportunities and allow improved water management for transplant establishment relative to fresh bare-root plants. New uses for plugs have been identified in recent years; for example, photoperiod and temperature conditioned plugs flower and fruit earlier than traditional transplants and plugs have been used for programmed greenhouse production. Tray plants have superior cold storage characteristics relative to bare-root, waiting-bed transplants. Both fresh and frozen plugs are used in a number of indoor and outdoor growing conditions and cultural systems.

Effect of Site Preparation and Reforestation Method on Survival and Height Growth of Scots Pine

The influence of site preparation and reforestation method on the performance of Scots pine (Pinus sylvestris L.) was followed during 16 growing seasons in northern Finland using a split-plot design in randomized blocks. The site-preparation methods were prescribed burning (BURN), patch scarification (PATCH), disk trenching (DISK) and ploughing (PLOU). The reforestation methods were sowing (SOW) and planting with containerized seedlings (CON) and bare-rooted transplants (BARE). The reforestation was repeated in three successive years. A total of 72000 reforestation spots was sown or planted on the 288 plots using the reforestation density of 2500 spots ha –1. Four of the eight clear-cut forest sites were dryish pine-dominated sites and four were moist, formerly Norway spruce-dominated sites. After 16 growing seasons, average survival was 49% on the pine sites and 33% on the spruce sites. Site preparation significantly affected survival on the spruce sites (PLOU 44%>DISK 23%) but not on the pine sites. The reforestation method had a significant effect only on the pine sites (CON 58%)>SOW 36%). The effect of site preparation on mean height was significant on the pine (BURN 271 cm>DISK 222 cm) and spruce sites (PLOU 269, BURN 256 cm>DISK 212 cm). The differences between the reforestation methods were highly significant on the pine (BARE 295 cm>CON 261 cm>SOW 186 cm) and spruce sites (BARE 309 cm>CON 255 cm>SOW 171 cm). The results of this study indicate that different site-preparation methods can be used successfully in Scots pine reforestation on dryish, formerly pine-dominated sites in northern Finland. Intensive site-preparation methods, such as ploughing or mounding, are needed if Scots pine is to be established on moist, formerly spruce-dominated sites. However, the low survival and wide variation in survival indicated that there is a high risk of failure on such sites.

Regenerating white spruce, paper birch, and willow in south-central Alaska

The current spruce bark beetle (Dendroctonus rufipennis Kirby) epidemic in interior Alaska is leaving large expanses of dead spruce with little spruce regeneration. Many of these areas are habitat for moose (Alces alces). To establish spruce regeneration and improve browse production for moose, paper birch (Betula papyrifera Marsh), willow (Salix spp.), and three stocktypes (plug+1 bareroot, and 1+0 plugs from two nurseries) of white spruce (Picea glauca (Moench) Voss) were planted in freshly cutover areas on Fort Richardson, near Anchorage. Four vegetation-management treatments were compared: broadcast site preparation with herbicides, banded site preparation with herbicides, mechanical scarification, and untreated control. Spruce seedlings had the greatest growth in the broadcast site preparation treatment (p < 0.01). Stocktype was the most important factor in spruce growth, with bareroot transplant seedlings being the tallest and largest 5 years after planting (p < 0.001). In the first 3 years, relative stem volume growth was greater for plug seedlings than for bareroot seedlings (p < 0.001). By year 4, relative growth rates were similar among all stocktypes. Treatment effects for paper birch and willow were confounded by moose browsing. Results indicate spruce can be regenerated and moose browse enhanced simultaneously in forests in interior Alaska.

Effect of Site Preparation and Reforestation Method on Survival and Height Growth of Scots Pine

Abstract The influence of site preparation and reforestation method on the performance of Scots pine (Pinus sylvestris L.) was followed during 16 growing seasons in northern Finland using a split-plot design in randomized blocks. The site-preparation methods were prescribed burning (BURN), patch scarification (PATCH), disk trenching (DISK) and ploughing (PLOU). The reforestation methods were sowing (SOW) and planting with containerized seedlings (CON) and bare-rooted transplants (BARE). The reforestation was repeated in three successive years. A total of 72000 reforestation spots was sown or planted on the 288 plots using the reforestation density of 2500 spots ha –1. Four of the eight clear-cut forest sites were dryish pine-dominated sites and four were moist, formerly Norway spruce-dominated sites. After 16 growing seasons, average survival was 49% on the pine sites and 33% on the spruce sites. Site preparation significantly affected survival on the spruce sites (PLOU 44%>DISK 23%) but not on the pine sites. The reforestation method had a significant effect only on the pine sites (CON 58%)>SOW 36%). The effect of site preparation on mean height was significant on the pine (BURN 271 cm>DISK 222 cm) and spruce sites (PLOU 269, BURN 256 cm>DISK 212 cm). The differences between the reforestation methods were highly significant on the pine (BARE 295 cm>CON 261 cm>SOW 186 cm) and spruce sites (BARE 309 cm>CON 255 cm>SOW 171 cm). The results of this study indicate that different site-preparation methods can be used successfully in Scots pine reforestation on dryish, formerly pine-dominated sites in northern Finland. Intensive site-preparation methods, such as ploughing or mounding, are needed if Scots pine is to be established on moist, formerly spruce-dominated sites. However, the low survival and wide variation in survival indicated that there is a high risk of failure on such sites.

Strawberry Transplant Propagation in Elevated Horizontal Troughs

Commercial strawberry cultivars are vegetatively propagated in field nurseries. Mother plants produce daughter plants on stolons in response to long photoperiods and high temperatures. The daughter plants are primarily removed from the field as a bare-root transplant. These bare-root transplants can be extremely stressed in this digging process, resulting in plant variability and pathogen infestation. A strawberry transplant production system has been developed that uses micropropagated disease free mother plants in elevated horizontal culture. The mother plants are grown in suspended plastic troughs (10-cm width by 10-cm depth) with a soilless medium consisting of vermiculite and perlite. The mother plants are subfertigated via drip tubing to avoid leaf wetness. Stolons produced by the mother plants hang over the trough and continue to grow down toward the ground. The stolon tips, are harvested and rooted in plug trays. This study compared proliferation rates of several strawberry cultivars. The benefits of the elevated system were: disease-free plants, high-density daughter plant production, all the runners could be removed at one time and separated for propagation, and the daughter plants had active root tips that established quickly.

Establishment in Treeshelters II: Effect of Shelter Color on Gas Exchange and Hardiness

We investigated the microclimate, gas exchange, and growth of field-grown Norway maple (Acer platanoides L.) and green ash (Fraxinus pennsylvanica Marsh) trees nonsheltered, and in brown and white shelters. Shelter microclimate—air temperature (Ta), vapor pressure deficit (VPD), and radiation—and tree leaf area, growth in diameter, stomatal conductance (gs), and photosynthesis were measured during the first growing season after bare-root transplanting. Bark temperatures in midwinter were also measured. Treeshelter microclimate was greenhouse-like compared to ambient conditions, as shortwave radiation was lower, and midday Ta and relative humidity were higher. Although trees in shelters had greater shoot elongation and higher gs than trees grown without shelters, photosynthesis was not different. White shelters allowed 25% more shortwave radiation penetration and increased Ta by 2 to 4 °C and VPD by 0.5-1 kPa over brown shelters. However, tree growth and gas exchange generally were not affected by shelter color. Winter injury was increased for trees in shelters and varied with species and shelter color. Both species exhibited shoot dieback in shelters the spring following a winter where bark temperatures varied 40 to 50 °C diurnally. More new growth died on maple, particularly in white shelters where several trees were killed. These data suggest that supraoptimal summer and winter temperatures may reduce vigor and interfere with cold tolerance of some species grown in shelters.

Transplant Container Shape and Strawberry Transplant Growth

Bare-root strawberry transplants have been conventionally used for establishment of strawberry fruiting fields. These bare-root transplants have variability in vegetative vigor that results in irregular flowering patterns. We have been experimenting with a containerized transplant system to produce uniform transplants. Increasing transplant container volume by increasing perimeter, rather than depth, has resulted in increased plant size, but also increases transplant production costs. This study evaluated three container perimeters (17, 25, 32 cm) and three container shapes (circular, elliptical, and biconvex) such that different cell perimeters had the same greatest diameter. All containers had a depth of 3.5 cm. Root imaging analysis (MacRHIZOTM) was used to measure root growth in the container as well as root growth 3 and 6 weeks after transplanting. Increasing container perimeter led to increased plant growth before and after transplanting, but did not affect fruit production. Transplant container shape did not significantly alter plant growth or fruit production. Biconvex and elliptical containers required 25% and 15% less surface area, respectively. Therefore, a biconvex shaped container can be used to increase plant density during transplant propagation, decreasing surface area needed and reducing production costs.