with regard to root pruning, root disturbance, and potting medium removal. The three planting methods for pecan trees are 1) container tree planted straight from the container with no root pruning and no disturbance (container as is), 2) container tree
Frederic B. Ouedraogo, B. Wade Brorsen, Jon T. Biermacher, and Charles T. Rohla
Glenn B. Fain and Patricia R. Knight
On 24 Apr. 2003, 3-gallon (11.4-liter) Quercus shumardii were potted into 13.2-gallon (50-liter) containers using a standard nursery mix. Treatment design was a 3 × 2 × 2 factorial with two fertilizer placements, three irrigation methods, and two herbicide rates. Controlled-release fertilizer 17N–2.9P–9.8K was dibbled (placed 10.2 cm below the surface of the container media at potting) or top-dressed at a rate of 280 grams per container. Irrigation was applied using one of three methods: 1) a spray stake attached to a 3-gallon- (11.4-L-) per-hour pressure compensating drip emitter; 2) a surface-applied pressure-compensating drip ring delivering water at a rate of 2.3 gallons (8.9-L) per hour; and 3) the same drip ring placed 4 inches (10.2 cm) below the container substrate surface. A granular preemergent herbicide (oxyfluorfen + oryzalin) was applied at 2.0 + 1.0 lb/acre (2.24 + 1.12 kg·ha-1). At 75 days after treatment (DAT), containers with no herbicide and top-dressed fertilizer had a percent weed coverage of 46% compared to 18% for dibbled containers with no herbicide. At 180 DAT weed top dry weight was greater for top-dressed containers compared to dibbled. None of the treatments in the study had any effect on height increase. At 240 DAT, trees irrigated with drip rings at the surface had a 28% greater caliper increase among the dibbled fertilizer-treated containers. Trees irrigated with the drip ring placed below the surface and fertilizer top-dressed had the smallest caliper increase. Irrigation method had no effect on weed control in this study; however, a repeat fall application showed a significantly greater weed control with the drip ring below surface compared to the spray stake.
Karla M. Addesso, Anthony L. Witcher, and Donna C. Fare
Adoption of biological control tools in woody ornamental nursery production has lagged behind other agriculture fields. One of the major obstacles to adoption is lack of information on the efficacy of various biological control agents in nursery production systems. The predatory mite Amblyseius swirskii, sold commercially as “swirski mite,” is a generalist predatory mite that has recently been adopted as a generalist control for a wide range of mite and insect pests, including thrips (Thripidae), whiteflies (Aleyrodidae), eriophyid mites (Eriophyidae), broad mite (Polyphagotarsonemus latus), and spider mites (Tetranychidae). A controlled-release sachet formulation of swirski mite was evaluated in three experiments to determine whether size of the tree, timing of first application, or sun intensity would affect treatment efficacy. Pest numbers on plants was evaluated biweekly for 12 weeks. The swirski mite sachets controlled broad mite and spider mite outbreaks on red maple trees (Acer rubrum) grown in nos. 3 and 15 nursery containers, respectively. Application at the time of red maple rooted cutting transplant was not necessary to achieve summer-long control of pests. No outbreaks of target pests on flowering dogwood (Cornus florida) in no. 5 containers grown under both full sun and shade, but with low levels of broad mite persisting in the shade treatment and thrips persisting in sun. These results suggest that swirski mite is a promising candidate for biological control in woody ornamental nursery production.
Amy Jo Waldo and James E. Klett
Ninety trees are being used and have been in the field since 1994. The three species studied include: Fraxinus pennsylvanica Patmore (Green Ash), Quercus macrocarpa (Bur Oak), and Pinus nigra (Austrian Pine); 30 of each species. Each species has been harvested in three different nursery production methods including balled and burlapped, plastic container, and fabric container. During the 1996 growing season, the following data was recorded for each tree, growth increments, caliper size, and tree heights. For the two deciduous species, both dry weights and leaf area were recorded. Some sap flow measurements were taken using a non-intrusive stem heat balance method, on the same tree species with varying production methods. All three species showed the greatest growth increments and heights for those trees planted in fabric containers. In regards to trunk caliper size, Pinus nigra showed that the balled and burlapped, and fabric containers had larger calipers than those planted in plastic containers. Fabric container trees were larger in caliper than plastic container trees, which was larger than the balled and burlapped on Quercus macrocarpa. The plastic container and balled and burlapped resulted in greater calipers on Fraxinus pennsylvanica than the fabric containers. Quercus macrocarpa also showed that both leaf area and dry weight were greatest for trees planted in fabric containers, followed by the other production methods. Trees in plastic containers exhibited the greatest leaf area and dry weight for Fraxinus pennsylvanica. Overall, the fabric container trees in all three species illustrated the highest-quality trees, followed by those planted in plastic containers, and then balled and burlapped. Minimal data was recorded for transpiration rates in 1996 and will be further investigated in 1997.
Daniel C. Milbocker
Pyrus calleryana, Decne, `Aristocrat'; Cryptomeria japonica, D. Don; Populus maximowiczii, Henry × `Androscoggin' and Koelreuteria bipinnata, Franch. trees were grown in low-profile containers. The optimum height and width of these containers was 20 to 30 cm and 84 cm, respectively. Pine bark and mixtures containing 50% or more of pine bark were preferable to mixtures containing leaf mold for filling the containers because the former weigh less. Roots penetrated pine bark mixtures better than sphagnum peat mixtures and also retained their shape better during transplanting. When grown in low-profile containers, trees grew fibrous root systems; after transplanting, roots grew downwardly radial and trees were able to withstand extremely difficult landscape conditions.
Roberta J. Tolan and James E. Klett
Patmore green ash (Fraxinus pennsylvanica `Patmore'), Bur oak (Quercus macrocarpa), and Austrian pine (Pinus nigra), were used to measure growth differences of trees produced using three different production methods: balled and burlapped, plastic container, and fabric container (grow bag). Two irrigation frequencies were also established. A pressure chamber was used to measure the xylem water potential and to determine tree water requirements and irrigation scheduling. The balled and burlapped trees showed the least new growth of the three production methods across all three tree types. The production method showing the most new growth varied by genera. Plastic container ash trees grew considerably more than the fabric container ash; fabric container oak grew significantly more than plastic container oak; and there was no measurable difference between the new growth of the plastic container and fabric container pines. The fabric container transplants required more frequent irrigation than did the balled and burlapped trees. Under high temperature and drought conditions, fabric container trees showed stress earlier than did the balled and burlapped or plastic container trees.
Rashid Al-Yahyai*, Bruce Schaffer, and Frederick S. Davies
The effect of soil water depletion on plant water potential and leaf gas exchange of carambola (Averrhoa carambola L. cv. Arkin) in Krome very gravelly loam soil was studied in an orchard and in containers in the field and in a greenhouse. The rate of soil water depletion was determined by continuously monitoring soil water content with multi-sensor capacitance probes. Stem water potential and leaf gas exchange of carambola in containers were reduced when the soil water depletion level fell below 50% (where field capacity = 100%). Although there was a decrease in the rate of soil water depletion in the orchard as the soil dried, soil water depletion did not go below an average of 70%. This was presumably due to sufficient rainfall and capillary movement of water in the soil. Therefore, soil water content did not decline sufficiently to affect leaf gas exchange and leaf and stem water potential of orchard trees. A decline in soil water depletion below 40% resulted in a concomitant decline in stem water potential of the container trees in the field and greenhouse to below -1.0 MPa. Stomatal conductance, net CO2 assimilation, and transpiration declined significantly when stem water potential was below -1.0 MPa. The reduction of net CO2 assimilation and transpiration was proportional to the decline in stomatal conductance of container trees in the field and greenhouse. Thus, soil water depletion in Krome very gravelly loam soil must be less than 50% before water potential or leaf gas exchange of carambola is affected. Based on these results, irrigation scheduling should be based on physiological variables such as stem water potential and stomatal conductance or the amount rather than the rate of soil water depletion.
Ken Tilt, Charles Gilliam, John Olive, and Emmett Carden
Crape myrtle (Lagerstroe-mia L. × `Natchez'), live oak (Quercus virginiana Mill.), and Chinese pistachio (Pistacia chinensis Bunge) were planted into a sandy loam soil directly in the field or in grow-bags. Root and top growth were measured in March and July of the second year. Some of the trees were transplanted to 20-gal (76-liter) containers in March or July and grown for 3 months. Chinese pistachio developed a poor root system in field soil and was not ready for harvest in March or July. There was no difference in height, caliper, or top fresh weight for crape myrtle. Caliper and top fresh weight were similar for live oak trees. However, live oaks grown by traditional field production methods were taller than trees produced in grow-bags. With March transplanting, both crape myrtle and live oak trees from traditional field plantings were taller than trees transplanted from grow-bags 3 months after transplanting into containers. Tree top weight, caliper, and root ratings were similar for March-transplanted crape myrtle. Live oak trees transplanted from grow-bags had similar caliper and top weight but a higher root rating. July-transplanted crape myrtle trees had similar values for all variables 3 months later. All live oaks died when transplanted from traditional field plantings to containers in July. All live oaks grown in grow-bags survived transplanting.
Rolston St. Hilaire, Cathleen F. Feser, Theodore W. Sammis, and Anderson S. St. Hilaire
Accurate measurement of evapotranspiration (ET) is difficult and expensive for large, in-ground container (pot-in-pot) plants. We engineered and used a simple and inexpensive system to determine evapotranspiration of in-ground container trees. The system was shop-assembled and used a block and tackle system attached to a collapsible tripod. A unique container harness system attached to the block and tackle system was used to lift containers that were sunken in the ground. Containers were weighed with a battery-operated balance that was accurate to 1 g (0.04 oz) at its maximum load capacity of 60 kg (132.3 lb). One person operated the system, and the weight of the system exclusive of the balance was 17.5 kg (38.50 lb). Gravimetric water use data obtained with the system werecombined with meteorological data to compute crop coefficients (Kc) of mexican elder (Sambucus mexicana). The system detected small changes in daily water use of mexican elder trees grown in 76-L (20-gal) in-ground containers. Crop coefficients ranged from 0.17 to 0.71. The acquisition of evapotranspiration data from relatively large, containerized landscape plants may be facilitated because the system is simple, inexpensive, and accurate.
Alison A. Stoven*, Hannah M. Mathers, and Daniel K. Struve
A study was conducted to determine if similar quality shade tree liners could be produced using a retractable-roof greenhouse structure versus an outdoor environment. All plants were started in a heated greenhouse on campus in 250 XL-sized containers. The species included Eastern redbud, red oak (both grown from seed) and Autumn Blaze maple and Prairifire crabapple (both grown from rooted cuttings). On 15 Mar. 2003, half the plants remained in the heated greenhouse and the other half were moved to a Cravo retractable-roof structure and placed on heating mats set at 22 °C. In May, all of the plants (retractable and greenhouse) were upshifted into 3-gallon Spin-out® treated containers. Trees in each environment were fertilized with either Osmocote® (20 N, 2.2 P, 6.6 K), nine month release, applied broadcast at 45 g/pot, or with a 100 ppm-N water-soluable fertilizer (21 N, 3.1P, 5.9 K), applied at 0.1 g N/day. All trees received the same irrigation volume (1 L/day). All trees were grown according to nursery standards including bamboo staking, taping and regular pruning. Plants were arranged in a completely randomized design in each environment. The Cravo structure provided a more uniform environment with reduced air and soil temperature fluctuations versus the outdoor environment. Liners produced in the Cravo structure were taller, had greater caliper and root and shoot mass. Slow release fertilizer produced larger plants. Root dry weight for trees inside the Cravo environment increased nearly five times over the harvest dates of July to October with the maples having the largest root weight.