Trunk Caliper Research Articles

Root Pruning but not Irrigation in the Nursery Affects Live Oak Root Balls and Digging Survival

Abstract Irrigation placement and irrigation volume during field production of live oak (Quercus virginiana Mill.) in a sandy soil had no effect on trunk caliper [mean = 6.3 cm (2.5 in)] or tree height [mean = 3.8 m (12.4 ft)]. Root pruning had no impact on caliper and a slight (P < 0.06) impact on height. Irrigation placement and volume had little effect on number of cut roots at the edge of the root ball. Root pruning with a hand spade or in combination with root-pruning fabric placed under the liner at planting increased the number of roots at the edge of the root ball. Root pruning with fabric in combination with spade pruning increased the small-diameter (<5 mm) root weight: shoot ratio but reduced the total root weight: shoot ratio. Irrigation placement and volume during production did not affect summer nor winter digging survival. Trees that were not root pruned had poorer survival in the summer and winter digging seasons than those receiving either of the root-pruned treatments. In contrast, summer and winter survival was similar for root-pruned trees indicating that live oak can be dug in summer as well as the more traditional winter period as long as trees are root pruned during production. Trees pruned with fabric placed under the liner at planting in combination with spade pruning survived better than traditional spade root pruned trees.

Field Performance and Molecular Evaluations of Pecan Trees Regenerated from Somatic Embryogenic Cultures

Field evaluations were conducted of pecan [Carya illinoinensis (Wangenh.) C. Koch] trees regenerated via somatic embryogenesis to assess if the trees maintained clonal fidelity and exhibited true-to-type characteristics. Phenotypic and molecular comparisons were made of trees from two different tissue culture lines after 4 years in the field. Factors evaluated included shoot growth, leaf morphology, and susceptibility to fungal scab [Cladosporium caryigenum (Ellis & Langl.) Gottwald] and southern pecan leaf phylloxera (Phylloxera russellae Stoetzel). Genetic fidelity was examined using amplified fragment length polymorphism (AFLP) analysis. Statistically significant differences were observed between the culture lines in phenotypic leaf characteristics (i.e., specific leaf weight and leaf length-to-width ratio), number of shoots per 1-year-old branch, and in the frequency of scab lesions on leaves. No between-line differences were observed in trunk caliper, average and total shoot growth, shoot length per cross-sectional area, or presence of phylloxera galls. AFLP analysis readily detected differences between culture lines. Cluster analysis generally grouped trees together that were regenerated from the same line. Trees within a culture line usually exhibited similar leaf characteristics, but not shoot growth or tree height. A few trees exhibited more extreme leaf characteristics and differed from each other. However, they were statistically similar to most of the other trees in the population evaluated. AFLP data revealed that some trees exhibited greater divergence and less similarity than other trees from the same line. The nature and significance of such variation at this time are not related to any detectable phenotypic differences.

162 The Influence of Root Restriction on Flowering, Fruiting, Tree Growth, Yields, and Fruit Quality of Apple Trees

`Fuji'/MM.111, `Pink Lady'/M.7A, and `Summerfield'/M.7A apple trees were planted in several types of individual root restrictive bags in the field in 1995. Bags were made of Knit and Woven fabrics, Galvanize hardware cloth (6.4 cm) with various holes sizes and of different bag volumes. The bags confined the development of large roots to within the bag. Roots that penetrated the bag resulted in root branching and large root inhibition. As the roots enlarged, roots penetrating the bags were restricted in diameter by the fabric hole size. Roots enlarged to some degree on both sides of the fabric holes but were not killed by girdling within the first few years. Root restriction bags decreased trunk caliper, shoot growth, pruning weights, number of cuts per tree, increased flowering, fruit numbers, and weight per tree. Fruit firmness, soluble solids and color was increased and starch was lower than the nonbagged controls. In cage and tank trials pine and/or meadow voles easily penetrated all of the fabric and polypropylene bags within 24 h, except for the galvanized hardware cloth (6.4 cm). Susceptibility of each material to vole damage was tested by placement of an apple inside a small bag of each. Root restriction bags seemed to be a viable alternative to dwarfing rootstocks for control of tree size, early flowering, and early fruiting.

Survival and Growth of Transplanted Large-And Small-Caliper Red Oaks

Red oak (Quercus rubra L.) of 2 caliper sizes, 8.4 and 3.6 cm (3.3 and 1.4 in.), and 2 vigor classes (high and low) within the small-caliper trees, were transplanted to compare growth and establishment over a 4-year period. Possible confounding factors such as pre-transplant vigor, genetics, relative root-ball to backfill volume, and relative canopy to root-ball volume were controlled to determine whether small-caliper trees establish more rapidly than large-caliper trees. Large-caliper trees had high mortality, 58%, while no small-caliper trees died. Based on trunk caliper and height growth after transplanting, surviving large-caliper trees established faster than small-caliper trees—demonstrating that transplanted large-caliper red oaks can establish as rapidly as small-caliper red oaks.

Effect of Irrigation and Berm on Growth of Peach Trees during Establishment

Long-term success in peach production requires the best possible site, but the ideal site is difficult to find. Risk of crop loss to spring freeze dictates that trees be on high ground. As a result, the best site available may have less than optimum soil. Effects of irrigation on peach tree growth are well documented. Raised beds have been used in other crops to insure adequate water drainage away from roots of crop plants. Results from larger beds or berms in combination with irrigation on peaches have been reported in Ohio, but little information is available for the southeast production region. In this study, berms on a Teller Fine Sandy Loam soil were constructed with a road grader in Oct. 1993. The berms were 55.8 cm high, 61 cm wide at the top, and sloped ≈30° to a base width of 4.3 m. `Flameprince'/Lovell trees were planted in Mar. 1994, 6.1 m between rows and 5.5 m between trees in rows. The experiment was a split-plot design with four replications and three trees per treatment replication. Treatments consisted of no irrigation, 40% or 80% pan evaporation (PE) replacement in combination with berm or flat planting surface. Irrigation was supplied by means of emitters which applied 3.7 L per hour. Two emitters per tree were located in the row 45.7 cm either side of the tree trunk. During the first 4 years there was no significant difference between 40% and 80% PE irrigation treatments. Likewise, no significant interactions occurred. Tree trunk caliper, canopy area, and height were greater in irrigated plots and the same or greater from trees in flat plots in all cases.

The Influence of Drought on Growth and Gas Exchange in Fraxinus species

Fraxinus americana, F. pennsylvanica, and F. nigra were subjected to short-term drought of 4, 8, and 16 days. Seedlings were obtained from a commerical nursery and grown in 4:1 pine bark:sand media for 3 months prior to the onset of the stress. Seventy-two trees with six replicates per stress treatment were arranged in a completely randomized design. Following each stress period, the appropriate trees were well watering and monitored through recovery. Leaf photosynthesis, shoot growth, leaf emergence, terminal bud set, trunk caliper and soil moisture content were measured through the stress and recovery periods. Drought suppressed shoot growth and leaf emergence in all species; however, Green Ash maintain active growth at higher rates than either White or Black. Leaf photosynthesis was reduced in both White and Black following 4 days of drought whereas Green ash was not adversely effected until day 10. Trees were harvested following recovery and dry weight fractions of leaves, stems, and roots recorded.

Effect of Preemergent Herbicides on Growth of Dwarf Nandina, Eleagnus, Asiatic Jasmine, Bradford Pear, and Arizona Ash

The list of species that are known to tolerate the use of Factor® (prodiamine), a preemergent herbicide, in a containerized production system is limited. Plants of swarf nandina (Nandina domestica `Firepower'), eleagnus (Eleagnus × eggingei), and Asiatic jasmine (Trachelospermum asiaticum) growing in 3.8-L containers were obtained from a local nursery and treated with herbicide treatments to determine effects on growth. Plants were treated with one or two applications of Factor® 65WG at either 0, 1.4, 2.8, or 5.5 kg·ha–1 (0.9, 1.8, or 3.6 kg·ha–1 active ingredient, respectively). The first application was made on 10 Aug. 1995 and the second application was made on 19 Oct. 1995. Plants were grown under 30% Saran shade and watered and fertilized as needed. Plants of Arizona ash (Fraxinus sp.) and Bradford Pear (Pyrus calleryana `Bradford') ptted in 19-L containers were treated with herbicide treatments on 25 Oct. 1995 for fall weed control at a local nursery. Treatments included a single application of Factor® 65WG at either 0, 1.4, 1.8, or 2.8 kg·ha–1 (0.9, 1.2, or 1.8 kg·ha–1 active ingredient, respectively) with or without Gallery® (isoxaben) at 1.2 kg·ha–1 (0.9 kg·ha–1 active ingredient). There was no effect of the herbicide treatments on growth of eleagnus. Herbicide treatments did not affect shoot dry weight and did not have a deleterious effect on shoot length and root dry weight of Asiatic jasmine or affect trunk caliper growth of the two tree species. Factor® did affect the growth of dwarf nandina. Plant height and shoot and root dry weight were not affected. However, plant width was decreased by all Factor® treatments when compared to untreated plants.

The Effects of Three Nursery Production Methods on Tree Growth Rates

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.

Growth of Argentine Mesquite Inoculated with Vesicular-Arbuscular Mycorrhizal Fungi

Argentine mesquite (Prosopis alba) seedlings were inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungi, Glomus intraradices , container-grown for five months, and transplanted into a simulated landscape in Tempe, Arizona. After transplanting, mesquite trees were either drip irrigated at regular intervals or nonirrigated for one year. Six months after transplanting, VAM fungal colonization was observed only in the roots of inoculated mesquite but by 12 months, roots of both inoculated and noninoculated mesquite were colonized by VAM fungi. Higher levels of VAM fungal colonization occurred in roots of irrigated mesquite. While irrigation promoted mesquite shoot growth, VAM inoculation inhibited shoot growth of nonirrigated trees. Trunk caliper was greater for irrigated trees than for nonirrigated trees and was not affected by VAM infection. VAM fungi promoted the growth of thinner roots for irrigated trees and thicker roots for nonirrigated trees after six months. At the conclusion of the study, root growth was enhanced by drip irrigation and was not affected by previous VAM fungal inoculation.

Field-Grow Fabric Containers do not Affect Transplant Survival or Establishment of Green Ash

Survival and growth of green ash (Fraxinus Pennsylvania) transplanted as balled and burlapped or from field-grow fabric containers (FGFC) filled with field soil alone or field soil amended with hydrophilic gel, peat, or slow-release fertilizer were studied for two years at two locations. Height and trunk caliper increases were not affected by treatment at either location. Canopy width, dry weights, and root numbers also did not differ among treatments when the study was terminated. Plants grown in FGFC had roots which tended to circle in a manner similar to container-grown trees.

Effect of Copper-Treated Containers on Transplant Survival and Regrowth of Four Tree Species

Abstract Northern red oak (Quercus rubra L.), scarlet oak (Q. coccinea Muenchh.), sweetgum (Liquidambar styraciflura L.), and ‘Autumn Flame’ red maple (Acer rubrum L.) liners were produced in copper-treated (100 gm Cu(OH)2/1 white latex paint) or untreated black plastic 3.8 1 containers (Lerio C-700) in 1989. In spring 1990, liners were transplanted into field plots. Half the liners produced in untreated containers were root pruned just before transplanting, half were not. Liners grown in copper-treated containers were not root pruned before transplanting. Survival percentage was high for all species ranging from 92% for red maple to 65% for scarlet oak. Three years after transplanting, red and scarlet oak liners produced in copper-treated containers had higher survival rates (but not statistically significant) and greater regrowth (taller, greater trunk caliper and percent central leader formation) than liners produced in untreated containers, whether root pruned or not before transplanting. Regrowth of red maple and sweetgum were not affected by container type used during liner production. The study demonstrates species differences to transplanting; each species responds to transplant via a unique combination of growth characteristics. Transplant responses are expressed up to three years after transplanting.

Effect of Root Pruning Prior to Transplanting on Establishment of Southern Magnolia in the Landscape

Roots of field-grown southern magnolia (Magnolia grandiflora) were pruned once during dormancy, following the first shoot growth flush or after the second growth flush, prior to transplanting in the winter. During the first year after transplanting, root pruned trees grew at a slightly faster rate than unpruned trees but growth rates were similar for root pruned and unpruned trees the second and third year after transplanting. There was nodifference in post-transplantgrowth among root pruning treatments. Trees required, at most, 1 year per inch of trunk caliper to become established in the landscape.

EFFECT OF ROOT PRUNING SOUTHERN MAGNOLIA PRIOR TO TRANSPLANTING ON RATE OF ESTABLISHMENT IN THE LANDSCAPE

Roots of four-year-old, field-grown southern magnolia (Magnolia grandiflora L.) were pruned in 1987 once during dormancy, following the first shoot growth flush or after the second growth flush, prior to transplanting in January 1988. By the end of the 1987 growing season, root pruning at all stages of growth reduced leaf number, tree height, trunk caliper, and total-tree leaf area and weight compared with unpruned controls. Total root weight was less for trees pruned during dormancy or following the first growth flush. Root pruning increased the proportion of fine roots (0 to 5mm-diameter class) to coarse roots (>5 to 10-mm diameter class). Shoot:root ratios were not affected by root pruning. During the first year after transplanting, root pruned trees grew at a slightly faster rate than unpruned trees but growth rates were similar for root pruned and unpruned trees the second and third year after transplanting. Trees required, at most, 1 year per inch of trunk caliper to become established in the landscape.

Effects of preplant deep tillage of soil amendments on soil mineral analysis, citrus growth, production and tree health

Two rates of peat, shrimp hull waste, humate, bentonite clay, gypsum, and a calcium humate were preplant strip tilled 1.2 m deep and 1.6 m wide down the center of row in a new citrus grove site 13 km southeast of St. Cloud, FL, to determine their effects on soil mineral analysis, tree growth, fruit production, and health. Gypsum and calcium humate were reapplied to surface soil annually and humate was reapplied twice, 3 and 5 years after planning. Nine months after the first application, Ca, Mg, K, S, Cu, B, Fe and Zn were highest in soil of the humate treatment, no other amendment appeared to influence soil minerals; 27 months after treatment none of the amendments altered major changes in soil minerals. Hexosamines were significantly higher in soil treated with shrimp waste than the control 5 months after application but bot 21 months after application. No treatment caused a significant increase in trunk caliper in each of 3 years beginning in 1985. Cumulative ratings for foot rot caused by Phytophthora parasitica for each treatment from 1985 to 1988 showed that gypsum significantly reduced foot rot. This effect may have been the result of the increase in leaf Ca and S and bark Ca, in the gypsum treatment. Fruit production in 1989 and early development of blight symptoms in 1989 and 1990 were not significantly different from the control.

Treeshelter Use in Producing Container-grown Trees

Treeshelters were used for the nursery production of Cedrus deodara Loud. (deodar cedar), Quercus ilex L. (holly oak), and Magnolia grandiflora L. (southern magnolia) trees growing in 19-liter containers. Air temperature, relative humidity, and CO, concentration were higher inside the treeshelters than outside. Trees grown inside treeshelters were 74% to 174% taller than trees grown without shelters. Trunk caliper of Magnolia and Quercus was not affected, however, for Cedrus trees caliper was larger for trees grown without a shelter. Upon removal of the shelter, Cedrus trees were incapable of supporting their own weight. Lateral branch development was inhibited and leaf senescence was greater with Magnolia trees grown in a shelter. Quercus trees grown in shelters were ready to be transplanted into the landscape. Water use was similar for trees grown with or without shelters. Trees grown in shelters had lower root fresh weights.

Relationship between Malate Dehydrogenase Isozyme Genotype and Plant Vigor in Peach

The relationship between malate dehydrogenase (MDH) isozyme genotype and plant vigor in peach [Prunus persica (L.) Batsch] was examined in two F2 populations (selfed `Belle of Georgia' and `Cresthaven') segregating at the Mdh1 locus. Total progeny examined were 1610 and 998 in the `Belle of Georgia' and `Cresthaven' populations, respectively. In both populations, plant vigor (as defined by total height and trunk caliper after 1 year of growth) was significantly less in Mdh1-1/Mdh1-1 homozygotes. Homozygous Mdh1-2/Mdh1-2 individuals showed the greatest vigor, and were significantly different in vigor from Mdh1-1/Mdh1-1 homozygotes in both populations and from Mdh1-1/Mdh1-2 heterozygotes in the `Belle of Georgia' population. A significant deviation from the expected 1 Mdh1-1/Mdh1-1: 2 Mdh1-1/Mdh1-1: 1 Mdh1-2/Mdh1-2 ratio was observed in the `Belle of Georgia' population, suggesting moderate lethality of homozygous Mdh1-1/Mdh1-1 genotypes.

Impact of Ozone on Growth of Peach, Apricot, and Almond

Almond (Prunus amygdalus Batsch cv. Nonpareil), apricot (Prunus armeniaca L. cv. Royal Blenheim), and peach [Prunus persica (L.) Batsch cv. Halford] grafted nursery stock seedlings were exposed once per week for 4 hours to a maximum O3 concentration of 0.25 μl·liter-1 in field exposure chambers. Exposures were repeated for a total of 4 months in 1986 (year 1) and 1987 (year 2). Trunk caliper, number of shoots, and net growth (total seasonal weight increase) were measured at the end of each year. Almonds appeared to be the most sensitive to O3. Almond seedlings exhibited extensive foliar injury from O3, while apricot and peach seedlings were relatively insensitive. Total net growth of O3-exposed almond was reduced during both years relative to the controls and an impact on caliper was evident after year 2. Apricot seedlings exposed to O3 developed a thinner trunk but more shoots than the controls in both years. Peach tree seedlings exposed to O3 had fewer shoots than the controls at the conclusion of year 2 but thicker trunks after both years. No significant difference in variance or shape of distribution of net growth within the treatment populations between O3-exposed seedlings and controls was detected for any of the three fruit crops. The impact of O3 on young, nonbearing perennial fruit crops may be most evident in specific growth characteristics, such as net growth or trunk caliper.

Production of Fuchsia and Tibouchina Standards Using Paclobutrazol or Chlormequat

Paclobutrazol treatments of 0, 0.125, 0.250, and 0.500 mg/plant improved the form of Tibouchina urvilleana (DC.) standards and eliminated the need for pruning during the display season. Paclobutrazol did not improve the form of Fuchsia × hybrida Hort. ex Vllm. Paclobutrazol inhibited trunk caliper development in both species. Paclobutrazol at 0.125 mg/plant slightly increased Tibouchina flower size. Chlormequat at 0, 1000, or 2000 mg/plant did not hasten flowering of Tibouchina. Chemical names used: ß-[(4-chlorophenyl) methyl]-α- (1,1-dimethylethyl) -1H-1,2,4-triazole-1-ethanol (paclobutrazol); α-chloro-N,N,N-trimethylethanammonium chloride (chlormequat).

RELATIONSHIP BETWEEN MALATE DEHYDROGENASE GENOTYPE AND PLANT VIGOR IN PEACH

The relationship between malate dehydrogenase (MDH) genotype and plant vigor in peach [Prunus persica (L.) Batsch] was examined in two F2 populations (selfed `Belle of Georgia' and `Cresthaven') segregating at the Mdhl locus. Total numbers of progeny examined were 1610 and 998 in the `Belle of Georgia' and `Cresthaven' populations, respectively. In both populations, plant vigor (as defined by total height and trunk caliper after 1 year of growth) was significantly less in homozygous F/F (Mdh1-1/Mdh1-1) individuals. Homozygous S/S (Mdh1-2/Mdh1-2) individuals showed the greatest vigor, and were significantly different in vigor from homozygous F/F (Mdh1-1/Mdh1-1) individuals in both populations and from heterozygous F/S (Mdh1-1/Mdh1-2) individuals in the `Belle of Georgia' population. A significant deviation from the expected 1 F/F:2 F/S:1 S/S ratio was observed in the `Belle of Georgia' population, suggesting moderate lethality of homozygous F/F genotypes.

Growth and Transplantability of Magnolia grandiflora Following Root Pruning at Several Growth Stages

Roots of field-grown southern magnolia (Magnolia grandiflora L.) were pruned once during dormancy, following the first shoot growth flush or after the second growth flush or twice at the following times: during dormancy and following first growth flush, during dormancy and following second growth flush, following first and second growth flush before transplanting in the winter. By the end of the growing season, root pruning at all stages of growth reduced leaf number, tree height, trunk caliper, and total tree leaf area and weight compared with unpruned controls. Total root weight was less for trees pruned during dormancy or following the first growth flush. Root pruning increased the proportion of fine roots (0- to 5-mm-diameter class) to coarse roots (> 5- to 10-mm-diameter class). Shoot: root dry weight ratios at transplanting were not affected by root pruning. Root-pruned trees grew at a faster rate following transplanting than unpruned trees. Despite these initial differences. trees in all treatments were the same size 1 year after transplanting.