Severe Pruning Research Articles

O pessegueiro no sistema de pomar compacto: III. Épocas de poda drástica na diferenciação floral

Pesquisou-se, na região de Jundiaí, SP (23°8'S), a influência das épocas de poda drástica na diferenciação floral dos pessegueiros Tropical' e 'Aurora-2', conduzidos em alta densidade de plantio (1.667 plantas por hectare). Realizaram-se tais podas em 30 de setembro, 30 de outubro e 30 de novembro de 1986. Coletaram-se as gemas para análise mensalmente, a partir do 30° dia da poda: constatou-se, através de cortes histológicos das gemas, que a poda drástica precoce, de 30 de setembro, não prejudicou a diferenciação floral dos pessegueiros, que se iniciou em fevereiro, a cerca de cinco meses da decepa; em abril, a maioria das gemas de flancos encontrava-se com as sépalas, as pétalas, os estames e o pistilo completamente formados. As demais épocas de poda interferiram no processo de diferenciação floral, reduzindo o número de botões florais e, conseqüentemente, a densidade florífera das plantas. Nos pessegueiros conduzidos com poda normal, a organogênese floral, processada no início do verão (dezembro-janeiro), persistiu até o outono (abril).

Effects of Mechanical Pruning on the Yield and Quality of Muscadine Grapes

Dixie muscadine grapes (<i>Vitis rotundifolia</i> Michx.) were mechanically pruned and then either adjusted to 800 or 400 nodes per vine or not hand pruned following trimming for three consecutive years. Vines were trained to a quadrilateral cordon system and mechanical pruning cuts were made 15 to 20 cm from the cordon. Mechanical pruning with no touch-up resulted in much higher yields during the first and second year, but not the third. Vines hand pruned to 400 nodes had the lowest yield during all three years. Increasing pruning severity increased berry weight and generally increased soluble solids and pH. Wine produced from the mechanically pruned vines with no touch-up had a weaker muscadine aroma intensity and a lighter color in the first year, but wines produced from this treatment in subsequent years were similiar in muscadine character and color to wines from the other treatments.

Long term cone production and growth responses to crown management and gibberellin A4/7 treatment in a young western hemlock seed orchard

At age 5–6 years, rooted cuttings in a western hemlock (Tsuga heterophylla) clonal seed orchard received either a severe (ST) or moderate (MT) top pruning (upper 50 and 25% of live crown removed, respectively), or were left untopped (UT). Over the following 6 years, UT trees increased in height from 1.5 to 3.9 m, whereas through annual and biennial top and side pruning, MT trees grew to 2.2 m and ST trees were maintained at 2.0 m. Crown pruning had no effect on the subsequent annual production of seed or pollen cones. Spray applications of gibberellin A4/7 in years 2 and 4 of the study increased 5-fold and 2-fold the percentage of trees producing a medium and greater crop, respectively, of seed and pollen cones in each year 3 and 5.

Vulnerability of Stressed Palms to Attack by Rhynchophorus cruentatus (Coleoptera: Curculionidae) and Insecticidal Control of the Pest

One field study and two experiments were done to test whether palms must be stressed for successful infestation by Rhynchophorus cruentatus (F.). In the field study, 8% of 290 transplanted mature cabbage palmettos, Sabal palmetto (Walter), in a site in Broward County, Fla., became infested with immatures of R. cruentatus and died, compared with no infestations or mortality in a control group of 92 undisturbed palms after 140 d. In Experiment 1, 2-yr-old potted Canary Island date palms, Phoenix canariensis Hortorum ex Chabaud, were grown in a screened enclosure and either stressed by severe pruning or left unstressed. All palms were bagged with fine-meshed polyethylene netting and each was challenged with two male and two female R. cruentatus . Thirty-one percent of the 13 stressed palms were infested with immatures of R. cruentatus and died within 56 d compared with a 15% infestation and mortality level in 13 unstressed palms. In Experiment 2, finemeshed polyethylene bags were used to confine 10 males and 10 females of R. cruentatus onto individual mature cabbage palmettos in the field that were either stressed by severing of the stem or unstressed. All of the three stressed palms were infested with R. cruentatus , compared with none of the five undisturbed palms within 84 to 112 d. These data suggest that R. cruentatus is a secondary invader of stressed or dying palms and not a threat to healthy palms. Propoxur (70% wettable powder [WP], 21.0 g [All/liter); chlorpyrifos (50% WP, 1.2 g [AI]/liter); lindane (25% WP, 0.6 g[AI]/liter); dimethoate (0.49 kg/liter emulsifiable concentrate [EC], 1.2 g [AI]/liter) and methomyl (90% WP, 1.0 g [AI]/liter) killed R. cruentatus adults in a bioassay done with pineapple tops, although methomyl failed to produce 100% mortality after 168 h. The mean time to mortality for R. cruentatus was <24 h for chlorpyrifos, propoxur, and lindane and 42 h for dimethoate. Prophylactic insecticide treatment applied to palms before transplanting is recommended for control of attacking weevils.

Growth and Fruiting of ‘Delicious’ Apple Trees as Affected by Severity and Season of Pruning

Abstract Individual scaffold limbs on 5-year-old ‘Red Prince Delicious’ apple (Malus domestica Borkh.) trees on five rootstocks were unpruned or pruned in Aug. 1981 or Feb. 1982 using three severities at each time. Responses to summer and dormant pruning were similar; no significant interactions occurred. In Dec. 1982, branch circumference was inversely related to pruning severity. Compared to the control, all pruning severities decreased shoot number and increased mean shoot length in 1982; only the most severe pruning suppressed total shoot growth. Flowering and fruiting in 1983 were inversely related to pruning severity.

Long-term improvement in the rooting of plum cuttings following apparent rejuvenation

SummaryNine years after plants of the dwarfing plum rootstock Prunus insititia cv. Pixy were taken from culture in vitro and grown as stockplant hedges in the field, cuttings taken from these hedges rooted in greater percentages and produced more roots than cuttings taken from hedges of conventional stockplants. Pruning the stockplants severely in winter enhanced rooting of both the conventional and in vitro-derived cuttings compared with lighter pruning. The overall benefit due to severe pruning was similar to that from the in vitro-derived source, and the highest rooting level and most roots were produced by cuttings from severely pruned plants from the in vitro source. The nature of the enhanced rooting due to the micropropagation source and severe pruning was that roots developed earlier than in cuttings from conventional and lightly pruned stockplants, with the likely benefit of reducing cutting exposure to sub-optimal environmental conditions. The increased rooting potential was more consistent from year to year in winter cuttings made from the proximal portion of shoots which had completed their annual growth than in summer cuttings made from the distal portion of actively growing shoots in early summer. Shoot apices taken from field-grown stockplants in the eighth summer after leaving cúlture in vitro initially grew more vigorously than those from the conventional source when taken back into culture in vitro.

Poda em uvaieira (Eugenia uvalha CAMB.)

Uvaieiras com quatro anos de idade foram submetidas a podas no mês de agosto de 1984, consistindo a observação em três tratamentos: a) Controle, sem podas, b) Corte de ramos finos, com até 5mm de diâmetro e c) Corte de ramos com até 10mm de diâmetro. A poda mostrou-se muito prejudicial à produção de frutos ocorrida no mesmo ano, apresentando médias de 4,118, 0,860 e 0,230 quilogramas por planta, para os tratamentos controle, poda leve e poda severa,respectivamente. Na safra seguinte, as produções dos diferentes tratamentos tenderam a equilíbrio ocorrendo médias de produção de 7,297, 5,111 e 4,531 quilogramas por planta para os tratamentos controle, poda leve e poda severa.

Response of Tibouchina to Chlormequat, Paclobutrazol, and Fertilizer

Abstract Tibouchina urvilleana is a flowering tropical shrub with large (60–80 mm diameter) violet-blue flowers borne in terminal branched panicles. The foliage is downy with red margins. Tibouchina blooms from mid-summer into late fall. The shrub withstands “a few degrees of frost” (1). Tibouchina has potential for wider use although container production has been limited since severe pruning is required to maintain its shape. Growth retardants may aid in commercial production of compact Tibouchina plants.

Influence of Leaf Removal, Root Pruning, and Soil Addition on the Growth of Greenhouse-grown Strawberry Plants

Abstract Experiments were conducted to examine strawberry (Fragaria × anannassa Duchesne) plant renovation practices, singly and in combination, for effects on vegetative growth of greenhouse-grown, potted strawberry plants. The major results of these experiments were as follows: a) most of the plants that were both defoliated and root-pruned after fruit harvest died; b) there was a negative linear relationship between the number of leaves removed and the number of new leaves and runners produced; c) root, leaf, and total plant dry weights were negatively correlated with the severity of root pruning; and d) soil addition after fruit harvest decreased the shoot : root ratio of multiple-crown plants, but had no effect on single-crown plants.

Restoration of high adventitious root regeneration potential in mature Betulapapyrifera Marsh, softwood stem cuttings

Grafted mature (flowering) Betulapapyrifera Marsh, scions were used to investigate restoration of high adventitious root regeneration potential in softwood stem cuttings. Scion manipulation (defoliation), serial propagation (using previously rooted cuttings as stock plants), hedging (severe pruning), and micropropagation were used as possible restoration treatments. Over a 15-month period, more than 8000 softwood stem cuttings were taken for propagation. Serial propagation more than doubled (from 20 to 44%) rooting response. Rooting response of tissue cultured microcuttings resulting from adventitious shoot initiation averaged 95% for 35 clones. By comparison, rooting response of open pollinated seedling families was 87% and stem cuttings from stock plants grown from tissue cultured microcuttings averaged 75%. Variation in clonal rooting response among propagation times represented a greater source of variation than that attributed to serial propagation or clone. Scion manipulation and hedging were ineffective in increasing stem cutting rooting potential. High rooting potential in mature birch can best be restored via tissue culture.

The Effects of Different Intensities of Pruning on the Growth ofPinus radiatain South Africa

SYNOPSIS Five pruning schedules were tested using a Latin Square design at the Stormsriver State Forest, Tsitsikamma Forest Region. Treatments included those standard at the time and combinations of prunings at earlier ages or to greater heights. The severity of each pruning regime was expressed with a severity index factor which incorporates the percentage live crown removed, age and mean tree height. Volume increment loss (as much as 16,7%) and the extent of epicormic shoot development were significantly correlated with the index factor. It is concluded that severe pruning of Pinus radiata leads to loss of growth and stimulation of epicormic shoot development. Recommendations are made for an improved pruning regime.

Influence of Training System, Pruning Severity, and Thinning on Yield, Vine Size, and Fruit Quality of Vidal blanc Grapevines

Vidal blanc grapevines were trained to four training systems: <i>(1)</i> High Cordon - a bilateral cordon at the top wire (1.7 m); <i>(2)</i> Low Cordon - bilateral cordon at the bottom wire (1.0 m); <i>(3)</i> High Head - a high head with the trunk maintained at or just below the top wire; and <i>(4)</i> Low Head - a low head with the trunk maintained at or just above the bottom wire. In addition, three pruning severities were applied (10 + 10, 15 + 15, and 20 + 20). Data were collected over a seven-year period from 1977 through 1983. The vines were evaluated for yield, vine size maintenance, fruit quality, and winter survival. Vines trained to the two cordon systems were superior to those trained to either head system. The labor savings associated with the High Cordon coupled with the reduced levels of crop loss due to winter damage resulted in that being the training system of choice. The large cluster status of the cultivar makes crop control problematic. Tentatively, we propose that crop may be controlled via a pruning severity of 15 + 10 when coupled with flower cluster thinning to one cluster per shoot.

Effects of Pruning on Root and Shoot Growth of Ilex crenata ‘Compacta’

In 2 experiments, shoot pruning at potting reduced root growth of transplanted rooted cuttings (liners). However, tip pruning of plants increased root growth compared to severe pruning (50% of shoots) and increased shoot numbers compared to nonpruned plants. In experiment 1 severe shoot pruning of transplanted liners in September resulted in increased shoot numbers compared to nonpruned plants, while in a second experiment, severe shoot pruning in May had no effect on shoot numbers.

The Influence of Summer Pruning and Fruit Cropping on the Carbohydrate, Nitrogen, and Nutrient Composition of Apple Trees

Abstract Traditionally, the size control achieved in summer-pruned apple (Malus domestica Borkh.) trees has been attributed to the removal of shoot leaf area before it could replace the storage carbohydrate depleted during its initial growth. Therefore, tissues of young Top Red ‘Delicious’/M 9 trees grown in pots, and mature, field-grown ‘Jonathan’/M 26 trees were summer-pruned and subsequently analyzed for carbohydrate and nutrient element content. Increasing the severity of summer pruning (the length of shoot removed) did not affect the concentration of water-soluble reducing sugars (SRS) or insoluble hydrolyzable carbohydrates (IHC) in the basal shoot section of the Top Red ‘Delicious’/M 9 trees 11 weeks after pruning. Summer pruning 1) increased leaf SRS, N, K, B and stem IHC and 2) decreased leaf Ca and Mg in shoot regrowth. Levels of Fe, Ca, Zn, Al, and Na in the leaves of regrowth were not affected by summer pruning. There was no significant effect of pruning on SRS or IHC levels in the roots. A separation of the carbohydrates by gas chromatography revealed increasing glucose and fructose concentrations in the roots as pruning severity increased, but sorbitol, sucrose, and phloridzin concentrations in roots were not significantly affected. Neither previous season’s summer pruning nor fruit cropping of ‘Jonathan’/M 26 trees affected SRS or IHC of spur shoots in March or June, except that presence of fruit reduced IHC of spur leaves in June. SRS levels in roots in June were reduced by the previous year’s cropping, but not influenced by summer pruning. Root IHC was not influenced by either pruning or cropping treatments. Spur leaf N, Ca, Mg, Mn, and Al were reduced on defruited trees, with K, Ca, Mn, and Al generally being increased by summer pruning. Pruning and cropping treatments generally did not affect levels of P, Fe, B, Cu, Zn, or Na in spur leaves in June; but summer pruning increased K concentration in harvested fruit.

Root Damage by Western Corn Rootworm and Nutrient Content in Maize1

AbstractLittle is known about the effects of root pruning by insects on nutrient content of maize (Zea maysL.). The objective of this study was to evaluate root damage effects caused by western corn rootworm (WCR, Diabrotica virgifera virgiferaLeConte) larval feeding on Fe, Na, K, Ca, Mg, and N contents in shoots and seeds of maize hybrid ‘Pioneer 3978’. The experimental design was a randomized complete block, and treatments included applications of 0, 1000, 2000,4000, and 8,000 WCR eggs per lineal meter of row in 1982 and 0,4000, and 12 000 WCR eggs per lineal meter of row in 1983. Maize seeds were planted ca. 23 cm apart in Brookings sicl (pachic Udic Haploborolls) soil. Aboveground plant samples were collected before intense larval feeding and after adult beetle emergence. These shoot samples and grain harvested at maturity were weighed and analyzed for their nutrient content. Severe root pruning decreased shoot dry weight and reduced grain yields at harvest by 13.5% in 1982 and by 9.7% in 1983. Contents of K, Mg, and Ca decreased and Fe and Na contents increased in shoots in 1982, but were not affected by root pruning in 1983. Accumulation of Na and Fe in shoots was attributed to compensatory branch root growth at critical stages of plant development. Root pruning may have caused new root development or branching into parts of the soil where Fe and Na could be obtained. Grain yield and grain Na content were related directly to the amount of root pruning in 1982. In 1983, grain yield was reduced and element content was altered by root pruning, but not in a simple linear manner. The results suggested that further studies of root pruning by WCR larvae of additional hybrids and their inbred parents may aid identification of elemental functions for maize.

Time and Severity of Summer Pruning Influences on Young Peach Tree Net Photosynthesis, Transpiration, and Dry Weight Distribution

Abstract Young peach trees 1) trained to a single shoot or 2) allowed to branch, were pruned by removing 50% of current growth at either or both of 2 summer dates. Another group of trees had 0%, 25%, 50%, and 75% shoot growth removed by pruning in midseason. Net photosynthesis (Pn) and transpiration (Tr) were increased within 3 days after pruning at either date. Plants pruned twice at 30-day intervals had a 2nd cycle of increased Pn and Tr, with rates returning to levels of unpruned controls within 24 days. Distribution of water soluble carbohydrates in various plant tissues was not altered by pruning. Pruning at 60 days reduced root starch, whereas pruning again at 90 days increased total root carbohydrate content. Pruning early in the season increased lateral shoot formation, and terminal bud formation was delayed by pruning. Plant dry weight was reduced by all pruning treatments, with delayed pruning and increasing pruning severity resulting in greatest reductions. Distribution of dry weight was not altered substantially by pruning, and a balance of growth was maintained between different plant parts.

Yield and Quality of ‘Niagara’ Grapes as Affected by Pruning Severity, Nodes per Bearing Unit, Training System, and Shoot Positioning

Abstract A 4-year study was conducted on ‘Niagara’ grapes (Vitis labrusca L.) to examine the effects of 3 pruning severities (based on nodes retained), 3 levels of nodes/bearing unit (3, 6, and 9), 2 training systems [Geneva Double Curtain (GDC) and Bilateral Cordon (BC)], and 2 canopy management treatments (shoots positioned and shoots not positioned) on yield and fruit quality. Leaving heavy fruit loads suppressed yields in the 4th and final year of this study as a result of reduced node fruitfulness. The 3 node spurs were not as productive as the 6 and 9 node canes. GDC training produced higher yields than BC training in the 3 high yielding years of the study while maintaining vine vigor. Shoot positioning was more beneficial in increasing yields on the BC training system than on the GDC training system, because of the crowded conditions of the canes on the BC system. The effects of these variables on fruit quality were small, but the heavy fruit loads did result in fruit with a reduced percentage of soluble solids and pH, increased acidity and light color (increased CDM ‘L’ values). Shoot positioning reduced fruit pH, slightly in-creased acidity, and produced darker color (decreased CDM ‘L’ values). Under Arkansas growing conditions, if harvest is delayed beyond 14% soluble solids, it is possible that unacceptable fruit pH and acidity levels will exist.

Tillage and Low‐Pressure Center‐Pivot Irrigation Effects on Corn Yield1

AbstractLow‐pressure sprinkler irrigation systems have the potential to save energy, but also may aggravate soil‐ and water‐management problems. The objective of this research was to determine the influence of center‐pivot sprinkler irrigation method in combination with various tillage practices on corn (Zea mays L.) yield and yield components. A center‐pivot irrigation machine was redesigned to apply water by high‐pressure‐impact (HPI), low‐pressure‐impact (LPI), and low‐pressure‐spray (LPS) nozzles. Nozzles were sized and spaced to apply three different amounts of water: 100% (full irrigation), 75 and 50%. Three tillage treatments were used—till‐plant (T), disk (D), and till‐plant with chisel after last cultivation (C)—for each method and amount of water applied. The field study was conducted over a 4‐year period (1978 to 1981) on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls). Yields were influenced by the seasonal distribution and amount of precipitation, irrigation water applied, tillage, and the combined management inputs. The method of water application (HPI, LPI, and LPS nozzles) did not significantly (P &gt; 0.10) influence grain yield. In 1979, the chisel tillage treatment produced significantly less grain than other treatments because severe root pruning limited stored water uptake during an extremely stressful period immediately following the chisel operation. No inherent differences in productivity were associated with low‐pressure center‐pivot‐sprinkler irrigation, or with various conservation‐tillage practices used in combination with reduced‐pressure‐sprinkler irrigation. Therefore, use of these practices can reduce production costs without reducing yield.

The influence of desiccation and root pruning on the survival and growth of broadleaved seedlings

SummaryRoot systems of Fraxinus and Betula seedlings dried out rapidly under controlled conditions of high temperature and low relative humidity, the thinnest roots being most susceptible. Lateral roots were easily damaged and died within 24 h exposure. In comparison of root pruning and desiccation treatments only the most severe pruning of parts of the main root axis had an adverse effect on growth in water culture. However, seedlings replanted in soil after varying desiccation periods showed growth reductions after only 12 h drying. Soaking previously desiccated root systems in water promoted some recovery in Betula, demonstrating that desiccation damage was not altogether irreversible. Further experiments demonstrated that losses of lateral roots during plant handling might account for 20–40% of the total root carbohydrate, with important differences between species. However, there was sufficient carbohydrate to allow recovery and rapid growth of less severely pruned and desiccated seedlings. In these cases root losses appeared to stimulate the production of fresh lateral roots, potentially improving soil contact and allowing rapid uptake of water and nutrients. The effects of desiccation with respect to root size distribution and plant handling are discussed.

Responses of apple summer cuttings to severity of stockplant pruning and to stem blanching

SummaryReasons for relatively free-rooting of shoots on stoolbeds compared to less-ready rooting of cuttings obtained from hedges were investigated. Leafy cuttings of apple rootstock M.9 and the easier-to-propagate MM.106 rooted better under mist when obtained from ultra- severely pruned stockplants in the form of non-earthed stools, than from conventional hedges with a permanent framework of c. 1 m. Reducing hedges to about half their normal height led to intermediate rooting, as did obtaining the cuttings from the trunks rather than the tops of bushes. Improved rooting was expressed as either an increased rooting percentage or more roots per rooted cutting. When the combination of rootstock, pruning level and propagation duration caused neither extremely high nor very low rooting, a positive response was obtained to blanching the stem bases by excluding light, as occurs when soil is placed around the stems of stool shoots. Black adhesive tape was most effective experimentally for blanching, but response...