Severe Pruning Research Articles

Développement de rejets épicormiques sur des séquoias californiens : intensité de l’élagage, génotype, caractéristiques des rejets

• Young coast redwood (Sequoia sempervirens (D. Don.) Endl.) trees were pruned to various heights to examine the effect of pruning severity on epicormic sprouting. Seven separate stands were used with as many as six treatments per stand in coastal Humboldt County, California, USA. • Epicormic sprout development was affected by pruning severity but primarily at the most severe pruning treatments that removed all but the branches in the top 15% of tree height. Less severe treatments produced sprouts but the number and size of these sprouts were comparable to unpruned trees. • Natural clonal patterns were also used to explore patterns of sprouting between genotypes. Linear mixed-effects models were developed to predict sprouting frequency as a function of pruning severity while accounting for the nested data structure (i.e., stem sections sampled nested within genotypes within treatments within sites). • Comparing variances attributed to each of these random effects indicated that at any level of pruning severity, differences in epicormic sprouting between genotypes and sites expressed soon after pruning had disappeared after six growing seasons. Epicormic branches were more common two years after pruning than six years indicating many branches were dying. Branches were more common in the middle of the pruned bole, possibly because of competition from basal sprouts and the expanding tree crown.

Results of cherry rootstock evaluations in Hungary

The paper gives a review on the results of the latest rootstock evaluation projects in Hungary. Several cherry rootstock evaluation projects were carried out in Hungary during the last two decades. The evaluated rootstocks are partly mahalebs selected in Hungary, but more or less all the most important new rootstocks from different countries are involved. The aim of these evaluation projects was to find appropriate rootstocks in a wide range of vigour for our climate and soil conditions. The conclusion of the last 20 years of research in Hungary proved just the opposite of believes, that high density orchard can only be planted with dwarfing rootstocks. Before choosing the right rootstock the most important is to consider adaptability, precocity and productivity. Dwarfing and semi-dwarfing rootstocks showed proper results only with irrigation or very good site conditions. These rootstocks are very precocious, but branches form easily blindwood. This must be corrected by severe pruning in the first years. The relatively small leaf surface area can also be disadvantageous, but it can be controlled by pruning, fruit-thinning, irrigation and fertilization. After studying different rootstocks semi-vigorous rootstocks seem to be the most adequate for different site conditions in Hungary. Fast initial growing and competent precocity are their favourable characters. From the vigorous group of clonal mahalebs or seedlings are highly recommended first of all for poor site condition (sandy, lime soils with high pH). They turn to bearing early and easy to find them in the Hungarian nurseries. But on vigorous rootstocks trees might need stronger summer pruning.

Effects of living crown reduction on needle element status of Scots pine

A wide range of biotic and abiotic factors, operating over different time perspectives and intensities, cause defoliation and a rapid decrease in the crown size of trees. Scleroderris canker disease [Gremmeniella abietina (Lagerb.) Morelet] has caused widespread crown reduction and tree mortality in Scots pine in forests in Scandinavia during the last three decades. In the 1980's, attempts were made to show, on the basis of the higher foliar N and S concentrations of affected pines in the diseased area, that sulphur and nitrogen deposition predispose trees to G. abietina. Unfortunately, in many studies on defoliated trees, exceptionally high or low needle mineral nutrient concentrations are still often interpreted as one of the causes of tree injury and not, conversely, as the result. In this thesis, three different field experiments, with foliar analysis as the main study method, were conducted in order to asses the possible long-term effects of living crown reduction on the needle nutrient concentrations of Scots pine trees in southern Finland. The crown ratio and length of the living crown were used to estimate the amount of defoliation in the reduced canopies. The material for the partial studies was collected and a total of 968 foliar samples were analysed individually (15-17 elements/sample) on a total of 488 sample trees (140 diseased, 116 pruned and 232 control trees) during the years 1987-1996 in 13 Scots pine stands. All the three experiments of this thesis provided significant evidence that severe disease-induced defoliation or artificial pruning of the living branches can induce longlasting nutritional changes in the foliage of the recovering trees under the typical growing conditions for Scots pine.The foliar concentrations of all the 17 mineral nutrients/elements analysed were affected, to a varying degree, by artificial pruning during the following three years. Although Scots pine, as an evergreen conifer, is considered to have low induced chemical responses to defoliation, this study proved experimentally under natural forest conditions that severe artificial pruning or disease-induced defoliation of Scots pine trees may induce biologically significant changes in the concentrations of most of the important macroand micronutrients, as well as of carbon, in refoliated needles.

A functional association in Vitis vinifera L. cv. Cabernet Sauvignon between the extent of primary branching and the number of flowers formed per inflorescence

The number of primary branches (those branches that arise directly from the rachis) and the total number of flowers were counted for inflorescences of Vitis vinifera L. cultivar Cabernet Sauvignon over a range of climates and a number of seasons as part of a yield prediction study. Regression analysis indicated that the number of primary branches per inflorescence exerted a strong control over the total number of flowers per inflorescence, with highly significant (P < 0.01) relationships explaining between 51 and 80% of the variation in flowers per inflorescence. Because the extent of primary branching is largely determined prior to grapevine buds entering dormancy, this strong functional association between branching and flower numbers, suggests that season-to-season differences in potential inflorescence size will be greatly affected by conditions during that phase of primordial differentiation in the previous growing season. A general tendency for the number of flowers per inflorescence to be positively related to other measures of vine fertility, supports this view. Lower orders of branching (secondary and tertiary) down to formation of individual flowers at budburst, also have the potential to influence eventual inflorescence size. As to the timing of such influences, we noted that increased severity of winter pruning significantly increased both flowers per inflorescence (by 9%) and the number of primary branches per inflorescence (by 21%). Such responses provide strong support for our contention that although the extent of primary branching is largely determined prior to grapevine buds entering dormancy, differentiation of new primary branches in Cabernet Sauvignon inflorescences continues to occur after the onset of dormancy.

Plexiform-like lesions and increased tissue factor expression in a rat model of severe pulmonary arterial hypertension

Severe pulmonary arterial hypertension (PAH) occurs in idiopathic form and in association with diverse diseases. The pathological hallmarks are distal smooth muscle hypertrophy, obliteration of small pulmonary arteriole lumens, and disorganized cellular proliferation in plexiform lesions. In situ thrombosis is also observed. A detailed understanding of the disease progression has been hampered by the absence of an animal model bearing all the pathological features of human disease. To create a model with these characteristics, we gave young (200-g) rats monocrotaline 1 wk following left pneumonectomy; controls with vehicle treatment or sham operation were also studied. In experimental rats, pulmonary arteries had distal smooth muscle hypertrophy and proliferative perivascular lesions. The lesions had a plexiform appearance, occurred early in disease development, and were composed of cells expressing endothelial antigens. Three-dimensional microangiography revealed severe vascular pruning and disorganized vascular networks. We found that expression of tissue factor (TF), the membrane glycoprotein that initiates coagulation, facilitates angiogenesis, and mediates arterial injury in the systemic circulation, was increased in the pulmonary arterioles and plexiform-like lesions of the rats. TF was also heavily expressed in the vessels and plexiform lesions of humans with pulmonary arterial hypertension. We conclude that plexiform-like lesions can be reproduced in rats, and this model will facilitate experiments to address controversies about the role of these lesions in PAH. Increased TF expression may contribute to the prothrombotic diathesis and vascular cell proliferation typical of human disease.

Soil water dynamics in cropping systems containing Gliricidia sepium, pigeonpea and maize in southern Malawi

The water dynamics of cropping systems containing mixtures of Gliricidia sepium (Jacq.) Walp trees with maize (Zea mays L.) and/or pigeonpea (Cajanus cajan L.) were examined during three consecutive cropping seasons. The trees were pruned before and during each cropping season, but were left unpruned after harvesting the maize; prunings were returned to the cropping area in all agroforestry systems to provide green leaf manure. The hypothesis was that regular severe pruning of the trees would minimise competition with crops for soil moisture and enhance their growth by providing additional nutrients. Neutron probe measurements were used to determine spatial and temporal changes in soil moisture content during the 1997/98, 1998/99 and 1999/00 cropping seasons for various cropping systems. These included gliricidia intercropped with maize, with and without pigeonpea, a maize + pigeonpea intercrop, sole maize, sole pigeonpea and sole gliricidia. Soil water content was measured to a depth of 150 cm in all treatments at 4–6 week intervals during the main cropping season and less frequently at other times. Competition for water was apparently not a critical factor in determining crop performance as rainfall exceeded potential evaporation during the cropping season in all years. The distribution of water in the soil profile was generally comparable in all cropping systems, implying there was no spatial complementarity in water abstraction by tree and crop roots. However, available soil water content at the beginning of the cropping season was generally lower in the tree-based systems, suggesting that the trees continued to deplete available soil water during the dry season. The results show that, under rainfall conditions typical of southern Malawi, the soil profile contains sufficient stored water during the dry season (ca. 75–125 mm) to support the growth of gliricidia and pigeonpea, and that gliricidia trees pruned before and during the cropping season did not deleteriously compete for water with associated crops. Water use efficiency also appeared to be higher in the tree-based systems than in the sole maize and maize + pigeonpea treatments, subject to the proviso that the calculations were based on changes in soil water content rather than absolute measurements of water uptake by the trees and crops.

Improving adoptability of farm forestry in the Philippine uplands: a linear programming model

In the Philippines, smallholder farmers have become major timber producers. But the systems of timber production practiced have several limitations. In intercropping systems, the practice of severe branch and/or root pruning reduces tree-crop competition and increases annual crop yields, but is detrimental to tree growth and incompatible with commercial timber production. In even-aged woodlots, lack of regular income and poor tree growth, resulting from farmers’ reluctance to thin their plantations, are major constraints to adoption and profitable tree farming. In the municipality of Claveria, Misamis Oriental, the recent practice of planting trees on widely spaced (6–8 m) contour grass strips established for soil conservation suggests ways to improve the adoptability (i.e., profitability, feasibility and acceptability) of timber-based agroforestry systems. Assuming that financial benefits are the main objective of timber tree farmers, we develop a simple linear programming (LP) model for the optimal allocation of land to monocropping and tree intercropping that maximizes the net present value of an infinite number of rotations and satisfies farmers’ resource constraints and regular income requirements. The application of the LP model to an average farmer in Claveria showed that cumulative additions of widely spaced tree hedgerows provides higher returns to land, and reduce the risk of agroforestry adoption by spreading over the years labour and capital investment costs and the economic benefits accruing to farmers from trees. Therefore, incremental planting of widely spaced tree hedgerows can make farm forestry more adoptable and thus benefit a larger number of resource-constrained farmers in their evolution towards more diverse and productive agroforestry systems.

Identification of E2/E3 Ubiquitinating Enzymes and Caspase Activity Regulating Drosophila Sensory Neuron Dendrite Pruning

Ubiquitin-proteasome system (UPS) is a multistep protein degradation machinery implicated in many diseases. In the nervous system, UPS regulates remodeling and degradation of neuronal processes and is linked to Wallerian axonal degeneration, though the ubiquitin ligases that confer substrate specificity remain unknown. Having shown previously that class IV dendritic arborization (C4da) sensory neurons in Drosophila undergo UPS-mediated dendritic pruning during metamorphosis, we conducted an E2/E3 ubiquitinating enzyme mutant screen, revealing that mutation in ubcD1, an E2 ubiquitin-conjugating enzyme, resulted in retention of C4da neuron dendrites during metamorphosis. Further, we found that UPS activation likely leads to UbcD1-mediated degradation of DIAP1, a caspase-antagonizing E3 ligase. This allows for local activation of the Dronc caspase, thereby preserving C4da neurons while severing their dendrites. Thus, in addition to uncovering E2/E3 ubiquitinating enzymes for dendrite pruning, this study provides a mechanistic link between UPS and the apoptotic machinery in regulating neuronal process remodeling.

(57) Growth and Phenology of Lagerstroemia Hybrids in South Mississippi

Lagerstroemia indica ×fauriei `Tonto' and `Sioux' were planted in Mar. 1995. All other cultivars were planted in Oct. 1985. Plants were planted into a Ruston sandy loam on a 12 × 12 ft (3.7 × 3.7 m) spacing. Trees were pruned to develop multiple trunks. Trees are pruned annually in winter to remove any limbs smaller than 0.6 cm in diameter. Pruning cuts are made 6–8 in (15.2–20.3 cm) above prior cuts. Severe pruning is performed every 5 years. Trees were evaluated at 2-week intervals during the flowering season to determine total length of flowering and duration of good to superior flowering. Growth indices (height + width + perpendicular width)/3 were recorded after plants were dormant. Total days of flowering and floral display (0–5 with 0 representing no flowers and 5 representing superior flowering) were rated. `Muskogee' had the greatest growth index after the 2004 growing season. `Seminole' had the least. However, `Seminole' had the greatest number of flowering days. `Biloxi' had the fewest flowering days. `Tonto' had the most good to superior flowering days, while `Tuskegee' and `Muskogee' had the fewest. In 2005, `Muskogee' again had the greatest growth index, while `Sioux' had the least. `Yuma' and `Seminole' had the greatest number of flowering days, and `Biloxi' again had the fewest. `Tonto' again had the most good to superior flowering days, while `Biloxi' and `Acoma' had the fewest.

CRAPE MYRTLE EVALUATIONS IN SOUTH MISSISSIPPI

Lagerstroemia indica x fauriei `Tonto' and `Sioux' were planted in March, 1995. All other cultivars were planted in October, 1985. Plants were planted into a Ruston sandy loam on a 12 × 12 ft (3.7 × 3.7 m) spacing. Trees were pruned to develop multiple trunks. Trees are pruned annually in winter to remove any limbs smaller than ¼ in (0.6 cm) in diameter. Pruning cuts are made 6–8 in (15.2–20.3 cm) above prior cuts. Severe pruning is performed every five years. Trees were evaluated at 2-week intervals during the flowering season to determine total length of flowering and duration of good to superior flowering. Growth indices (height + width + perpendicular width)/3 were recorded after plants were dormant. Total days of flowering and floral display (0–5 with 0 representing no flowers and 5 representing superior flowering) were rated. `Muskogee' had the greatest growth index after the 2004 growing season. `Seminole' had the least. However, `Seminole' did have the greatest number of flowering days. `Biloxi' had the fewest flowering days. `Tonto' had the most good to superior flowering days while `Tuskegee' and `Muskogee' had the fewest.

Pruning Strategies to Maximize Tropical Mango Production From the Time of Planting to Restoration of Old Orchards

Pruning is an unavoidable necessity of virtually all arboreal fruit crops. In the tropics and subtropics, pruning of mango (Mangifera indica L.) is particularly important due to its tendency for frequent flushes, especially in humid tropics. Commercial orchards must maintain control of both tree size and orchard productivity in order to remain productive. Tip, formation, and severe pruning can be used in a variety of circumstances to produce predictable and useful results for a variety of purposes. For example, tip pruning can be used to encourage frequent flushing and branching of young trees to bring them into commercial production years earlier than if left alone. It can also stimulate timely flushes of lateral stems in an annual program to maintain tree size and prepare trees for synchronous flowering. Formation pruning shapes trees in an overgrown orchard to receive the maximum amount of light for high productivity and sets them up for annual pruning in a flowering management program. Severe pruning coupled with subsequent tip pruning of huge, nonproductive trees facilitates rapid restoration of orchard production. Each of these types of pruning can be used to get mango trees into production quickly and thereafter maintain maximum annual production while maintaining their desired size.

Comparison of growth potentials of epicormic shoots of nectarine trees grown on size-controlling and vigorous rootstocks

SummaryThe vegetative performance of four nectarine tree scion/rootstock combinations, with varying growth capacities, were analysed in the Spring after the canopy:root ratio was dramatically reduced by severe pruning in the dormant season. We anticipated that severe pruning and reduction of the shoot:root ratio would mitigate known root water supply limitations related to the various rootstocks and determine if other factors associated with the rootstocks would control the rates of epicormic shoot growth. The trees used in this field experiment were 3 years-old, with ‘May Fire’ nectarine grafted onto four different rootstocks: ‘Nemaguard’ (a vigorous seed-propagated control, P. persica P. davidiana hybrid) and three size-controlling rootstocks, ‘K146-43’, ‘P30-135’ (P. salicina P. persica hybrids) and ‘K-119-50’ (P. salicina P. dulcis hybrid). At the beginning of the trial, there were clear differences in plant dimensions, confirming the higher vigour induced by ‘Nemaguard’ compared to the other rootstocks. Reducing the canopy:root ratio was able to annul potential differences in weekly shoot-extension growth rates and cumulative extension growth of individual shoots during the Spring flush of re-growth after pruning. This supported the idea that there were no rootstock-specific signals (hormonal or physical) that caused large differences in extension growth rates of individual epicormic shoots on trees. However, there were clear differences in total epicormic shoot re-growth per tree that were associated with initial tree size at the time of severe pruning, indicating the importance of trunk and root storage in influencing the amount of growth stimulation after dormant pruning.

Effects of Pruning and Cluster Thinning on Yield and Fruit Composition of `Chambourcin' Grapevines

Response of yield components and fruit composition of `Chambourcin' (Vitis vinifera × V. rupestris) grapevines to three pruning levels of 15, 20, and 25 nodes retained for each pound of dormant prunings; and three cluster thinning levels of 1, 2, and 2+ clusters per shoot in 2002 and 1, 1.2, and 1.5 clusters per shoot in 2003 were measured at two vineyards in the lower midwestern United States. In both years of the study, there was very little interaction of pruning and cluster thinning. The proportion of non-count shoots increased within the canopy in response to increased pruning severity. Pruning weight means were lower in 2002 across all treatments compared to 2003. Pruning weights decreased with the increase in the number of clusters retained per vine. Pruning influenced yield only in 2003 when the proportion of count shoots decreased below 62% of the total, hence the relationship between number of shoots per vine and yield (R2 = 0.3452; P &lt; 0.0003). In both years of the study, the increase in severity of cluster thinning resulted in yield reduction but an increase in the total soluble solids in juice. Yield compensation was achieved by an increase in cluster weight of 38%, and 25% in response to a reduction of 37%, and 23% in cluster numbers; which translated into a yield reduction of only 10% and 3%, at Vineyards 1 and 2, respectively. Balanced pruning to 15 to 20 nodes per 1 lb of prunings and cluster thinning to 1 to 1.2 clusters/shoot optimized yield (9.7 kg/vine, 13.4 t·ha-1) and fruit composition, and maintained vine size (≥0.3 kg·m-1 of row). These results provide valuable information for growers of `Chambourcin' grapevines in the lower midwestern U.S., as well as in other climates with long growing seasons.

Ten-Year Growth and Epicormic Sprouting Response of Western Larch to Pruning in Western Montana

Abstract Western larch (Larix occidentalis Nutt.) is a fast-growing, deciduous conifer that is often managed for timber production in the inland Northwest. No previous study has documented the response of this species to artificial pruning. Trees pruned as part of a pruning cost study in 1992 were followed for 10 years to assess growth and epicormic sprout response. Trees were pruned to two heights: 2.4 and 5.5 m in three stands in western Montana. Epicormic sprouting occurred in a majority of trees in the first 2 years after pruning, but subsequently many sprouts died so that by year 10, only approximately 30% of trees had sprouts. Volume increment was adversely affected by more severe pruning among smaller trees pruned to the shorter lift. The volume increment of the trees that received the 5.5 m lift was generally unaffected, but trees receiving the 2.4 m lift were more sensitive to pruning. Initial tree diameter and residual crown length were important variables in predicting the 10-year volume increment in pruned trees. West. J. Appl. For. 20(4):228–232.

Effects of bulb storage, leaf and root pruning, on flower production in Cyrtanthus elatus

The effects of combinations of duration of bulb storage, storage temperature, and leaf and root pruning regimes before storage on flower production in Cyrtanthus elatus were studied in three experiments. In the first experiment, bulb viability was 93% after 49 days and declined at 98 and 147 days of storage at 1°C to 3%. Storage at 5°C for 147 days did not affect viability but flowering date was delayed 24 days. In subsequent experiments storage at 5°C did not delay flowering after 50 days, but after 100 days flowering was up to 23 days earlier and produced stems 17–22% shorter. Increasing severity of leaf and root pruning reduced the number of flower stems/bulb 46–60%, but did not affect stem length. With storage at 5°C it may be possible to spread the flowering season.

Pruning intensity and fruit load influence vegetative and fruit growth in an early-maturing peach tree (cv. Alexandra)

Introduction. The distribution of shoots and fruits in the tree is an important con- sideration to improve peach cropping. Therefore, the effects of intensity of pruning were inves- tigated for two years in trees with the same fruit load and, the following year, in trees with different fruit loads. Materials and methods. In an early-maturing peach orchard (cv. Alexandra), three pruning intensities were applied for three years: light, medium and severe. The first two years, the same fruit load was applied for the different pruning treatments; in the last year, three fruit loads per tree were tested: low, intermediate and high. Results and discussion. Increasing seve- rity of pruning stimulated average fruit weight and fruit diameter, limiting (2nd year) or not (3rd year) fruit yield. Severe pruning also tended to enhance young shoot growth on the shoot bearing fruit and on the scaffold branch. Fruit diameter improvement with severe pruning might be therefore explained by the increase in vegetative growth likely to enhance available assimilates for fruit growth. However, severe pruning could favor an alternation in flower setting, as observed in the 2nd year. Increasing fruit load stimulated fruit yield, but, with the highest fruit load, no significant fruit yield enhancement was detected compared with the intermediate fruit load. On the contrary, average fruit weight and fruit soluble solids always decreased with increasing fruit load. Conclusion. Intensity of pruning and fruit load must be well adapted to ensure an appro- priate peach production; excessive pruning and fruit load of an early-maturing peach cultivar should be avoided in order not to limit fruit yield and quality, respectively. France / Prunus persica / pruning / growth / production / fruit / quality

Topping and Manual Pruning Effects on the Production of Commercially Valuable Fruit in a Midseason Navel Orange Variety

The objective of this experiment was to determine how yield, size, and quality of fruit would respond to mechanical topping and manual pruning of mature `Frost nucellar' navel orange (Citrus sinensis) trees. Mechanically topping trees at 4.3 m (14 ft) or 4.9 m (16 ft) produced annual fruit yields and quality similar to that of untopped trees. Over the 4 years of this experiment, trees that were not manually pruned produced as much or more of the most valuable fruit sizes than either the severe or moderate manual pruning treatments without the associated pruning costs. Manual pruning did not improve fruit grade compared to unpruned trees. A highly significant positive and linear relationship was found between numbers of commercially valuable fruit and the total number of fruit produced annually within the range of 50,000 to 325,000 fruit/ha (20,235 to 131,528 fruit/acre). Manual pruning, which reduced total fruit numbers, reduced the number of commercially valuable fruit predictively according to this relationship.

PHOTOSYNTHETIC INHIBITION OF 'SEYVAL BLANC' GRAPEVINES WITH TERBACIL

PHOTOSYNTHETIC INHIBITION OF 'SEYVAL BLANC' GRAPEVINES WITH TERBACIL

Malformed Fruits in `Niitaka' Pear Influenced by Pruning Strength, GA and Mepiquat Treatment

This study was carried out to observe the effects of the pruning strength and the growth regulator on shoot growth and fruit shape in Pyrus pyrifolia cv. Niitaka. GA paste (GA) was known as a promoter of malformed fruits, but Mepiquat as an inhibitor. Light pruning treatment, of which removed the half of lateral shoots, decreased leaf area, weight, thickness, and the length of shoots and internodes in comparison to severe pruning. The occurrence of calyx perpetual fruit (CPF) in fruitlet stage was higher about 45% in severe pruning than in light pruning. Light pruning decreased malformed fruit by 10% compared to severe pruning at harvest stage, but there was no difference in soluble solid content of fruits between two treatments. Also light pruning decreased fruit weight. GA paste treatment on 50 days after full bloom significantly increased fruit weight, but Mepiquat decreased. In treatment of Mepiquat and GA the occurrence of malformed fruit was 31.3% and 35%, respectively and the index of symmetry was higher than control. Therefore, these results suggested that the light pruning has a positive effect on the production of symmetry fruit.

Topping and Pruning Effects on Yield and Fruit Size of Navel Orange

Yield, fruit quality parameters and pruning costs were compared among differentially-pruned, mature navel orange trees planted at a density of 222 trees per hectare (90 trees per acre) in 2000, 2001 and 2002. The experiment was designed as a replicated, split block with topping height as the main plot split by three levels of interior pruning as subplots. A tree was reduced in height by mechanical topping to 4.3 m, 4.9 m or left untopped and hand pruned according to one of the three following options: 1. scaffold removal in March of 2000 followed by dead-brushing in 2001, and 2002; 2. dead-brushing only in 2000, 2001, and 2002; or 3. no topping or dead-brushing. Scaffold removal resulted in removal of approximately 50% of the tree canopy. Data were collected from experimental trees surrounded by similarly topped and interiorly pruned border trees. A highly significant positive-linear correlation (r2 = 0.95) was found between the total numbers of fruit produced annually per hectare versus the total number of fruit sized 72 to 88 mm in diameter (i.e. fruit sized such that 88 to 48 may be packed in a standard 17-kg packing carton). This functional relationship existed whether reductions in fruit numbers were the result of severe pruning in March or from, apparently, weather-related year to year variability in fruit set. These results suggest that anything in this orchard that reduces fruit numbers below approximately 250,000 fruit per hectare at harvest (100,000 per acre) will result in a mathematically predictable decrease in the total number of harvested fruit sized 72 to 88 mm in diameter. Trees that were not topped and which had no interior pruning produced the largest number of valuable fruit without additional pruning costs.