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Andrew G. Reynolds, Amal Ehtaiwesh, and Christiane de Savigny

relative humidity, wind speed, solar radiation, and temperature values, which are downloaded from databases such as the Weather Innovations Network in Ontario. ET o values can then be used with a crop coefficient (normally based upon canopy volume) to

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Ryan N. Contreras, John M. Ruter, and Wayne W. Hanna

morphological comparison of field-grown material, the octoploid was shorter on both measurement dates, had a smaller canopy volume, shorter internodes, and smaller leaves than tetraploid H. acetosella ‘Panama Red’ ( Table 2 , Fig. 5 ). Table 2

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W. Alan Erb and Mark Pyeatt

This study was conducted in the greenhouse by running two experiments at different temperature regimes (22°C day and 13°C night and 33°C day and 22°C night). One-year-old tissue culture propagated plants were irrigated at three different soil moisture tension levels (5, 15, and 30 cnbars) and either exposed to moving or still air. The moving air treatment was created by two 51-cm-diameter fans running at either low (5.6 mph) or medium (8.2 mph) speed. Each experiment included, forty-eight plants arranged in a randomized complete block design. Each block consisted of a greenhouse bench containing two fans, a plastic dividing wall and two plant replications for each treatment. Canopy volume measurements were taken at the beginning, middle and end of each experiment to estimate growth rate. At the end of each experiment, total leaf area and leaf, stem and root dry weight data were collected. In the moderate temperature experiment, the still air treated plants had the highest canopy volume and leaf weight ratio while the moving air treated plants had the highest stem weight ratio. The only difference for the moisture treatments was the 5-cnbar treatment had the highest canopy volume. In the high temperature experiment, the still air treated plants had the highest canopy volume, total leaf area, leaf dry weight, shoot/root ratio, leaf weight ratio and leaf area duration while the moving air treated plants had the highest root weight ratio. The 5-cnbar treatment had the highest canopy volume and biomass accumulations. The 30-cnbar treatment had the highest root weight ratio.

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Flavia T. Zambon, Davie M. Kadyampakeni, and Jude W. Grosser

extracted using the Mehlich III method and analyzed using the ICP-AES method at the WaterAg Laboratory (Camilla, GA). The nutrient concentration was expressed as nutrient mass per unit of soil mass (mg·kg −1 ). The tree canopy volume and trunk cross

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James N. Cummins

Rootstock influence on tree architecture may be seen in a variety of expressions. Above ground effects include canopy volume and shape, crotch angles, branch display angles, relative distribution of long shoots and spurs, internode length, relative distribution of fruit buds and spurs, and trunk taper. Below the graft union, effects include relative distribution of fine vs. coarse roots, total root mass, and numbers, nature and distribution of burrknots. Many of these phenomena are indirect effects that stare from induction of fruiting by the rootstock, e.g., early fruit production induced by the rootstock will result in reduced canopy volume, reduced aboveground total mass, flatter branch display angles, and reduced root mass. The rootstock also plays a major role in the duration of shoot extension growth; by influencing the production of growth regulators in the shoot tip, the rootstock indirectly influences the inhibit ion of lateral buds and therefore the production of feathers.

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Anita N. Miller, Porter B. Lombard, Melvin N. Westwood, and Robert L. Stebbins

`Napoleon' grafted onto Colt, F/12-1, and MxM60 rootstock were planted into three types of tree holes: augered; backhoed, and backhoed plus fumigation. The auger treatment resulted in lower yields, smaller trunk cross-sectional area (TSCA), and smaller canopy volume when compared to backhoed holes. Fumigation had no significant effect. Trees on Colt rootstock were more precocious, had a smaller TCSA and canopy volume, greater cumulative yield efficiency, and, in 1987, the smallest fruit weight. The yield efficiency of Colt was the highest until 1988, when it was surpassed by MxM60, but was still similar to F/12-l. Yields were highest on trees of MxM60 in 1987 and 1988.

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Stephen S. Miller and Ross E. Byers

Seven-year-old `Blake'/`Lovell' peach [Prunus persica (L.) Batsch] trees were subjected to four pruning levels (none, light, heavy, and dehorned) each at three times (April, May, and June) in a factorial arrangement following freezing injury in January 1994. Pruning had a significant effect on canopy height, canopy volume and fruit yields. Peach trees pruned in April or dehorned (severe pruning) had less canopy volume in the first fruiting season (1995) after the pruning treatments were initiated than trees pruned in May or June and light or heavy pruned trees. In 1995, yields were lower for trees pruned in June, nonpruned or dehorned trees in 1994. These treatments also produced fewer large fruit at harvest and thus reduced dollar returns per hectare in 1995. In 1996, fruit numbers and fruit sizes did not differ among treatments, but dehorned trees had lower returns per hectare because trees were smaller. The results of this study indicate that peach trees subjected to moderate winter injury should be pruned no later than 2 to 3 weeks after bloom using a heavy level of pruning. There appears to be no economic advantage to dehorn pruning even though canopy volume can be reduced resulting in a smallertree with high quality wood. The results clearly illustrate the long-term negative effect of dehorn pruning on yields resulting from reduced canopy volume. Mean number of cankers per tree increased over time from 1995 through 1998, but pruning treatments did not affect the number of cankers produced. Pruning treatments did affect the size of cankers and the number with visible gumming.

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David C. Ferree

In 1981, four apple cultivars were established as a low trellis hedgerow on M.9 or free-standing central leaders on M.7 at the recommended or half the recommended spacing with the close planted trees either root pruned annually at bloom or hedged in August. Planting at half the spacing and annual summer hedging 2 sides decreased TCA 25% and canopy volume 51% with no effect on shoot growth, while annual root pruning decreased TCA 34%, canopy volume 50% and shoot length 25%. Planting at half spacing and either hedging or root pruning reduced yields per tree. Efficiency as measured by yield TCA was decreased by hedging and as measured by yield/m3 canopy volume was increased by both treatments with hedging having the greatest effect. The cumulative yield/ha was increased by both hedging and root pruning with no difference between them. Fruit size was decreased by close planting and root pruning caused a greater decrease than hedging. Close planting increased the number of spurs and shoots and LAI per unit volume of canopy with no difference between hedging or root pruning. `Empire' outproduced `Smoothee' and `Delicious' on the trellis and `Lawspur' had higher yields than any other cultivar in the central leader.

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Robert E. Rouse, Monica Ozores-Hampton, Fritz M. Roka, and Pamela Roberts

tree including a high and low height. The five measurements were averaged to represent the shoot length of that experimental unit. Tree canopy volume was determined by measuring the canopy in north-south and east-west directions and the tree height. The

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Nicole E. Burkhard, Derek H. Lynch, and David C. Percival

Within-row weed management of highbush blueberry (Vaccinium corymbosum L.) is reliant upon herbicide applications. However, in organic production, herbicides are typically not permitted and alternative methods must be used. The impact of thick (25-cm) mulch applications on weed pressure in an organic production system was initiated at a commercial operation in Nova Scotia, Canada, during 2005. A split-plot experimental design was used with five blocks (replications), six treatments, and five plants per split plot (cv. Duke). The whole-plot factor consisted of mulch/fertility treatments and included: i) control (no amendment); ii) ammonium sulphate fertilizer (30 kg·ha-1 N); iii) pelletized poultry manure (60 kg·ha-1 N); iv) pine needles (80 t·ha-1); v) horse manure and sawdust compost (550 t·ha-1); and vi) seafood waste compost (360 t·ha-1). The split-plot factor consisted of level of hand weeding (–/+). Weed control was assessed by sampling percent ground cover and weed shoot biomass in three 0.25-m2 quadrats in nonweeded subplots. Blueberry leaf N content, plant canopy volume, and berry yield (fresh weight and number) were recorded. The manure/sawdust compost and pine needle treatments had the lowest weed biomass and percent ground cover values, thereby providing the best weed control. Weed shoot biomass, blueberry leaf N, plant canopy volume, and berry yield were greatest in the seafood waste compost treatment. Results from this preliminary study indicate the potential of using these groundcover treatments to improve organic cultural management practices.