Since the 1970s, fruit scientists have understood that quality of tree fruit crops is related to the exposure of the fruit and the surrounding leaves to light. This has led to more narrow canopies with higher light distribution which resulted in improved fruit quality. Concurrently, pioneers in high-density plantings have shown that early yield and cumulative yield are higher and fruit quality is better with high-density orchards and this has resulted in large improvements in lifetime profitability. Since the early 2000s, there has been a trend toward even more narrow canopies (fruiting walls) often termed 2-D systems. Those advocating these narrow systems report improved fruit quality and the possibility of easier mechanization, especially now that robotic mechanical harvesters are being developed. However, there is little data indicating that such canopies will outyield more traditional high-density canopies and more importantly that they are more profitable than a 3-D high-density system. This presentation is aimed at stimulating a scientific discussion of the value of 2-D systems and whether they represent an important leap forward in tree fruit production from an economic perspective.
Canopy Management of Fruit Crops
Canopy and yield management begin before vineyard establishment. The concept of vine size and balance are important to achieving a manageable canopy and fruit zone. The grower is trying to balance the vegetative and reproductive processes of the vine, and the first steps are choosing the correct site, correct cultivar/rootstock, and the correct vine spacing.
Good canopy management begins with careful and proper vine training with special considerations given to canopy architecture, such as overall canopy height and fruit wire height. These dimensions will have great implications for the performance of canopy and fruit. The choice of training and trellis system, e.g. cane or cordon, VSP or high wire, single or divided systems, will impact canopy design, performance and management.
Wire moving is also a key part of shoot positioning. If it is done properly and in a timely manner, it can greatly enhance canopy architecture and reduce the amount of hand positioning needed. Timing is probably more critical for wire moving than any other canopy management practice. Wires are moved when shoots are rapidly growing. If done too early, the shoots will not stay in place. If too late, it becomes necessary to bend and tuck shoots, which often leads to breakage. Movable catch wires are preferred over fixed wires so they can be pulled away from the canopy and used to sweep shoots inside the wire and into an upward position. In most cases, two to three pairs of movable catch wires are adequate for this task. Shoots can be held in place with wire, plastic clips, or branch locks.
The purpose of leaf removal is to open up the interior of the canopy to light and air to help promote fruit ripening, reduce disease pressure and increase spray coverage. If conducted correctly, the benefits to grape quality can be dramatic as exposure can enhance fruit and wine flavor, color and wine texture.
Leaf removal can also take the form of lateral removal, which is sometimes preferred to retain basal leaves that protect fruit from sunburn while opening the interior of the canopy. Tunneling is a practice where lower, interior leaves are removed. This must be done by hand and is time consuming and expensive. It may be required where vines have high vigor and bigger canopies.
On a vertical shoot position system, other late-season canopy management practices include hedging, often on the sides and top of the canopy. The application of bird nets will also have an effect on canopy configuration and needs to be taken into consideration.
It may be necessary to repeat these canopy management practices later in the season to achieve the desired effect. For example, leaf removal may require an early, mid- and late-season pass. Crop thinning may also require multiple passes to get the crop size just right.
Canopy and fruit zone management are two distinct concepts and practices that are intertwined and anything done to one will affect the other. Crop size can affect vigor of a vine and is sometimes used to slow down vegetative growth. The canopy represents the solar panels that catch sunlight to convert to sugars and enhance ripening. The sugars also are used for energy to drive plant metabolic processes, including those that synthesize flavor, color, and phenolic compounds that characterize each variety. Manipulation of the canopy has a direct effect on fruit chemistry, composition, and quality.
Canopy Management Practices means bud fruitfulness and fruit yield per node. These practices include trellis-training systems, shoot positioning, shoot orientation, shoot trimming, leaf removal in the fruiting zone, control of shoot number and spacing, and control of shoot vigor. Canopy management of fruit trees deals with the development and maintenance of their structure in relation to size and shape to obtain a yield and best quality.
In simple language it is merely the manipulation of trees canopy (all the foliage and branches) in order to provide aeration to plant for better crop production. Canopy management is one of the most important fruit plant management practice. This forms the basis of the precociousness and longevity of the fruit trees in an orchard. The strong scaffold system help the trees to produce heavy crop loads of quality fruits without any major limb breakage. Regular annual pruning is essential for the induction of good amount of new Shoot growth. which will provide the tree maximum fruit bearing area uniformly over the whole tree. Un-pruned trees grow beyond limits provided for each tree in an orchard.
The basic objective of canopy management is to maximize light interception to optimize light distribution within canopy and to maintain proper airflow. In new plantations initial training and pruning is given to develop a strong framework of the tree whereas in old plantation the aim of canopy management is to reduce tree height and make provision of solar radiation inside the canopy by thinning excessive biomass. The objectives of canopy management are
Training: Basic objectives of training is to control vegetative vigour, increase light exposure for fruit/ foliage, increase air flow to prevent disease infestation and facilitate pruning and harvest methods and mechanization. While deploying the training systems, utilization of vertical and horizontal space should be taken into consideration. The choice of training system is a part of whole orchard management influencing planting distances, light interception and finally the success of the orchard in terms of obtained fruit quality and quantity. The various training methods that are used to control tree growth in many orchards are:
Cordon system: This is a system where in espalier is allowed with the help of training on wires. This system is followed in vines as these are incapable of standing on their stem. This can be trained in single cordon or double cordon and commonly followed in crops like grape and passion fruit.
Unmanaged tree canopy not only reduces the productivity of fruits but also detoriates the quality of produce as well. It enables profitable cropping, high, regular yields and improved farm management practices, leading to higher productivity. This system of management produces high and regular yields of good quality fruits and low labour requirement to meet ever rising production costs.
Tree canopy and bearing volume are two important factors in fruit production and fruit quality. Generally, trees with larger canopy and bearing volumes produce more fruit than smaller-canopy trees. Canopy management is an important aspect of citrus production in Florida to avoid problems associated with overcrowding and excessively tall trees, to improve light interception, and to improve pesticide distribution into the canopy, as well as to facilitate equipment operation within the grove. Proper control of vegetative growth is essential for the maintenance of healthy, productive citrus trees. The effect of insufficient light is frequently observed in mature citrus groves that are not managed regularly. Shading reduces yield and foliage on the lower parts of the trees. Sunlight not only influences flowering and fruit set but also enhances fruit quality and color development. Increased sunlight penetration within the tree canopy might also allow foliage to dry more quickly after a rain shower and could help reduce establishment of fungal pathogens. Therefore, adjustments must be made to the tree canopy to maximize sunlight interception.
Pruning is one of the oldest horticultural practices that changes the form and growth of a tree. The pruning process (1) adjusts tree shape and the ratio of the framework to the fruit-bearing shell of the canopy, (2) alters the shoot/root ratio, and (3) changes the carbohydrate (food storage) status of the tree. Pruning healthy, mature citrus trees can reduce yields in proportion to the amount of foliage removed and can delay fruiting of young, nonbearing trees. Pruning should therefore be limited to that required for future canopy bearing-surface development and to conduct efficient cultural and harvesting operations (Figure 1). Under Florida weather conditions, citrus trees often produce vigorous vegetative growth, which can result in overcrowding and shading. Therefore, canopy management is very important. In general, tree response to pruning depends on several factors, including variety, rootstock, tree age, growing conditions, time of pruning, and production practices. There is no fixed set of rules, and therefore each situation should be critically analyzed before any severe canopy management decisions. Growers are encouraged to gain a clear understanding of the basic principles regarding pruning and to take advantage of research results as well as to consult knowledgeable colleagues and custom operators for their observations and recommendations. 2ff7e9595c
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