Wednesday, August 8, 2012

Training Systems in Intensive Apple Cultivation: Slender Spindle


This post is in continuation of the previous post on Training Systems in Intensive Apple Cultivation: Trellis. This post explains about the Slender Spindle training system further modification of spindle bush training system.

Slender Spindle:

This is the system preferred by growers who wish to work exclusively from the ground and are not confident in building wire support systems. The slender spindle (SS) consists of an individual support post at every tree.

Slender Spindle Support System:

The post should be 2.4 - 3 m in length and of pressure-treated wood, concrete or metal to ensure it lasts the life of the orchard (perhaps 12 - 18 years). A diameter of 4 - 6 cm is preferred, since risk of frost heaving increases with larger diameters. The depth of the post in the ground should be 60 - 90 cm for stability leaving 1.5 to 2.5 m above ground. A common mistake is to have insufficient post height above ground.

Slender Spindle Training Pruning:

The tree is trained to a slender bell, or pear shape with the bottom whirl of branches acting as a permanent fruiting table. The leader and top of the tree is kept quite weak to contain height. Renewal pruning of mature trees consists mainly of removing 2 - 3 of the largest diameter branches on an annual basis during the dormant season.  Tree height does not exceed 2 - 2.5 m.

In the next post I shall be discussing about the Vertical Axis or French Axis training system. This system is followed mainly in France having average productivity of about 42 Tonnes per Ha.

Monday, August 6, 2012

Training Systems in Intensive Apple Cultivation: Trellies

This is in continuation to my previous blog on Training Systems of Apple Trees in Intensive Orchards where I mentioned about three basic training systems of apple trees in intensive cropping i.e. high density apple plantations. Today I am going to discuss about trellis.

Trellis:

Why trellis or any other support system based training system should be adopted for the HDP on clonal rootstocks. As you are now aware of the fact that the production can be optimized by harvesting 70 per cent of available light. Further the wood produced and fruit produced ratios are to be optimized. Why we produce wood? Wood is produced for structural strength. This is the reason for growing larger trees on strong scaffolds. If we want to grow HDP we must understand that support system is necessary to reduce wood production. This helps us in growing the trees with more fruiting wood than the structural wood. Therefore the production can be started at early stage of the plant/ orchard life. If the production can be taken as early as two to three years of planting, the breakeven point of orchard establishment can be met earlier.

The system basically consists of one or more high tensile steel wire(s) drawn tight and supported 2 - 3 m above the ground by a series of in-line posts spaced 6 to 10 m apart. The closer the spacing for the inline posts, the higher the degree of stability of the support system under strong wind or high crop load conditions.

The trellis support system is somewhat more complex than the Slender spindle and vertical axis to install. It does require a high level of skill to build the support system and be sure it is adequate to hold the trees and crop load. A post failure in this system can result in the loss of several trees. The standard anchoring system now in use is the "auger anchor" which is screwed into place. Posts are generally pounded or watered (water gun) into the ground.

The key problems of trellis systems are varieties with excessive vigorous or strong rootstocks that result in excessive pruning to contain the tree. Also, trellis systems support the total weight of the crop load and, as a result, must be exceptionally sturdy with posts for wire support located every few trees in the row.

In coming posts I shall be discussing about Slender spindle, Vertical Axis and Super Spindle training systems.