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Right time to prune Apple Tree & Disease

Posted on | January 2, 2012 | No Comments

Right time to prune an Apple tree is in winters (dormancy), reason because the apple tree draws down its energy supply from the smaller branches after leaf fall, and stores it in the main trunk and root system. It is important to appreciate the significance of this, for it has implications for the re-growth of new branches, growths in the spring if winter pruning of apple trees takes place. Pruning in the winter season, should therefore be carried out as late as possible usually one month before bud break in order to avert this vigorous flush of unwanted growth and also disease. Most of these growths will be tall upright shoot, sprouting out from the main branches. This growth is  known as water shoots and have no use for fruiting, though one or two of them can be retained for future training if needed. Hard pruning in the winter months will result in much excess growth – taking away much of the energy required for flower and fruit production.

 

Disease Development and pruning

Growth and dissemination of the bacteria are favored by cool & wet weather. Wounds need to  be present on the tree for infection to occur by any reasons. It can be caused by pruning cuts, frost or snow damage or leaf scars that are present in the fall after the leaves drop. Most common and dreaded disease for fruit trees known as Cytospora canker, a fungal disease, commonly infects trees as they mature. Studies have shown that late fall and early winter pruning increase the incidence of bacterial canker compared to late spring pruning. By summer, there is a decreasing potential for infection. It may, therefore, be wise to prune infected blocks, or at-risk blocks during the summer to lessen the potential for infection.

 

When pruning, it is important to take weather conditions into consideration. Newly created

wounds with the presence of rain are ideal for  infection to take place.

Bacterial Canker Management, we suggest a time gap between pruning and climate (Rains)

 

Time after pruning  Percent infection
0 hours 8%
24 hours 2.3%
72 hours 0%

 

These given time periods can avoid the problem of canker and can be followed as a precaution for the incidence of rain after pruning. In other words, it would seem wise to stop pruning fruit trees if rain is predicted within 72 hours of pruning.

Factors that predispose fruit trees to infection  include wounds, frost damage, improper soil pH, poor nutrition, excess nitrogen, and nematodes. There is a direct  relationship between higher infection levels and proximity to an old orchard.

Besides pruning cuts, one of the major causes of wounds on fruit trees is from winter injury.

Pruning & Training

Young fruit trees are pruned to make them to become  structurally sound for the coming fruit bearing years, to make them easy to take care of and to ensure the production of high quality fruit.

Advantages of Fruit tree Pruning:

  • Control tree structure for easy maintenance and for harvesting.
  • Gives strength to tree structure – develop strong branch structure
  • Sunlight and air distributed evenly throughout the tree
  • Fruit bearing gets regulated– removes excess vegetative fruit wood growth
  • Vegetative growth gets better – which helps strong buds and flowers
  • Undesirable wood gets removed – dried -dead, broken, and crossed branches.

The right time of the year  to prune fruit trees is the dormant season, Mid-December, January (best) which again depends on the orchard location, because it varies with the height usually 10 to 15 days and until the middle of February.

Types of pruning :

  • Thinning – is the removal of the entire shoot from where it originates this happens usually where excess vegetative growth happens or in case of un-maintained Fruit tree. Scissors/saw type pruning depends on growth with closer cuts. Close cuts heal faster while cut with stubs will be more susceptible to infection e.g. Canker.
  • Heading is the removal of the top part of a branch. In a heading cut select the right bud because the bud points the direction of the new branch.

When cut, the lateral bud becomes the terminal bud and growth continues in that direction. Strongest growth goes to the terminal bud.

Pruning Systems

  • The Central Leader System makes a small tree, about half the size of a vase type. Excellent for distributing of sunlight and air. Second year selects three to five lateral branches, lowest about 18-24″ height from ground, spaced evenly around tree,1 ½to 3 ½feet distant vertically. Head leader and laterals that may compete with the leader. Following this process of pruning for the coming years to develop another series of laterals every two to three feet higher up the central leader. It will be necessary to spread laterals physically when five to six feet long in order to form a proper angle (about 45°) with the trunk also can be done by support.
  • “Y” Type System starts at the 2 ½ of height as other systems. This system makes a fruit tree easy to train. Usually good for Apple, peaches,pear and plum. Space trees eight to ten feet apart in rows 18 feet apart. The “Y” is perpendicular to the row. Lateral branches should be developed from all side of each arm of the “Y.”
  • The Open Center System or Vase-Shaped System this pruning system  can be used on all types of fruit and nut trees. Good for pears and almonds. When pruning is done in the 1st year three to four limbs distributed evenly around trunk should be selected. A small growth on these branches should be left for early fruiting and sunburn protection. In the 2nd year select two or three limbs on each primary. Heading can be done on these back to ½ their length (24-30″). Rest all growth should be removed.

 

How  and when to Prune Fruit Trees basics

  1. Tree pruning should be done when the leaves have shed fully (In dormancy from mid Dec to Mid Feb). It’s easier to see what you are doing and removal of dormant buds (growing points) invigorates the remaining buds. Summer pruning removes leaves (food manufacture), will slow fruit ripening, and exposes fruit to sunburn. Summer pruning can be beneficial, however, when used to slow down overly vigorous trees or trees that are too large. It is usually done just after harvest.
  2. Right after planting a new tree, cut if off to short stick 18 to 24 inches high and cut from any side of shoots, remaining below that, to one bud. This encourages low branching and equalizes the top and root system. Paint the tree with lime paint to protect it from sunburn and borer attack.
  3. Young trees should be pruned fairly heavily and encouraged to grow rapidly for the first 3 years without any fruit. Leave most of the small horizontal branches untouched for later fruiting.
  4. Making out which branch to cut and from where to cut it, remember that topping a vertical branch encourages vegetative growth necessary for development of the tree and opens the tree to more sunlight. Topping horizontal branches is done to renew fruiting wood and too thin off excessive fruit. Horizontal branches left uncut will bear earlier and heavier crops.
  5. Mostly all upright branches usually remain vegetative and vigorous. Horizontal branches generally are more fruit bearing. A good combination of both is important, for fruits and  for the overall health of tree in coming years. Suckers, water sprouts and most competing branches growing straight up into the tree should be removed. Branches that are bending downwards lose vigor and only  produce few small fruit; cut off such branches.
  6. New shoots growth happens right where the cut is made and if its not clear or stub is there it can give growth to 2-3 shoots which are a waste of tree energy reserve; the influence of the cut only affects the buds within 1 to 10 inches of the cut surface not 3 to 4 feet down or above. The more heavy pruning gives more vigorous growth to the new shoots.
  7. Most of the pruning can be done in the top of the tree so that the lower branches are exposed to sunlight and air in summers. Sun exposed buds remains fruitful and produces the best quality fruits. Shaded branches eventually stop pollination, fruiting and sometimes result in infection.
  8. Cuts should be clean and close (within ¼”) of bud; without stubs.
  9. Make use of spreaders or tie down branches to get 45° angles of upright vigorous growing fruit trees.
  10. Cherries only summer prune the first 5 years. Peach remove 50% of last year’s growth. Apple, Pear, Plum and Apricot remove about 20% of last year’s growth.

Abandoned or Neglected Fruit Trees Prunnnig

Old, neglected apple trees that haven’t been pruned for several years are often tall, densely branched, unproductive, and may contain a large number of dead branches. The fruit produced on neglected trees are generally small, poorly colored with a low sugar content, and affected by the disease. Pruning of these trees increases fruit size, promotes better color development, increases sugar content, and decreases insect and disease problems by allowing better spray coverage and faster drying following rainfall. Pruning also makes it easier to harvest the fruit.

Extensive pruning is the first step in the renovation of neglected apple trees. The primary objectives of pruning are to reduce tree height and to thin out undesirable branches for better light penetration. Complete renovation of neglected apple trees may take 2 or 3 years. Old, neglected apple trees can be rejuvenated by following the pruning procedures outlined below. Pruning is best done in late winter/early spring (late February to early April).

  • Have a specific purpose or plan in mind. In this case, the focus is to rejuvenate the tree into one that is structurally sound, functional, manageable and attractive in the home orchard or landscape.
  • Know the age and type of wood where fruit buds form. Your initial consideration with neglected trees, however, is a tree structure, and more detailed pruning will come in later years.
  • Prune out all dead, diseased, and broken branches.
  • Lower the height of the tree by heading back large, upright growing scaffold branches to outward growing laterals. Up to 4 to 5 feet of growth can be removed in one year. If it’s necessary to remove the more top growth, spread out the pruning over 2 or 3 years.
  • Remove undesirable interior branches. Prune out the weakest of crossing limbs and closely growing parallel branches. Also, remove limbs growing toward the center, strongly growing upright branches, and water sprouts. (Water sprouts are rapidly growing, vegetative shoots which develop on the larger branches or the trunk of the tree. They often form just below a pruning cut.)
  • Prune off low-hanging branches.
  • If additional thinning is necessary, remove the weak spindly growth. The amount of pruning will be determined by the density of branches. Prune sufficiently to permit some light to penetrate the center of the tree when in leaf.
  • Once rejuvenated, only moderate pruning should be required in following years. Prune apple and other fruit trees on an annual basis.
  • Though the apple trees may be old, good quality fruit can be obtained by proper pruning and timely spraying.

 

Too much pruning will produce a wilderness of waterspouts or excessive shoot growth and may increase the potential for sunburn near sun-exposed pruning cuts and interior areas. Stand back and look at the tree several times to visualize where to get started and the future structure desired. As you get started, keep the following in mind:

  • A few large pruning cuts accomplish more than many small cuts.
  • Over the next two or three years, direct pruning toward selecting well placed new branches as eventual replacements for the old higher ones. Control excessive shoot growth by thinning and heading those that are left. Leave the tree open enough for light penetration needed for fruit bud formation on the new interior shoots. Continue to head back and thin out the top of the tree, gradually eliminating the old top as newer branches take over.

When pruning, avoid leaving stubs or pruning cuts that are made flush with the point of branch attachment. Note the presence of branch collars. The branch collar appears as a swelling at the base of the branch where attached. Branch collars are rings of wood with living cells which protect the pruning cut and generate new tissue that covers the wound in time. Thinning cuts should be made at the edge of the branch, leaving the collar intact.

Once pruned, much wood and brush will have been removed from the tree. Heavy pruning tends to invigorate the tree and stimulate a lot of vegetative growth the following spring.

Avoid the use of nitrogen fertilizers at least for a year or two following this heavy pruning.

Not: Till now no research supports the use of wound healing paste/sealing materials on pruning cuts;we suggest leave them exposed to air dry after pruning.

 

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