Wednesday, 13 July 2016

Pruning workshop with Ian Clarke

One of our elders, Ian Clarke, donated an entire day to teaching the community some of his 54 years of experience as an orchardist. What follows are some of his techniques of pest mitigation, pruning for abundance and slowing down growth. We began the day at the library community garden, pruning the apple trees Patrick planted in 1999 as chemical-free community free food.

One of the challenges of keeping apple trees is knowing how to maintain them to a height that can be netted without causing the root ball to create an oversupply of watery sap, which attracts wooly aphids. These trees are infested by them because of our previous pruning regimes. Ian had much to teach us.

James is shown how to put a bevel cut on the pruned branch with a pocket knife to expedite the healing process. If the bevel isn't applied the cut is prone to splitting and opening due to frosts. In these gaps diseases get the upper hand, such as silverleaf.

Over the day about 40 people participated in rare sunny weather. This winter has been more traditional than recent ones — bloody wet and cold.

Ian hands around a branch that shows the dreaded silverleaf fungus. It smells like rotting apples, and can very likely kill the tree.

Ian then showed us how to give a tree a girdle cut. This is not ring barking, which would create a complete ring around the tree and kill it. The girdle is instead an incomplete spiralling cut and used when it is not possible to root prune.

Here's the cut as it is finished. The idea is that the sap flow will be slowed because it cannot flow directly upwards, which in turn will slow the tree's growth for the next few years. Because we took about 50% off the canopy (because the trees are too high to net) we needed to make a girdle cut as the root ball will over feed the tree next season, causing pests such as wooly aphids to infest again on all the extra sap flow that the canopy cannot use up.

After each cut, we painted it to seal it off from disease.

We loaded up the ute trailer with the infected wooly aphid prunings. We'll need to burn them into biochar before the aphids awake in the spring, otherwise we can expect more infestation.

After lunch we moved on up to Rea Lands Park where more folk joined us for the afternoon workshop there.

Each tree has its own logic, says Ian, understanding it will make us better orchardists, (e.g. turning upright branches into laterals for greater fruit production, and knowing which branches to leave and which to remove.

A HUGE thank you to Ian for his generosity on Saturday. He has offered to do more for DCFG in the months to come. Ian also kindly sent us his notes for organic treatments of trees. Here they are:


Lime Sulphur

This corrosive compound is applied to deciduous fruit trees in their fully dormant stage, i.e. when all the leaves have fallen, typically late June or early July.  Lime Sulphur will clean up mosses & lichens on trees, kill over-wintering mite eggs & larvae, scale insects, woolly aphids and fungal spores.

Full waterproof protective clothing, including a facemask, is suggested when applying Lime Sulphur, not because it is toxic but because it is a skin and eye irritant.  It is also very smelly & the smell is difficult to remove should this spray contact the skin.  You may be sleeping with the dog if you get much skin contact!  Remember always to keep other family members well away from your spraying activities. 

Cover any desirable plants under & around your fruit trees prior to spraying.  Plastic sheets are ideal for this.

The secret of any good spraying is in the thoroughness of application.  Choose a day when the trees are dry and there is little wind.  Mix fresh Lime Sulphur at 5% (7% if scale insects are present, or if there is significant lichen) with water.  Spray the fruit trees very thoroughly.  Make sure you get the spray into the all the nooks & crannies under pressure, as this is where the nasties hide.  Pay particular attention to the vee's of branches and loose & flakey bark.  The spray should be running off the trees if you are doing a good job.     

When you have finished, wash & clean your spraying equipment very carefully as any residual Lime Sulphur may corrode metal parts & affect seals.  It may also have a detrimental action on the next spray your put in your sprayer.  Pump clean water through your sprayer until all traces of Lime Sulphur are gone.

Lime Sulphur gets fruit trees nice & clean and provides a good base on to which to apply spraying oil. 

Spraying Oil

This is water-soluble oil and is best applied as late winter oil at 2.5% concentration.  It is valuable in the control of mite, scale insects & insect larvae.  Spraying oil works by a smothering action, so, again, complete coverage is important.  As spraying oil is essentially non-toxic, full protective clothing is not essential, however you will need to wear full waterproof clothing, including facemask.  Again, cover tender plants under the fruit trees. 

When to apply a late-winter oil?  This varies considerably from season to season, also with the location and the variety of the fruit tree.  The time spread can be from mid-July to late September in the Southern Hemisphere.

STONE FRUIT should have late-winter oil applied at Bud Movement and your powers of observation will be need to determine when this is.  If you look carefully at a bud on stone fruit trees you will see scales covering the bud.  Bud movement is when these scales appear to start to slide one over the other.  A lighter area will start to appear on the scales.  The colour change is quite subtle.   Use a pocket microscope to help you see what is happening.     
On PIP FRUIT apply the oil spray at Green Tip.  This is easy to see, it is when the very first tiny green tips start to emerge from the buds and will vary with fruit variety.  Apply the spray as soon as you see these green tips, don't delay.

Your Oil Spray should always be combined with a Copper-based spray.


The products usually used are Copper Oxychloride or Cupric Hydroxide.  Try to obtain the latter as putting chloride products onto your land is not good.  Wear full waterproof clothing including a facemask when applying Copper products.
 On stone fruit, the first copper spray of (usually) three is combined with an oil spray as detailed above.  
On pip fruit usually only one copper spay is used, again combined with oil.

Pip Fruit; apply the Copper & Oil spray at Green Tip as detailed above. 

Stone Fruit; apply the Copper & Oil spray at Bud Movement, as above.  Two more sprays of Copper only are advised to protect the buds as they continue to open, typically over the next 10 - 14 days.  This is to prevent airborne fungal spores from entering underneath the opening bud scales.

After each spray remember to wash your sprayer thoroughly to remove residues.

The combination of Lime Sulphur, Oil and Copper sprays provides the basis for good orchard hygiene.  Eliminating as many problems as possible at this early stage is very much easier than waiting until they have compounded later in the season.  

Get the basics right and you are much more likely to have a successful crop of fruit from your trees.

Notes on sprays prepared by Ian Clarke, Daylesford