Pruning key to productive citrus trees: Miers

By GEOFF MIERS

Citrus trees are among the most productive fruit bearing trees that thrive in Central Australia. While with regular care they generally are easy to manage you do have to recognise problems and appropriately manage them.

Fertilising and irrigating to meet citrus tree needs are essential to produce quality and consistent fruit. Pruning is the third key to having highly productive trees.

Managing the growth of citrus trees by regular pruning will result in healthy trees capable of producing quality fruit and now is the time to tackle citrus pruning.

Citrus trees are a perennial crop that are capable of producing fruit annually for well over 30 TO 50 years (and longer) provided they are managed correctly. Low yields and poor quality fruit can largely be attributed to inadequate watering and a failure to provide sufficient nutrients.

Mostly these are the two reasons while citrus fail to produce good crops and fail to crop every year.

However inadequate management of the trees growth through a lack of pruning is the third major reason trees can produce reduced yields.

Pruning of citrus has essentially three main objectives that focus on improving fruit quality and annual yield consistency, improving plant health, maintaining tree size and shape improving management and harvesting efficiency and lastly assisting with the management and control of pests and diseases.

In the first instance all dead wood should be removed from the tree, followed by any unwanted sucker growth from the main trunk.

Most importantly any growth from below the graft should be removed as this will produce timber that will outgrow the rest of the tree, timber that will only produce wild or rough lemons that are generally useless. This growth will overtake the rest of the tree and in time will become the dominant tree.

While not a difficult art to master pruning of citrus trees should be undertaken with care as sloppy pruning and careless management can cause considerable damage to the tree.

When undertaking any pruning as a general rule you should prune back minor branches back to an outward facing bud or leaf so the new regrowth will grow outwards on an angle as against growing into the tree and being forced to grow upwards generally putting the fruit out of easy reach.

With minor branches pruning should be a simple task, a one action activity with a pair of secateurs, pruning on an angle with the highest point on the same side as the bud approximately 3-4mms above the top of the bud. The lowest point of the prune should be 1-2mms just above the bud.

The most common mistake is people prune half way between the buds of leaves. The wood left will never produce new growth and will in time slowly dieback, sometimes dying back well below the bud or leaf resulting in continues die-back of the branch.

When pruning a larger branch its best to do this in at least two stages. Saw off the branch well above where you finally want the branch trimmed back to. Often when pruning a larger branch in one action the weight will crack and tear off simply due to the weight the branch is carrying. 

Once having decided where you will make your first incision cut into the lower or underpart section of the limb approximately 30% to 40% in and then commence cutting above this incision and the branch should break freely from the tree without tearing of cracking the limb.

Wound healing over.

Once the major part of the limb has been removed you then repeat the exercise this time without a large weight being carried on the section you are removing.

When cutting off a larger limb completely you need with your final cut, cut back to flush with the collar. The collar is generally visible at the base of the branch.

By pruning off flush with the collar without damaging the collar this collar in time will completely grow over the wound sealing off the cut completely and thus limiting the entry of pests and disease into the tree through the wound.   

Fungal diseases can be a common problem experienced with trees in Alice Springs. The fungal spores can drift through the air and settle on different parts of the tree, can attach and multiply and before you know it you have a major problem that is capable of eventually killing the tree.

Addressing fungal systemic diseases can require several treatments and its best to seek expert advice and seek out the correct solutions. Sometimes trimming back lifting bark and treating with a copper spray is sufficient while in other instances a systemic fungicide is the solution. 

Photo one: Prune closer to the leaf node and prune with the highest point on
the same side as the bud or leaf node. Left as it is the prune will commence
dying back.

Photo two: Pruning a larger branch should be at least a twofold process. In
this photo the pruner has attempted to prune in one go and the weight of the
branch has torn off doing considerable damage the branch that was to be
left. First you should prune way up above where you want to prune, cut
underneath first then on top. Once the heavy part has been removed then
prune back to where you wish to prune without damaging the branch.