Watering

The installation of a permanent irrigation system is well worth considering.   The frequency and amount of watering your trees will require is dependent on a number of factors such as rainfall, soil type, evaporation rates, plant requirements etc. and will vary from season to season and from site to site however, as a general rule of thumb one good deep watering once a week should be sufficent for  most established trees planted in the ground in a normal season and is far more beneficialthan numerous small water applications every day or so for your trees.

Potted trees require much more frequent watering than trees planted in the ground. Potted plants may need to be watered every day during the heat of summer whilst conversely, the same plant may only need to be watered once or twice a fortnight in the middle of winter. The best way to tell if your potted fruit tree needs to be watered is to check how moist the potting mix is and then water the tree before the potting mix starts to dry out.

Note:

If potting mix dries out to far it can become hydrophobic.  A potting mix that has become hydrophobic actually repels moisture and is very difficult to re-wet.  When water is applied to a potting mix that is hydrophobic the water will “Track” through the potting mix and not be absorbed by the mix.  The application of a wetting agent such as eco-hydrate and/or submersing the pot in a large container of water and allowing it to soak for an extended period of time will assist in correcting this condition however, prevention is the best cure.  The regular monitoring of your plants water needs is by far the easiest and most effective way to keep your plants potting media from drying out too much and thus placing your plant under undue stress.

Weed Control

Fertilising

Apply fertiliser after new growth starts to appear (usually in 2-3 weeks).   We have found that a good rule of thumb for young trees is to apply small quantities of fertiliser every 6-8wks during the growing season (mid-August thru to early May in SE Qld) in conjunction with a biweekly application of a seaweed extract. If you do not want to use chemical fertilisers the use of a good quality organic fertiliser is a good option.  Application rates will vary from product to product so we strongly recommend you read the label first before application of any fertilisers. Poultry, horse or cow manures can all be successfully used on fruit trees as long as they are applied when they are well rotted.  The use of fresh manures will damage trees and should be avoid.  You will have to apply a larger quantity of organic fertiliser to achieve the same results compared to man-made chemical fertilisers. This is necessary because you have to compensate for the lower  levels of nitrogen found in organic fertilisers compared to that found in an equivalent volume of man-made fertiliser.

To achieve the best results from fertiliser application, all mulch from around the tree should be rolled back out of the way to allow the fertilisers to be applied directly to the soil surface.  The fertilisers should then be watered in thoroughly and the mulch reapplied.

Protection from Harsh Weather Conditions and Wildlife

All young trees are susceptible to harsh weather conditions and may need protection from the hot sun, drying wind or other harsh weather conditions such as cold/frost.  We have found the use of commercially available tree guards and/or structures made from shade cloth and/or hessian material is very effective in protecting/reducing damage to young trees.

This type of protection will benefit all young trees and especially tropical trees such as Lychees, Star Apples, Carambolas etc. however, special mention must be made of Avocados as they are especially sensitive to the over exposure of their stems to direct sun light.  Unprotected avocado stems will sunburn very easily which stress the plant and provides an easy access point for disease.  It is therefore highly recommended that their stems be protected from direct sun light by either painting the trunk with white water based paint or by providing shelter structures as mentioned earlier.  This should be done for the first 1 or 2 years after planting out or until the trees are large enough to provide shade for themselves. 

Hares, wallabies and/or any other plant eating animal such as your pet sheep, cow or goat do not differentiate between your newly planted fruit tree and their regular food sources and will make a quick meal out of any unprotected trees.  We therefore highly recommended that you place some form of fence or wire mesh guard around your trees if animals can get access to the area where your trees have been planted.  These guards do not need to add a lot of additional cost to each tree planting as the stakes for the tree guard can also double as a support for your wind break or even as the tie stakes for your tree’s support and the wire mesh can be reused many times.  Guards are a good investment/insurance even if they only save your plants once.

Mulch

The application of mulch is very important to maintain the health and vigour of your trees. Not only does mulch help retain precious soil moisture, thus reducing the need/frequency of watering, it also help insulates the plants feeder roots from the hot sun helping to maintain a constant soil surface temperature thus promoting healthy root growth.  Mulch also suppress the growth of weeds that compete with your tree for both food and water and helps to improve soil structure and thus its fertility by adding nutrients and organic matter to the soil as it decomposes.

As with most things though, too much of a good thing can have its down side.  The application of a mulch layer thicker than 100mm, whilst keeping moisture in, will also prevent moisture from light rain events from reaching the soil around your tree’s root system.  We therefore recommend that mulch is only applied to a maximum thickness of 100mm around the trees. 

Because mulch breaks down over time, it should be topped up on a regular basis (usually in August and again in December).  There is a myriad of organic materials available that will act as a good mulch (e.g. straw, hay, chaff, etc.) however, if available at a reasonable price, we have found that Soybean stubble or Lucerne hay/chaff is exceptionally good and is well worth using.  The only down side for this product is they do break down quiet quickly and need to be replaced every few months. 

If you choose to use fresh lawn clippings we recommend you only apply a thin layer, 20-30mm, of this material around your trees. This will permit the grass to start to break down before it begins to rot and become smelly.  The application of layers of green lawn clippings thicker than 30mm can result in the material remaining too wet.  This can invite mould problems, create smelly decay issues and can compact down to create a layer of material that actually repels moisture. 

Fruit Fly Control

The Queensland Fruit Fly (QFF) (Bactrocera tryoni) is a native insect pest that is endemic to eastern Queensland and north-eastern New South Wales but can now be found anywhere throughout eastern Australia.  QFF will infest both indigenous and introduced fruits alike and if left  uncontrolled, can destroy entire fruit crops.  QFF activity is at its greatest in warm humid conditions and therefore damage is normally more severe during mid and late summer than at other times of the year however, fruit fly activity is not strictly tied to a particular season.  If favourable weather conditions are present, fruit flies can continue their life cycle through into the cooler months provided suitable host fruit or vegetables are present.  This information is particularly important to the grower who wishes to  produce home grown fruit or vegetables as it gives him an indication as to when his fruit will be most prone to attack.  

The simple fact is, all fruit and even some vegetables grown here in S.E. Queensland are potential targets for fruit fly attack.  As a fruit grower, you have the 3 main methods available to you to overcome this pest:

            a.         Spraying,
            b.         Traps/baits, or
            c.         Exclusion.

Spraying   Spraying as the name suggests involves the application of a chemical to the crop to kill the fruit fly and/or its larvae.  The chemical used can be either man made or organic but this form of control generally only lasts for a relatively short period of time before it has to be reapplied.  Whilst we normally recommend the use of organic/low toxicity gardening methods, we acknowledge that, in some cases, it may be necessary to use harsher chemicals to bring a fruit fly population under.  Once you have a severe outbreak under control, you can then return to the use  of less drastic control methods. No matter what chemical you choose to use  ALWAYS read the labels, follow instructions concerning application methods, take notice of withholding periods and NEVER use more than the recommended application rates. 

Note.

The use of the chemical Fenthion (Lebaycid), which is one of the man-made chemicals that has been commonly used for fruit fly control in the past, is now being phased out for all pre and post-harvest use.

Traps/Baits  Traps and attractants are designed to lure and kill fruit flies and are an effective means of reducing the number of fruit fly in the garden. The Wild May fruit fly control system is an example of one of the organic trapping control method and it is one that we have personally used with good success. A number of other commercial systems are available and many homemade version can be found on the internet.   

Eco-naturalure is an example of an organic baiting system that provides excellent results when used as per directions.  It contains a fruit fly specific protein attractant that attracts both male & female fruit fly and a bacteria-derived insecticide called spinosad  which kills  both the male and female fruit flies.

Exclusion   Exclusion refers to the use of a physical barrier to stop female fruit fly from reaching your fruit or vegetables. This can range in size from a net/enclosure that covers an entire orchid down to single bag to cover an individual fruit. The use of old mosquito nets purchased from your local Op Shop is one low cost method we have seen used.  This method works quiet successfully however it can cause damage to the tree if the net is left on too long as the tree can start to grow through the net.  The method we prefer to use consists of  a simple hoop structure that is  positioned over your tree and constructed out of  poly water pipe and star pickets.  This is then covered using with a fruit fly exclusion netting that comes on a 3m wide roll.  The net is held off the  tree by the hoops and therefore will not damage/deform the new growth of the tree or be damaged itself as the tree starts to grow.  Another method we have heard of consists of the use of fly screened outdoor gazebos that have zipped sides to allow easy access for regularly inspection of trees and fruit harvest when it ripens.

No matter which of these methods you use, all nets must be either secured to the ground or around the tree’s trunk. If you are unsure as to whether there are fruit fly pupae in the ground under your fruit trees, it is advisable to  secure the bottom of the net to the trunk  of the tree so as to prevent any adult fruit flies emerging from the ground within the netted area and infesting your new season crop. 

An alternative to the total netting of your tree is the use of individual fruit bags or sleeves.  The bag or sleeve should be placed over the fruit you want to keep and tied off to exclude the fruit flies. The bags and/or sleeves need to then be secure to the plant with either a tie wire, clothes pegs or strings so that they are supported and don’t place undue strain on the fruit.  Once you have covered sufficient fruit for your needs any remaining flowers or developing fruit needs to be removed from the tree.

Cultural Hygiene

No matter which method of control you choose, some basic house-keeping is essential to reduce the impact QFF will have on your fruit crop.  No ripe fruit should be left lying under the fruit tree, as this creates an ideal breeding ground for the fruit fly. Spoilt fruit should be disposed of by either feeding it to poultry, immersing it in water for a period of time, or by placing the fruit it in a sealed black plastic bag  and leaving it in the sun for 5-7 days.  An alternative to placing the bag in the sun is to place the bag in a freezer for a couple of days. Both of these methods will destroy the QFF eggs and maggots thus preventing adult flies from developing. The bagged fruit can then be discarded in your garbage bin.

Thinning of Fruit

It is recommended that all fruit should be removed from your fruit trees for the first year after planting out into the ground.  This permits the tree to concentrate on producing a good root system for itself without the additional stress from fruit production.  Older trees may also benefit from the removal of some of their fruit load if excessive fruit set has taken place.  This practise is regularly carried out by commercial growers to promote the production of larger fuller fruit.

Pruning

Pruning of any sucker shoots originating from below the graft on a grafted tree is essential and should be done as soon as they are spotted.  Particular notice should be taken when a tree is young to check for this growth as any unchecked growth can easily over take the grafted portion of your tree, subdue the graft and/or kill the graft.  The resulting tree may, in the best case, produce a different quality fruit than originally expected or in the worst case, a tree that produces no edible fruit at all.

Other than the removal of sucker shoots, your fruit trees will need to be pruned often during its life.  This is necessary to establish your tree’s basic framework, promote good fruit cropping, and maintain its shape and/or size and to invigorate it when it gets older.  For example, most deciduous fruit trees will need an annual pruning to promote new growth/fruiting wood on which the next year’s crop will be born.  

With the large diversity of fruit trees now available to the home gardener, I am not going to go into specific pruning details or techniques here.  I suggest you consult one of the many good reference books written on this subject to obtain the specific pruning methods/ instructions applicable to your needs.  These are readily available from your local library or on line however, as is often the case, reading a text book is no substitute for someone demonstrating to you how to do a task and/or providing practical hands on experience.  Gardening groups, organic growers and fruit tree enthusiasts often hold field days specifically on pruning.  If you feel uneasy about pruning your trees after reading up on the subject, I would encourage you to seek out one of these groups and see if they can provide you with the practical experience/details you need.