Questions and Answers

If you can help us with any of the following questions, or have a question of your own, please let us know.

Pruning Stone Fruit

Q: When is it too late to prune stone fruit? I’ve been away and have just returned and my peach and nectarines look like the blossoms are about to open. Is it to late to prune at this stage? A: Peaches and Nectarines fruit on previous years wood so leaving the shoots from last year will encourage fruit this year. However if you want fruit next year you will have to encourage new growth this year which will involve some pruning. It certainly is not too late to prune when the trees are about to bud in fact some advice is that it is better to prune when the tree starts to show some life, as it reduces the risk of disease entering through the pruning cuts. Summer pruning is also encouraged, however do not be too severe as major pruning can produce sap weeping from the cuts and from the branch unions, as the tree is full of energy at that time

Walnut toxicity

Q: Walnut Toxicity – I have a three year old walnut tree growing in a section of my garden, growing very vigorously. When I purchased and placed it in my garden I was not aware of its toxic impacts on some plant species.

I have several Australian natives plus two pistachios in its proximity. I have searched the internet looking for impacts on Australian native plants but can find nothing. I do not want to risk losing the other plants if there is any chance that the walnut will kill them as it grows. My instinct is to remove the walnut tree but I would hate to do it unnecessarily.

A:  It’s called allelopathy and is basically the walnut tree protecting it’s turf by exuding a chemical called juglone, and it applies mainly to the American Black Walnut. What we call the English Walnut (actually Persian, and the one most commonly grown locally) does produce the same chemical but to a far lesser extent. There are numbers of them growing among native trees, in the hills, without any affect. There is little evidence of any research that has been done in this regard.

Many other tree species, most notable among them various eucalypt species, produce chemicals which also have an allelopathic effect on other plants.

Not letting the leaf fall in autumn remain to compost will help, as it is the leaves that contribute particularly to the juglone in the soil.

What is the best time to graft Passionfruit?

Q: What is the best time to graft Passionfruit?

A: Most grafting is done in late winter or early spring before new growth begins.

How are Feijoas pollinated?

Q: How are Feijoas pollinated?

A: It seems that feijoas need pollination by honeyeaters and even blackbirds from another tree in a neighbour’s garden. They are attracted by their sweet flowers.

Why do grafted fruit trees bear fruit sooner than seedlings?

Q: Why do grafted fruit trees bear fruit sooner than seedlings?

A: Grafted trees fruit earlier as the the bud used is physiologically more mature than seedling material hence it is “ready” to fruit earlier than seedling material.

Can Hazel nuts be grown successfully in Adelaide?

Q: Can Hazelnuts be grown successfully in Adelaide?

A: Generally only in the colder regions such as the Adelaide Hills, although there are some varieties that have lower chilling requirements.

Navel Orange Query

Q: What navel orange has flesh consistently the colour of a ruby grapefruit? The growers said that they were Washingtons, and the colour was due to their organic growing methods.

A: Valencias with colour are blood oranges but need the cold to achieve their colour. When grown in the tropics oranges can have very little colour, even be green skinned yet ripe, so maybe these navels are grown in a cold area to achieve their red colour.

The Cara Cara strain of navel orange has consistent ruby flesh. It is sold as ruby red navels.

Should a fig tree be fertilised in winter?

Q: Should a fig tree be fertilised in winter?

A: No you should not fertilize it in winter. It needs to “sleep”. Wait until spring to fertilize it. Quite often figs do better with compost and little fertiliser.

How are seedless grapes grown?

Q: How are seedless grapes grown?

A: They are propagated by removing sections of the plant called vine eyes. The bud where the leaf would grow is cut out, planted and roots form. Generally they are grown from cuttings.

Can someone ID this strange fruit for me please?

Q: Can someone ID this strange fruit for me please?

Osage Orange
Osage Orange

A: It’s an Osage Orange (Maclura pomifera (RAF.) Schneid.) and not to be confused with true oranges, which are members of the Rutaceae family of plants. The Osage orange is in the Mulberry or Fig family, namely the Mor­aceae family.

The Osage Orange fruit is not good for eating: it is full of an acrid milky juice and small brown seeds. .

Why do oranges look quite green in the tropics?

Q: Why do oranges look quite green in the tropics?

A: Tropical oranges are greener because the night temperatures are warmer, which causes more chlorophyll to migrate into the peel. They are still ripe and sweet though.

When can citrus be budded?

Q: When can citrus be budded?

A: When sap is flowing and there has been a recent growth flush so that the bark is still slipping. Buds are taken, preferably from an upper section of the tree, not a watershoot with spikes. Leaves are removed leaving part of the leaf stalk. The budwood can be grafted immediately or kept in the fridge for up to six weeks.

Avocado grafting techniques?

Q: Avocado grafting techniques?

A: Chip buds work with avocado. Do not take budwood after fruiting or in winter. Bend a twig and take buds from the top of the wood which does not bend easily. The top of the twig will usually bend a lot while lower wood is stiff. Take from the area between them. Graft on to a seedling leaving some leaves below to support the plant. The graft should be encouraged by bending down any nurse branches left on the seedling to give the graft dominance. Take off regrowth near the graft but leave leaves below for food supply.

Bird deterrents?

Q: Bird deterrents?

A: Crow bird scarers and other scarers work for a while. Non-drying Glue can cause severe problems to birds if it gets on their feathers and taste repellents are available but have limited effect. Exclusion Netting is the most effective.

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