Infertile fig frustration | In the Green Room

I’m a keen backyard fruit and veggie grower, and a lot of my plants do very well. However, I’ve got a fig tree that’s been quite a poor performer for years now which is so unlike figs which usually fruit under awful conditions. This hasn’t fruited for 3-4 years. It’s a black genoa I bought from a nursery a while back, and aside from a kind of mosaic discolouration on the leaves, I can’t see anything wrong with it. It might be getting some competition from the feijoa near it, and there’s a eucalypt too, but that doesn’t seem to be a problem for any of the other plants.

I've given direct water, more fertiliser but nothing seems to help. A solution would be brilliant.

Adrian, South Bunbury

Thanks for the question, Adrian. The blemishes on the leaves certainly match up with the fairly common fig tree mosaic virus, which I’d say is the source of your problem.

The virus, which can be introduced to plants by a either a mite known as Aceria fici, or ‘eriophyd mite’, or by infected grafts/cuttings, which may be spread through poor practice in nurseries and horticultural production.

It’s especially likely to be the virus because it’s most common on black figs, like the one you’re describing.

Unfortunately, scientists are yet to discover a cure or control for the actual virus, though its spread can be reduced by controlling the mites using white oil, and taking care to use ‘clean’ grafts and cuttings.

Of course, that’s not much use to you at this stage.

One option, depending on how attached you are to this tree, is to remove it and start over, taking care to select a healthy tree not affected by the mosaic virus.

Alternatively, you can try to make the best of what you’ve got with a few maintenance tricks.

Prune back the worst-affected branches – figs can take fairly hard pruning, up to a third of their initial size – to stimulate new growth, which is where most fruit production occurs.

Fig trees like a pH around 6-7, so a soil test might help you adjust your fertilizer routines, and, depending on what you feed it, you may want to consider supplementing with some trace element mix or rock dust, as figs like some extra calcium, magnesium and potassium.

Of course, a tree with the mosaic virus is never going to be as prolific as a completely healthy tree, but making sure all the other growing conditions are in order will improve your odds of salvaging this plant.

Do you have a gardening question for Jess? Send your queries to jess.cockerill@fairfaxmedia.com.au or call 9550 2409.