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Restoring the Zest in Citrus

If your lemons have lost their zing and your citrus are in crisis, don't despair. The Bug Man (Ruud Kleinpaste) has the solutions for you.

Citrus time in the garden and you'd be surprised how many questions we get about citrus problems. It's unbelievable. Number one — what are these lumps on my fruit and on my leaves? It makes the fruits and the lemons so ugly.

Got an example, right here. Wonderful little lumps on the fruit and on the leaves. It's a disease — a fungal disease called verrucosis.


The nice thing about the disease is it's purely cosmetic. It doesn't damage fruit; it's a skin disease. So, if you want to leave it, be my guest. But if you want to control it organically, a simple spray with copper or copper oxychloride over the bush, maybe three or four times a year, will protect the leaves from being infected.

And what about yellow leaves? If it's older leaves it's very likely to be a deficiency of magnesium. The funny thing is, if it's on the older leaves and not on the newer leaves, they nick the magnesium from the older leaves because there's only so much to go around. So magnesium is soluble within the plant.

To control this, chuck some Epsom salts or magnesium sulphate on the ground, water it well in, and you give the whole plant a boost of magnesium.

Yellow tips

But when the leaves that are yellow are at the tips, you have a problem. These new leaves show typical symptoms of a deficiency of a trace element like zinc or iron. Zinc and iron cannot be nicked from the old leaves and therefore translate as a whitening of the new leaves.

This is not temporary. This is for ever. But the problem can be solved quite simply, down below.

You see, zinc and iron are locked up by the soil in alkaline conditions. So what we really need to do is make the soil more acid. Firstly, the cause of becoming alkaline could be a concrete strip. Very simple. It's made of cement. It's made of lime. Every time it rains and every time you water the plants, bits of lime go into the soil, making it more alkaline. So my first recommendation is who needs them? Get rid of them.

Remove concrete edging

Secondly, if you really want to make your pH a little bit more in the acid sort of direction, a simple thing to use is aluminium sulphate. A bit over the soil and it will bring down the pH to a more acid level, thereby unlocking the zinc and iron in the soil, and the citrus can take it up.

If you want to give a little more iron on top of that, sulphate of iron is the stuff to use.

So it's actually very simple to remedy this problem. But you've got to know about the pH of the soil. There could be plenty of food there. Availability's the problem. That's all there is to it.

Click below for Part Two of "Restoring the Zest in Citrus"

LEMON TREE BORER — And How to Get Rid of It

Reproduced with permission from NZOOM Home and Garden content,
from the previous website of  TVNZ News

The views expressed here are not necessarily those of the RNZIH

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Last updated: June 2, 2004