Advice on citrus leaf miner

Argall Family (grargall@alphalink.com.au)
Mon, 12 Apr 1999 11:13:22 +1000

Citrus leaf miner has only been in Australia for a decade or so. I had a
modest/manageable problem with it on some trees when the orchard was young,
in the early 1990s. But not for some years, until the last month (which is
late summer-autumn here), despite the fact that a conventional farmer has
leaf miner in poorly managed trees about 150 yards away.

When the trees were younger I also had problems with aphid at this time of
year. So many people had advised me on the virtue of iron for citrus that I
had been giving them an iron top up (using an azoterbacterial ferric scum
from backwaters in the creek). I then realised that iron may drive out
potassium, and a potassium weakness in the autumn may be the source of the
aphid problem. I stopped the iron addition (except for the creek water which
seems fairly high in dissolved ferrous salts, hence the ability of
microorganisms to deposit ferric scum), added a small amount of ash and no
aphid problem since. Coincidentally or otherwise, no leaf miner.

The spread over quite a few branches of the leaf miner activity just now was
possible because of a month's absence. It's an easy matter to remove and
destroy leaves where the miners may be.

The incidence is on trees well apart, in a permaculture/mixed up orchard, on
the trees which have been most in the sun in a sheltered valley/intense
planted environment, trees which may have more fresh shoots. Some of these
trees may have been short on water, others abundant.

My question is whether anyone has associated this pest with any particular
nutritional deficiency or some such circumstance?

thanks in advance for any advice

Dennis Argall

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