SOIL care has been a 23 year journey for orchardists Wendy and John Graham.
The couple look after 650 custard apple trees, 200 lime-producing citrus and share 30 Murray Grey breeders with their neighbour on 26ha of rich red soil at Lindendale, atop the Alstonville Plateau. They have been producing without pesticides for the last 18 years.
Seven years ago they stopped spraying herbicides and yet their produce is regarded as high quality by the market.
The Sydney couple chose the property, back in 1993, for lifestyle reasons as they were keen to raise children away from the big smoke.
“We were total amateurs,” admitted Mrs Graham.
But the fact that they were not bound by tradition allowed them to explore an alternative world of biological farming.
In the beginning they followed ‘normal’ production methods, which involved spraying glyphosate under the tree canopy to keep the soil bare. They mowed between rows and kept the property looking ‘neat’.
But they soon learned that biological farming success depends not so much on what you do as what you don’t.
“We admit it has taken us a long time to feel comfortable with inter-rows that look a bit like a jungle,” says Mrs Graham.
“It is a process of constant learning,” said Mr Graham.
The tipping point for the couple came early in their career, as they pondered what to do with trees that looked old and well past their use-by date.
Fortunately the Northern Rivers is home to some inspirational education on the subject of biological farming and they consulted TAFE teachers Dave Forrest and Alan Coates and joined a very active local chapter of SoilCare.
They were fortunate because TAFE courses in biological farming today are a mere shadow of what they once were, much to the disappointment of students and teachers.
In the limes there were real problems with citrus gall wasps laying eggs in stems and deforming the tree.
“We tried cutting the affected limbs and burning them but with no result,” said Mr Graham.
However, an installation of Megastigmus from Bugs For Bugs resulted in gall wasp eggs being preyed upon to the point that a balance was created between good and bad bugs. Within two years there was control.
That success pushed the Grahams to look at other issues in their orchard - in particular sooty mould on both the custard apples and limes, with ants literally farming scale insects so they could harvest their exuded nectar-like residue. Mould grew on that residue.
“You could wash it off, of course, but it affected market quality and so we had to spray,” recalled Mrs Graham.
Information from the central Queensland citrus industry pointed the Grahams in the direction of another biological approach, using the predatory insect Red Chilocorus - again provided by Bugs For Bugs, to control scale which eliminated the mould issue.
Mealybugs were another concern controlled by Cryptolaemus; Aphytis attacked armoured scale and Green Lacewing was introduced as a general predator.
The fact that the Grahams were selling limes at that time to Woolworths - and continued to do so after the biological treatment - was proof of their success. They no longer sell to the supermarket chain, preferring instead to market their own line of lime cordial.
Of course once a biological approach is instigated then the chemical spraying regime must cease - or so too will the bugs. And so the Grahams’ orchard began to look something like a hippy garden.
That’s because bugs need places to live, and tall grases and seed producing weeds are all part of that.
However in the sub-tropics on red soil vegetation simply cannot be allowed to run rampant and so a mix of brush cutting and gradual reduction of spray has resulted in a system where alternate rows are mown when grasses and weeds reach the knees. That way there is some habitat for bugs.
Orchard management also involved the introduction of creeping groundcovers like pinto peanut, clovers and marcu lotus which have the dual role of reducing weed opportunities and fixing nitrogen in the soil.
For the past seven years the Grahams have not sprayed herbicides at all.
“Weeds are a repairing structure,” points out Mr Graham. “Some, like dandelions, have long roots in the soil that allow movement of nutrients.”
In addition there is extensive mulching, using compost gleaned from tree waste - to encourage a balance of fungal associations with the roots of the custard apples and limes.
In fact the Grahams have completely stopped spraying with copper sulphate.
“That was a massive step to remove copper from our toolkit,” said Mrs Graham. “But the results speak for themselves.”
