Stimulate beneficial insects, key to biodiversity to control the “bad guys” attacking macadamia crops


Research to better protect macadamia orchards against pests, thereby increasing production, profitability and minimizing the use of chemical sprays, is beginning to bear fruit.

Over the past five years, the Macadamia Integrated Pest Management (IPM) program has tested combinations of biological, cultural and chemical controls in on-farm trials in orchards in New South Wales and Queensland.

Ruth Huwer, an entomologist with the NSW Department of Primary Industries, said she had discovered that a suite of tools needed to be used on the farm to control pests.

“Surveillance is the most important tool that we have to look at in IPM, we have to know what the parasites are and when they are present. Timing is crucial,” she said.

“Plus, good coverage is crucial and that’s where cultural control comes in, opening up your canopy and also increasing your biodiversity with different inter-rows.

“We want to reduce the intake of broad spectrum insecticides. But without saying that they cannot be used at all, they are just meant to be a last resort.”

Entomologist Dr Ruth Huwer working in her lab at the Wollongbar Primary Industries Institute in North New South Wales.(Provided: NSW DPI)

Researchers began a small-scale inter-row cultivation trial at the Alstonville Tropical Horticultural Center, planting native flowering shrubs and plants to increase the number of natural enemies.

Dr Huwer said it was too early to draw any conclusions from the yield data obtained.

The center is also conducting another trial comparing IPM options with minimal intake of broad-spectrum pesticides with conventional treatments.

“We can use some chemicals that are not yet readily available to industry and see where they possibly fit in the future, chemicals that will be available soon,” she said.

New emerging pests such as bark beetles, beetles, macadamia seed weevil and Leptocoris spp. bug have been identified since the start of the project.

While the fruit bug has proven to be the main pest, research has now identified the difference between damage caused by another bug, the Leptocoris spp., allowing more targeted management of pests by producers.

Spiders the silent slayers

Ross Arnett standing next to an inter-row crop in his macadamia orchard.
Ross Arnett between his cover crops and the macadamias in his Lindendale orchard.(Provided: Ross Arnett)

In the northern rivers, the research was conducted on two farms, one conventional and the other Ross Arnett’s organic orchard, where data is collected primarily during flowering.

“There are 30 trees on my property monitored every two to three weeks to see what the beneficials and pests are in the orchards, are there in those trees, so we are monitoring that over time to see how the orchard is behaving. on that front, ”Mr. Arnett mentioned.

“For the past three years I have only had to spray the entire orchard with insecticide… just to control the weevil.

Mr. Arnett keeps his pests under control by using parasitic wasps and other beneficial insects, as well as increasing biodiversity with cover crops along the rows and around the perimeter of the orchard.

“You can have a lace bug in a flower and give it a few kicks on a board and you can see angry little spiders running away.

“It’s those little hidden creatures that you can’t see that do all the work.”

Mustard plants growing between rows of macadamia.
Inter-row mustard plants increase the number of natural enemies in a macadamia orchard as part of an integrated pest management system.(Provided: NSW DPI)

Mr Arnett said spraying for pest control should be avoided at all costs.

“If you have to spray, you have to spray, because at the end of the day, whether you’re doing regenerative farming or conventional farming, you still have to make a living off your farm.

“But we are trying to do it, in regenerative agriculture, in a more environmentally friendly way and to strengthen ecology, soils and tree health, in this process.”

A sunflower with an insect and bees.
A killer bug attacks a bee while four native bees feed on a sunflower in an inter-row of Ross Arnett’s macadamia orchard.(Provided: Ross Arnett)

Mr Arnett hoped that NSW DPI research would provide the incentive for other farmers to consider pest control options like cover crops.

But, he added, it was easier said than done due to the height of the trees in the local orchards.

“We have trees that are 15 meters high and probably 8 meters is the optimal height for a macadamia, for the equipment we need to use and to get enough light in the orchard so that you can grow ground covers.” , did he declare.


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