Boosting beneficials and biodiversity key to controlling pests

Research into better protecting macadamia orchards from pests, therefore lifting production, profitability, and minimising the use of chemical sprays, is beginning to bear fruit.

NSW Department of Primary Industries entomologist Dr Ruth Huwer said it has found a suite of tools needs to be used on-farm to control pests.

"Monitoring is the most important tool that we need to look at in IPM, we need to know what pests are around and when they're around. Timing is crucial," she said.

"Also, 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 input of broad-spectrum insecticide. But not saying that they can not be used at all, they're just meant to be a last resort."

Researchers are one year into a small-scale trial on inter-row cropping at the Centre for Tropical Horticulture at Alstonville, planting native shrubs and flowering plants to increase the number of natural enemies.

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

"It definitely is beneficial, but we need to know whether that also has impact on your quality and yield at the end," she said.

The centre is also running another trial comparing IPM options with minimum broad-spectrum pesticide input with conventional treatments.

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

New emerging pests such as scolytid beetles, scarab pests, Macadamia seed weevil and the Leptocoris spp. bug have been identified since the project started.

While the fruitspotting bug has been found to be the main pest, research has now identified the difference between the damage caused by another bug, the Leptocoris spp., enabling more targeted pest management by growers.

"Growers were not able to tell the difference before, or we weren't able to tell the difference, and the management of the two different pest species can be different," she said.

In the Northern Rivers the research has been conducted on two farms, one conventional and the other Ross Arnett's biological orchard, where data is collected mostly during flowering.

"There's 30 trees on my property monitored every two to three weeks to see what beneficials and what pests are in the orchards, are there in those trees, so we track that over time to see how the orchard's performing on that front," Mr Arnett said. 

"The last three years I've only had to do one spray in the whole orchard with insecticide … just to control weevil."

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

"If you can build spider numbers up, they're fantastic. They're the silent killers in the orchard of the nasties," he said. 
"You can have lace bug in a flower and give it a couple of taps out on a board and you can see little angry spiders run off.

"It's those little hidden creatures that you don't see that are doing all the work." 

In the Northern Rivers the research has been conducted on two farms, one conventional and the other Ross Arnett's biological orchard, where data is collected mostly during flowering.

"There's 30 trees on my property monitored every two to three weeks to see what beneficials and what pests are in the orchards, are there in those trees, so we track that over time to see how the orchard's performing on that front," Mr Arnett said. 

"The last three years I've only had to do one spray in the whole orchard with insecticide … just to control weevil."

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

"If you can build spider numbers up, they're fantastic. They're the silent killers in the orchard of the nasties," he said. "You can have lace bug in a flower and give it a couple of taps out on a board and you can see little angry spiders run off.

"It's those little hidden creatures that you don't see that are doing all the work." 

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

"If you can improve the biodiversity in the orchard you will suppress your insect pressure," he said. But, he added, it was easier said than done due to the height of trees in local orchards.

"We have trees that are 15 metres tall and probably eight metres is the optimum height for a macadamia tree, for the equipment we have to use, and to get enough light in the orchard so that you can grow ground covers," he said.

Source: ABC Rural

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