US findings prompt trial success in local almonds

Research in California, showing activity on the adult stage of a species similar to the Carob moth, led to grower trials in orchards last season facilitated by senior agronomist at E.E. Muir & Sons, Mildura, Graeme Judd.

Mr Judd said the United States research had been conducted with the active ingredient spinetoram on the navel orange worm.

“Physiologically, navel orange worm is closely related to Carob moth so I was interested to see if we could replicate it with Delegate insecticide in Australian almond orchards,” he said.

High pest pressure orchards in Hillston, NSW and Sunraysia, Victoria were chosen for the trials, with Delegate applied at night in January when the almonds were between one and five per cent hull-split.

“We compared Delegate to the industry standards for the control of Carob moth and also looked at activity on Carpophilus beetle,” Mr Judd said.

“In a comparison with another Carob moth insecticide, Delegate had six per cent damage and the comparison product had 16.3 per cent damage.

“A separate trial had Delegate against an alternative comparison product with just one per cent damage compared to 4–6 per cent damage from the other treatment.

“In general, Delegate did an exceptionally good job. It produced a better result than the other products on the pests based on this year’s trials.”

Mr Judd said one interesting finding in the trials was the activity of Delegate on Carpophilus beetle.

“We sampled 300 nuts from one of the trials to see the effectiveness of both products on Carob moth and Carpophilus beetle.

“In the Delegate sample there was one mummy nut but no live pests. In the other product sample, there were five live Carob moth grubs and two live beetles.”

Carpophilus beetle is currently not on the Delegate label, however work is being conducted by Corteva to determine its efficacy on this pest.

Mr Judd said early results from the Corteva work have been very encouraging and a decision on whether to add it to the label will be made soon.

Indications are that both Carob moth and Carpophilus beetle can be controlled with a Delegate insecticide application at the early hull-split stage.

The trials were conducted on the Nonpareil almond variety which is widely grown in Australia and throughout the world because of its demand by processors.

“Nonpareil almond variety is the most susceptible to damage from Carob Moth and Carpophilus Beetle due to being a ‘softshell’ variety,” Mr Judd said. “Hard shell varieties such as Carmel, Monterey and others are far less susceptible.”

Mr Judd said the trials demonstrated the ability of Delegate to control adult moth populations as well as larvae at a critical time of the season.

“Carob moths fly at night, so if you can spray to reduce moth numbers and break the breeding cycle it will provide better control.

“Delegate is definitely having an effect on moth numbers. It is reducing the numbers that are able to breed as well as getting control of the Carob moth larvae themselves.”

The Carob moth lays its eggs along the suture line on the almond kernel and Mr Judd said there is a small window of opportunity to spray with an insecticide before the larvae make their way into the nut.

“Delegate has ovicidal and larvicidal activity on the juvenile pest and is an excellent option to reduce the amount of damage.

“Carob moths are a challenge for Australian almond growers and often start in the off-season with the expensive process of poling mummy nuts out of the trees.

“We monitor flight numbers with in-orchard traps and will occasionally conduct an insecticide application in the late-September to mid-October period if the pressure is high.”

Mr Judd said Prodigy, from Corteva was an ideal option to control the first generation of Carob moth larvae, followed by Delegate for the second generation at hull split.

Prodigy is a Group 18 and Delegate is a Group 5 insecticide, so they work well in rotation.”

Both options can also be rotated with other modes of action to help prevent resistance.

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