Leeton citrus grower Dean Morris relies on many things to ensure his crops are as fruitful as possible, including his gut feelings. 

Mr Morris used those instincts to successfully use deficit irrigation to increase brix on very vigourous rootstocks.

Even though he has refined his technique over the years, he still relies on that gut feel every year.

Mr Morris will expand on his technique at the 2019 Citrus Tech Forum, to be held in Adelaide on March 6 and 7. 

NSW DPI researcher Tahir Khurshid, who is now undertaking research on deficit irrigation to improve flavour profiles, will also discuss his research.

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Mr Morris planted 40 hectares of Afourers in 2007, planting 20 hectares on vigorous rootstock such as rough lemon and macrophylla and 20 hectares on traditional rootstocks.

The theory was fruit on the vigorous rootstock would mature earlier, enabling them to pick the same variety for 12 weeks.

“I had an inkling we could get 12 brix or better by reducing the water applied for the last 12 weeks,” Mr Morris said.

“I’d also learned from Andrew Harty when he was in New Zealand, growing Sstsuma mandarins for the Japanese market, and had further discussions with Professor Martinez (of Spain).”

Mr Morris said with trial and error, the group achieved the minimum target of 12 brix for the brand.

“We achieved high fruit yields with acceptable taste to the trade and better fruit size,” he said.

Trees are planted on large mounds, with two drippers per tree, providing complete control when water is turned off.

Roots are in the top 40 cm of soil, so they’re not affected by large amounts of rainfall.

“We had 700mm in June, July, August in 2016 and still met the target,” Mr Morris said.

Although Dr Khurshid’s research is “fine-tuning” methods employed by Mr Morris and other growers, he said he still relied on that reliable “gut feeling.

“I look at the tree, taste the fruit, and if fruit is getting soft, I turn the water back on,” he said. 

Importantly, the technique is also efficient in many areas.

The technique saves one megalitre of water per hectare, cuts power costs, does not affect fruit size and causes minimal fruit drop.

Mr Morris said the practice was becoming common in the US and other countries and said every Australian grower must continually improve fruit quality to maintain the industry’s advantage over competitors.

“Our industry’s biggest threat are our overseas competitors,” Mr Morris said.

“South American countries will take us out of China like they did in the US if we don’t improve.

“If we do nothing and rest on our laurels, everyone will catch up.”

Register for the forum at www.citrusaustralia.com.au/events.

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