Handheld citrus greening detection device requires 'cultural change' - FreshFruitPortal.com

Handheld citrus greening detection device requires 'cultural change'

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Handheld citrus greening detection device requires 'cultural change'

A new device developed in Brazil promises to help growers bring citrus greening under control much more quickly, detecting the disease before visual symptoms appear. brazil device

Since 2005, citrus greening, or HLB, is estimated to have caused US$4.5 billion in damages in Florida alone, and has resulted in 27 million trees being cut down in Brazil.

Instituto de Física de São Carlos professor Jarbas Caiado de Castro Neto and his research team spent almost two years developing the handheld machine, which measures the light wavelength given off by orange tree leaves to determine whether they are infected.

The research was carried out in conjunction with Dr. Debora Milori of the Brazilian Corporation of Agricultural Research (EMBRAPA).

"What the user does is put the device against the leaf and push the start button, then an LED with a specific wavelength shines onto the leaf, and the machine measures the return light on its spectrometer," Castro told www.freshfruitportal.com.

"So you get the spectrum of light emitted by the leaf, and the shape differs from healthy leaves to symptomatic leaves or asymptomatic leaves."

Castro said although the device could detect HLB with 85-90% accuracy, compared to around 30-60% when visually inspecting trees, the biggest advantage by far was the ability to catch the disease when the tree had not yet displayed visual symptoms.

"From when the tree gets infected, it takes about a year-and-a-half until you start to see any changes in the leaves. In that time the tree is propagating the disease, but you will have no idea that it's infected," he said.

"So if you detect HBL-infected trees in the asymptomatic phase and cut them down, then you limit its ability to infect other trees on the farm."

The technology is now being tested out on farmland owned by major Brazilian orange producer Citrosuco to get full approval, which Castro expected would take up to one year.

He added these tests would be of paramount importance if the device were to be adopted on a global scale, as farmers would want to be certain before cutting down supposedly infected trees which were not yet displaying symptoms.

"This is a big cultural change in farming practices - the grower will have to put a lot of trust in the diagnostics of the equipment, otherwise they will cut down a healthy tree," Castro said.

"This is what we're doing now in these tests. We are measuring the tree and saying 'this one is already diseased, but you can't see', and then what we do is wait, and later the inspectors will be able to see that the tree is indeed infected.

"So I would say the equipment is working fine, but we will need time for the cultural practices to change."

The device only currently works with different orange tree varieties, but in the future it is hoped it could be developed to work with other citrus crops.

Castro said his business plan was orientated toward the worldwide market, and if the device were adopted on a wide scale on all citrus farms affected by HLB, the disease could be brough under control impressively quickly.

"We did some analysis and found that if you cut the tree in the asymptomatic phase you could completely control the disease within two or three years," he said.

"And the cultural change will be particularly big in the first year, because that's when you're going to have to cut down more trees than normal - because you're cutting all the asymptomatic trees. But the second year is about normal then from the third year it starts to get smaller."

Photo: Jarbas Caiado de Castro Neto

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