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Student worker Christopher Baker controls the computer while Assistant Researcher Kathy Vaughn moves a leaf of a corn plant onto the hyperspectral camera.(Photo By Christian Nansen)

Spider mites on a corn leaf, as seen with the hyperspectral camera.(Photo By Christian Nansen)

As part of the experimental setup, the corn leaf is kept in horizontal position on a white calibration boards.(Photo By Christian Nansen)

 

 

Smile! Researcher Uses Camera To Spot Disease and Insect Damage Early in Plants

Early detection is essential when developing integrated management strategies against insects and diseases in crops. This is why Texas AgriLife Research grain entomologist Christian Nansen is focusing in on using a hyperspectral camera.

Like a spectrometer, this camera collects reflectance data from very narrow wavelength bands across the visible light spectrum and reflectance curves can provide information about the physiological status of the plant.

With the camera, Nansen can look at the surface of the leaf and detect whether it is going through stress from diseases, insects or weather extremes much earlier than when the plant show symptoms (like wilting leaves) that are detectable with the naked eye.

“Just like when we start having the flu, our body responds and we get a fever,” Nansen said. “The fever is because our body is mobilizing its immune system. When a plant undergoes stress caused by diseases, insects or the environment (like drought), it will cause changes in its metabolism and that leads to subtle changes in the way it reflects light.

“We can use this camera to detect stress at an earlier stage than by visual inspection, and early detection means that it may be easier to control the pest problem.”

The camera will also detect any damage done by insects and can help to detect signs of infestation before it is too late.

 “When scouting for spider mite infestation, you need to take a lot of samples if the infestation level is low,” he said. “But with spectral imaging, you can see it earlier and it is less intrusive (non-destructive) as we do not have to remove leaves from the plants.”

The technology is similar to that of remote sensing in that it can be used in mobile applications. For example, instead of having the camera in an airplane, Nansen said the camera can be placed over the crop canopy mounted either on a four wheeled all-terrain vehicle or on center-pivot irrigation systems.

Nansen is still in the early stages of testing the technology. He and his research group are starting by collecting spectral profiles of healthy and stressed plants (stressed by arthropods and diseases) and developing classification algorithms.

So far, Nansen has used the camera in tests on early detection of zebra chip in potatoes, cotton root rot, spider mite stress and salt tolerance in cotton plants.

Potato producers currently must use visual clues of stress on plants in order to detect zebra chip, a disease that has no treatment, and decide whether the affected crop is able to be harvested.

Nansen said the zebra chip effect causes the potato to turn brown after frying. At this time, it does not appear to affect quality and does not show up in baking potatoes, but the discoloration after frying can be problematic for the potato chipping industry.

He hopes to be able to use the hyperspectral process to determine when the disease starts to occur and what is happening to the plant at the time of infection.

“We think we can also obtain a much higher accuracy using the reflectance technology to scan the potatoes and see how it will be after frying,” Nansen said.

Nansen has been pleased with how the camera has been working. "It has been very good and we are acquiring some unique experiences with this camera," he said.