Friday, August 30, 2013
Inspection and detection of citrus trees are the first lines of defense against the spread of Huanglongbing (HLB), a bacterial disease spread by an insect known as the “Asian Citrus Psyllid.” The California Citrus Research Board has enlisted the aid of NASA through a “Space Act Agreement” signed earlier this year. With funding provided by the CRB, researchers are experimenting with the use of NASA’s AVIRIS to produce aerial maps of the distribution of citrus trees to help guide inspection efforts. The maps for this study will be able to distinguish details larger than 4 m (12 feet).The researchers also expect that AVIRIS will be able to distinguish infected trees from healthy trees and propose to test that capability in 2014. The ability to survey hundreds of thousands of acres from the air in a matter of days could be crucial to the early detection of the spread of the disease into new areas.
The initial airborne campaign, using AVIRIS installed in a DHC-6 contracted from Twin Otter International, was conducted last week. Three days of flight data were collected over several areas in the central valley and southern California.
Capitalizing on the citrus campaign, an additional flight day was obtained last week to explore the capabilities of imaging spectroscopy to characterize nitrogen and water stresses in maize, sorghum, and tomato plants. The flights lines were selected to cover a set of field experimental trials that are being conducted at the Russell Ranch Sustainable Agriculture facility outside of Davis, California to induce specific gradients of stress in the agricultural systems. The unique capabilities of AVIRIS were used to evaluate the ability of imaging spectroscopy data to constrain canopy biochemical and energy balance parameters. Field measurements were also made to link airborne imagery to canopy structure and biogeochemistry and to facilitate canopy radiation transfer modeling.