Project: 2003-02. Report - Assessment of needle–cast diseases using aerial photographs (2003–02)
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Date: 2004 Author: Forest Research Publication: Report Project reference: 2003-02 This field guide is available for purchase from: |
Executive summary:
Periodic defoliation of radiata pine by the eco–physiological disorder known as Strasseria appears to have increased in frequency over the last 20 years. This disorder, as well asCyclaneusma needle–cast, results in growth loss.
• A survey technique was trialed to assess the incidence and severity of Cyclaneusma needlecast from aerial photographs. It was based upon a visual interpretation of very large scale aerial imagery.
• The disease severity of Cyclaneusma needle–cast on 101 trees was assessed in the field and compared to the disease severity of the same trees assessed on imagery taken with the
following specifications:
Oblique and vertical.
Stereoscopic and monoscopic.
Flying heights of 100 m, 300 m and 600 m.
• Results indicate that colour, oblique, stereo images taken at a flying height of 600 m would enable the incidence and severity of Cyclaneusma needle–cast to be obtained with an
accuracy comparable with field assessments once assessors were experienced and fully trained in disease assessment techniques. The same survey technique could also be used for
assessing Strasseria.
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Forest Research
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