STUD IES ON SOME CITRUS DISEASES BY REMOTE SENSING TECHNIQUES

Abstract

Citrut plantation is widely spread in Egypt in all parts of the country. Citru$ trees are liable to be attacked by many pathogens causing considerable yield losses. This study was Icarried out concerning two of the most important citrus diseases in !Egypt i i.e. gummo is as a fungal disease and psorosis type A as a virus disease. I

The tant materials included healthy and infected trees of six different citrus spec1es anvarieties i.e. Baladi, Navel, Sweet and Valencia oranges (Citrus sine1sis L

Obsek); iliapefruit (Citrus paradisi Macf) and Mandarine (Citrus reticulata Bj' anco) I I at two locaiions i.e. Shibin El-Kom and Kaha.

The study included the following main parts:

i I- Isolati.on and/or identification of the causal agents of the two diseases undefItaken in this! study. Pathogenicity tests also were carried out. .

II - Using remote sensing techniques in disease detection to differentiate between I healthy and infected plants. This part included the following studies:-

! - easuring the spectral reflectance of different healthy and infected !citrus trees to find out the changes according to the infection. These Leasurements were carried out by: I

Field hand held radiometer that measure reflectance in four different I 'I spectral bands (from 0.5 to 1.1 urn) that resembles the bands used in

the Landsat Multispectral Scanner (MSS) i b ) Laboratoric spectrophotometer ranging from 400, 420,440 up tb 800

nm.