Disease Index for the Rust Puccinia psidii on Rose Apple in ... - ctahr

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Category 2 • More than 10 spots per leaf. • Leaf spots may merge, causing <strong>for</strong>mation of larger necrotic areas that are 25 mm (1 inch) or more long. • Urediniospores are few, and teliospores may be present. • Shot-holes, created by <strong>the</strong> loss of <strong>the</strong> diseased tissue, may also be present. As in Category 1, this level of spotting may reflect a low inoculum level, low environmental humidity, or host resistance due to leaf maturity at <strong>the</strong> time <strong>the</strong> leaves were infected. 6 Close-up of leaf spot and empty pustules Abaxial Abaxial Adaxial
Category 3 • Occurs on young leaves. • Less than 30 percent of <strong>the</strong> leaf area is covered with rust pustules. • Leaves are not severely infected, and stem lesions are rare. • Check <strong>for</strong> presence of teliospores. This generally represents infection of young tissue when <strong>the</strong> environment was dry. Close-up of two clusters of pustules (groups of urediniospores) Adaxial, few spores Abaxial, many pustules and urediniospores 7
Page 1 and 2: Disease In
Page 3 and 4: A series of disease indexes is bein
Page 5: Category 1 • Ten spots or fewer p
Page 9 and 10: Category 5 • Leaves become necrot
Page 11 and 12: Field survey for <

Disease Index for the Rust Puccinia psidii on Rose Apple in ... - ctahr

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