Sr9a

(Green et al., 1960) (Plate 3 8)

Synonym

Sr9 (Knott and Anderson, 1956).

Low Infection Type

1- to 2, 23.

Environmental Variability

Low (Green et al., 1960; Loegering and Harmon, 1969).

Origin

Common wheat. Sr9a was first reported in Red Egyptian.

Pathogenic Variability

Wheats with Sr9a produce differential seedling responses in North America (Green et al., 1960), central America, Brazil and possibly Kenya (Luig, 1983). Sr9a is ineffective in tests with Australian pathotypes (Green et al., 1960) and on the Indian subcontinent.

Reference Stocks

i: ISr9a-Ra C.I.14169 (Loegering and Harmon, 1969); Red Egyptian/6*Marquis (Green et al., 1960); Red Egyptian/10*Marquis (Knott, 1965); Sr9a/9*LMPG (Knott, 1990).

s: Chinese Spring*4/Red Egyptian 2B (Sears et al., 1957).

v: Red Egyptian C.I. 12345 Sr6 Sr8a (Knott and Anderson, 1956).

Source Stocks

CIMMYT: Lerma Rojo 64 Sr2 Sr6 Sr7b. Inia 66 Sr2 Sr8a Sr11.

Europe: French Peace Sr7a Sr13 (Knott, 1983).

USA: TAM107. Centurk Sr5 Sr6 Sr8a Sr17. Sentinel Sr6 Sr8a Sr17. Colt Sr6 Sr8a Sr17 Sr24.

 

A. Seedling leaves of (L to R): ISr9a-Ra, Spica, Renown and Bowie; infected with University of Missouri culture 17-53B. Spica and Renown do not carry Sr9a but have a degree of resistance (IT 3C) relative to Bowie (3+). No illustration of the low infection type was possible with cultures available in Australia.
B. Seedling leaves of ISr9a-Ra infected with USDA Cereal Rust Laboratory pt. BDCN. Courtesy AP Roelfs.

 

Use in Agriculture

Not widely used.