Diseases and their control in lucerne - Agriculture Western Australia.
Fungal diseases can attack the foliage, crown or roots.
The infected leaves gradually turn yellow and fall. During prolonged wet, moderately cool weather infected plants suffer the worst defoliation. Spots may be found on the stems, especially during warm, humid weather when growth is lush. The colour of these spots is due to masses of fungal spores which, if touched, leave a reddish-brown smear on the skin. Rust is the only leaf-spotting disease of lucerne with this characteristic.