Lesson 4: Rust

1
Lesson 4 Rust
Rust disease is known to occur wherever sorghum
is grown. However, rust is serious in
South-east Asia and southern India reducing grain
yield and forage quality. Under environmental
conditions favoring rust development, poor
earhead exertion and shriveled grain caused by
rust infection may result in grain yield losses
up to 65.
2
Lesson 4 Rust
Young plants are rarely affected by rust. The
typical symptoms are seen in 1.5 to 3 months old
plants. Scattered purple, red, or tan flecks
appear on both surfaces of leaves (Fig.) and in
resistant cultivars the symptoms develop no
further.
Rust flecks on leaves
3
Lesson 4 Rust
In susceptible cultivars typical rust pustules
develop, mainly on the lower leaf surfaces. When
fingers are passed on such leaves reddish powder
can be seen on the fingers. In highly
susceptible cultivars the pustules occur so
densely that almost the entire leaf tissue is
destroyed (Fig.).
Healthy leaf on left. Rust affected leaf on the
right
4
Lesson 4 Rust
The pustules may also occur on leaf sheaths and
on inflorescence stalks.
Pustules on inflorescence stalks
5
Lesson 4 Rust
Management In areas where rust becomes
economically important disease, growing resistant
cultivars like PSH 1, SPH 837, CSV 17 etc. is the
only solution. Selective fungicides that
suppress the disease are usually not economical.