Rust

 (Puccinia purpurea Cook)

 Symptoms

• The  typical symptoms of rust  appear as scattered purple  or red  flecks  on both surfaces of the leaves.
• The color of flecks varies  depending upon plant pigmentation.
• In resistant plants, these remain restricted while in susceptible ones, these enlarge and appear like blisters that are brown to dark red pustules.
• As the leaf matures, the dried epidermis over the pustules ruptures, releasing the aggregates of reddish brown urediniospores.
• Gradually, most uredinia are converted into telia and the color of pustules changes from reddish brown to dark or blackish brown.

 

Fig. 1: Red flecks of rust fungus on the leaf

Control measures

• Grow rust resistant cultivars, such  as SSV 84, NTJ 2. CSH 25 and CSH 22SS
• Spray  Calixin 75EC/WP, Dithane  M-45 @ 0.2%,  or Mancozeb @ 0.2% three times at 10-day intervals starting from 30 days after emergence.