Diseases in wheat

Black Rust

Caused by : Fungus

Causal Organism: Puccinia graminis tritici

Symptoms:

• The uredial pustules occur on stem, leaf sheath, leaves and earheads but the stem is often most severely affected.
• The pustules of black rust are reddish-brown in color and elongated in shape.
• This rust spreads fast under relatively warmer and humid environmental conditions.
• By the time the crop matures, dark, black, elongated tetial pustules are formed.
• The name black rust was given to this rust due to the prominence of its dark black telia.

Control Measures:

• Grow rust-resistant varieties of wheat recommended for a particular area such as HD-2733, HD-2428, HD-2189, U.P.2425, PBW-343, HW-291, HW-2004, HS-240, VL-719 etc. it is safer to divide the total farm area for wheat cultivation under 3-4 different varieties of wheat. In other words, sowing the total area with a single variety is unsafe.
• Avoid late sowing of late maturing varieties. Late sown crop is more exposed to rust damage.
• Do not use excess nitrogenous fertilizers, as very high nitrogen dose favours rust development. Use of high dose of potash is known to reduce rust infection. Apply balanced doses of nitrogen and potash as recommended.
• Damage by wheat rust may be minimized by spraying Zineb or Mencozeb 75 WP. Spraying is recommended only when a good crop of wheat is threatened by rusts. Spraying is not economical on a poor crop of wheat. Spray 0.2 per cent Zineb or Mencozeb 75 WP and 0.1 per cent Sandovit (spreader-sticker) as outlined below:
  1. Give first spray when rust pustules are seen. This normally occurs during the last week of January or first week of February. About 375 liters solution per hectare is enough for this application.
  2. Give second spray 10 days after the first. Use 750 liters solution per hectare.
  3. Give third and fourth sprays at an interval of 14 days. Use 1000 and 1250 liters solution per hectare, respectively.