17[7] Peanut Rust [EDFS

This leaflet is produced by the Ministry of Agriculture & Livestock, Solomon Islands, with support
from IPPSI: Improved Plant Protection in Solomon Islands, a project financed by ACIAR, the
Australian Centre for International Agricultural Research, Canberra. Authors: Helen Tsatsia, MAL &
Grahame Jackson, TerraCircle Inc.

Extension Fact Sheet 34:

Peanut Rust

Common name: Peanut rust

Scientific name: Puccinia arachidus

Hosts: The fungi infect peanuts, and some other plants belonging to the genus
Arachis.

Damage

Infection causes leaves to turn yellow (photo, left), dry, curl and drop. It is not known
what losses occurs in Solomon Islands, but it is likely that yields are reduced by 50%,
probably much more. Infected plants mature 2-3 weeks early.

Once infections occur, rust develops very rapidly, faster than the diseases caused by
early and late leaf spots (see Fact Sheet No. 36).

Biology and Life Cycle

The rust infects leaves, petioles, pegs (the shoots that grow into the ground) and
stems. On the leaves, the spots are at first yellow, rapidly turning orange and then red-
brown as masses of spores develop and break through the leaf surface (photo, right).
The lower surface produces the most spores.

The spread of rust depends on wind to disperse the spores, and humidity to provide
conditions for infection at the leaf surface.

Detection and inspection

Inspect plants regularly, at least once a week, looking for the red-orange spots.

Management

Cultural control:

Cultural control is important, but note that rusts only survive in living plants; they do
not survive in crop remains or in the soil. Spores are spread in moist, warm air, and
periods of cloudy wet weather favour outbreaks of the disease; these are common
conditions in Solomon Islands.

The following should be done:

•  Remove any volunteer plants from the last crop;
•  Plant new crops as far away as possible from older crops, especially those with

rust infections;

• If it is not possible to avoid planting near older crops, do not plant down wind

from them; otherwise, spores will easily spread to the new crops.

Resistant varieties:

There are varieties that differ in resistance to rust, but there is no information about
the resistance of those grown in Solomon Islands.

Chemical control:

•  Carry out regular inspections;
•  Begin to spray as soon as rust spots are seen, even if they appear only on one or a

few plants. Spray at regular intervals: 10-14 days is best, continuing until 14 days
before harvest;

• Spray more often if the first treatment is late, and there are many plants with rust

spots. In most cases, spraying should begin no later than 30-35 days after planting;

• Use chlorothalonil (the trade name is Bravo). It is effective against rust, and also

leaf spot diseases. READ THE INSTRUCTIONS BEFORE SPRAYING.