Coffee rust, caused by the fungus Hemileia vastatrix, is a major threat to coffee crops worldwide. It starts with small yellow spots on leaves, growing to orange pustules underneath. These erupt, releasing spores that spread with wind and rain, infecting other leaves. Infected leaves turn brown, drop, and weaken the plant, leading to reduced yields and even death. This devastating disease has historically crippled coffee production in regions like Sri Lanka and Central America.

1. Coffee Rust: A Threat
to Coffee Growers
Coffee rust is a disease that poses a severe threat to coffee growers
worldwide. The coffee crop is constantly exposed to various pests and
diseases, including the well-known coffee berry borer, coffee leaf miner,
and diseases such as coffee rust and coffee wilt. The impact of coffee rust
has been devastating, with significant effects on coffee production in Sri
Lanka and beyond.
by Sathiya Aravindan

2. Identification and Impact
1 Identification
The disease is caused by the fungus Hemileia vastatrix, later renamed as
Wardia vastatrix. It was first reported by H.J Berkeley in 1870.
2 Spread and Devastation
In the 1970s, coffee rust spread from Africa to Brazil, causing severe
devastation. Efforts to contain the spread, such as creating a safety zone,
were unsuccessful.
3 Impact on Sri Lanka
Coffee rust has had a significant impact on coffee production in Sri Lanka,
leading to substantial yield reduction.

3. Systematic Position and
Symptomatology
Systematic Position
Domain: Eukarya
Kingdom: Fungi
Phylum: Basidiomycota
Class: Pucciniomycetes
Order: Pucciniales
Family: Pucciniaceae
Genus: Hemileia /
Wardia
Species: vastatrix
Symptomatology
Small, yellow-colored
powdery lesions appear
on the upper side of the
leaves. Severe infections
lead to the lesions
coalescing and enlarging,
turning into orange-
colored urediniospores.
This results in premature
leaf fall and a drastic
reduction in yield.
Pathogen
Morphology
Produces asexual spores
called Uredionospores
and sexual spores called
teliospores. Coffee rust is
also called the autoecious
demicyclic rust.

4. Epidemiology and Management
Strategies
1 Epidemiology
The spores mainly enter through the
stomata and require good rain
splash for germination. Temperature
between 15 to 28 ℃ is highly
conducive for spore germination.
2 Management Strategies
Cultural methods include growing
resistant varieties and planting
seedlings in a well-spaced manner.
Chemical methods involve
employing Sulphur fungicide, while
biological methods use biocontrol
agents.

5. Urediniospores and Teliospores
3M
Urediniospores
Capable of producing 3,00,000 to
5,00,000 spores
Millions
Teliospores
Capable of producing millions of spores

6. Spore Germination and
Temperature
Spore Germination
Spores mainly enter through the stomata and require good rain splash for
germination.
Optimal Temperature
Temperature between 15 to 28 ℃ is highly conducive for spore germination,
with 22℃ being the optimal temperature.

7. Resistant Varieties and Seedling
Planting
Resistant Varieties
Growing resistant varieties such as
Cauvery to minimize yield loss.
Seedling Planting
Planting seedlings in a well-spaced
manner to avoid dampness and create
unfavorable conditions for disease
development.

8. Chemical and Biological Methods
Chemical Methods Sulphur dusting at the rate of 25kg/ha
Biological Methods Employing biocontrol agents such as
Darluca filum and Penicillium
brevicompactum

9. Devastating Effect and Spread
1 Devastating Effect
Coffee rust has caused severe
devastation, with significant effects
on coffee production.
2 Spread
In the 1970s, coffee rust spread from
Africa to Brazil, causing widespread
damage.

10. Autoecious Demicyclic Rust
Autoecious Rust
The rust pathogen does not require any
other host to complete its life cycle.
Demicyclic Rust
The rust pathogen completely lacks the
uredial stage in its lifecycle, a concept still
under investigation.

11. V. Sathiya Aravindan
M.Sc., Agri Plant Pathology
Annamalai University