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Farm management · Pest or disease

Coffee leaf rust

The fungal disease that strips coffee trees of their leaves. How Hemileia vastatrix infects, why it spread from Ceylon to Hawaii, how resistance genes and races interact, and how producers control it.

Across the chain: History · Science

Source-checkedby Coffearium verification pass· Last source-checked 16 Oct 2026· Prepared with AI assistance· 14 sources (11 tier A)· 3 contested· Updated 22 Oct 2026
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Contents
  • Coffee leaf rust is caused by the fungus Hemileia vastatrix. Orange spore masses form on the underside of the leaf, and infected leaves fall early.1,2
  • Spores germinate only in liquid water; infection runs between about 15 and 28 °C and enters through stomata on the leaf underside.2,3
  • Rust this year cuts next year’s crop, because next season’s cherries grow on this season’s shoots.2,7
  • Resistance in several Timor Hybrid derivatives is being lost as new races of the fungus appear; more than 50 races were known by 2017.1
  • In the 2008–2013 epidemic, Colombia’s production fell by 31% on average against 2007, and Central America’s by 16% in 2013 against 2011–12.4

What coffee leaf rust is#

Coffee leaf rust is a disease of the coffee leaf caused by the fungus Hemileia vastatrix.1 Its signs are orange spore masses on the underside of the leaf.1,2 The American Phytopathological Society calls it the most economically important coffee disease in the world.2 A 2017 review puts its losses at one to two billion US dollars a year.1

The fungus is known only from coffee plants (Coffea species). It reproduces almost entirely through one kind of spore, the urediniospore, which infects new leaves again and again.1 No alternate host for its rare sexual spores has been identified.1 For C. arabica, the review names rust as one of the main limiting factors.1 Several resistance genes that breeders have moved into arabica come from robusta (C. canephora).1,12

How the fungus infects a leaf#

A spore needs liquid water on the leaf to germinate. High humidity alone is not enough; rain or heavy dew is.2,3,9 On a wet leaf, temperature decides how fast it happens.3 Infection runs between a minimum of about 15 °C and a maximum of about 28 °C, with an optimum of 22 °C.2

The germinating spore grows towards a stoma, one of the breathing pores on the underside of the leaf. It enters only there.1,2 The whole infection needs about 24–48 hours of continuous wetness.2 Inside, the fungus grows into the leaf. After 10–14 days, new spore pustules break out through the stomata.2,9

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  1. Spore in a water film. A urediniospore lands on the underside of the leaf. It germinates only in liquid water from rain or heavy dew.2,3
  2. Germ tube and appressorium. The germ tube grows to a stoma and forms a swelling, the appressorium, over it.1
  3. Entry and colonisation. The fungus enters through the stoma and grows inside the leaf. Infection takes about 24–48 hours of wetness.1,2
  4. Yellow spot. Small pale yellow spots on the upper surface are the first visible sign.2
  5. New spores. About 10–14 days after infection, a pustule (uredinium) pushes a bouquet of orange spores out through the stomata.2,9 A 2017 review gives about three weeks.1
  6. Spread. Splashing rain moves spores within the plantation; wind carries them over long distances.2
  7. Leaf drop. Infected leaves fall early, which weakens the tree.1,2
The repeating (asexual) cycle of Hemileia vastatrix on a coffee leaf, shown in a cut through the leaf. Schematic, not to scale.1,2

What it does to the tree and the harvest#

Badly infected leaves fall early. The tree loses part of its capacity to photosynthesise and becomes weaker.2 Severe attacks can kill twigs and even whole trees.2,11

The damage reaches into the following year. Next season’s cherries grow on this season’s new shoots, so rust this year reduces next year’s crop.2 A review of rust in Brazil describes the same effect: lower production in the year after an epidemic.7 In Brazil, the review reports losses of 30–50%.7

Rust is usually milder at altitudes above 1,200 m in Brazil, where conditions favour it less.7 A 2017 review notes that it has been reported increasingly at higher altitudes.1 Trees carrying a heavy crop are more susceptible.3

From Ceylon to Hawaii#

The disease was first recorded in 1861 near Lake Victoria in East Africa, on wild coffee.1 Planters in Ceylon (Sri Lanka) reported a “coffee leaf disease” in 1867. The fungus was described as Hemileia vastatrix in 1869.1,2 Soon after, it wiped out coffee growing in Ceylon, and British planters turned to tea.1,2,13

The rust then crossed the coffee lands of the Indian Ocean and the Pacific, from 1870 to 1920.1 Estates in Asia were replanted with robusta.13 In the late nineteenth century, liberica coffee stood second only to arabica in the coffee trade.14 The rust reached the Atlantic coast of Africa in the 1950s and 1960s.1

The Americas stayed free until 1970.2 In January 1970 rust was found on arabica in southern Bahia, Brazil.7 It spread through South and Central America in the 1970s and 1980s.1 A US Department of Agriculture datasheet of 2015 named Hawaii as the exception among coffee-growing regions.9 Hawaii found it in October 2020, on Hawaii Island and Maui; by July 2021 it was on all the main islands.10

Since 2008, a series of outbreaks across the Americas has become known as the “Big Rust”.5 In Colombia and Central America, the epidemic of 2008–2013 cut production and hit the livelihoods of thousands of smallholders and harvesters.4

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  1. 1861. First record, near Lake Victoria in East Africa, on wild coffee.1
  2. 1867–1869. Planters in Ceylon report a leaf disease (1867); the fungus is described as Hemileia vastatrix (1869).1,2
  3. 1870–1920. Spread through the coffee zones of the Indian Ocean and the Pacific.1
  4. 1927. A rust-resistant plant is found on Timor: the origin of the Timor Hybrid.1
  5. 1950s–1960s. Rust reaches the Atlantic coast of Africa.1
  6. 1970. First found in the Americas, in southern Bahia, Brazil.2,7
  7. 1970s–1980s. Spread through South and Central America; present in Puerto Rico since the 1980s.1,9
  8. 2008–2013. Epidemic in Colombia and Central America.4,5
  9. 2020. Detected in Hawaii (October 2020); on all main islands by July 2021.10
How coffee leaf rust spread around the coffee-growing world, 1861–2021. Dates to scale; markers schematic.1,2,4,7,9,10

How producers control it#

Producers have managed rust in four main ways: finding resistant plants, breeding resistant varieties, chemical control and agroecological control.5 Resistant varieties are considered the most effective and durable option.1

Resistant varieties. Most rust-resistant arabica varieties descend from the Timor Hybrid, a natural cross of C. arabica and C. canephora.1,12 Their resistance is being lost in several of them, as new forms of the fungus appear.1 The varieties themselves are covered in the entry on arabica varieties.

Fungicides. Copper fungicides protect the leaf but must be on it before infection.2 Systemic fungicides, such as triazoles and strobilurins, can also stop infections that have already started.1,2,7 Sprays are aimed at the underside of the leaves, where infection happens.2

Farm management. Trees with a heavy crop are more susceptible.3 In a controlled study, low nitrogen fertilisation raised sporulation, most of all under high light.6 Low profitability led to poorer farm management before the 2008–2013 epidemic.4 Shade has two sides: one study proposes it as part of rust control, while a review found that medium shade favours the rust.3,6

The life cycle in detail#

Spores and germination. Urediniospores are dikaryotic, with two nuclei in each cell, and form the repeating asexual cycle.1 Germination requires free water; humidity alone does not trigger it.2,3 Germination is optimal at about 24 °C.1 Below 15 °C spores do not germinate.3 A US Department of Agriculture datasheet gives 15–30 °C for germination and the other infection steps.9 For infection as a whole, one review gives 15 °C minimum, 22 °C optimum and 28 °C maximum.2

Penetration. The germ tube forms an appressorium over a stoma on the lower leaf surface. A penetration hypha then grows into the substomatal chamber.1 Infection needs about 24–48 hours of continuous free moisture.2

Latent period. The time from infection to new spores is the latent period. Reported values are 10–14 days2,9 and about three weeks.1 Temperature controls its length; one review summarises models that predict it from daily maximum and minimum temperatures.3

Sporulation. One lesion produces four to six crops of spores, about 300,000 urediniospores, over 3–5 months.2 Rain splash spreads spores within a plantation; long-range spread is mainly by wind.2

Sexual stage. Teliospores occur rarely and germinate in place to form four basidiospores. Basidiospores cannot infect coffee, and no other host plant has been identified.1 The fungus has long been treated as asexual. Population studies have nevertheless found signs of random mating.1

Weather, altitude and epidemics#

On a wet leaf, temperature is the most important environmental factor for spore germination.3 Rust intensity is lower at higher altitudes.3 In Brazil the disease is usually less severe above 1,200 m.7 Long-term Cenicafé observations in Colombia found more rust at high altitude in warmer El Niño years than in La Niña years.11

A 2015 review of the Colombian and Central American crises names two main drivers: economics and weather.4 Low profitability led to reduced management, and weather conditions consistent with climate change enhanced the epidemics.4 A 2017 review describes the same convergence of agronomic, climatic and economic factors.1

Races, SH genes and the gene-for-gene model#

Nine resistance factors have been identified in coffee, named SH1 to SH9.3 SH1, SH2, SH4 and SH5 come from C. arabica. SH3 was introgressed into arabica from C. liberica. SH6 to SH9 come from robusta and occur in the Timor Hybrid and other interspecific hybrids.1

The fungus carries matching virulence genes, v1 to v9.1 Coffee and rust interact according to Flor’s gene-for-gene model, in which each SH gene has a matching virulence gene (v1 for SH1, and so on).1,3 In this model, a resistance gene in the plant works only against rust that lacks the matching virulence gene. A plant with SH3 resists every race without v3. A race that carries v3 overcomes SH3.1 A plant with several SH genes can be infected only by a race that carries all the matching v genes. In 1989 a review noted that virulence to SH3 is more complex than this simple matching predicts.3

A physiological race is a group of isolates with a distinct combination of virulence genes.1 Races are identified by inoculating a set of coffee “differentials”, plants with known resistance genes. In 1989 there were more than 30 known races.3 By 2017, more than 50 races and 23 coffee differentials had been identified.1

Timor Hybrid derivatives and lost resistance#

The Timor Hybrid populations derive from a plant found on Timor in 1927. In the 1950s they were shown to be natural hybrids of C. arabica and C. canephora.1 Breeders chose the Timor Hybrid as their main source of resistance genes, because it crosses readily with arabica.12 Crosses made at the coffee rust research centre CIFC in Portugal gave the Catimor and Sarchimor populations. Similar populations were made in Colombia and Brazil.1 Together they are the source of most rust-resistant varieties grown as of 2017.1

Resistance in several Timor Hybrid derivatives is being lost, as new races appear that can overcome it.1 In Brazil, few varieties are completely resistant; most show various levels of partial resistance.7 F1 hybrids showed lower sporulation than an inbred line in a controlled study, possibly through hybrid vigour.6

Host factors: fruit load, light and nitrogen#

Fruit load. Susceptibility increases with berry yield. When immature berries were removed, disease severity fell to almost half.3 Overbearing can make rust worse.3

Light and shade. Leaves exposed to high light intensity generally become more susceptible.3 Bright sunlight may also kill the fungus in the leaves.3 The 1989 review concluded that medium levels of shade favour rust on susceptible varieties most.3 In a 2017 controlled-environment study, high light combined with low nitrogen gave heavy sporulation, and a warmer temperature regime (27–22 °C) gave about 2,000 times more sporulation than a cooler one (23–18 °C), as the abstract puts it; the results section reports about 10,000 times more spores per infected leaf area in the inbred line Caturra.6 The authors proposed vigorous varieties, shade and suitable nitrogen fertilisation as part of an agroecological approach.6

Plant vigour. The 2017 study found that measurements of photosynthesis (chlorophyll fluorescence) helped predict how much the rust would sporulate.6

Chemical control#

Copper. Copper fungicides are preventive.1 They must be on the leaves before infection occurs.2 Copper builds up in soil over years of use.2

Systemic fungicides. Curative treatments use systemic fungicides.1 In Brazil, rust is managed with protectant and systemic fungicides, including copper, triazoles and strobilurins, applied by decision rules that vary with the risk.7 The combined or alternate use of copper and systemic products is advised.1 One practice is copper early in the season, then one or occasionally two systemic sprays later in the season.2

Application. Sprays are directed upward to reach the lower leaf surface, and intervals between sprays are kept under 21 days.2 The guidance opened here describes foliar sprays.2 In a Brazilian field trial from 2010 to 2012, a triazole applied to the soil, followed by foliar sprays of a triazole and a strobilurin, also controlled rust and raised yields.8

In the greenhouse part of that study, single fungicides reduced rust severity by between 8.9% and 98.5% against untreated plants.8

020406080100%Trifloxystrobin(strobilurin)8.9%8 Azoxystrobin (strobilurin)79.4%8 Triadimenol (triazole)82.0%8 Cyproconazole (triazole)93.2%8 Epoxiconazole (triazole)96.6%8 Pyraclostrobin(strobilurin)98.5%8
Data table
%Source
Trifloxystrobin (strobilurin)8.9%8
Azoxystrobin (strobilurin)79.4%8
Triadimenol (triazole)82.0%8
Cyproconazole (triazole)93.2%8
Epoxiconazole (triazole)96.6%8
Pyraclostrobin (strobilurin)98.5%8
Reduction in rust severity on three-month-old coffee seedlings in a greenhouse, by fungicide, compared with untreated plants. Triazoles: triadimenol, cyproconazole, epoxiconazole; strobilurins: azoxystrobin, trifloxystrobin, pyraclostrobin. Data: Zambolim et al. 2015.8
Fungicide Group Reduction in rust severity (greenhouse)
Trifloxystrobin Strobilurin 8.9%8
Azoxystrobin Strobilurin 79.4%8
Triadimenol Triazole 82.0%8
Cyproconazole Triazole 93.2%8
Epoxiconazole Triazole 96.6%8
Pyraclostrobin Strobilurin 98.5%8

Forecasting. Infection depends on leaf wetness and temperature, and models predict the latent period from daily maximum and minimum temperatures.2,3 The 2015 review of the Central American crisis proposes early warning systems as one of its solutions.4

Biological control#

Spores of H. vastatrix are parasitised by another fungus, Lecanicillium lecanii.1 It cannot control the rust effectively, but it can reduce spore viability and disease severity.1 The same fungus mainly attacks the green coffee scale, Coccus viridis, an insect.1 No biological product opened for this entry has been shown to control rust on its own in the field.

The 2008–2013 epidemic in numbers#

The 2015 review gives these production losses:4

  • Colombia: production fell by 31% on average in the epidemic years, compared with 2007.4
  • Central America: production fell by 16% in 2013 compared with 2011–12, and by 10% in 2013–14 compared with 2012–13.4
  • Employment in Central American coffee fell by 16% in 2012–13 and by 7% in 2013–14 because of the epidemic.4

A 2017 review states that the disease can cause yield losses of up to 35%.1 The figures measure different things: national production against a reference year, and yield losses.

Cup and supply#

According to a 2017 textbook chapter, there is no evidence that diseases or pests change the synthesis of specific compounds in the bean directly.11 Their effect on quality runs through the plant. Strong defoliation from rust weakens trees, and weak plants give lower yields and can give lower quality.11

The indirect effects are larger. According to the same book, resistant varieties from Timor Hybrid crosses raised productivity, but as of 2017 their cup quality was debated in some cases, for example Costa Rica 95.12 Breeding showed that introgressed varieties with good quality are possible when quality is a main selection criterion.12 For buyers, an epidemic means lower volumes, in the epidemic year and in the year after.4,7

Reference values#

Parameter Value reported Source
Water for germination Liquid water (rain, heavy dew); humidity alone not enough Arneson2; Kushalappa & Eskes3; USDA9
Germination temperature Optimum about 24 °C; no germination below 15 °C; 15–30 °C range Talhinhas et al.1; Kushalappa & Eskes3; USDA9
Infection temperature 15 °C minimum, 22 °C optimum, 28 °C maximum Arneson2
Wetness for infection About 24–48 h continuous Arneson2
Entry Stomata on the lower leaf surface only Talhinhas et al.1; Arneson2
Latent period 10–14 days; about 3 weeks Arneson2; USDA9; Talhinhas et al.1
Spores per lesion About 300,000 in four to six crops over 3–5 months Arneson2
Resistance genes SH1–SH9 Kushalappa & Eskes3; Talhinhas et al.1
Races known More than 30 (1989); more than 50 (2017) Kushalappa & Eskes3; Talhinhas et al.1
Spray interval Under 21 days Arneson2
Losses, Brazil 30–50% Zambolim7
Altitude, Brazil Usually less severe above 1,200 m Zambolim7

Open questions#

  • Light during germination. A need for darkness during germination is often stated, but none of the sources opened for this entry gives one, so it is left out.
  • Why resistance breaks down. How new races arise in a fungus thought to be mainly asexual is not settled; signs of recombination have been found.1
  • Shade. Whether shade raises or lowers rust depends on the balance between less plant stress and more leaf wetness; studies opened here point both ways (see Contested).3,6
  • Mycoparasites in practice. Lecanicillium lowers spore viability, but its value as a control tool on farms is not established.1
  • Current spread. No global map of rust presence updated in 2026 was opened for this entry (as of October 2026); the last dated addition found is Hawaii (2020).10

Key studies#

Talhinhas et al., 2017 – One and a half centuries around the tropics. A review of the pathogen’s history, life cycle, genetics, races and control. It traces the SH resistance genes and v virulence genes, reports more than 50 races, and explains why resistance from the Timor Hybrid is being lost.

Molecular Plant Pathology 18(8), 1039–1051 · doi:10.1111/mpp.12512

Kushalappa & Eskes, 1989 – Advances in coffee rust research. A classic review of rust epidemiology. It sets out the need for free water, the role of temperature in germination and latent period, and the effects of crop load, light and shade on disease.

Annual Review of Phytopathology 27, 503–531 · doi:10.1146/annurev.py.27.090189.002443

Avelino et al., 2015 – The rust crises in Colombia and Central America. Quantifies the production and employment losses of the 2008–2013 epidemics. It traces them to low profitability and weather, and proposes resistant varieties, early warning and producer training.

Food Security 7, 303–321 · doi:10.1007/s12571-015-0446-9

Toniutti et al., 2017 – Environment, genotype and rust. Grew one inbred line and two F1 hybrids of arabica under set temperature, light and nitrogen, then inoculated them. Warmth, high light and low nitrogen raised sporulation; the hybrids sporulated less, significantly so in all treatments of the warmer regime (see F1 hybrids).

Frontiers in Plant Science 8, 2025 · doi:10.3389/fpls.2017.02025

McCook & Vandermeer, 2015 – The Big Rust and the Red Queen. Places the outbreaks since 2008 in two centuries of history. Producers have relied on four strategies: finding resistant plants, breeding, chemical control and agroecological control.

Phytopathology 105(9), 1164–1173 · doi:10.1094/PHYTO-04-15-0085-RVW

Contested
  • Optimum temperature: a teaching review gives 22 °C for infection, with 15 °C minimum and 28 °C maximum2; a 2017 review gives about 24 °C as the optimum for germination1, and a US Department of Agriculture datasheet 15–30 °C for germination and infection.9 The values refer partly to different steps.
  • Time from infection to new spores: 10–14 days in a teaching article and in a US datasheet that draws on it2,9, about three weeks in a 2017 review.1 The latent period shortens or lengthens with temperature.3
  • Shade and rust: a 1989 review found that medium shade favours rust most on susceptible varieties and that high light makes leaves more susceptible3; a 2017 controlled study proposes shade as part of an agroecological approach6; full-sun monoculture was introduced in Latin America partly to combat rust.11
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Sources

  1. ATalhinhas, P.; Batista, D.; Diniz, I.; Vieira, A.; Silva, D. N.; Loureiro, A.; Tavares, S.; Pereira, A. P.; Azinheira, H. G.; Guerra-Guimarães, L.; Várzea, V.; Silva, M. C. (2017). The coffee leaf rust pathogen Hemileia vastatrix: one and a half centuries around the tropics. Molecular Plant Pathology 18(8), 1039–1051. doi:10.1111/mpp.12512 · other copies
  2. AArneson, P. A. (2000). Coffee rust. The Plant Health Instructor, American Phytopathological Society (updated 2011). doi:10.1094/PHI-I-2000-0718-02 · other copies
  3. AKushalappa, A. C.; Eskes, A. B. (1989). Advances in coffee rust research. Annual Review of Phytopathology 27, 503–531. doi:10.1146/annurev.py.27.090189.002443 · other copies
  4. AAvelino, J.; Cristancho, M.; Georgiou, S.; Imbach, P.; Aguilar, L.; Bornemann, G.; Läderach, P.; Anzueto, F.; Hruska, A. J.; Morales, C.; et al. (2015). The coffee rust crises in Colombia and Central America (2008–2013): impacts, plausible causes and proposed solutions. Food Security 7, 303–321. doi:10.1007/s12571-015-0446-9 · other copies
  5. AMcCook, S.; Vandermeer, J. (2015). The big rust and the Red Queen: long-term perspectives on coffee rust research. Phytopathology 105(9), 1164–1173. doi:10.1094/PHYTO-04-15-0085-RVW · other copies
  6. AToniutti, L.; Breitler, J. C.; Etienne, H.; Campa, C.; Doulbeau, S.; Urban, L.; Lambot, C.; Pinilla, J. C. H.; Bertrand, B. (2017). Influence of environmental conditions and genetic background of Arabica coffee (C. arabica L) on leaf rust (Hemileia vastatrix) pathogenesis. Frontiers in Plant Science 8, 2025. doi:10.3389/fpls.2017.02025 · other copies
  7. AZambolim, L. (2016). Current status and management of coffee leaf rust in Brazil. Tropical Plant Pathology 41(1), 1–8. doi:10.1007/s40858-016-0065-9 · other copies
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  9. AMackesy, D.; Sullivan, M. (2015). CPHST pest datasheet for Hemileia vastatrix. USDA-APHIS-PPQ-CPHST.
  10. AHawai`i Department of Agriculture (2021). Coffee leaf rust confirmed on Kaua`i and Moloka`i (news release NR21-17). Hawai`i Department of Agriculture.
  11. BLambot, C.; Herrera, J. C.; Bertrand, B.; Sadeghian, S.; Benavides, P.; Gaitán, A. (2017). Cultivating Coffee Quality – Terroir and Agro-Ecosystem. In: Folmer, B. (ed.), The Craft and Science of Coffee, Academic Press, ch. 2, pp. 17–49. doi:10.1016/B978-0-12-803520-7.00002-5 · other copies
  12. BHerrera, J. C.; Lambot, C. (2017). The Coffee Tree – Genetic Diversity and Origin. In: Folmer, B. (ed.), The Craft and Science of Coffee, Academic Press, ch. 1, pp. 1–16. doi:10.1016/B978-0-12-803520-7.00001-3 · other copies
  13. BMorris, J. (2017). We Consumers – Tastes, Rituals, and Waves. In: Folmer, B. (ed.), The Craft and Science of Coffee, Academic Press, ch. 19 (pp. 470–471 cited). doi:10.1016/B978-0-12-803520-7.00019-0 · other copies
  14. ADavis, A. P.; Shepherd-Clowes, A.; Cheek, M.; Moat, J.; Luo, D. W.; Kiwuka, C.; Kalema, J.; et al. (2025). Genomic data define species delimitation in Liberica coffee with implications for crop development and conservation. Nature Plants 11, 1729–1738. doi:10.1038/s41477-025-02073-y · other copies

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