There is currently no known alternate host nor reported cases of infection by basidiospores of H. vastatrix, yet the fungus is able to overcome resistance by plants and scientists do not know exactly how.

[5] The predominant hypothesis is that H. vastatrix is heteroecious, completing its life cycle on an alternate host plant which has not yet been found.

[5] An alternative hypothesis is that H. vastatrix actually represents an early-diverging autoecious rust, in which the teliospores are non-functional and vestigial, and the sexual life cycle is completed by the urediniospores.

Recent studies and research papers have shown that CLR is under-researched compared to pathogens of other cash crops and that there are many factors that can influence the incidence and severity of the disease.

Professional research and breeding programs such as CIRAD are developing F1 hybrid coffee trees such as Starmaya that have broad genetic resistance to CLR as well as good yield and cup quality, with research showing that F1 hybrids have higher yields and cup quality than conventional Coffea arabica cultivars.

[11] For example, Starmaya is the first F1 hybrid coffee tree that can be propagated in a seed garden rather than the more complicated and expensive process of somatic embryogenesis.

Copper-based fungicides, such as Bordeaux mixture, have proven to be effective and economical, and work best when applied at inoculum levels below 10%.

Cultural methods such as pruning branches to allow more air circulation and light penetration can help dry the moisture on the leaves.

[14] There is a complex interaction between shade, meteorological effects such as rainfall or dry periods, and aerial dispersal of rust.

Hemileia vastatrix is an obligate parasite that lives mainly on the plants of genus Coffea but is also capable of invading Arabidopsis thaliana but does not develop haustoria.

It was reported first by a British explorer from regions of Kenya around Lake Victoria in 1861, from where it is believed to have spread to Asia and the Americas.

Rust was first reported in the major coffee growing regions of Sri Lanka (then called Ceylon) in 1867.

The causal fungus was first fully described by the English mycologist Michael Joseph Berkeley and his collaborator Christopher Edmund Broome after an analysis of specimens of a "coffee leaf disease" collected by George H.K.

During 1913 it crossed the African continent from Kenya to the Congo, where it was found in 1918, before spreading to West Africa, the Ivory Coast (1954), Liberia (1955), Nigeria (1962–63) and Angola (1966).

Hemileia vastatrix affects the plant by covering part of the leaf surface area or inducing defoliation, both resulting in a reduction in the rate of photosynthesis.

Transmission over large distances is likely the result of human intervention by spores clinging to clothes, tools, or equipment.

[23] Although temperature and moisture are key factors for infection, dispersal, and colonization, plant resistance is also important in determining whether Hemileia vastatrix will survive.

The disease coffee leaf rust (CLR) was first described and named by Berkley and Broom in the November 1869 edition of the Gardeners Chronicle.

Many coffee estates in Sri Lanka were forced to collapse or convert their crops to alternatives not affected by CLR, such as tea.

[17]: 171–2  The planters nicknamed the disease "Devastating Emily"[24] and it affected Asian coffee production for over twenty years.

[17]: 171–2  From Brazil, the disease spread to most coffee-growing areas in Central and South America by 1981, hitting Costa Rica and Colombia in 1983.

Coffee prices rose as a result, although other factors such as growing demand for gourmet beans in China, Brazil, and India also contributed.

[27][28] USAID estimates that between 2012 and 2014, CLR caused $1 billion in damage and affected over 2 million people in Latin America.

[29] The reasons for the epidemic remain unclear but an emergency rust summit meeting in Guatemala in April 2013 compiled a long list of shortcomings.

In a keynote talk at the "Let's Talk Roya" meeting (El Salvador, November 4, 2013), Dr Peter Baker, a senior scientist at CAB International, raised several key points regarding the epidemic including the proportional lack of investment in research and development in such a high value industry and the lack of investment in new varieties in key coffee producing countries such as Colombia.

[18] Typical coffee cultivars maintained by farmers before the epidemic included Caturra, Bourbon, Mundo Novo, and Typica,[29] all of which are susceptible to H. vastatrix.

[34][35] CLR disease is a big problem in coffee plantations in Peru, declared in sanitary emergency by government (Decreto Supremo N° 082-2013-PCM).