[1][2] Plant breeders have tried to improve yield quantities in crops like wheat from the beginning of agriculture.

With the genetic distances known predictions can be made for the best combinations concerning the two foreign genotypes carrying gene Lr37, VPMI and RL6081 and local South African cultivars.

[citation needed] In 1899, Eriksson concluded that the rust should be considered a separate authentic species.

[citation needed] This name was used by Gauemann (1959) in his comprehensive book about rust fungi of middle Europe.

[7] George Baker Cummins and Ralph Merrill Caldwell (1956) built off the broad species concept and also discussed the validity of P. rubigo-vera, which was based on a uredinial-stage basionym.

[9] Cummins (1971), in his rust monograph for Poaceae, introduced an ultra-broad species concept for P. recondita and listed 52 binomials as its synonyms.

[10] A stream of thought opposite to broad morphologically-based concepts also gained traction among uredinologists.

This idea was introduced into the classification of graminicolous rust fungi by Urban (1969), who believed a taxonomic name should reflect both morphology and ecology of a species.

[12] Meanwhile, as his research continued Urban considered morphological, ecological, and field experiences while studying wheat leaf rust, coming to consider the fungi as a part of the species Puccinia persistens with its aecial stage on Ranunculaceae members, totally different from P. recondita, which produces its aecial stage on Boraginaceae family members.

[13] Molecular and morphological studies proved Urban's taxonomy for wheat leaf rust to be correct.

To complete its sexual phase, P. triticina requires a second host (Thalictrum flavum glaucum)[2] on which it will overwinter.

In places where Thalictrum does not grow, such as Australia, the pathogen will only undergo its asexual life cycle and will overwinter as mycelium or uredinia.

After around 10–14 days of infection, the fungi will begin to sporulate and the symptoms will become visible on the wheat leaves.

Urediniospores are relatively resilient and can survive in the field away from host plants for periods of several weeks.

In general, spores move west to east due to the winds resulting from the rotation of Earth.

Puccinia triticina can survive the same environmental conditions as the wheat leaf, provided infection but no sporulation has occurred.

[16][17] For the 2020 season, USDA ARS's Cereal Disease Laboratory found 36 races in North America: BBBQD, LBDSG, LCDJG, LCDSG, MBDSD, MBTNB, MCDSB, MCDSD, MCJSB, MCTNB, MLPSD, MNPSD, MPPSD, MPTSD, MSBJG, TBBGS, TBBJS, TBRKG, TBTDB, TBTNB, TCBGS, TCGJG, TCJTB, TCSQB, TCTBB, TCTNB, TCTQB, TDBGS, TFPSB, TFTSB, TGBGS, TNBGJ, TNBGS, TNBJJ, TNBJS, and TPBGJ.

Across the entire surveyed period (92-02) the most popular were: ‘Pepital’ (Lr10+Lr13), ‘Haven’ (Lr26), ‘Hussar’ (Lr26), ‘Ritmo’ (Lr13), ‘Lynx’ (Lr17+Lr26), ‘Kris’ (Lr10+Lr13), ‘Terra’ (Lr13), ‘Sleipner’ and ‘Hereward’.

)[20] Small brown pustules develop on the leaf blades in a random scatter distribution.

Symptoms can range in severity from barely aesthetic to completely overrun on the leaf surface.

Early-maturing cultivars as well as spring wheat should be sown as early as possible to avoid peak rust periods.