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Tan spot, caused by Pyrenophora tritici‐repentis (Died.) Drech. (anamorph = Drechslera tritici‐repentis [Died.] Schoem.) is considered one of the major foliar diseases of durum wheat (Triticum durum Desf.). This study was initiated in an attempt to utilize artificial inoculation techniques to estimate heritability of tan spot reaction and measure the association of disease reaction with plant height and maturity. The resistant durum wheat accession PI 184526 was crossed to the moderately susceptible ‘Calvin’ and pairs of F4 and F5 progenies were derived by single seed descent (SSD). The SSD progenies were inoculated in the greenhouse with fungal isolate PyD7 at a growth stage corresponding to 10.0 to 10.5 on the Feekes scale and tan spot ratings were recorded 9 d later. The standard unit heritability of tan spot rating based on the mean of three replications was 0.44. The SSD F4 progenies were grown and inoculated in the field at a growths tage similar to that in the greenhouse experiment. The simple correlation between greenhouse end field disease ratings ranged from r = 0.29 to r = 0.50 depending on type of disease severity rating. The correlation of days to heading and disease severity was negative (r = −0.42 to −0.58) and significant (P < 0.01). Disease severity did not appear to be associated with plant height even though the population segregated for the semidwarf character. In a separate experiment, near‐homozygous F5 progenies were derived in a hierarchical manner and were evaluated in the greenhouse to estimate additive genetic variance and additive ✕ additive epistatic variance of tan spot ratings. A significant amount of additive genetic variance was detected in the population, whereas, the additive ✕ additive genetic variance was not significant. The narrow‐sense heritability estimate was H = 0.73 indicating that selection for tan spot resistance was feasible in this population.

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