[6] Stiles obtained another rust isolate from spearmint and found it did not infect oregano or related species.

This suggests the strains of P. menthae are host specific within the plant family Lamiaceae.

More research is required to determine more information regarding the degree host specificity of P. menthae.

As the season progresses, the spots turn into brown pustules, teliospores, surrounded by a chlorotic halo.

Mature aecial spores develop from spermogonia and cause hypertrophy, twisting, and distortion in young peppermint shoots.

Moisture heavily influences this stage of the life cycle as high humidity confers an infection of urediospores.

[10] Urediospore sori is produced on the undersides of the host leaves and are protected from solar radiation.

A significant reduction in yield can result in a loss of income for mint growers.