Leaf rust is common on Kentucky bluegrass (Poa pratensis L.) in southern New England in cool weather. The rust is problematic for sod producers as infected sod cannot be sold. This rust appears when the daily high temperatures drop below 75° F and persists until the first hard frost. Sequencing of the ITS region of the 35S rRNA subunit suggests that the rust is Puccinia pseudostriiformis, which is a form of stripe rust.

Rust response varies among cultivars. The identification of tolerant or resistant cultivars would permit sod producers to decrease or fungicide applications. Two Kentucky bluegrass variety trials were evaluated to identify cultivars with good rust resistance. The 2000 Kentucky bluegrass NTEP trial was evaluated in 2005 and 2006. The 2006 URI Kentucky bluegrass trial was evaluated in 2006. The 2000 trial contained 193 entries; the 2006 trial contains 92 entries. Entries were rated on a scale of 1-9 with 9 being no visible rust. Results were evaluated using Fischer's LSD. The seven commercially available entries included in the top group in both 2005 and 2006 for the NTEP trial were ‘Voyager II', ‘Moon Shadow', ‘Apollo', ‘Chelsea', ‘Royce', ‘Mercury', and ‘Diva'. All of these entries scored 6.3 or higher in both years. The best entry in the URI trial in 2006 was ‘Barimpala', which developed no detectable rust. ‘Moon Shadow' and ‘Reveille' had slight amounts of rust, but were statistically similar to ‘Barimpala'. ‘Midnight' is popular with sod producers; it is very susceptible with scores of 2.3, 2.0, and 2.3. Several cultivars advertised as having excellent stripe rust resistance based on trials in the western United States developed severe rust in Rhode Island. This suggests that if the rust is indeed P. pseudostriiformis it is a different race than that found in the West.