Technical Abstract: Puccinia psidii is a rust fungus of neotropical origin that attacks and causes extensive damage to new foliage and soft stems of the invasive tree Melaleuca quinquenervia (melaleuca) in Florida. Herein, we evaluated the impact of this rust on melaleuca saplings and coppices. Puccinia psidii defoliated, deformed, and killed branch-tips of saplings and sprouts from coppices of melaleuca. Rust infected plants were significantly shorter and bushier than healthy plants. Additionally, P. psidii affected the nutrient status of melaleuca leaf tissues. Total non-structural (soluble and non-soluble) carbohydrates in dry samples were significantly lower (P=0.05) in rust-infected (1.53 mg/g) than in healthy foliage (2.06 mg/g) of the same age. Starch content, however, was higher in rust-infected (0.43 mg/g) than in healthy (0.32 mg/g) leaves. Similarly, C/N ratios in melaleuca leaves increased with increased level of rust-pustule coverage on the leaves.