Leaf Rusts

Leaf Rusts of Hardwoods and Needle Rusts of Conifers

Poplar Leaf Rust -Melampsora medusa

Poplar leaf rust

Uredinia on the bottom of a poplar leaf. They arrear as small yellow fruiting bodies called sori. These produce urediniospores that reinfect poplars

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Uredinia sori on leaf viewed with a hand lens.

Uredinia of poplar leaf rust

View of the uredinia using a stereoscope.

Poplar leaf rust telia

Later in the season, telia (black spots) form on the bottom of leaf at sites where the uredinia were located.

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Telia appear as hardened dark fruiting bodies. The teliospores are embedded in the telium which is in the leaf.

diagram of telia in leaf

Diagram showing teliospores in the leaf and basidiospores being produced. The basidiospores infect larch.

poplar leaf rust spores

Two leaves as seen under the sterioscope. A leaf with uredinia is on the right and a leaf with telia is on the left.

Poplar leaf rust on fir

Pycnia and aecia of poplar leaf rust are produced on larch and fir needles. Aecia can be seen in this photo.

Willow rust

Another related rust is willow rust, caused by a different Melampsora species. Aecia can be seen on these leaves.


Red Pine Needle Rust -Coleosporium asterum

Red pine needle rust pycnia

Red pine needle rust in early spring with pycnia on the needles.

Red pine needle rust

In summer aecia form on the needles producing aeciospores that infect aster and goldenrod.

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Aeciospores are enclosed in a structure called a peridium (white membrane) that bursts releasing the aeciospores.

Aster red pine needle rust

Uredinia (gold/yellow areas) on the bottom of aster leaves. Some telia are also starting to form on the leaves (dark areas).

Goldenrod red pine needle rust

Uredinia on the bottom os a goldenrod leaf.

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Uredinia (bottom leaf in photo) and telia (top leaf in photo) on golden rod leaves in the laboratory. Another alternate host is aster.