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Rust fungi are highly specialized plant pathogens with several unique features. Taken as a group, rust fungi are diverse and affect many kinds of plants. However, each species has a range of hosts and cannot be transmitted to non-host plants. In addition, most rust fungi cannot be grown easily in pure culture.
Leaf spots can vary in size, shape, and color depending on the age and type of the cause or pathogen. Plants, shrubs and trees are weakened by the spots on the leaves as they reduce available foliar space for photosynthesis. Other forms of leaf spot diseases include leaf rust, downy mildew and blights. [4]
First appearing as small yellow pustules on leaves, bolls, and stems, the spots will then transform into larger, orange/red pustules [2] which release aeciospores. [3] Rust lesions can cause leaves or stems to become weak and break or fall off, resulting in decreased photosynthetic ability and extreme difficulty during harvest.
A leaf of Philodendron maximum. The leaves are usually large and imposing, often lobed or deeply cut, and may be more or less pinnate. They can also be oval (Philodendron 'White Princess'), spear-shaped, divided (Philodendron tripartitum) or in many other possible shape variations. The leaves are borne alternately on the stem.
Several members of the order Pucciniales are commonly called leaf rusts: . Wheat leaf rust caused by Puccinia triticina; Hemileia vastatrix which causes Coffee leaf rust; Leaf rust (barley) or barley leaf rust or brown rust or barley brown rust...
Plants infected by chrysanthemum white rust exhibit spots on the upper surfaces of leaves. These spots are initially pale-green to yellow in color and up to 5mm in diameter, but may turn brown as the tissue becomes necrotic. On the underside of the leaf, stems, and flower, spots develop into pink or white waxy telial clusters/pustules where ...
5. Low Humidity. Light brown spots scattered across fiddle leaf fig leaves can be caused by dry air. If the brown spots in question have a pox-like look instead of being in a single area of the ...
The most identifiable sign of P. helianthi is the uredinia which forms rust-colored pustules on leaves, stems, petioles, and bracts. These darken into black, telial resting pustules once temperatures decrease. Flask-shaped pycnia appear as yellow-orange spots, 6mm or less, on the upper side of leaves in early spring.