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Spores produced from the fungus-induced swellings on juniper stems can be infectious up to 6 km. The disease causes a yellow-orange spot that turns bright red on leaves of pear trees. The disease can be particularly damaging on pear, resulting in complete defoliation and crop loss if not treated.
Rust, Kern's pear Gymnosporangium kernianum. Rust, Pacific Coast pear Gymnosporangium libocedri. Rust, pear trellis (European pear rust) Gymnosporangium fuscum. Rust, Rocky Mountain pear Gymnosporangium nelsonii. Side rot Phialophora malorum. Silver leaf Chondrostereum purpureum. Sooty blotch Gloeodes pomigena. Thread blight (Hypochnus leaf blight)
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]
Carotenoids are the dominant pigment in coloration of about 15–30% of tree species. [6] Autumn leaf color is a phenomenon that affects the normally green leaves of many deciduous trees and shrubs by which they take on, during a few weeks in the autumn season, various shades of yellow, orange, red, purple, and brown.
On the apple tree, the infections occur on leaves, fruit and young twigs. [4] The brightly colored spots produced on the leaves make it easy to identify. Small, yellow-orange spots appear on the upper surfaces of the leaves, anytime from April to June. [5] These spots gradually enlarge and turn orange or red and may show concentric rings of color.
Patrick George, the founder of Heartwood Tree Service in Charlotte, said that between fall and late spring can be a tricky time to tell if a tree is ready for removal. Various species react to ...
Orange or yellow paints are used for harvest boundaries, and trees within those areas have blue, orange, green, or yellow paint, depending on whether they are to be taken or spared.
Gymnosporangium globosum is a heteroecious rust fungus that requires two hosts to complete its life cycle. Its telial stage occurs on eastern red cedar, Rocky Mountain juniper, southern red cedar, and other common junipers while its aecial stage will be found on apple, crabapple, hawthorne, and occasionally on pear, quince, and serviceberry.