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Black rot, leaf spot and canker Botryosphaeria obtusa Sphaeropsis malorum [anamorph] Black spot (of Japanese pear) Alternaria alternata. Blister canker Helminthosporium papulosum. Blister disease Coniothecium chomatosporum: Blue mold rot Penicillium spp. Penicillium expansum. Botrytis spur and blossom blight Botrytis cinerea
In southern Germany apple and pear trees have been a part of the landscape for a long time, and are difficult to protect. The decline of apple and pear trees from their landscape can be expensive to replace and could have a negative effect on tourism. In the long-run, fire blight is a very important factor of economy and society. [citation needed]
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]
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.
Like many rusts, G. sabinae requires two different hosts to complete its life cycle from year to year. Juniper is the winter host and pear is the summer host. Spores (called aeciospores) are produced from the fungal lantern-shaped growths which protrude from the blisters on the underside of the pear leaf which become airborne and infect junipers.
Symptoms include dying growing tips and bushy, stunted growth; extreme cases may prevent fruit set. Crop-specific symptoms include: Apple - interacting with calcium, may display as "water core", internal areas appearing frozen; Beetroot - rough, cankered patches on roots, internal brown rot. Cabbage - distorted leaves, hollow areas in stems.
Prunus black Rot on a Black Cherry tree. Black rot is a name used for various diseases of cultivated plants caused by fungi or bacteria, producing dark brown discoloration and decay in the leaves of fruit and vegetables: A disease of the apple, pear and quince caused by a fungus (Botryosphaeria obtusa or Physalospora cydoniae)
Symptoms include bleeding cankers on the tree's trunk and dieback of the foliage, in many cases leading to the death of the tree. P. ramorum also infects a great number of other plant species, significantly woody ornamentals such as Rhododendron , Viburnum , and Pieris , causing foliar symptoms known as ramorum dieback or ramorum blight.