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Once on the leaves, the spores germinate and penetrate through the stoma. [2] The subsequent infection causes chlorosis of the leaves in localized yellow spots. As the season continues into summer, apothecia begin to form, giving rise to brown-black leaf lesions that resemble spots of tar. [2] Leaves retain their yellow border from the initial ...
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]
Hoya carnosa Hoya mindorensis, Sydney, Australia.. Hoya is a genus of over 500 species of plants in the dogbane family, Apocynaceae, commonly known as waxflowers. [2] Plants in the genus Hoya are mostly epiphytic or lithophytic vines, rarely subshrubs, with leathery, fleshy or succulent leaves, shortly tube-shaped or bell-shaped flowers with five horizontally spreading lobes, the flowers in ...
When lettuce is infected with INSV, it shows a number of symptoms, such as yellowing leaves, dead spots, and stunted growth. On the inner leaves there are patterns of necrosis and chlorosis. At the base of the ribs of infected lettuce plants there is significant necrosis and lesions. The necrotic tissue can look brown to dark brown.
Hoya serpens is a small trailing vine found in the Himalayas and surrounding areas. It has small round leaves that are 1.5 to 2 cm long. It has small round leaves that are 1.5 to 2 cm long. The leaves are dark green, hairy, and have grey spots intermittently dispersed.
Hoya macgillivrayi is a vine with stems less than 20 mm (0.79 in) in diameter and containing white, milky sap. Its leaves are glabrous, egg-shaped to lance-shaped, up to 200 mm (7.9 in) long and to 80 mm (3.1 in) wide with two to five colleters. The flowers are fleshy, glabrous, flattened bell-shaped, dark reddish-pink, sometimes with a white ...
Hoya australis is a succulent climbing vine to subshrub that typically reaches a height of 4–10 m (13–33 ft). It has fleshy or leathery, elliptic, oblong, egg-shaped or more or less round leaves up to 150 mm (5.9 in) long and 120 mm (4.7 in) wide.
Infected leaves are filled with numerous black lesions that cover an obvious portion of the leaf. [5] These lesions first appear as small purple spots which turn red to brown and then black. Most spots are circular but can amalgamate to form large, irregular dead patches. [6] These spots tend to enlarge and separate from healthy tissue.