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Black leaf, also known as black spot disease can be caused by different types of fungi and bacteria. Most common being Asterina, Asterinella, Diplotheca, Glomerella, Gnomonia, Schizothyrium, Placosphaeria, and Stigmea. Black leaf can affect many different plant species in a wet, damp climate. It may appear as black spots on leaves, stems, and ...
A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions often have a centre of necrosis (cell death). [1]
Halo blight causes small water-soaked spots on leaves. These spot progressively turn dark brown and are surrounded by a wide greenish yellow halo. The necrotic spots remain small unlike that of common blight. [4] Similar to foliage symptoms, halo blights causes water-soaked spots on vegetative pods. It also causes streaks along pod sutures.
Phyllosticta citricarpa infects mostly citrus plants. However, this fungus is also seen to infect other plants such as golden apple, mango and guava as well. [10] There are some plants that are more susceptible to the pathogen than others. Lemon and late maturing citrus, such as Valencia orange, are the most susceptible hosts. [citation needed]
Black spot (class Leotiomycetes: family Helotiales) Diplocarpon rosae syn. Marssonina rosae – Marssonina rosae causes black spots on leaves. [4] The spots, which may be as much as 12 mm across, are generally circular and have an irregular edge often with a yellow halo. Leaves frequently turn yellow and fall early.
The black spots are circular with a perforated edge, and reach a diameter of 14 mm (1 ⁄ 2 inch). Badly affected plants, however, will not show the circular patterning, as they combine to cause a large, black mass. The common treatment of the disease is to remove the affected leaves and spray with antifungal solutions.
Blight is a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. [1] Accordingly, many diseases that primarily exhibit this symptom are called blights. Several notable examples are: [citation needed]
People can observe P. infestans produce dark green, then brown then black spots on the surface of potato leaves and stems, often near the tips or edges, where water or dew collects. [9] The sporangia and sporangiophores appear white on the lower surface of the foliage. As for tuber blight, the white mycelium often shows on the tubers' surface. [10]