![]() infestans can survive in dry conditions for an hour and even more in cloudy weather. During unfavourable conditions, the sporangia wall bursts out to release free zoospores. In wet conditions, the sporangia form biflagellate zoospores within three to five hours and require 12 hours of free moisture. The fungus may disperse into new infection sites, and later a fungal mycelium develops sporangia. Lesions or blisters develop in seedlings or tubers after an attack of the fungus ( P. Generally, the asexual phase is more common. The sexual mode of the disease cycle occurs through oospores, resulted after the fusion of oogonium and antheridium. The asexual mode of the disease cycle occurs via sporangia either indirectly by zoospores or without an intermediary through the germ-tube formation. If no one follows control measures for the disease management, then the whole field may be affected that may emit an offensive odour. infestans causes 24-45 mm deep rotting in tubers, or we can say it affects the whole potato. Wet rot: The potato tuber develops the growth of white colonies outside and secretes water.infestans causes 5-15 mm deep rotting in tubers. Dry rot: Bluish-black and reddish-brown fungal growth develop outside and inside of the potato tuber.Later, leaves start falling and rotting in tubers also occur.Within several days (generally 1-4), leaf rotting occurs by the development of tan coloured blisters (in dry weather) and growth of blue-grey mycelium (in moist weather).In certain areas of the plant, leaf blistering may occur.The lower leaf develops brown and black lesions.The appearance of watery, light green or yellow blisters on the leaf foliage.The signs and symptoms of late blight in potatoes include the following: The infection or late blight in potatoes may occur at any stage of plant growth. The foliage becomes shrivelled in dry climatic conditions, whereas leaves become dead and give a foul smell in moist conditions. Then, the plant foliage acquires rapid blistering. When the pathogen gets favourable conditions, lesions proliferate, and the infection spreads upward from the lower leaves and petioles. We can see blisters or lesions on leaves as small dead spots with varying colours (brown to purple-black) during this stage.īesides the plant foliage (including veinlets and margins), the infection also spreads to the areas like rachis, petiole and stem. Phytophthora infestans predominantly attack plant foliage. Free moisture from rain, dew and irrigation methods.The infection by the Phytophthora infestans is favoured by the following factors necessary for the pathogen to cause infection and disease development: In severe cases, there is a complete loss of crop.It reduces productivity as well as the quality of the crop.Leaf or foliage develops spots of different colours during crop development.Phytophthora infestans can cause severe damage to potato crops by affecting the following: infestans is 120 ☏ for a time limit of half an hour. Primary sources of inoculum include the infected seeds or potatoes kept in storage and culled or volunteer potatoes. infestans spreads intracellularly through its slender and unbranched haustoria. It acts like an obligate parasite that requires a living host and invades the host cell. infestans is a coenocytic oomycete or water mould. Phytophthora infestans is a causal organism causing late blight or potato blight, and the term itself denotes a plant destroyer. In addition, you will get to know the symptoms, disease cycle and the control measures of the late blight in potatoes. This post describes the effects, favourable factors, and mode of action of the pathogen responsible for potato blight.
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