what are some plants diseases?

Answer 1

Diseases of Plants, deviations from the normal growth and development of plants incited by micro-organisms, parasitic flowering plants, roundworms, viruses, or adverse environmental conditions. Plant diseases attributable to these causes are estimated to number more than 25,000; the resulting estimated annual losses to farmers are enormous. Injuries to plant life due primarily to insects, mites, or animals other than roundworms are not regarded as plant diseases.

Bacterial diseases are marked by various symptoms, including soft rot, leaf spot, wilt of leaves and stems, canker, leaf and twig blight, and gall formation. Fire blight, a disease of apple and pear trees, is historically interesting because it was the first plant disease in which a bacterium was shown to be the inciting agent. Infected trees exhibit a blackening of the flowers, leaves, and twigs, and the disease may finally involve the entire tree, causing serious damage and even death. Citrus canker, an Asian disease of the orange tree and its relatives, is characterized by corky growths on the fruit, leaves, and twigs. Common scab of potato, bacterial canker of tomato, angular leaf spot of cotton, and black rot of crucifers are other prevalent bacterial plant diseases. Crown gall, or plant cancer, which occurs in a wide range of woody plants and some herbaceous groups, is a striking example of bacteria-induced disease.

The majority of plant diseases are caused by fungi. Fungus diseases have been observed and commented on since ancient times. Biblical records mention blights and mildews on the cereal and vine crops of the ancient Hebrews. Fungus diseases were responsible for several major catastrophes in various parts of the world. Prominent among these diseases was the late blight, a disease of the potato, which invaded Europe after 1845 with particularly devastating results in Ireland. Powdery mildew of the grape, native to America, became established in France and nearly wrecked the French wine industry. A parasitic root fungus, Hemileia vastatrix, destroyed the coffee plantations of Sri Lanka and other Oriental countries. In the United States the chestnut, an important timber-, nut-, and tannin-producing tree, was eliminated by an introduced Oriental fungus. More than 1,400 species of rust fungi, all parasitic, and several hundred species of smut fungi occur in North America alone. Equally large numbers of fungi in other groups produce a large array of diseases characterized by leaf spots, ulcerous lesions, blights, powdery and downy mildews, cankers, wood rots and stains, root rots, wilts, club root, and various other symptoms.

Nematodes, or roundworms, are an important cause of disease in plants. For many years attention was focused on the root-knot nematodes, which cause fleshy root knots or galls on plants. More recent investigations have been concerned with other species, including the stem or bulb nematodes, which live in the leaves, stems, bulbs, and roots of narcissus, phlox, and many other plants, and the leaf nematodes, growing in herbaceous plants including the begonia and chrysanthemum. The golden nematode of the potato plant and of related plants and the soya bean cyst nematode are causing increased concern.

Answer 2

there are hundreds of plant diseases. Agrobacterium tumefaciens is a bacterium that causes crown gall disease on many plants. Erwinia is another bacterial organism that cause soft rot of many plants, especially potatoes. Rust is a fungus that attacks a number of plants and Black spot is another fungus.

Answer 3

Dutch Elm disease.