Planting blighted tubers is also a potential source of the disease. These may remain in the soil after the previous crop, or in dumps where potatoes have been discarded after grading. The fungus survives the winter in blighted tubers. Potato blight is caused by the Phytophthera Infestans, which is an oomycete pathogen. (b) The Spread of the disease Source of Potato Blight There are two main factors to be considered: As yet there is still no means of eradicating an outbreak in a crop. Potato Blight is still the most serious disease of potatoes in Ireland despite recent advances in fungicides, improved varieties, better disease forecasting, and so on. Botanic Gardens College of Horticulture.Early season applications often fail to control secondary spread of the disease.įor Current information on disease recommendations ins specific crops including information on chemical control & pesticide management, please visit the New England Vegetable Management Guide website. Spray applications should be scheduled by spore trapping or forecasting systems (TOM-CAST) to be most effective. Avoid working the plants when they are wet.Stake plants to improve air circulation and reduce the contact of the plant with soil.Careful attention to the timing of irrigation (avoid late afternoon or evening) and proper plant spacing to reduce the amount of time during which the plants remain wet can reduce disease spread.Fertilize properly and keep plants growing vigorously.Control susceptible weeds (ie horsenettle) and eliminate volunteer plants and cull piles.Start with disease-free seed, transplants, and seed tubers.Once introduced, conidia are spread by splashing water, workers and equipment working when foliage is wet, and insects. The pathogen can also survive on stakes and cages and be carried in seed. lycopersici overwinters in infected crop or solanaceous weed hosts debris. Infection is favored by mild, rainy weather. Actively growing, young tissue and vigorous plants with adequate nitrogen generally do not express symptoms. Primary infection can occur on older foliage early in the season, but most secondary spread occurs as the plants age. The fungus enters the leaves directly or through wounds. solani survives between crops on infected plant debris, soil, other solanaceous host weeds and can be carried on tomato seed and infected tubers. If many leaf lesions develop on a leaf, it may turn yellow, then brown, and wither. Black pycnidia (fruiting bodies) within lesions are visible with a hand lens. Lesions are small, circular, with dark brown to purple borders and tan to gray centers. Septoria leaf spot usually appears on lower leaves after the first fruit develops. Lesions can increase in size during storage and tubers become shriveled. The underlying flesh is dry, leathery, and brown. Tuber lesions are dark, sunken, and circular often bordered by a purple to gray raised tissue. Foliar symptoms on potato are quite similar, though defoliation rarely results. Infected fruit often drop and losses of 30-50% of immature fruit may occur. Lesions can become quite large, involve the whole fruit, and have characteristic concentric rings. Fruit can become infected either in the green or ripe stage through the stem attachment. In the late summer when conditions are favorable for disease development, lesions can become numerous and plants defoliated, reducing both fruit quantity and quality. As the lesions enlarge, they often develop concentric rings giving them a ‘bull’s eye’ or ‘target-spot’ appearance. The tissue surrounding the initial lesion may become yellow, and when lesions are numerous entire leaves may become chlorotic. It first appears as small brown to black lesions on older foliage. Identification:Įarly blight occurs on the foliage, stem, and fruit of tomato. Uncontrolled, the disease may cause serious defoliation, resulting in decreased yield and quality. Early blight caused by the fungus Alternaria solani occurs wherever potatoes and tomatoes are grown.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |