Orient rows in the direction of prevailing winds, avoid shaded areas, and avoid wind barriers.Irrigate early in the day to promote rapid drying of foliage. Avoid overhead (sprinkler) irrigation.Promote good air circulation by proper spacing of plants.Where this is not practical, plow residue into the soil to promote breakdown by soil microorganisms and to physically remove the spore source from the soil surface. Remove and destroy crop residue at the end of the season.Be sure to control volunteers and susceptible weeds. Practice crop rotation to non-susceptible crops (3 years).Use only clean seed saved from disease-free plants.Eradicate weeds and volunteer solanaceous crop plants.Lesion appear in largest numbers when plants are bearing fruit. Infection is heaviest on lower leaves first and defoliation moves from the bottom of the plant up. Infection is more severe on plants stressed poor fertility or other problems. Lesions may develop 2 days after infection under favorable conditions. Conidia are wind disseminated and generally infect during rainy or humid weather when temperatures are between 24-29 C. The fungus survives on infected plant debris between crops, or on solanaceous weeds in warmer climates. Fruit infections may begin in either the green or ripe stage and appear as a sunken decay and are usually covered with a black mass of spores.Įarly blight is present in all tomato growing regions and causes damage wherever a humid climate or frequent dews create conditions for infection. Alternaria may also cause cankers on the tomato stems which may expand to cause collapse of young plant stems. Lesions forming on the leaf rachis or petiole may cause entire leaves to turn brown and shrivel. As multiple leaf spots coalesce entire leaflets collapse. As lesions enlarge they usually produce concentric rings giving the lesion a target-like appearance. Isolates on potato dextrose agar and other media produce yellowish to reddish diffusible pigments in the media.Įarly blight symptoms typically begin first on young tomato leaves as small necrotic spots that appear dry and papery. Conidia have 9–11 transverse septa (cross walls) and long beaks. The conidia are 12-20 X 120-296 um and are found singly or in chains of two. Early blight is caused by Alternaria solani (Ell.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |