Plant diseases management in urban Ecosystems.

In order to aplly plant diseases management, principles all of biotic and abiotic agents affecting forestry ecosystems and landscape of Tehran and Karaj were investigated. During 1997 to 2001, plantations in various parts 0f Tehran and Karaj were surveyed and many samples of affected trees were collected. Infected tissues were surface sterilized and cultured on different media. Of all biotic agents of plants pathogens, only fungal pathogens isolated and detected and no any other biotic agent were obtained. In this study, effect of the abiotic agents including food quality, temperature, light, soil humidity and soil structure on growth of trees were investigated, where it was necessary, soil profile in nearby root of weakness trees were dugged and soil analysis was conducted. Result showed that, although some fungi diseases including dutch elm disease, stem rot of mulberry, wilt of locust, dieback disease of Eucalypt trees and powdery mildews diseases are very important in urban forest ecosystems and landscapes of Tehran and Karaj and should receive due attention, but main difficulties were affected trees in Tehran and Karaj ecosystems, frequently abiotic factors including nutrient deficiencies, alkaline of soil, heterogicity soil's structure, cement around tree's collars and incorect of planting practies. These abiotic factors are predisposition trees to attack of biotic agents, sometimes without identification causal organism, chemical control measure is applied. In these cases, applying chemical compounds may result in environmental contamination. Totally, results of this research indicate that, lack of any success in disease control is due to incorrect of causal agent of the disease in urban ecosystems. Generally, in urban ecosystems, it is not necessary applied chemicals to control plant disease. Instead, they should be managed. The target of plant diseases management consist the best use of the whole methods and practices which will result in control on a tree and reduction of the damages. In this research, altimately management programs are provided for major diseases caused by biotic and abiotic agents in urban ecosystems. However, by applying plant disease management guidelines for mentioned diseases, there wouldn't be any necessity to perform chemical control of the diseases in urban ecosystems.