![]() reported that the optimal temperature for in vitro growth of V. In southern Spain, Bejarano-Alcázar et al. albo-atrum occurred between 12 and 32☌, but symptom expression was greatest between 20 and 28☌. Using soil tanks, McKeen found that infection of potato by V. Soil temperature is a critical factor for the development of Verticillium wilt and fungal growth. ![]() However, the development of symptoms in relation to inoculum density is variable and strongly influenced by environmental and soil conditions. Ī recent study on Verticillium wilt in olive trees has shown that overall disease incidence is related to initial inoculum density in the soil. dahliae, respectively, under controlled conditions in artificial inoculation tests. dahliae, respectively, and susceptible and moderately resistant to ND V. However, the most widely used olive cultivars in Spain (i.e., Picual and Arbequina) have been found to be highly susceptible and susceptible to D V. Planting resistant cultivars is the most effective measure for controlling and limiting the spread of Verticillium wilt. Infections with the D pathotype are of greater concern because the pathogen can spread rapidly over short and relatively long distances through windblown infected leaves that fall early and in large numbers from diseased trees. dahliae pathotypes also have different modes of dispersal and produce different spatial patterns of disease. Infections with the D pathotype can be lethal to the plant, whereas ND-infected olive trees may eventually show remission from symptoms. Conversely, the ND syndrome comprises two symptom complexes: (i) apoplexy, a rapid and extensive dieback of twigs and branches of olive trees without loss of leaves occurring in late winter, and (ii) slow decline, mainly characterized by flower mummification and necrosis of inflorescences along with leaf chlorosis and necrosis, which occurs during springtime. These symptoms can develop from late fall to late spring. The D syndrome is characterized by early drop of asymptomatic green leaves from individual twigs and branches, eventually leading to complete defoliation and necrosis. dahliae in olive trees has resulted in two main disease syndromes -defoliating (D) and non-defoliating (ND), which are induced by specific D and ND V. As a result of xylem colonization by the pathogen, water flow decreases, leading to water stress. These structures germinate multiple times in response to root exudates and favorable soil environmental conditions, forming hyphae that penetrate the plant root, grow across the root cortex, and upon reaching the xylem vessels facilitate the rapid upward spread of the pathogen by conidia transported in the transpiration stream. dahliae, constitute the main potential infective inoculum of the pathogen in field soils, where it can survive for up to 15 years. Microsclerotia, the long-lasting surviving structures of V. Such changes include the use of self-rooted planting stocks to establish high-density plantings, drip irrigation, reduced or no tillage, and high inputs of fertilizer in newly cultivated soils or fertile soils previously cropped with plants susceptible to V. In Spain, the spread of Verticillium wilt in olive trees has been associated with the expansion of olive cultivation and changes in cropping practices aimed at increasing yields. The disease was first observed in Italy in 1946 and is now present in many Mediterranean countries and in California, USA. Verticillium wilt (VW) of olive ( Olea europea L.), caused by the fungus Verticillium dahliae Kleb., is the most important soil-borne disease affecting olive trees worldwide, and can cause severe yield losses and plant death.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |