The objectives of this research are: (1) to evaluate elite Paradox hybrid clones for resistance to Phytophthora citricola, a virulent and prevalent crown and root pathogen affecting California walnuts and (2) to determine specific etiology of a root and crown rot problem in upper Sacramento Valley orchards on Paradox walnut rootstock. Two screens for resistance to P. citricola were completed in...

Trees in three Scots pine stands seriously infected by Heterobasidion annosum were classifi ed according to their crown condition into four classes, from healthy to dead trees. After cutting the stands, the classifi cation was compared with the symptoms of annosum root rot on stump surfaces (pitched area) and with the extension of decay in the roots of excavated stumps. When dead trees were inc...

to determine the role of fusarium species associated with sugar beet root  and crown rot, diseased samples were collected  from different fields of sugar beet in iran including khorasan, khuzestan west azarbayejan, qazvin, tehran, kermanshah ,kerman,lorestan ,hamedan,charmahal va bachtiary provinces during growing seasons 1999-2002. in total, 94 isolates of fusarium were obtained. based on morp...

charcoal rot disease, caused by macrophomina phaseolina has become a restrictive agent for annual crops in iran. the disease incidence reaches up to 90 percent in some infested areas. high air temperature and drought stress associated with this disease, are the main factors for increasing the disease incidence and severity. in order to isolate the pathogenic agents, pieces of infected root and ...