page_title: Phragmidium violaceum
section_title: Management
hierarchical_section_title: Phragmidium violaceum / Management
caption_attribution_description: English: Blackberry plants infected with rust fungus, a biological control agent for blackberry. The newly released strains of the European blackberry rust fungus (Phragmidium violaceum) are highly host-specific for weedy blackberries.
context_page_description: Phragmidium violaceum is a plant pathogen native to Europe, Africa, and the Middle East. It primarily infects Rubus species.
  It has been used in the biological control of invasive blackberry species in Chile, Australia, and New Zealand. In 2005, it was discovered growing on Himalayan blackberry plants in Oregon. This accidental introduction does not appear to be infecting native vegetation, so it offers hope for reducing the impact of invasive blackberries in the Pacific Northwest.
context_section_description: Cultural tactics along with dormant season lime sulfur can help to reduce the initial inoculums source. The chemical tactics function to protect the healthy younger plant tissues. By removing the old fruiting canes early, after the harvest it will prevent the spreading of the infection. Chemical controls can be effective as well. Chemical protection will need to start by applying lime sulfur to the leaves that are infected. Fungicide application during fall, in the month of September, is the most beneficial for the health of the plant. There may be development of fungal resistance if there is overuse of any single product. The fungicides are primarily protectants therefore, cannot eradicate the disease after it becomes established. The biological control works when an uncharacterized population and or a mixture of strains of a pathogen from the native range of the target weed is released in the area into which the weed is introduced. The strain F15 was released as a biological control agent in 1991 and 1992. The release of the additional strains can originate the potential to increase the genetic diversity of the population of P. violaceum. The occurrence through recombination or the increase in the effective population size can in turn improve the impact of the biological control agent. Biological control agent is likely to be successful, however there is a high potential for the failure of additional strains due to the amount of inoculums involved in the pathogen strain recruitment. The amount of inoculums released is small when compared with the well-adapted pathogen that exists in the population
caption: Symptoms of the lower surface of the infected plant showing yellow pustules.
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