2008 Annual Report 1a.Objectives (from AD-416) The goal of this research is to develop a disease management program for blackberry rust and assess the potential risk to cultivated black berries in the Pacific Northwest. 1b.Approach (from AD-416) The disease management system will be developed through complementary laboratory, greenhouse, and field experiments design to increase our understanding of P. violaceum biology and the efficacy and appropriate timing of various fungicide applications. Documents SCA with OSU. Formerly 5358-22000-030-04S (6/07). 3.Progress Report Teliospore germination was measured weekly and compared to a predicted phenology based on weather and spore germination data from Montpelier, France. Teliospore germination in Oregon closely matched the predicted window (late March to late April). About half of teliospores germinated before Evergreen blackberry became susceptible to infection. A rotational trap plant study involving 600 potted blackberry plants was completed at two locations in western Oregon. Specific infection events were identified in this study. The trap plant experiments show that the inoculum that initiates the new disease cycle is local and not originating at distant sources. Fields experiments were conducted at two locations in western Oregon to evaluate appropriate timing and application intervals of fungicides. Lime sulfur applied as a delayed dormant (early April) provided significant suppression of infections initiated by basidiospores. An early May application of fungicide (Rally 40W) provided better overall suppression of infections initiated by summer spores than did fungicide applications delayed until mid-May. An autumn fungicide trial in Evergreen blackberry demonstrated that the fall infection is significant, and likely impacts plant vigor the following spring. This experiment identified fungicides with activity against P. violaceum. These data were used to obtain a 24C special local need registration for myclobutanil (Rally 40W). Asexual perrenation in leaves or leaf bud was scouted for and not observed, which is consistent with previous descriptions of the disease cycle. Growth chamber experiments with constant temperature indicated the disease was optimal between 10 to 20 C (50 to 68 F) and required at least 6 h of leaf wetness required for infection. Similarly, experiments simulating diurnal temperature fluctuations observed in the field indicate that average daily temperatures with over 9 hours leaf wetness are optimal for infection. Interruption of leaf wetness prior to accumulation of 6 continuous hours resulted in no infection. The data will be used to develop infection risk models forecast to help time fungicide applications. A collection of 87 Rubus spp. and varieties has been screened for susceptibility under optimal conditions for disease development. The blackberry species (R. armeniacus, R. erythrops, R. grabowskii, R. geoides, R. insularis, R. lanciniatus, R. lindebergii, R. ulmifolius [f. bellidiflorus]) and varieties (Black Satin, Burbank thornless, Chester, Ebony King, Evergreen thornless, Everthornless, Hull thornless, Dirksen Thornless, Watlab) were confirmed as susceptible to P. violaceum infection to some degree. One raspberry sp. (R. hawaiensis) was demonstrated to be susceptible. Genetically distinct isolates will be screened against this collection individually. Methods of ADODR monitoring included in person meetings, teleconferences, e-mail and technical advice to Cooperator’s personnel.