Single‐uredinium cultures of Uromyces appendiculatus (Pers) Unger from Honduras, Dominican Republic, Puerto Rico, Tanzania and USA were evaluated for virulence on 19 standard bean (Phaseolus vulgaris) rust differential lines/cuitivars that had been previously selected on the basis of resistance to bean rust. A disease rating scale, based on uredinium diameter, was used to study pathogenic variability of the bean rust fungus. Virulence of the cultures was measured by the vector of disease score (mds) on all 19 differentials and the nearest centroid sorting algorithm was used to cluster the cultures according to virulence similarity. A total of 373 different virulence patterns was identified from more than 2000 cultures and were grouped into four virulence clusters. None of the cultures produced a susceptible reaction on all the differentials. Cultures that produced uredinia > 0.5 mm in diameter in 15 differentials were considered to have high virulence. About 59, 15, 20, 5 and 0%, respectively, of the Honduran, Dominican, Puerto Rican, USA and Tanzanian cultures were highly virulent. The lines/cultivars Ecuador 299, Mexico 235, 51051, NEP‐2, Mexico 309, California Small White 643, A × S 37, and Aurora had a high degree of resistance to most cultures and can be used as sources of broad resistance. Virulence patterns of the differentials indicated redundancy in some host parasite interactions and the need to modify the composition of the differential lines/cultivars.

Bean rust, caused by Uromyces appendiculatus, is one of the major diseases in dry and snap bean production world-wide. Numerous advancements in disease management have been made to reduce rust losses. Host resistance is an important component of rust management. However, durability of disease resistance has often been short due to the use of single genes for resistance interacting with extremely high virulence diversity of the bean rust fungus. The challenge to increase durability of resistance has led to strategies such as gene pyramiding of race-specific resistance, selection and use of partial resistance, and investigation and discovery of leaf morphological features that may slow the rust epidemic. Germplasm with multiple sources of rust resistance has been developed in specific bean seed classes and released for public and commercial use in intensive production systems such as those in the United States. However, progress to develop rust resistant germplasm for the subsistence agriculture of Latin America and Africa where intercropping and mixed cultivars dominate the production system has been slow. Incorporation of high yielding, disease-resistant components as partial replacement in farmer's mixtures has the potential to reduce severity in the crop and increase yield in the presence of rust. This strategy would not erode the genetic diversity that is historically known to enhance resistance durability and for many years has given stability in production in the subsistent agriculture systems.

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8Five bacterial isolates collected from dogwood leaves were evaluated for powdery mildew control in 9 shadehouse and greenhouse environments by using foliar sprays and/or root drenching. Two 10 isolates displayed superior bioactivity and suppressed powdery mildew similar to conventional 11 fungicide thiophanate methyl (Cleary's 3336F®). The two bacteria disrupted powdery mildew spore 12 germination and ruptured spore membranes causing spore lyses. Bacterial filtrates without bacterial 13 cells were also effective in suppressing powdery mildew and disrupting spore germination and 14suggested the involvement of secondary metabolites. The two biocontrol agents (BCAs) colonized 15 roots endophytically and promoted plant growth. 16 17

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