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English:  The annual increase in soybean production to meet the increasing demands is limited by environmental constraints, fungal diseases and insect pests. Sclerotinia stem rot (caused by Sclerotinia sclerotiorum) is increasing in importance both locally and globally and the wide host range challenges disease management strategies. Soybean rust (caused by Phakopsora pachyrhizi) is a serious yield limiting foliar disease that has increased in importance due to rapid spread over large geographic areas. Reliable and repeatable screening methods have limited the quest for stable resistance to these diseases. Genetic variability in S. sclerotiorum isolates need elucidation since this could assist in the identification of stable resistance. Similalry, understanding the physiological processes associated with host response to to the respective pathogens could be useful in identifying new mechanisms of resistance or the timely implementing of appropriate control strategies. The absence of disease resistant cultivars, in particular to soybean rust, has necessitated extensive use of fungicides as a control method to ensure acceptable yields.  A study was conducted to compare the reaction of experimental soybean lines to soybean rust in the greenhouse and evaluate epidemiological factors that need to be considered in field evaluations of germplasm. Greenhouse trials indicated significant differences in rust severity between lines while field data illustrated the importance of differences in relative life time at disease onset, apparent infection rate, AUDPC and relative life time at which 100% disease severity was reached. The importance of multiple evaluation criteria was emphasized. Constraints to achieving acceptable levels of disease resistance are the absence of a correlation between greenhouse and field results and repeatability of data over seasons and localities. Although lines differed in disease severity only Selection 43 showed a combination of late disease onse, Afrikaans:  Die jaarlikse toename in sojaboonproduksie om te voldoen aan die aanvraag word belemmer deur faktore soos omgewingsveranderinge, plantsiektes en insekplae. Sclerotinia stamvrot veroorsaak deur Sclerotinia sclerotiorum se belangrikheid neem toe en die wye gasheerreeks maak die beheer van hierdie patogeen ‘n uitdaging. Sojaboonroes veroorsaak deur Phakopsora pachyrhizi, is ‘n ernstige blaarsiekte en word aangetref in al die belangrike sojaboonproduksiegebiede wêreldwyd. ‘n Beperking in evaluering van siekteweerstand is dat die metodes wat gebruik word nie herhaalbaar en betroubaar is nie. Die evaluering van genetiese variasie van S. sclerotioum isolate is belangrik aangesien dit gebruik kan word om moontlike weerstandsbronne te identifiseer. ‘n Beter begrip van die fisiologiese prosesse in sojaboonplante tydens infeksie kan daartoe lei dat nuwe bronne van weerstand geïdentifiseer kan word of dat beter beheermetodes geïmplementeer kan word. Die afwesigheid van weerstandbiedende kultivars, spesifiek teen sojaboonroes, lei daartoe dat chemiese beheermetodes steeds grootskaals gebruik word om aanvaarbare oesopbrengste te kry.  ‘n Studie is gedoen om die reaksie van eksperimentele lyne teen sojaboonroes in die glashuis sowel as om die epidemiologiese faktore wat belangrik is vir veldevaluering van kiemplasma te ondersoek. Glashuisproewe het aangedui dat daar duidelike verskille in die vatbaarheid vir roesinfeksie tussen lyne is. Velddata het aangedui dat lyne verskil in die relatiewe leeftyd met die aanvang van siekte, die tempo van infeksie, die area onder die siekte-ontwikkelingskurwe en die relatiewe leeftyd van die gasheer wanneer 100% siekte aangeteken is. Alle lyne was vatbaar vir sojaboonroes. Die belangrikheid van veelvuldige evalueringskriteria by die evaluering van siekteweerstand is beklemtoon. Die swak korrelasie tussen glashuis- en velddata, asook die konsekwentheid van data oor seisoene en lokaliteite, is ‘n bron van kommer. Alhoewel lyne verski, Protein Research Foundation