This paper examines the making and remaking of Taiwan's banana export market in response to the devastation caused by an outbreak of a novel infectious plant disease, Fusarium wilt disease Tropical Race 4 (TR4, Fusarium oxysporum f. sp. Cubense). Taiwan was the world's fourth-largest exporter of bananas in the 1960s before the collapse of the market in the early 1970s. While scholars have drawn on actor-network theory-inspired performativity approach to understand the role of non-human actants in market-making, insufficient attention has been given to the distinct impacts of microbes on cases such as that of Taiwan's banana export market. Microbes' creative and ever-evolving qualities constantly present challenges related to the control and containment of such non-human entities, for which no pre-existing or universally applicable solutions exist. Consequently, there is a lack of research that provides useful frameworks to understand such disease-plagued markets. To bridge this gap in the literature, we examine the remaking of Taiwan's banana export market in the aftermath of the TR4 crisis using a case study approach and develop the notion of pathological markets. Inspired by recent scholarship on biosecurity and related care practices, we outline two characteristics that shape pathological markets: (a) speculative and probiotic care practices and (b) the rescaling of market organisations. The results of the fieldwork conducted as part of the present study in laboratories, government offices and on banana farms lead us to contend that the growth and development of particular microbes in multispecies environments such as Taiwan's banana farms constantly pose significant challenges for market farming. Moreover, to co-exist with the threats posed by the growth and development of microbes such as those which cause Fusarium wilt disease TR4, growers in Taiwan's banana export market rely heavily on probiotic and speculative care practices. [ABSTRACT FROM AUTHOR]