Survey, Identification and Growth Behaviour of Fusarium oxysporum f. sp. psidii in Guava

Abstract:

Guava (Psidium guajava L.) is an economically important fruit crop severely affected by wilt disease, which poses a major constraint to its productivity. The present investigation was undertaken to study the incidence, causal organism and its characteristics in Ahilyanagar district of Maharashtra. A roving survey conducted across major guava-growing areas revealed that wilt is a predominant disease with variable incidence across locations, ranging from low (around 2.27%) to comparatively higher levels (up to 7.14%), indicating its widespread occurrence and economic significance. Based on cultural, morphological and microscopic characteristics, the pathogen was identified as Fusarium oxysporum f. sp. psidii. The fungus exhibited white to pink mycelial growth on PDA, with abundant sporulation. Microscopic observations revealed the presence of both microconidia (aseptate, oval to elliptical) and macroconidia (multicellular, sickle-shaped with 3–4 septa), confirming its identity. Further studies on morphological, cultural and physiological characteristics indicated that the pathogen showed variable growth on different culture media, with maximum growth observed on Richard’s agar followed by PDA. The fungus produced hyaline, septate mycelium with characteristic conidial structures. Physiological studies revealed that the pathogen exhibited maximum mean mycelial growth at 25°C and pH 6.5 conditions, which play a crucial role in its survival and pathogenicity. These findings provide a better understanding of the biology and ecology of the pathogen, which is essential for developing effective management strategies against guava wilt