Confirmation of the Pathogenic Potential of Fusarium oxysporum f. sp. Pisi Causing Wilt Disease in Pea Crops

Abstract

This study aimed to verify the disease causing ability of Fusarium oxysporum f. sp. pisi, responsible for wilt disease in pea crops, under controlled conditions. Pea plants displaying typical wilt symptoms were collected and the pathogen was isolated from the collar region using PDA. The fungus formed distinctive white to pinkish-white fluffy colonies with moderate aerial mycelium and was identified by its cultural and morphological characteristics. To confirm the potential of the pathogen, the pathogen was mass-multiplied on sorghum grains and added into sterilized soil in earthen pots. Sterilized seeds of the PSM-3 pea variety were planted and the development of symptoms was observed regularly. Both naturally infected and artificially inoculated plants showed early and late signs of wilt. Early infections (30 days after sowing) caused the stem to shrink near the collar region and sometimes led to seedling collapse. Later infections (60 days after sowing) were characterized by drooping petioles and rachis, gradual yellowing and drying of leaves and total plant wilting. Dissection of infected plants revealed internal browning or blackening of the vascular tissues and poorly developed root systems. All inoculated plants wilted within 45 days and the pathogen were successfully re-isolated in PDA, thus satisfying Koch’s postulates. These results confirm that F. oxysporum f. sp. pisi is highly virulent and can produce typical wilt symptoms in pea, establishing its role as the causal agent of the disease.