Variability Among Isolates of Fusarium Oxysporum f. Sp. Carthami from Maharashtra State

All the sixty eight isolates of Fusarium oxysporum f, sp. carthami collected from major safflower growing areas of Maharashtra state were morphologically different. The size of microconidia ranged from 2.86 to 26.64 um in length, whereas that of macroconidia ranged from 10 to 48 um in length with 1–3, 1–4 and 1–5 septations. The isolates also exhibited variation in cultural characters viz., pigmentation, colony growth (on PDA) and nature of mycelium. The studies on pathogenic variability indicated that the Focr isolates from different geographical areas showed a wide range in their pathogenicity. Most of the isolates were found to be very weakly pathogenic to the variety NARI-6 and hybrids viz., NARI-NH 1 and DSH-129 recording wilt reaction as moderately resistant (MR: 1–10% wilting) and tolerant (T: 10–20 % wilting). However, ail the Focr isolates recorded highly pathogenic reaction (> 50% wilting) to variety Nira and Bhima. Similarly, twenty one Focr isolates recorded tolerant reaction (10–20% wilting) on variety A-l. The results indicated the existence of morphological, cultural and pathogenic variability among the Focr isolates.