If you've ever had sweet basil plants droop and die suddenly in midsummer, the likely cause was fusarium wilt. This soil-borne fungal disease is found almost everywhere, and it can endure in the soil for years. Infected young plants will show dark brown lines on their stems.
A hybrid sweet basil, 'Nufar', has remarkable tolerance to the most commonly found strains of fusarium wilt. Like other Genovese-type sweet basil (Ocimum basilicum), 'Nufar' is very productive and has excellent flavor and large leaves, but is much less susceptible to wilt.
Charlie Nardozzi is a senior horticulturist at National Gardening.