Tuber rot — Tapioca
Macrophomina phaseolina, Botryodiplodia theobromae, Fusarium spp.
Symptoms
The initial symptoms are leaves turning brown and wilting. The leaves may remain attached to the plant or drop to the ground. The infected plant will show a scorched appearance. The examination of roots reveals root dieback and swelling of tubers. Tubers may have light brown, dark gray, blue or pink discoloration. The rotting roots may be soft and produce a foul odor. In some cases, white fungal structures can be seen at the base of the stem, particularly during the wet season.
Recommendations
Use for sett treatment as preventive measure. Bio Control: Mix 2.5kg Trichoderma viride / T. harzianum with 100–250 kg of well-decomposed Farmyard Manure (FYM) and 50 kg neem cake. Incubate for 7–10 days under shade and apply to the soil as prophylactic measure. Keep a minimum of 10 days gap between any other chemical application.
To control spread of the infection, drench the soil around the root zone of the infected plant and surrounding plants.