Pink root rot disease of onion (Pyrenochaeta terrestris) was controlled using physical and chemical method.%
In vitro Bavislin (50%) Benlale (50%) and Folicure (25%) prevented fungal growth and sporulalion al 3,5 and 10 ppm. respectively. Topsin-M 70 (70%), Vilavax-75% and Vitavax- 300 showed the same effect at 50 ppm. Vitavax-200 completely inhibited fungal growth al 100 ppm. Ronilan W.P. (50%). Ronilan dust (5%). KZ 120 (50%). Sumisclex W.P. (50%). Sumisdcx D FI. (50%) were the least effective and failed to inhibit fungal growth and spore production even at 300 ppm.
In greenhouse, Folicure, Sumisclex W.P., Sumisclex D.FI. and Ronilan W.P. minimized pink root infection and severity on the susceptible cv. Giza-20 followed by Ronilan dust and KZ-120.
Under field conditions. Folicure, Sumisclex, D.FI. and Sumisclex W.P. were significantly the most effective in reducing infection to the least possible level and caused the highest bulblet production, followed by Ronilan W.P., Ronilan dust and KZ-120.
Under greenhouse as well as field conditions, disease incidence was reduced when nitrogen application was decreased or where phosphorus or potassium was increased in combination with nitrogen.
The tenth of January was the best lime of planting for minimizing pink root rot incidence and obtaining the highest yield. More disease occurrence and less yield could be gamed with early planting. Shandaweel-I cv. was relatively resistant and gave the highest yield under field conditions, Giza-20 cv. showed high susceptibility to the disease and gave the lowest yield while Giza-6 cv. was intermediate.