Short Term Soil Solarization and Sclerotial Germination Stimulants as Control Measures against White Rot Disease in Onion Plants under Naturally Infested Field Conditions

Abstract

The impact of short term soil solarization (STSS) and sclerotial germination stimulants (SGS) to reduce the density of the sclerotial population of Stromatinia cepivora, and white rot disease of onion plants have been studied under field conditions. In laboratory tests, the mycelium of S. cepivora was killed when exposed to hot water for 20 and 1.0 min. at 56.0 and 59.0oC respectively. The fungal
sclerotia were killed when exposed to hot water for the same times at 61.0 and 64.0oC, respectively. The summer of 2022 the application of the 15-day soil solarization effect on sclerotial viability in a field setting. The findings showed that at 10, 20, and 30 cm depths, respectively, soil solarization decreased the sclerotial viability by 75.0%, 68.9%, and 64.2% respectively. At zero time before
application of sclerotial germination stimulants, there were 170 viable sclerotia/kg of soil in solarized soil (ss) and 520 viable sclerotia/kg of soil in un-solarized (us) soil. The viability of sclerotia was shown to be lower in solarized soil than in un-solarized soil when all sclerotial germination boosters were applied. With allium wastes, the viability was reduced by 92.7%, the greatest reduction was achieved. Subsequently by ss+ onion oil and ss + garlic oils which decreased viability by 87.9 and 86.7 % respectively. As for white rot, the results showed that in solarized soil as compared to unsolarized soil, all sclerotial germination stimulants were more successful. The most successful treatment, which decreased white rot disease by 90.3%, is ss + Allium wastes. Followed by ss + onion
oil and ss+ garlic oil which reduced disease incidence by 84.7 and 85.8 % respectively. In soil that had been solarized as opposed to soil that had not, all sclerotial stimulants performed better. The most successful treatment is ss + Allium wastes, which resulted in a 221% increase in onion yield.