Integration between soil solarization and four biofungicides for controlling garlic white rot disease

Abstract

Impact of soil solarization and different biofungicides and/or Folicur fungicide as dipping treatment on the incidence of white rot and bulb yield of garlic was investigated.  Results revealed that solarization treatment reduced percentage of white rot (WR) of garlic plants and increased garlic bulb yield compared to un-solarized infested soil under greenhouse and filed conditions. On the other hand, dipping garlic cloves before planting in four biofungicides i.e. Bio Arc, Bio Zeid, Bio Nagi and Bio-4 and/or Folicur fungicide significantly reduced WR disease incidence compared with untreated cloves. Dipping treatment with Folicur fungicide (tebuconazole) gave the highest reduction of WR % followed by the biofungicides i.e. Bio Nagi and Bio Zeid, respectively under greenhouse and field experiments during the two growing seasons (2015/16 and 2016/17), meanwhile, Bio-4 followed by Bio Arc resulted the least effective ones in this respect. Integration between solarization and dipping treatments increased the efficacy of WR reduction with high significant differences compared to un-solarized infested soil under greenhouse and filed conditions. Soil solarized plus Folicur fungicide followed by Bio Nagi and Bio Zeid, respectively were most superior integrated treatments for suppressive garlic white rot disease under greenhouse and filed conditions. Bio Nagi achieved closer results to Folicur fungicide for controlling WR incidence at the two successive seasons. However, the most superior integration treatment for increasing garlic yield was solarization treatment combined with each of Bio Nagi, Bio Zeid and Bio Arc, respectively. Population densities of total fungi, bacteria and actinomycetes in artificially infested soil were greatly reduced directly after solarization than before solarization. Solarization treatment alone or in combined with different dipping treatments were greatly decreased the total fungi, bacteria and actinomycetes population counts as  compared with un-solarized infested soil one during the three timing intervals (30, 60 and 90 days after planting). The suppressive effect of solarization and dipping treatments was more effective in reducing soil microbial counts during the first 30 days of planting, then was decreased gradually from 60 to 90 days after planting. However, the total counts of bacteria and actinomycetes were slightly increased in solarized soil after 60 days then it rapidly increased at the 90 days interval.