Influence of Garlic Foliar Treatment with some Plant Extracts on Purple Blotch Disease in Relation to Plant Growth, Yield and some Biochemical Responses

Abstract

The experiments were carried out during 2018/2019 and 2019/2020 seasons. Greenhouse experiments carried out at Department of Plant pathology, Faculty of Agriculture, Ain Shams University. Field experiments were carried out at Kaha Vegetable Research Farm, Kaliobia Governorate. Compared with untreated infected garlic plants Sids-40 cultivar, all foliar applications with aqueous extracts of each of henna (Lawsonia inermis), licorice (Glycyrrhiza glabra), rosemary (Salvia rosmarinus), mixtures of them at levels 5% and 10% for each extract or Ridomil plus (2.5g /L) showed significant decrease in purple blotch severity and resulted in significant increases in phenolic compounds, oxidative enzymes activity i.e., CAT, POD and PPO during two growing seasons. However, significant decreases of proline content were resulted in the treated infected leaves during both seasons. Spraying with licorice and mixtures of extracts at5% and10% resulted the highest significant decreases of disease severity under both greenhouse and field conditions. Also, licorice at10% exhibited the highest values of plant length, fresh and dry weight of plants, values of bulb weight, total yield at harvest and after curing. Mycelial inhibition test proved that all extracts have an inhibitory effect on mycelial growth of A. porri and licorice extract exhibited the highest effect, even still lower than Ridomil Plus effect. It can be concluded that all aqueous extracts tested were able to reduce the disease severity as a result of either direct microbial growth inhibition or induction of garlic plant resistance against A. porri, thus as well was associated with improved plant growth parameters and garlic yield.