Controlling downy mildew of maize caused by Peronosclerospora sorghi by foliar sprays of phosphonic acid compounds

Downy mildew in maize caused by Peronosclerospora sorghi (Weston and Uppal.) C.G.Shaw, was significantly controlled by foliar spray of phosphonic acid (20%) and its formulations like Aliette (0.25%) and Akomin (0.25%) 20 days after sawing (DAS), under greenhouse and field conditions. The reduction in disease incidence and severity under field conditions was reflected by an increased yield of 54-73%. Moreover, the treatments also suppressed sporulation of P. sorghi on diseased foliage, although they did not affect conidial germination in vitro. The inhibitory effect of phosphonic acid and its different mode of action coupled with its low cost compared to metalaxyl, makes it a potential alternative, for metalaxyl in control of downy mildew. (C) 1999 Elsevier Science Ltd. All rights reserved.