Sensitivity of Different Isolates of Pythium aphanidermatum to Old and Novel Fungicides
Sensitivity of Different Isolates of Pythium aphanidermatum to Old and Novel Fungicides
Ghulam Sarwar Shah1,2, Maqsood Anwar Rustamani1, Rab Dino Khuhro1, Rehana Naz Syed1 and Abdul Mubeen Lodhi1
ABSTRACT
Pythium aphanidermatum is one of the most devastating soil-borne pathogens in the warmer climates of the world. It is more damaging in vegetables by causing seedling rots, root rot, pre- and post-emergence damping-off, cottony-leak, cottony blight, and stalk rot diseases. An advantageous combination of various factors makes the control of Pythium aphanidermatum difficult. However, synthetic fungicides provide quick and effective control. Therefore, we checked the sensitivity of different isolates of P. aphanidermatum to 17-old and novel fungicides. Against all isolates, the fungicides’ main effect, concentration’s main effect, and fungicides’ × concentration’s effect are highly significant. Generally, based on their effectiveness, all tested fungicides were divided into three groups i.e., highly effective, moderately effective, and completely ineffective. All isolates of P. aphanidermatum were grown at par with the control when exposed to different concentrations of mandipropamid and fluoxastrobin. Both fungicides completely failed to cause any negative effects on in vitro growth of all isolates. On the other hand, all isolates appeared extremely sensitive to 10 fungicides including azoxystrobin, copper oxychloride, difenoconazole, propiconazole, azoxystrobin+difenoconazole, trifloxystrobin+tebuconazole, hexaconazole, mancozeb+mefenoxam, myclobutanil, and flutolanil. All isolates except Pa 12 (which grew only at 250 ppm of azoxystrobin) failed to tolerate 250-8000 ppm concentrations of these fungicides and produced no growth under in vitro conditions. To some extent, the tested isolates showed variable responses to fosetyl aluminium, iprovalicarb+propineb, thiophanate-methyl, cymoxanil+mancozeb, and propineb. The isolates grew well at lower concentrations, gradually inhibited, and failed to grow at higher concentrations. The findings of the present research will help to design an effective control strategy against P. aphanidermatum with effective fungicides under field conditions.
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