Effects of colonisation by different strains ofConiothyrium minitanson the viability of sclerotia ofSclerotinia sclerotiorum

Abstract

White mold is a major disease in commercial soybean production. An effective measure to reduce the negative effects of Sclerotinia sclerotiorum is the use of bio-fungicides. Strains of Coniothyrium minitans were isolated and efficacy tests against S. sclerotiorum was studied. The efficacy of pycnidiospores sprays of strain N09 (GenBank Accession No HQ908274) from Iowa, United States and strain CON/M/91-08 of Contans® WG were compared in a series of experiments. Sclerotia viability was significantly (P<0.05) lower in both sclerotia-infestedsterilized-soils (SISS) and unsterilized-soils (SIUS) sprayed with N09 compared with CON/M/91-08 and control at 3˚C for 75d and 90d sampling. Similarly, sclerotia viability was significantly (P<0.05) lower at 23˚C for 45, 60, and 75d sampling in SISS and 45, 75 and 90 d 2 sampling in SIUS compared with CON/M/91-08 and control. In contrast, viability of N09 colonies were significantly (P<0.05) higher than that of CON/M/91-08 both at 3˚C and 23˚C in SISS across sampling periods. While in SIUS, N09 colonies were significantly higher at 3˚C for 15, 30, 45, 75 and 90 d sampling, and at 23˚C for 30, 60 and 75 d sampling. Also, (i) N09 had a faster growth rate and produced 1.5 times more pycnidiospores than CON/M/91-08, (ii) mycoparasitism by N09 was faster than CON/M/91-08 and (iii) co-inoculation of sclerotia and the strains, N09 showed lower sclerotia reproduction than CON/M/91-08. Our data suggest that the new strain N09 has a greater efficiency than CON/M/91-08 in killing sclerotia.

Biocontrol of Three Severe Diseases in Soybean

“…Usage of C. minitans strain CON/M/91-08 reduced the sclerotia number in soil and the disease severity index of SSR in soybeans [26,27]. Pycnidiospores suspension of another C. minitans strain, N09, was sprayed into sclerotia-infected soil and had a significant impact on the viability of S. sclerotiorum sclerotia [49].…”

First Report of Clonostachys rosea as a Mycoparasite on Sclerotinia sclerotiorum Causing Head Rot of Cabbage in India

“…After examining the conidiophore and conidial production of the effective C. rosea , TNAU-CR 02 isolate, the spore suspension was prepared by harvesting the conidia from the 3-week-old colonies grown on PDA at 23 °C. Conidia of C. rosea , TNAU-CR 02 were washed off the Petri dish by gently rubbing the sporodochia and mycelial colonies with a sterile brush and 5 mL sterile distilled water containing 1% fructose to release spores [ 62 ]. The final concentration of the undiluted spore suspension was calculated using a haemocytometer and adjusted to 1 × 10 7 spore mL −1 .…”