Effects of soil temperature and moisture on survival of Coniothyrium minitans conidia in central China

Abstract

A study was conducted to investigate effects of soil temperature and moisture on survival of the mycoparasite Coniothyrium minitans in soils free of its host fungus Sclerotinia sclerotiorum in central China. Survival of C. minitans conidia was monitored in non-irrigated soil (yellow-brown clay soil) and in submerged soil under the influence of seasonal fluctuations of soil temperature from −0.1 to 37 °C and precipitation from 1.2 to 10.4 mm d −1. Results showed that in non-irrigated soil, C. minitans survived for 750 days with the concentration decreasing from 7.2 × 10 5 to 3.9 × 10 4 cfu g −1 soil. In submerged soil, C. minitans survived for 150 days over the summer-to-autumn period and the winter-to-spring period with the concentration decreasing more rapidly than that in non-irrigated soil. Studies on the effects of constant temperature and moisture on survival of C. minitans in soil showed that at 4, 10, 20 and 28 °C, C. minitans survived for 360 days in soil containing 6.3%, 18.5% or 45.4% of water (w w −1). At 30, 35, 37 and 40 °C, survival of C. minitans became moisture dependent. Good survival in soil containing 6.3% of water and poor survival in soil containing 18.5% or 45.4% of water were observed. C. minitans survived very poorly (⩽1 day) at 45 and 50 °C irrespective of soil moisture. These results suggest that C. minitans can adapt to soil temperature and moisture conditions in central China and can be a promising agent used to treat soil for control of S. sclerotiorum.