Biological Control of White Mold Using Contans

Welcome to the course "Biological Control of White Mold Using Contans". White mold affects a number of fresh market and processed vegetable crops, including beans, cabbage family crops, legumes, and squash family crops

Contans is the trade name for Coniothyrium minitans, a fungus that is very effective at colonizing and killing Sclerotinia sclerotiorum, the fungus that causes white mold. This course will introduce you to the life history of both Sclerotinia sclerotiorum (the pathogen) and Coniothyrium minitans (the biocontrol agent). We’ll walk through results of research about Contans, and then explore how to use that research information to inform white mold management on the farm. Finally, we’ll delve into some integrated white mold management plans that include Contans.

I. The Disease and the Pathogen

White mold is a significant disease of a wide range of agronomic and horticultural crops (excluding monocots such as corn and onions). The causal agent of white mold is Sclerotinia sclerotiorum (Ss), a fungus that appears first on plant parts as a white mold. Ss often shows up on plants from spores. Ss mycelia can grow on host plant roots, stems, leaves, or fruits.

II. Contans and Coniothyrium minitans

Contans is the trade name for the biocontrol fungus Coniothyrium minitans (Cm). Cm was initially cultured by ?? from white mold sclerotia, along with a collection of other fungi such as X,Y,X, all of which colonize sclerotia and eat the insides, ultimately killing the sclerotia. In most studies Cm has been shown to be the most effective of these fungi at killing sclerotia, which is why it was commercialized as a biocontrol agent.

A single spore of Cm can land on a sclerotium, infect it, and grow throughout its inner tissues as mycelia. When Cm runs out of energy, it generates a pycnidium (plural = pycnidia). These pycnidia hold chains of spores, and these spores ooze out of the pycnidium in droplets when it is warm and wet. In rainy weather these spores splash away from their pycnidium, onto other plants or sclerotia. Through this mechanism, Cm can splash its way around a field and onto many new sclerotia. Each new sclerotia that is infected will grow up its own pycnidia filled with spores, which also will ooze spores under the right environmental conditions, creating a 'biocontrol epidemic' in the field.