Can organic plant protection products damage crops?

September 30, 2020

Protecting crops against pests and diseases is essential to ensure a secure food supply. Around 95 percent of food comes from conventional agriculture, which uses chemical pesticides to keep crops healthy. Increasingly, however, organic pesticides are also being sought as an alternative. Some organic pesticides contain live spores of the fungus Trichoderma, which have the ability to suppress other pathogens. Researchers at the University of Göttingen have now discovered that one Trichoderma species can cause severe rot in cobs of maize (corn). The results were published in the journal Frontiers in Agronomy.

The massive outbreak of a previously unknown species of Trichoderma on corn cobs in Europe was first detected in Southern Germany in 2018. In affected plants, grey-green spore layers formed on the grains of corn and between the leaves that form the husks of the cobs. In addition, the infested grains germinated prematurely. For this study, the scientists brought maize plants in the greenhouse into contact with Trichoderma by inoculation. They were then able to prove that the dry matter content of the maize cobs is greatly reduced. Annette Pfordt, PhD student at the Department of Crop Sciences of the University of Göttingen and first author of the study, analysed 18 separate Trichoderma strains mainly from maize cobs in Southern Germany and France over two years. She found that some of these strains are highly aggressive with a cob infestation of 95 to 100 percent. By means of molecular genetic analyses, these spores could be assigned to the relatively new species Trichoderma afroharzianum. Within this species of fungus, previously unknown plant-pathogenic strains seem to have evolved which are now responsible for this newly discovered disease affecting maize.

"The species used in organic plant protection products is a close relative, namely Trichoderma harzianum. Strains of this species were not as aggressive in the study, but in the inoculation experiments they also led to a slight infestation on the cob," says Pfordt. "Although the investigations carried out so far show that the Trichoderma strains used in organic plant protection products differ from the aggressive forms now found, it is also clear that the risks from the use of living microorganisms in plant protection must be thoroughly investigated," adds Professor Andreas von Tiedemann, head of the Department of Plant Pathology and Protection at the University of Göttingen.

In vegetable growing, "Trichoderma agents" can be used, for example to control diseases such as Botrytis (grey mould) or Fusarium and to reduce rotting pathogens on the crop products. Various organic products containing Trichoderma are available on the market. They are used almost exclusively in organic farming. Trichoderma species belong to the ascomycetes and are found worldwide in the soil, on plant roots, in decaying plant remains and on wood. They act as decomposers of substrates and as antagonists of other microorganisms. This is the first time that they have been described as pathogens on plants.
-end-
Original publication: Annette Pfordt, Simon Schiwek, Petr Karlovsky, Andreas von Tiedemann. Trichoderma afroharzianum ear rot - a new disease on maize in Europe. Frontiers in Agronomy (2020). https://doi.org/10.3389/fagro.2020.547758

Contact:

Professor Andreas von Tiedemann
University of Göttingen
Department of Plant Pathology and Protection, Crop Sciences
Tel: 49 (0)551 39 23701
Email: atiedem@gwdg.de

Annette Pfordt
University of Göttingen
Department of Plant Pathology and Protection, Crop Sciences
Email: annette.pfordt@uni-goettingen.de

University of Göttingen

Related Fungus Articles from Brightsurf:

International screening of the effects of a pathogenic fungus
The pathogenic fungus Candida auris, which first surfaced in 2009, is proving challenging to control.

Research breakthrough in fight against chytrid fungus
For frogs dying of the invasive chytridiomycosis disease, the leading cause of amphibian deaths worldwide, the genes responsible for protecting them may actually be leading to their demise, according to a new study published today in the journal Molecular Ecology by University of Central Florida and the Smithsonian Conservation Biology Institute (SCBI) researchers.

Researchers look to fungus to shed light on cancer
A team of Florida State University researchers from the Department of Chemistry and Biochemistry found that a natural product from the fungus Fusicoccum amygdali stabilizes a family of proteins in the cell that mediate important signaling pathways involved in the pathology of cancer and neurological diseases.

The invisibility cloak of a fungus
The human immune system can easily recognize fungi because their cells are surrounded by a solid cell wall of chitin and other complex sugars.

Taming the wild cheese fungus
The flavors of fermented foods are heavily shaped by the fungi that grow on them, but the evolutionary origins of those fungi aren't well understood.

Candida auris is a new drug-resistant fungus emerging globally and in the US early detection is key to controlling spread of deadly drug-resistant fungus
Early identification of Candida auris, a potentially deadly fungus that causes bloodstream and intra-abdominal infections, is the key to controlling its spread.

Genetic blueprint for extraordinary wood-munching fungus
The first time someone took note of Coniochaeta pulveracea was more than two hundred years ago, when the South African-born mycologist Dr Christiaan Hendrik Persoon mentioned it in his 1797 book on the classification of fungi.

How a fungus can cripple the immune system
An international research team led by Professor Oliver Werz of Friedrich Schiller University, Jena, has now discovered how the fungus knocks out the immune defenses, enabling a potentially fatal fungal infection to develop.

North American checklist identifies the fungus among us
Some fungi are smelly and coated in mucus. Others have gills that glow in the dark.

Tropical frogs found to coexist with deadly fungus
In 2004, the frogs of El Copé, Panama, began dying by the thousands.

Read More: Fungus News and Fungus Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.