University and industry research team is searching for biocontrol alternatives to chemical crop protection products
The drive is on to find biocontrol alternatives to chemical pesticides.
Researchers with the Federal Research Centre for Cultivated Plants (JKI) in Darmstadt, Germany, and Trifolio-M GmbH in Lahnau, Germany, a biological pest control company, recently showed that some licorice varieties can improve plant tolerance against biotic stressors, such as fungi.
“The co-operation between the JKI institutes in Darmstadt and Braunschweig (Institute for Epidemiology and Pathogen Diagnostic) as well as Trifolio-M promoted the discoveries of licorice potential even further,” said Adam Schikora, senior researcher and lecturer with JKI.
Read Also
Farm equipment dealership chain expands
This summer, AgWest announced it was building two new dealership buildings in Manitoba to better service its expanding market area — one in Brandon and the other in Russell.
“Not only the antifungal and antibacterial features were analyzed but also the potential to enhance the plant immune system turned out to be very interesting.
In the pharmaceutical, cosmetic, food and confectionary industries, the interest focuses primarily on the roots of the licorice plant. The leaves and upper parts of the plant are byproducts and often neglected. We show their potential as a base for plant protection products, which may be utilized in both conventional and organic agriculture systems.”
According to the researchers’ report, phytochemical studies on licorice plant glycyrrhiza glabra leaves showed the chemical profile differed from licorice root extracts. Previous work by Schikora and his colleagues demonstrated that crude licorice leaf material was highly effective in controlling fungal and oomycete plant pathogens and inhibiting infections of important agricultural crops.
Researchers tested the impact of licorice leaf extract on the virulence of common, highly pathogenic bacteria in arabidopsis and tomato. The extract was also tested and positively evaluated on cucumbers and potatoes. The results showed that the extract could modulate a plant’s immune responses to pathogens.
The extract was also shown to act against a late blight-causing oomycete. Oomycetes are water moulds or fungal-like organisms that cause disease in plants and animals. The oomycete being studied was resistant to metalaxyl, the active ingredient in several synthetic fungicides.
“We know that the release of the zoospores (produced by oomycetes) is inhibited for some extract varieties,” said Schikora. “However, except for this microscopic observation, little is known on the exact mode of action. This is definitely our top priority research quest.”
He said the first field trials are expected to be carried out this year. They will test the performance of the extract and identify the best application timing.
“The tests will run together with already commercialized biological products that are established in spraying programs,” he said.
Licorice is a robust, blue-flowering perennial plant that grows worldwide and is native throughout southwest Asia and the Mediterranean region. It is used as a medical agent and, because of its sweet taste, plays an important role as a flavouring agent in the confectionary industry, beer breweries, liqueur and brandy production and in the tobacco industry.
However, demand for licorice is increasing and a supply problem has emerged.
Schikora said over-harvesting of the plant has led to environmental damage in many areas, which has led to a decline in licorice quality and quantity. To reverse this trend and ensure a sustainable resource with a consistent supply of leaves and raw materials, cultivation of the plant is proving a viable option.
The licorice plant is highly adaptable and can grow under harsh conditions such as soil salinity, drought, and low soil fertility, all of which are threats to agriculture.
“Cultivation of licorice on saline soils has a great potential to rehabilitate abandoned lands, thereby enhancing environmental sustainability,” he said.
“Long and short-term impacts of licorice cultivation have shown that it has a positive impact on soil health because of its many advantages such as protection against erosion, reducing upward salt movement, improving soil fertility by its nitrogen fixation ability and many other qualities.”
Schikora said interest in their research has already been shown by vineyard owners in wine-growing regions.
“We have received positive feedback since this extract offers the possibility to decrease copper limits defined for the organic vineyard systems. In view of the repeated discussions about the complete phasing out of copper-based plant protection compounds and lack of effective alternatives, we are optimistic that we can provide an alternative solution.”
Schikora said launching licorice in Europe would help reduce the dependency on chemical pesticides for growers and provide a safe alternative to ensuring healthy crop yields.
“In the (European Union), growers are facing the reduction of a number of active substances. Due to novel safety regulations, many products have been withdrawn from the market while others still on the market are unlikely to meet the new standards, resulting in an effective loss of fungicides. Licorice may help to overcome those challenges.”
Researchers plan to focus on the immune system-inducing action of licorice leaf extract and its interaction with crops. They must determine if the antibacterial potential of licorice leaf extract is valuable for all commercial crops.
For the time being, the crops already tested (tomato, potato, cucumber, and arabidopsis), show the protection is present.
The research appeared in the journal Plant Disease published by The American Phytopathological Society.
