Trichoderma strains for control of stem canker of brassicas

From the report “Optimal Trichoderma strains for control of stem canker of brassicas: molecular basis of biocontrol properties and azole resistance“, of Adam Dawidziuk, Delfina Popiel, Joanna Kaczmarek, Judyta Strakowska, and Malgorzata Jedryczka, published in BioControl.

Oilseed rape (Brassica napus L.) is one of the fastest expanding crops worldwide, with the European Union currently producing the highest amount of oilseed rape seeds and oil.

Leptosphaeria maculans (Desm.) Ces. et de Not is one of the most damaging pathogens to oilseed rape production worldwide. It is responsible for phoma leaf spotting and stem canker, also termed blackleg. The fungus is highly polymorphic and is responsible for yield losses of economic significance in all areas of intensive rapeseed cultivation.

Genus Trichoderma contains the most powerful agents used in biocontrol. The study demonstrated that T. harzianum, T. hamatum and T. longibrachiatum can effectively control phytopathogenic fungi Leptosphaeria maculans and L. Biglobosa. The most effective was T. harzianum, which not only reduced the growth of oilseed rape pathogens in dual cultures, but also exhibited the inhibition zone, which is a typical symptom of antibiosis. The effects of Trichoderma on pathogens’ growth (in dual cultures on agar media) and on disease severity (on seedlings in controlled conditions) were also confirmed by field experiments.

Additionally, spraying with conidiospores in the autumn was helpful in reducing the incidence and severity of phoma leaf spots. It has also accelerated the degradation of plant stubble and the decomposition of pathogens’ fruiting bodies.

Furthermore, all Trichoderma isolates showed higher cellulolytic activity and enhanced resistance to flusilazole treatments as compared to Leptosphaeria spp., which coincided with upregulation of 14α-sterol demethylases and an AbcG5 transporter.

The effects we observed justify the use of Trichoderma to enhance the resistance of oilseed rape against pathogens, which in turn may lead to a decrease in the use of pesticides.