Experimental assessment of phytopathological risks in CELSS

Year-long experiment with non-sterile CELSS conducted in the Laboratory of controlled biosynthesis of phototrophs revealed the following phytopathological risks for higher plants based life support system. The major risk is contamination of CELLS by phythopathogenic fungi of Fusarium species causing root rot of cereals. In our experiments it was estimated that one infected plant produces about 1500 conidia of Fusarium per day, and these conidia are ready to infect new plants in 6-8 hours after formation. In the system based on conveyor cropping this leads to fast spreading of disease via nutrient solution and accumulation of newly formed conidia in the substrate. No other soil borne pathogens were observed during all the time of experiment. Another risk is associated with previously undescribed bacterial stalk rot of wheat. The disease affects weakened plants and seems to be non-dangerous for plants growing under optimal condition. At least one case of mass death of plants was associated with poisoning plants by cyanobacterial toxins. Among agriculturally significant insect pests only thrips were found. Unexpectedly no phytopathogenic nematodes were observed despite on the fact that free living nematodes colonized the CELSS from the very beginning of the experiment. We assume that predatory fungi Arthrobotrys oligospora developed in the rhizosphere and feeding on the free living nematodes created a biological barrier to phytopathogenic nematodes.The study was supported by the Russian Science Foundation (Project no.14-14-00599 _)