Selection of bacteria and fungi for control of soilborne seedling diseases of maize

Abstract

Plant-based screening experiments were conducted with the aim of identifying biocontrol bacteria and fungi for seed treatment of maize. Candidate microorganisms were evaluated for their protective effects against soilborne infections by species of Fusarium, Globisporangium (syn. Pythium) and Rhizoctonia. The microorganisms tested were bacteria and fungi from maize roots or other sources, including some active microbial components of commercial biocontrol products. Due to the method of isolation chosen, the majority of bacteria from maize roots were spore formers, most of them species of the genera Bacillus,Brevibacillus and Paenibacillus. In pot tests with the potting substrate inoculated with F. culmorum, the level of control provided by seed treatment with the most efficacious bacterial and fungal isolates was comparable or close to the chemical reference seed treatment thiram. The most effective bacteria were species of Pseudomonas, Burkholderia and Streptomyces. Among a subset of approx. 100 bacteria studied, the in vivo and in vitro activities against F.culmorum were only weakly correlated, although some strains deviated from this pattern. The most effective fungi were two strains of Clonostachys rosea and isolates of Trichoderma. The latter and a strain of Gliocladium virens provided also protection against R.solani. Activity against Globisporangium ultimum was recorded for one isolate of Trichoderma and the two strains of C. rosea. A reduction in the impact of seedborne F. culmorum was also observed after seed treatment with two strains of F. oxysporum f. sp. strigae. The results are discussed in relation to previous reports on rhizosphere bacteria of maize and their use in biocontrol of plant pathogens or for plant growth promotion.

Characterization of a Disease-Suppressive Isolate of Lysobacter enzymogenes with Broad Antagonistic Activity against Bacterial, Oomycetal and Fungal Pathogens in Different Crops

“…There are only a few studies in the literature on the efficacy ad planta so far, none of which have been conducted with the phytopathogens tested here. In vivo/ad planta analyses are of high importance in the evaluation of biocontrol agents, because efficacy in in vitro tests does not directly correspond to efficacy on plants [ 40 , 41 ]. For L. enzymogenes , there are ad planta studies showing efficacy against Py.…”

Seed dressing with M451 promotes seedling growth in wheat and reduces root phytopathogenic fungi without affecting endophytes

“…Briefly, uniformly sized grains were washed in a solution of 4.5% (w/v) NaOCl:water (1:1 ratio) for 20 min. For the experimental groups, uniformly sized grains were treated with different concentrations of three different solutions: 1) 0.1% and 0.05% M451 (a water-based solution of TGV-28 [ Figure 1 ]; Human Microbiology Institute) in combination with 0.01% NaH 2 PO 4 (Sigma Aldrich, St. Louis, MO, USA) for 30 min, 2) 0.01% NaH 2 PO 4 for 30 min (Sigma Aldrich), and 3) Maxim XL v/v1:10 dilution in water for 12 h according to the manufacturer’s instructions (Syngenta Canada Inc., Guelph, ON, Canada) ( Costa et al., 2019 ; Pfeiffer et al., 2021 ). Subsequently, the grains from control and M451-treated groups were washed three times with autoclaved distilled water and then air-dried on filter paper.…”

Location of Pathogen Inoculum in the Potting Substrate Influences Damage by Globisporangium ultimum, Fusarium culmorum and Rhizoctonia solani and Effectiveness of Control Agents in Maize Seedlings

“…The kernels were then separated from the liquid by passing through a sieve, dried overnight in a laminar flow hood and sown the following day. The chemical seed treatment Thiram SC 700 (686 g/L thiram) was applied at a rate corresponding to 4 g active ingredient per kg of seed, as described in [7].…”

“…Compared to chemical seed treatment, the use of these alternatives is still limited to certain countries, regions and crops. There is, however, great interest and demand to explore the potential of these sustainable alternatives [6] and to develop new agents and combinations [7].…”