The objective of this study was to determine the effects of ILeVO (fluopyram) and VOTiVO (Bacillus firmus I-1582) seed treatments on Heterodera glycines second-stage juvenile (J2) root penetration and behavior. In a growth chamber experiment, roots of soybeans grown from treated or untreated seeds were inoculated with H. glycines J2s at soil depths of 2.5, 5, or 7.5 cm. ILeVO significantly reduced H. glycines root penetration compared with the untreated control, but only when J2s were inoculated at a soil depth of 2.5 cm, which was near the seed. Changes in nematode behavior were assessed by collecting 60-s videos of J2s after 2 h of exposure to exudates from treated seeds or radicles from treated seeds or from soil leachates in which treated seeds were planted. X- and y-coordinates of each of the 13 reference points were recorded every hour for 24 h. A custom program analyzed and transformed the coordinates into nematode motion parameters (speed and total change in curvature). ILeVO, but not VOTiVO, seed exudates significantly reduced J2 speed relative to the untreated control. Soil leachates from ILeVO or VOTiVO treatments had no consistent effect on H. glycines speed or total change in curvature compared with the untreated control. In another experiment, treated or untreated seeds were incubated in wells of 6-well tissue culture plates containing 11.5% Pluronic gel. Seeds were removed after 2 h, and approximately 50 J2s then were pipetted into each well. The plates were scanned every 60 min for 24 h, and the number of J2s in each well that moved a minimum distance of ≥300 µm was determined using another custom software program. ILeVO, but not VOTiVO, significantly reduced the movement of J2 populations relative to control wells in which no seeds were added. And wells that had seeds, treated or not, yielded significantly less J2 movement compared with the no-seed control. The results of these experiments indicate that ILeVO reduces activity on H. glycines J2s but may not affect nematodes beyond a limited area surrounding the treated seed.
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Avicta and Clariva Affect the Biology of the Soybean Cyst Nematode, Heterodera glycines
Nematicidal seed treatments are a relatively new strategy for managing plant-parasitic nematodes in row crops. Two such seed treatments, Avicta (abamectin) and Clariva (Pasteuria nishizawae), are marketed by Syngenta for use against Heterodera glycines in soybean production in the upper Midwest. The specific effects of these seed treatments on the biology of the nematode have not been previously reported. The effects of Avicta and Clariva on H. glycines hatching, movement, attraction, penetration, development, and reproduction were determined in controlled-environment experiments. Avicta inhibited juvenile movement and penetration at the seed depth and 3 cm below the seed. Clariva inhibited juvenile movement and penetration 3 and 5 cm below the seed and nematode development within the roots of young plants. Both seed treatments affected nematodes in 10- and 20-day-old plants, but effects were not detected on nematodes developing in older plants (30 and 60 days) with larger root systems. These results provide details of the specific mechanisms of early-season protection provided by Avicta and Clariva seed treatments.
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- Award ID(s):
- 1556370
- NSF-PAR ID:
- 10334498
- Date Published:
- Journal Name:
- Plant Disease
- Volume:
- 102
- Issue:
- 12
- ISSN:
- 0191-2917
- Page Range / eLocation ID:
- 2480 to 2486
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1094/PDIS-01-18-0086-RE
