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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Plant Pathology Research » Research » Publications at this Location » Publication #179006
Title: EFFECTS OF PRE-PLANT SOIL TREATMENTS ON NEMATODE COMMUNITIES

Author
item WANG, KOONHUI - UNIV. OF FLORIDA
item MCSORLEY, ROBERT - UNIV. OF FLORIDA
item Burelle, Nancy

Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 3/24/2005
Publication Date: N/A
Citation: N/A

Interpretive Summary: Because nematodes play a central role in soil nutrient cycling, it is important to understand the effects of soil management practices on their populations to improve both nematode and nutrient management strategies. A 2-year field trial was conducted in Florida to examine nematode communities in soil treated with methyl bromide (MB), 6-weeks of solarization (S), cowpea cover crop for 3 months (CP), a combination of solarization and cowpea cover crop (S+CP), and a weed fallow control. Nematode populations were monitored during the course of fall pepper (Capsicum annuum) production during both years. Immediately after treatment, MB reduced total numbers of bacterivores, fungivores, herbivores, and predators, as well as fungivore: bacterivore ratio (F/B), compared to the control in both years. MB also reduced diversity, maturity index (MI) and structure index (SI), but increased enrichment index (EI). Although solarization had similar broad spectrum impact on nematode communities in year 1, it only reduced richness and diversity in year 2. Cowpea cover crop alone reduced total abundance of fungivores and herbivores, F/B, and CI, but increased total abundance of omnivores and SI compared to the control in year 1, whereas it increased total abundance of bacterivores, fungivores, omnivores, and predators and EI, but decreased diversity in year 2. Combining solarization with cowpea had a similar effect on nematode communities as S in year 1, but increased total abundance of omnivores in year 2. Three months after pepper crop was planted, total abundance of each trophic group did not differ from the control in most treatments, except in the MB in year 1. However, F/B, richness, and diversity were lower (P<0.05) in all these pre-plant treatments than the control. In year 2, 3 months after peppers were planted, total abundance of bacterivores, and fungivores, as well as richness in plots receiving pre-plant treatments were lower than the control. Differences in response of nematode communities to treatments in year 2 may be due to a severe hurricane season, resulting in proliferation of fungal pathogens at the experimental site.

Technical Abstract: While nematodes play important roles in soil nutrient cycling, many pre-plant soil management practices act as perturbations to nematode communities. A 2-year field trial was conducted to examine nematode communities in soil treated with methyl bromide (MB), 6-week solarization (S), cowpea cover cropping for 3 months (CP), a combination of solarization and cowpea cover crop (S+CP), and a weed fallow control. At termination of pre-plant treatments, MB reduced (P<0.05) total abundance of bacterivores, fungivores, herbivores, and predators, as well as fungivore: bacterivore ratio (F/B), richness and channel index compared to the control in year 1. Except for total predatory nematodes, these indices were also affected in year 2. In addition, MB also reduced diversity, maturity index (MI) and structure index (SI), but increased (P<0.05) enrichment index (EI) in year 2. Although solarization had great impact on nematode communities in year 1, it only reduced (P<0.05) richness and diversity in year 2. Cowpea cover crop alone reduced (P<0.05) total abundance of fungivores and herbivores, F/B, and CI, but increased total abundance of omnivores and SI compared to the control in year 1, whereas it increased total abundance of bacterivores, fungivores, omnivores, and predators and EI, but decreased diversity in year 2. Combining solarization with cowpea had a similar effect on nematode communities as S in year 1, but increased (P<0.05) total abundance of omnivores in year 2. Three months after pepper (Capsicum annuum) crop was planted, total abundance of each trophic group did not differ from the control in most treatments, except in the MB in year 1. However, F/B, richness, and diversity were lower (P<0.05) in all these pre-plant treatments than the control. In year 2, 3 months after peppers were planted, total abundance of bacterivores, and fungivores, as well as richness in plots receiving pre-plant treatments were lower than the control. Differences in response of nematode communities to treatments in year 2 may be due to a severe hurricane season, resulting in proliferation of fungal pathogens at the experimental site.