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United States Department of Agriculture

Agricultural Research Service

Research Project: Alternatives to methyl bromide soil fumigation for vegetable and floriculture production Title: Susceptibility of Several Weeds Common in Florida Agricultural Production to Meloidogyne Spp.

Authors
item Burelle, Nancy
item Rosskopf, Erin

Submitted to: Society of Nematologists
Publication Type: Abstract Only
Publication Acceptance Date: April 18, 2012
Publication Date: N/A

Interpretive Summary: Documenting shifts in existing and newly emerging weed populations, and how these changes affect nematode populations is required as vegetable and ornamental producers transition from broad-spectrum fumigants to more sustainable methods for nematode control. In a Florida field trial examining alternatives to fumigants for production of field-grown cut flowers, weeds were collected, identified, and evaluated for galling by root-knot nematodes (Meloidogyne spp.). Cheeseweed mallow (Malva parviflora L.) was determined to be infected with Meloidogyne arenaria, and greenhouse experiments confirmed and quantified the host status under controlled conditions. This was the first report of M. parviflora as a natural host of M. arenaria. In greenhouse trials to assess galling and egg production of three common root-knot nematode species, M. incognita, M. arenaria, and M. javanica on weeds common in Florida production, Portulaca oleracea (purslane), Eleusine indica (goosegrass), Aeschynomene americana (American jointvetch), Solanum americanum (American black nightshade), Cyperus esculentus (yellow nutsedge), and Amaranthus retroflexus (redroot pigweed) were evaluated. Although recommended as a cover crop in the southern U.S., A. americana was evaluated as a weed following a heavy volunteer infestation of an experimental field in southeastern Florida where galling was observed on roots. Portulaca oleracea and A. americana roots supported the highest number of juveniles (J2) of all three species of Meloidogyne, and had the highest number of eggs/g root for all three species. However, although P. oleracea supported very high numbers of nematode J2 in roots, galling was moderate to low for all three Meloidogyne species. In contrast, galling on A. americana was higher than for P. oleracea for all three species, and more representative of the numbers of J2 isolated from roots. Low levels of apparent galling combined with high egg production, increases the potential for P. oleracea to affect populations of these three root-knot nematode species to a degree that may not be immediately recognized. Also. A. americana may serve as an important host of the three species of root-knot nematode tested in southern regions of Florida.

Technical Abstract: Documenting shifts in existing and newly emerging weed populations, and how these changes affect nematode populations is required as vegetable and ornamental producers transition from broad-spectrum fumigants to more sustainable methods for nematode control. In a Florida field trial examining alternatives to fumigants for production of field-grown cut flowers, weeds were collected, identified, and evaluated for galling by root-knot nematodes (Meloidogyne spp.). Cheeseweed mallow (Malva parviflora L.) was determined to be infected with Meloidogyne arenaria, and greenhouse experiments confirmed and quantified the host status under controlled conditions. This was the first report of M. parviflora as a natural host of M. arenaria. In greenhouse trials to assess galling and egg production of three common root-knot nematode species, M. incognita, M. arenaria, and M. javanica on weeds common in Florida production, Portulaca oleracea (purslane), Eleusine indica (goosegrass), Aeschynomene americana (American jointvetch), Solanum americanum (American black nightshade), Cyperus esculentus (yellow nutsedge), and Amaranthus retroflexus (redroot pigweed) were evaluated. Although recommended as a cover crop in the southern U.S., A. americana was evaluated as a weed following a heavy volunteer infestation of an experimental field in southeastern Florida where galling was observed on roots. Portulaca oleracea and A. americana roots supported the highest number of juveniles (J2) of all three species of Meloidogyne, and had the highest number of eggs/g root for all three species. However, although P. oleracea supported very high numbers of nematode J2 in roots, galling was moderate to low for all three Meloidogyne species. In contrast, galling on A. americana was higher than for P. oleracea for all three species, and more representative of the numbers of J2 isolated from roots. Low levels of apparent galling combined with high egg production, increases the potential for P. oleracea to affect populations of these three root-knot nematode species to a degree that may not be immediately recognized. Also. A. americana may serve as an important host of the three species of root-knot nematode tested in southern regions of Florida.

Last Modified: 10/24/2014
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