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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #151323
Title: REPRODUCTION OF MELOIDOGYNE SPECIES ON YELLOW GRANEX ONION AND POTENTIAL YIELD SUPPRESSION

Author
item Davis, Richard
item LANGSTON, DAVID - UNIVERSITY OF GEORGIA

Submitted to: Nematropica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2003
Publication Date: 10/1/2003
Citation: Davis, R.F., Langston, D.B. 2003. Reproduction of Meloidogyne species on yellow granex onion and potential yield suppression. Nematropica. 33:179-188.

Interpretive Summary: Onion is grown worldwide and is common in most countries. The root-knot nematodes Meloidogyne incognita, M. javanica, and M. arenaria are widely distributed throughout the world and are present in some of the major onion producing states in the U.S. Onion fields in Georgia often have high levels of root-knot nematodes, though it is not known which species are present or if the onion crop has been damaged. Our objective was to determine the relative abilities of M. incognita, M. javanica, and M. arenaria to reproduce on onion and to determine if M. incognita causes damage to onion. The three root-knot species we studied were all capable of significant reproduction on onion, though soil temperatures during the onion growing season in Georgia probably limit reproduction to one or two generations. Direct-seeded onions can suffer reductions in yield and economic return, but transplanted onions appear to be more tolerant and suffer little or no reduction in yield or economic return. Regardless of nematode damage, direct-seeded onions in Georgia have a lower economic return than transplanted onions even though production costs are significantly lower. If the economic return of direct-seeded onions can be improved and growers begin direct-seeding, then nematode management will become an important part of onion production.

Technical Abstract: The suitability of onion (Allium cepa cv. Sweet Vidalia) as a host for Meloidogyne incognita, M. arenaria, and M. javanica was evaluated. The effect of M. incognita on yield and economic return of direct-seeded and transplanted onions also was evaluated. Nematode reproduction was evaluated in two greenhouse trials with six replications each. Single onion transplants were inoculated with 8,000 eggs of one nematode species, and eggs were extracted and counted from onion roots 54 days after inoculation in both the first and second trials. The level of reproduction differed between trials (P'0.05), so data were analyzed separately. All three nematode species increased with final egg counts of 19,300 for M. incognita, 32,100 for M. arenaria, and 40,350 for M. javanica in the first trial and 167,200 for M. incognita, 71,600 for M. arenaria, and 101,950 for M. javanica in the second trial. Final egg counts were similar (P'0.05) among the three species in the first trial, but M. incognita produced more eggs (P'0.05) than M. arenaria in the second trial. The application of 1,3-D in direct-seeded onions increased the weight (kg/ha) of large and colossal sizes in both seasons and the weight of small and medium sizes in 2002-2003. In transplanted onions, the weight of colossal onions was increased in 2001-2002, but weights were unaffected in 2002-2003. Onion is a good host for all three Meloidogyne species tested, and M. incognita can reduce yields and economic return when onions are direct-seeded. Transplanted onions in this study did not suffer economic loss.