Studies of the Biology, Pathogenicity and Control of the Lance Nematode, Hoplolaimus Galeatus, on Dent Corn, Zea Mays
Willut, James Michael
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https://hdl.handle.net/2142/70591
Description
Title
Studies of the Biology, Pathogenicity and Control of the Lance Nematode, Hoplolaimus Galeatus, on Dent Corn, Zea Mays
Author(s)
Willut, James Michael
Issue Date
1983
Department of Study
Plant Pathology
Discipline
Plant Pathology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Plant Pathology
Abstract
In monoxenic culture, Hoplolaimus galeatus fed on excised roots of corn as a semiendo- and endoparasite. It penetrated all portions of the root, but preferred the zone of elongation and lateral root wounds. Yellowish-brown lesions were associated with feeding sites. Discoloration was most extensive in the vascular cylinder, which appeared to be the preferred feeding site. Histological sections revealed extensive mechanical damage, necrosis and cell rupture caused by migration and feeding in the cortex and feeding in the vascular cylinder. Eggs hatched 9-15 days after oviposition at 27 C and 13-19 days at 22 C in monoxenic culture. Second-stage juveniles developed to adults in 36 days in a soil system at 27 C. The nematode was pathogenic under both greenhouse and controlled-temperature conditions, but it adversely affected plant growth only during the second of 2 croppings and under relatively high population pressure resulting from inoculation with 1000 or more nematodes/pot. Shoot and root weights were affected more than was shoot height. Over a 20-32 C range of constant temperatures, the nematode reduced plant growth only at 24 and 28 C. In a greenhouse test, all cultivars supported reproduction, but the degree varied widely. Seven inbreds supported more nematodes in roots than did 7 hybrids. No distinct differences in population development of H. galeatus, Pratylenchus scribneri or Longidorus breviannulatus were detected on 6 hybrids evaluated under field conditions. Aldicarb applied to 4 of the cultivars reduced populations of P. scribneri and L. breviannulatus but not those of H. galeatus. Yields differed widely among hybrids both on untreated soil and in response to nematicide treatment. Over 4 biweekly planting dates and 2 growing seasons, populations of H. galeatus were not affected by planting date, but those of P. scribneri generally developed to higher levels on both untreated and carbofuran-treated corn the earlier the planting. Yields of treated and untreated corn were higher in May plantings. Yield increase was greater the earlier the planting in a hot growing season.
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