Effect of Aldicarb and Resistance on Yield Components of Soybean and Population Dynamics of Cyst Nematode (Heterodera, Illinois, Phomopsis)

Group three soybean cultivars resistant and susceptible to races three and four of Heterodera glycines were grown in three fields in Southern Illinois treated and nontreated with aldicarb and naturally infested with race three of the soybean cyst nematode. Cyst nematode reduced the height of plants primarily by reducing the internode length, but also in plots with heavy infestations by reducing the number of nodes per plant. Cyst nematode reduced also the mean leaf area per plant via a reduction in the number of leaves per plant and mean leaf area. Aldicarb increased yield components and growth of both the resistant and susceptible cultivars. The incidence of Macrophomina phaseolina was highest in plots of the susceptible cultivar not treated with aldicarb at the location with the highest infestation. At two locations severity of M. phaseolina was higher in plants treated with aldicarb than nontreated plants, but the severity of Phomopsis spp. was lower in treated plots. No significant effect of aldicarb on infection of seeds was observed. In greenhouse experiments the cultivar Fayette exhibited greater phytotoxicity symptoms than Williams 79. The Fayette plants were severely stunted at rates equivalent to twenty but not fourteen pounds per acre. Greenhouse-grown plants treated with aldicarb exhibited greater late season internode elongation than nontreated plants. Reproduction of soybean cyst nematode was reduced at all locations by resistance, however, there was some reproduction on the resistant cultivar, especially in plots with high initial infestations. At one location resistance reduced reproduction on both resistant and susceptible cultivars. These results confirm previous observations that aldicarb stimulates plant growth in addition to its insecticidal-nematicidal activities. The results show also that interactions between soybean cyst nematode and late season fungal pathogens do occur and may be related to changes in plant growth and morphology.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Plant Pathology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Mueller, John David

• Agriculture, Plant Pathology

Identifier

(UMI)AAI8409812

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/70592