Effect of Meloidogyne incognita parasitism on yield and sugar content of sugar beet in Georgia

Authors: Davis, Richard; Webster, Theodore; Scully, Brian; BRENNEMAN, TIMOTHY - University Of Georgia

Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 5/26/2017
Publication Date: 12/1/2017
Citation: Davis, R.F., Webster, T.M., Scully, B.T., Brenneman, T. 2017. Effect of Meloidogyne incognita parasitism on yield and sugar content of sugar beet in Georgia. Journal of Nematology. 49:488.

Interpretive Summary:

Technical Abstract: Sugar beet (Beta vulgaris) is typically grown as a summer crop for edible sugar production in the north-central and western US, but it could be incorporated as a winter crop into annual cropping systems in the southern US where the sugar would be used for biofuel and plastic production. Sugar beet roots are severely galled by Meloidogyne incognita, which is common throughout the southeastern US, but M. incognita juveniles do not penetrate roots when soil temperature is below 18 C and do not continue to develop or reproduce below 10 C. In much of the southeastern US, soil temperatures are above those levels at planting and for several months prior to harvest but below those levels for much of the day during the coldest part of the winter. We conducted a field study for two growing seasons to determine the extent to which M. incognita reproduced on sugar beet grown as a winter crop in Georgia and the effect of M. incognita on yield and sugar content. A factorial arrangement of treatments was used with four genotypes (three M. incognita susceptible and one resistant) planted in the fall each year in plots treated or not treated with the nematicidal fumigant 1,3-dichloropropene and harvested the following spring. Fumigation affected yield and sugar content differently in 2015 than 2016, so data were not combined for analysis. Fumigation reduced root galling and increased yield in both years, but the yield increase was greater in 2015 than 2016. The effect of fumigation on root galling was similar between years and among genotypes. Yield differed among sugar beet genotypes in both years. Fumigation increased the yield of all genotypes in 2015 but increased only the yield of one susceptible genotype in 2016; yield of the other two susceptible genotypes increased numerically but not statistically, whereas yield of the resistant genotype was numerically greater in the non-fumigated plots. In both years, fumigation affected yield of the resistant genotype less than that of the susceptible genotypes. Sugar content, measured as degrees Brix, was increased by fumigation in 2015 but not 2016, and the resistant genotype had greater sugar content than the susceptible genotypes in both years. We conclude that sugar beet grown as a winter crop in Georgia can suffer significant yield losses from RKN parasitism, which may result in reduced sugar content in some years.