Semester of Graduation
Master of Science (MS)
The reniform nematode Rotylenchulus reniformis is a major pathogen of soybean and cotton in Louisiana. Previous studies have shown that populations of reniform nematode throughout the southern United States vary in reproduction and pathogenicity. Limited studies have been conducted to evaluate the reproduction and pathogenicity of populations of R. reniformis endemic in Louisiana. Studies with isolates of the nematode from eight cotton-producing parishes focused solely on reproduction of the root-associated infective and swollen female life stages with and without attached egg masses on the cotton genotypes MT2468 Ren3, M713 Ren5, and Stoneville 4946GLB2 and the soybean genotypes PI 548316, PI 90763, and Progeny 4930LL. Data from greenhouse-based, 30-d-duration tests showed significant differences in life stage totals per root system among the eight isolates. Data from subsequent greenhouse studies with isolates of the nematode from West Carroll (WC), Morehouse (MOR), Rapides (RAP), and East Carroll (EC) parishes showed that on cotton there were significantly greater numbers of females with egg masses and total life stages on roots for the WC isolate than for the other 3 isolates.
Subsequent laboratory tests with durations of 14-21 days employed isolates of the nematode from WC, MOR, RAP and EC parishes. Soybean and cotton plants were grown either in steam-sterilized soil or in soilless germination pouches. Overall, genotypes of cotton were better able to distinguish populations of the nematode on roots than were the genotypes of soybean. After 14 days for both cotton and soybean, the greatest numbers of infective and swollen females and root-associated totals were observed with the WC isolate of the nematode. After 21 days, numbers of swollen females with egg masses and root-associated life stage totals for cotton were significantly greater for the WC isolate than for the other isolates. Germination pouches showed that, on tomato, the WC and RAP isolates had greater numbers of swollen females and total root-associated stages than the other two isolates. Total egg mass contents, the sum of the numbers of eggs and hatched juveniles, were greatest for the WC isolate of the nematode and averaged 30 per egg mass.
McInnes, Benjamin, "Distinguishing Isolates of Rotylenchulus reniformis Endemic in Louisiana on the Basis of Root-associated Females and Egg Masses" (2017). LSU Master's Theses. 4357.