Infection of Sorghum Varieties by the Cotton Root-knot
Nematode, Meloidogyne incognita
M. McClure, Plant Pathology Department
S. Husman, Pinal County Cooperative Extension
M. Schmitt, Plant Pathology Department
Twenty three varieties of sorghum, Sorghum bicolor, were evaluated for susceptibility to the
cotton root-knot nematode, Meloidogyne incognita race 3. Eggs per gram of root were used as a
measure of nematode reproduction and host susceptibility. The nematode reproduced on all
varieties tested. Mean egg counts were lowest on the varieties Northrup King (NK) KS-737,
M.F.; NK 1580,M; NK Ks-735 M.F.; NK 714Y M.F.; NK Lt. Bronze X 609 M.; Ciba-NK C-1506, M.; and
Pioneer 8877, but these varieties are still considered to be hosts capable of sustaining or
increasing nematode populations in cotton fields. All varieties were better hosts than
The cotton root-knot nematode, Meloidogyne incognita race 3 is a wide-spread problem in
Arizona including those areas where sorghum is grown in rotation with cotton. Sorghum is a
known host of M. incognita but susceptibility varies greatly among varieties (McSorley and
Gallaher, 1992) and post-season nematode populations fluctuate accordingly. Fortnum and
Currin (1988) tested several varieties of sorghum for susceptibility to M. incognita and found
that, compared to tomato, nematode reproduction was low, results that have been affirmed by
Ibrahim et al. (1993). However, recent field trials in Arizona have shown that yield of
cotton lint can be increased by pre-plant treatments of Telone when cotton follows sorghum.
Therefore, greenhouse trials were conducted to determine the susceptibility of selected sorghum
varieties to M. incognita race 3.
Materials and Methods
Seeds of 23 sorghum varieties were sown, 4 seeds to a pot, in
6-inch-diameter plastic pots,
containing a sterile 3:1 mixture of washed mortar sand and sandy loam.
Ten days after sowing,
when the seedlings had reached a height of 2 inches, they were
inoculated with 4,700 M.
incognita infective juveniles per pot. Daytime greenhouse temperature was
28 +- 4 C and night temperature at 20 +- 3 C.
Plants were harvested
80 days after inoculation,
the roots gently washed to remove adhering soil, and the nematode eggs
extracted in 20 %
household bleach. Each variety was replicated three times (three pots) and the
was repeated twice.
Results are shown in
While there was considerable in variation in nematode reproduction among
sorghum varieties, all varieties were suitable hosts for the cotton root-knot
nematode, M. incognita and, based on the number of eggs recovered from
infected root systems, sorghum is a better host than cotton.
Sorghum rotation with cotton should be avoided if the land is infested with
- Fortnum, B.A. and R. E. Currin III . 1988. Host suitability of grain
sorghum cultivars to Meloidogyne spp. Annals of Applied Nematology 2: 61-64.
- Ibrahim, I. K. A., Lewis, S. A. and D. C. Harshman. 1993.
Host suitability of graminaceous crop cultivars from isolates of
Meloidogyne arenaria and M. incognita. Journal of Nematology
- McSorley, R. and R. N. Gallaher, 1992. Comparison of nematode population
densities on six summer crops at seven sites in North Florida. Journal of
Nematology (Supplement) 24:699-706.
This is a part of publication AZ1006:
"Cotton: A College of Agriculture Report," 1998, College of Agriculture, The University of
Arizona, Tucson, Arizona, 85721.
Any products, services, or organizations that are mentioned, shown, or indirectly
implied in this publication do not imply endorsement by The University of Arizona.
The University is an Equal Opportunity/Affirmative Action Employer.
This document located at http://ag.arizona.edu/pubs/crops/az1006/az100610i.html
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