Journal of Nematology (1998) 30, 100-107

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I.A.M. Saeed, A.E. Macguidwin and D.I. Rouse (1998)
Effect of initial nematode population density on the interaction of Pratylenchus penetrans and Verticillium dahliae on 'Russet burbank' potato
Journal of Nematology 30 (1), 100-107
Abstract: Four similar growth chamber experiments were conducted to test the hypothesis that the initial population density (Pi) of Pratylenchus penetrans influences the severity of interactive effects of P. penetrans and Verticillium dahliae on shoot growth, photosynthesis, and tuber yield of Russet Burbank potato. In each experiment, three population densities of P. penetrans with and without concomitant inoculation with V. dahliae were compared with nematode-free controls. The three specific Pi of P. penetrans tested varied from experiment to experiment but fell in the ranges 0.8-2.5, 1.8-3.9, 2.1-8.8, and 7.5-32.4 nematodes/cm3 soil. Inoculum of V. dahliae was mixed into soil, and the assayed density was 5.4 propagules/gram dry soil. Plants were grown 60 to 80 days in a controlled environment. Plant growth parameters in two experiments indicated significant interactions between P. penetrans and V. dahliae. In the absence of V. dahliae, P. penetrans did not reduce plant growth and tuber yield below that of the nematode-free control or did so only at the highest one or two population densities tested. In the presence of V. dahliae, the lowest population density significantly reduced shoot weight and photosynthesis in three and four experiments, respectively. Higher densities had no additional effect on shoot weight and caused additional reductions in photosynthesis in only one experiment. Population densities of 0.8 and 7.5 nematodes/cm3 soil reduced tuber yield by 51% and 45%, whereas higher densities had no effect or a 15% additional effect, respectively. These data indicate that interactive effects between P. penetrans and V. dahliae on Russet Burbank potato are manifested at P. penetrans population densities less than 1 nematode/cm3 soil and that the nematode population density must be substantially higher before additional effects are apparent.
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Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Verticillium dahliae Potato (Solanum tuberosum) U.S.A. (mid N)
Pratylenchus penetrans Potato (Solanum tuberosum) U.S.A. (mid N)