|Dong, W - UNIV OF GA|
|Brenneman, T - UNIV OF GA|
|Culbreath, A - UNIV OF GA|
Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 10, 2008
Publication Date: November 1, 2008
Citation: Dong, W.B., Brenneman, T.B., Holbrook Jr, C.C., Timper, P., Culbreath, A.K. 2009. The interaction between Meloidogyne arenaria and Cylindrocladium parasiticum in runner peanut. Plant Pathology 58:71-79. Interpretive Summary: Cylindrocladium black rot (CBR) and the peanut root-knot nematode both cause significant losses to peanut production, and losses are greatest in fields that have both pathogens. USDA-ARS has recently release Tifguard, a variety with resistance to nematodes. The objective of this study was to evaluate the potential impact of nematode resistance on CBR disease. The addition of nematode eggs increased CBR disease and reduced yield for two nematode susceptible varieties, however, Tifguard did not show increased disease, and there was no yield reduction. Tifguard should be a valuable variety for peanut growers who need to manage both root-knot nematode and CBR.
Technical Abstract: Cylindrocladium black rot (CBR), caused by Cylindrocladium parasiticum, and root-knot nematode, Meloidogyne arenaria, both infect and cause damage to the roots of peanut. Greenhouse and microplot experiments were conducted with the runner type peanut genotypes C724-19-15, C724-19-25 and Georgia-02C with different levels of resistance to nematode and CBR to better understand the interactions between the two pathogens. In the greenhouse, inoculation of 500-3000 eggs per plant of M. arenaria did not affect the level of root rot induced by 1.0 to 5.0 micorsclerotia of C. Parasiticum per g soil. In microplots, the root rot ratings from Georgia 02C and C724-19-25 were higher in plots infested with M. arenaria (0.4-2.0 eggs per cm3 soil) and C. parasiticum than in plots with C. parasiticum alone; however, M. arenria did not increase the root rot ratings on the nematode resistant C724-19-15. This was inconsistent with results in the greenhouse. Gall indices were not affected by C. parasiticum inoculations in the greenhouse or microplots. In both2006 and 2007, a significant interaction between C. parasiticum inoculum densities and nematode level was observed on plant mortality. CBR inoculum greatly increase mortality on C724-19-25 and Georgia-02C, but not on C724-19-15, in the presence of M. arenaria. The mortality increase was more apparent at lower levels of both pathogens, but on nematode-susceptible cultivars plant mortality was more with co-inoculations of two pathogens than from either alone. Simultaneous inoculation with the two pathogens decreased yield of C724-19-25 and Georgia-02C as C. parasiticum inoculum levels increased, but even the largest inoculum of M. arenaria (2.0 eggs per cm3 soil) did not decrease yield of C724-19-15.