Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 14, 1999
Publication Date: N/A
Interpretive Summary: Ring nematodes are widely distributed throughout the world with certain species considered to be economically important to the stone fruit industry. Probably the most studied ring nematode species on Prunus is Mesocriconema xenoplax. This ring nematode is the only plant-parasitic nematode that has been associated with the peach tree short life (PTSL) disease complex in the southeastern United States. Tree loss due to PTSL in South Carolina alone was estimated at over $5 million per year. New preplant alternatives to chemical control (i.e., nematode suppressive ground covers) that are less hazardous to man and also more environmentally safe must be found to protect peach trees from this ring nematode. Pensacola and Tifton 9 bahiagrass were evaluated from 1991-98, as a potential preplant ground cover management strategy in suppressing the ring nematode population density and to determine the influence long-term preplant bahiagrass rotations have on peach tree growth and incidence of PTSL. Results indicate that tree growth was greatest in Pensacola bahiagrass killed sod and least in the unfumigated weed plots. However, PTSL tree survival in both preplant bahiagrass treatments did not differ from trees planted in unfumigated soil. Additionally, preplanting wheat was as effective as preplant methyl bromide fumigation in increasing tree survival from PTSL. These data provide useful insights into the use of bahiagrass as a preplant alternative to chemical control of the ring nematode.
Technical Abstract: The effects of four preplant ground cover systems as alternatives to chemical control of Mesocriconema xenoplax were investigated from 1991-98. Phase 1 was initiated in 1991, in an orchard known to be infested with M. xenoplax and having a history of peach tree short life (PTSL). Ground cover systems included: i) Pensacola bahiagrass, ii) Tifton 9 bahiagrass, iii) winter wheat (Triticum aestivum Stacy'), and iv) natural weeds that were maintained over the entire orchard floor. Phase 2 was initiated in 1994, when herbicide was applied to the ground cover plots and half the weed plots were fumigated with methyl bromide. Peach trees were planted into all plots in 1995. Fumigation effect on M. xenoplax population density collapsed 25 months after application. Young peach trees grew faster in killed Pensacola bahiagrass sod and fumigated soil, intermediate in Tifton 9 bahiagrass and wheat plots and slowest in unfumigated weed plots 13 months after planting. By the end of the experiment, tree growth was greatest in Pensacola bahiagrass killed sod and least in the unfumigated weed plots. Preplant wheat was as effective as preplant methyl bromide fumigation in increasing tree survival from PTSL.