Submitted to: Nematropica
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 1996
Publication Date: N/A
Interpretive Summary: Peach tree short life (PTSL) continues to be a problem in the peach growing regions of the southeastern United States. Fewer chemical nematicides are available to growers to control the ring nematode, which is responsible for making trees more susceptible to this disease complex. New alternatives to chemical control must be found to suppress the ring nematode and protect peach trees against PTSL. Since 1990, 1) peach seedling rootstock BY520-9 (Guardian) was identified as providing greater tree survival than Lovell (standard) on PTSL sites and appears to have some root-knot nematode resistance; 2) preplanting wheat/sorghum has been shown to suppress ring nematode populations on some PTSL sites; and 3) a bacterium associated with peach roots has been identified as killing ring nematode eggs in the laboratory and may prove to be an important biocontrol agent for the nematode. The new Guardian rootstock, wheat/sorghum rotation, and (or the bacterium could be used in an IPM program to combat PTSL in the Southeast. The impact of these data could provide growers with the needed alternatives to chemical control for ring nematode, thus providing greater tree survival to this dreaded disease complex.
Technical Abstract: Peach tree short life (PTSL) continues to be a major problem in peach growing regions of the southeastern U.S. Trees, usually 3-6 years old when affected, die before the orchard reaches full productivity. The ring nematode, Criconemella xenoplax, is the major biotic factor responsible for increasing susceptibility to cold injury and/or bacterial canker, Pseudomonas syringae, which are responsible for the sudden collapse of peach trees associated with the PTSL syndrome. In S.C. alone, 1.1 million trees died from PTSL between 1980-92 representing a monetary loss of greater than 6 million $U.S. annually. In recent years, disease management strategies of PTSL have been based on nonchemical approaches, including host resistance, biological control, & cultural practices for suppression of C. xenoplax. In 1991, peach seedling rootstock BY520-9 (Guardian) was identified as providing greater tree survival than Lovell (standard rootstock) on PTSL sites. Preliminary results also indicate some degree of root-knot nematode resistance in newly released Guardian peach rootstock. Preplanting wheat & sorghum has proven useful in suppressing population density of C. xenoplax on some PTSL orchard sites. Investigations into preplanting bahiagrass to suppress C. xenoplax are continuing. A bacterium (Pseudomonas aureofaciens) associated with peach roots is being studied as a potential biocontrol agent for the ring nematode. A water diffusible substance that kills C. xenoplax eggs appears to be an important mechanism of suppression of the nematode.