Multivariate Geostatistical Modeling of Phytophthora rubi and Pratylenchus penetrans in Red Raspberry Fields

Area of Science:

• Plant Pathology
• Soil Science
• Agricultural Entomology

Background:

• Soilborne pathogens Phytophthora rubi and Pratylenchus penetrans significantly reduce commercial red raspberry field longevity in the U.S. Pacific Northwest.
• Current management relies on pre-plant soil fumigation, which faces increasing regulatory and cost challenges.
• Understanding pathogen spatial distribution is crucial for developing effective, targeted disease management strategies.

Purpose of the Study:

• To assess the spatial distribution of disease severity, Phytophthora rubi, and Pratylenchus penetrans in commercial red raspberry fields.
• To investigate the interactions between soil physical characteristics and pathogen densities.
• To provide insights for developing targeted integrated pest management (IPM) strategies for red raspberry production.

Main Methods:

• Field surveys were conducted in four red raspberry fields in Oregon and Washington.
• Geostatistical analyses and spatial autoregressive modeling were employed to analyze pathogen distribution and disease severity.
• Soil samples were analyzed for Phytophthora rubi and Pratylenchus penetrans densities and disease severity was assessed.

Main Results:

• Disease severity and pathogen populations (Phytophthora rubi and Pratylenchus penetrans) exhibited spatial clumping within the surveyed fields.
• Soil texture and field elevation did not consistently correlate with the distribution of either pathogen.
• Disease severity was primarily driven by Phytophthora rubi root infestation, with no significant interactions observed between P. rubi and P. penetrans within the roots.

Conclusions:

• Phytophthora rubi is the primary driver of disease severity in red raspberry fields, despite the presence of Pratylenchus penetrans.
• Pathogen distribution is clumped, suggesting that targeted management approaches could be effective.
• Further research into the spatial ecology of these pathogens can support the development of sustainable integrated pest management strategies for red raspberries.