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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #135120
Title: OREGON BLUEBERRY SURVEY: PHYTOPHTHORA AND PYTHIUM

Author
item Linderman, Robert

Submitted to: Proceedings of the Oregon Horticultural Society
Publication Type: Proceedings
Publication Acceptance Date: 4/2/2002
Publication Date: 4/15/2002
Citation: Linderman, R.G. 2002. Oregon blueberry survey: phytophthora and pythium. Proceedings of the Oregon Horticultural Society.

Interpretive Summary: In August of 2001, we sampled 55 fields in Oregon to assess the presence of Phytophthora and Pythium spp. in blueberry fields under production conditions and to determine whether any relationships exist between field characteristics, root distribution, and soil characteristics. Phytophthora spp, frequently the most serious P. cinnamomi, were detected in 24% of fields sampled and the incidence was higher in the upper 15 cm of the soil. Within fields with detectable Phytophthora spp., Phytophthora spp. were detected, on average, in ~49% of samples. Pythium spp. were detected in 85% of the fields, most commonly in the upper 15 cm of the soil. Occurrence of Pythium spp. varied with cultivar, field age, bed type, irrigation type, and presence of mulch. Decreased vigor ratings of plants correlated with increased incidence of Pythium. However, most plants infected with either the Phytophthora or Pythium root rot pathogens largely remain symptomless under good soil drainage conditions where new root generation can offset effects of root rot damage.

Technical Abstract: In August of 2001, we sampled 55 fields in Oregon to assess the presence of Phytophthora and Pythium spp. in blueberry fields under production conditions and to determine whether any relationships exist between field characteristics, root distribution, and soil characteristics. Phytophthora spp, frequently the most serious P. cinnamomi, were detected in 24% of fields sampled and the incidence was higher in the upper 15 cm of the soil. Within fields with detectable Phytophthora spp., Phytophthora spp. were detected, on average, in ~49% of samples. Pythium spp. were detected in 85% of the fields, most commonly in the upper 15 cm of the soil. Occurrence of Pythium spp. varied with cultivar, field age, bed type, irrigation type, and presence of mulch. Decreased vigor ratings of plants correlated with increased incidence of Pythium. However, most plants infected with either the Phytophthora or Pythium root rot pathogens largely remain symptomless under good soil drainage conditions where new root generation can offset effects of root rot damage.