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Updated: Jan 28, 2026
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An Effective Inoculation Method for Phytophthora capsici on Black Pepper Plants
Published on: September 16, 2022
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Epipremnum, a new host for Phytophthora capsici.
1Department of Microbiology, University of Massachusetts, Amherst 01003.
Plant Disease
|March 2, 2019
Summary
Phytophthora capsici was identified as the cause of significant rot in Pothos plants imported from Costa Rica. This pathogen caused severe disease in Pothos but not in pepper or squash plants.
Area of Science:
- Plant Pathology
- Mycology
- Horticultural Science
Background:
- A Massachusetts nursery experienced significant crown, petiole, and leaf rot in Pothos (Epipremnum aureum) plants between 1999 and 2001.
- The affected Pothos plants were imported from Costa Rica, indicating a potential for introduced plant diseases.
Purpose of the Study:
- To identify the causal agent of the observed rot in imported Pothos plants.
- To characterize the pathogen's morphology, mating type, and sensitivity to metalaxyl.
- To confirm the pathogen's pathogenicity on Pothos and other plant species.
Main Methods:
- Five Phytophthora isolates were recovered from diseased Pothos tissues and subjected to morphological characterization.
- Mating type analysis, sporangial and oospore measurements, and metalaxyl sensitivity tests were performed.
- Pathogenicity tests were conducted on Pothos, pepper (Capsicum annuum), and squash (Cucurbita pepo) seedlings.
Main Results:
- Morphological and mating type analyses identified the five isolates as Phytophthora capsici, mating type A1.
- The pathogen exhibited optimal growth at 20-30°C and was sensitive to 5 ppm metalaxyl.
- Koch's postulates confirmed Phytophthora capsici pathogenicity, causing severe rot in Pothos but no disease in pepper or squash.
Conclusions:
- The isolated Phytophthora capsici, belonging to the CAPB (tropical) subgroup, is responsible for significant rot in imported Pothos plants.
- The pathogen's host specificity, not affecting pepper or squash, is a key characteristic.
- These findings highlight the importance of monitoring imported plants for potential pathogens like Phytophthora capsici.
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