Cause Globisporangium paroecandrum (formerly Pythium paroecandrum), G. mastophorum (formerly P. mastophorum), and possibly other Pythium or Globisporangium spp. as well as the fungi Pythium spp., Rhizoctonia solani, and Fusarium spp. Globisporangium paroecandrum, G. mastophorum, and Rhizoctonia solani have been documented as pathogenic on parsley; Fusarium oxysporum has been recovered from diseased parsley in Oregon and California. Pythium and Globisporangium are favored by cool, overly wet soil conditions, Rhizoctonia by warm soil temperatures, and Fusarium tolerates a wider host range.
Symptoms Seeds either fail to emerge from soil or collapse soon after emergence and a girdling canker develops at the soil line.
Cultural control
- Plant seed under optimal conditions for quick emergence and vigorous growth.
- Use sterile soil or potting mix to start seeds. Also disinfect any tools and equipment that might be used and contaminate the media.
- Avoid reusing pots or trays from a previous crop for propagation. If pots must be reused, then wash off all debris and soak in a sanitizing solution or treat with aerated steam for 30 min.
Chemical control
- Allegiance-FL (Group 4) at 0.75 fl oz/100 lb seed plus a dye. To control Pythium and Globisporangium spp. See label for reentry restrictions.
- Apron XL (Group 4) at 0.085 to 0.64 fl oz/100 lb seed when Pythium and Globisporangium are a problem. See label for reentry restrictions.
- Dynasty (Group 11) at 0.1 to 0.38 fl oz/100 lb seed plus a dye. 4-hr reentry.
- Maxim 4FS (Group 12) at 0.08 to 0.16 fl oz/100 lb seed. To control Fusarium, Rhizoctonia, and other fungal spp. 12-hr reentry.
- Orondis Gold (Group 49 + 4) at 13.9 to 27.8 fl oz/A as an in-furrow, transplant water or banded soil application at planting. May be applied through drip after emergence. Preharvest interval is 7 days. 48-hr reentry.
- Thiram 42-S (Group M3) at 2.5 to 5.0 fl oz/100 lb seed plus a dye. For use in Oregon (SLN OR-100002) and Washington (SLN WA-060022, WA-060023) only. For export only.
Biological control
- Actinovate AG at 3 to 12 oz/A as a soil drench at planting. 4-hr reentry. O
- Bexfond at 7 to 14 fl oz/A. 4-hr reentry. O
- Double Nickel LC at 0.5 to 4.5 pints/A as a soil drench at planting. 4-hr reentry. O
- LALSTOP K61 as a seed soak or dry seed treatment, soil-spray or drench, etc. See label for rates and application methods. 4-hr reentry. O
- Rootshield WP at 3 to 8 oz/100 gal water for greenhouse soil drench and field chemigation or at 16 to 32 oz/A as an in-furrow spray. 4-hr reentry. O
- SoilGard at 2 to 10 lb/A at 4-week intervals will suppress Globisporangium, Pythium and Rhizoctonia. See label for specific application types and timings. Can be applied on the day of harvest. 4-hr reentry. O
Reference Hershman, D.E., Varney, E.H., and Johnson, S.A. 1986. Etiology of parsley damping-off and influence of temperature on disease development. Plant Disease 70:927-930.
Koike, S.T., Gladders, P., and Paulus, A.O. 2007 Vegetable Diseases: A Color Handbook. St. Paul. MN: APS Press.
Tsuchida, C.T., Mauzey, S.J., Hatlen, R., Miles, T.D., and Koike, S.T. 2018. First report of Pythium root rot caused by Pythium mastophorum on parsley in the United States. Plant Dis. https://doi-org.oregonstate.idm.oclc.org/10.1094/PDIS-12-17-1903-PDN.