Beet, Red (Beta vulgaris)-Damping-off

Cause The soilborne fungi or fungus-like microorganisms, Pythium spp. and Rhizoctonia solani, attack before, during, and after germination. In Oregon, Pythium spp. are the major cause of pre- and post-emergence damping-off of young beet seedlings and are favored by cool soil temperatures. Rhizoctonia solani is more often associated with post-emergence damping-off of older seedlings and is favored by warmer soil temperatures. Aphanomyces cochlioides causes post-emergence damping-off and is favored by wet soils and temperatures between 68°F and 86°F. These microorganisms can survive several years in soil and can infect other plant species including beans, other legumes, and some weed species.

Symptoms Seedlings either do not emerge or emerged seedlings' stems often blacken and wilt. Very few infected seedlings survive.

Cultural control

  • Encourage rapid emergence by managing planting depth (shallow), timing, and soil moisture. Work soil at moisture conditions that reduce soil compaction.
  • Rotate beet crops with grass and grain.
  • Placing phosphate fertilizer in a band 1 inch below seed often prevents damping-off.
  • If the stand has been lost, replant ideally in dry, warm weather because it is more favorable for germination.

Chemical control

  • Seed treatments.
    • Acquire at 0.7 fl oz/100 lb seed plus a dye. For control of Pythium only. 24-hr reentry
    • Allegiance-FL at 0.75 fl oz/100 lb seed plus a dye. To control Pythium spp. only. See label for reentry restrictions.
    • Apron XL at 0.085 to 0.64 fl oz/100 lb seed plus a dye, if Pythium is a problem. See label for reentry restrictions.
    • Captan 4F at 12 fl oz/100 lb seed plus a dye.
    • Dynasty at 0.1 to 0.38 fl oz/100 lb seed plus a dye. 4-hr reentry.
    • Maxim 4FS at 0.08 to 0.16 fl oz/100 lb seed plus a dye. For control of pathogenic Fusarium, Pythium, and Rhizoctonia spp. See label for reentry restrictions.
    • Mertect 340-F at 0.002 mg ai/seed plus a dye. To control pathogenic Fusarium spp.
    • Spirato 480FS (Group 12) at 0.08 to 0.16 fl oz/100 lb seed plus a dye. 12-hr reentry.
    • 42-S Thiram at 8 fl oz/100 lb seed plus a dye. See label for reentry restrictions.
  • Soil-applied fungicides.
    • Quadris at 0.4 to 0.8 oz/1000 row feet applied in a 7-inch or less band either in-furrow at planting or as a directed spray at cultivation. 4-hr reentry.
    • Ridomil Gold SL may be banded or surface applied at 1 to 2 pints/A. Band-rate determinants include band width and row spacing; see label. Incorporate 2-inches deep when used. 48-hr reentry.

Biological control

  • Actinovate AG at 3 to 12 oz/A on 7- to 14-day intervals will suppress Aphanomyces and other soilborne pathogens. 1-hr reentry. O
  • Actinovate Lawn & Garden at 0.5 to 1 teaspoon/gal water. H O
  • Amplitude at 3.2 to 4.8 fl oz/100 lb seed pieces, 6 to 8 fl oz per 1,000 ft row as an in-furrow treatment, or 3 to 4 quarts/A as a chemigation treatment on 14- to 21-day intervals. Preharvest interval is 0 days. 4-hr reentry. O
  • Bio-Tam 2.0 at 2.5 to 5 lb/A as a broadcast at sowing. See label for different methods and rates of application. 4-hr reentry. O
  • Double Nickel LC at 0.5 to 4.5 pints/A for soil application on 14- to 28-day intervals. Can be applied the day of harvest. 4-hr reentry. O
  • Prestop as a soil drench or incorporation into growing medium. 4-hr reentry. O
  • Rootshield Home and Garden at 1 to 3 Tbsp/gal water as a soil drench at planting. H O
  • SoilGard 12G at 0.5 to 10 lb/A at 4-week intervals will suppress Pythium and Rhizoctonia. See label for specific application types and timings. Can be applied on the day of harvest. O
  • Stargus at 6 to 8 fl oz per 1,000 ft row as an in-furrow treatment, 3 to 4 quarts/A as a soil drench on 10- to 14-day intervals, or 3 to 4 quarts/A as a chemigation drip treatment on 14- to 21-day intervals. Preharvest interval is 0 days. 4-hr reentry. O
  • Tenet WP at 2.5 to 5 lb/A as a broadcast at sowing. See label for different methods and rates of application. 1-hr reentry. O

Reference Harveson, R.M., Hanson, L.E., and Hein, G.L. 2009. Compendium of Beet Diseases and Pests, 2nd Ed. St. Paul, MN: APS Press.