Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Onion -- Fusarium Basal Rot
 
Cause: Fusarium oxysporum f. sp. cepae is a soilborne fungus that can affect onion and other Allium spp. The fungus lives a long time in soil. Infection often is associated with pink root, maggots, or other insect injury.
Symptoms: Bulbs may become infected at any point during their time in the field. Yellowing and browning of leaves begins at the tip and moves downward. Plants exhibit weak growth and may wilt. Red-brown rot appears where roots are attached to the basal plate. Rot and discoloration usually affect all of the base and up into the bulb scales; affected tissue appears brown and watery when bulbs are cut open. Sometimes, a white moldy growth develops on the stem plate or between affected scales. Bulbs may appear normal at harvest, but rot may progress in storage.

 
Cultivar Resistance: Plant resistant cultivars. In a Malheur County, OR test, these cultivars had less basal rot: 'Golden Cascade', 'Cima', 'Oro Grande', 'Valient', and 'Cashe'. Other onion cultivars described as tolerant but not tested in Oregon are 'Bronze Reserve', 'North Star', 'Sassy Brassy', and 'Sentinel'.
Cultural control:

  1. Use 4-year or longer crop rotations.
  2. Protect plants from insect, fertilizer, or other injury.
  3. Storing bulbs at 39oF minimizes postharvest losses.
Chemical control: Preplant soil fumigation effectively controls the disease on mineral soils but not on peat soils. Note Fall fumigation is more effective than spring.
  1. Telone C-17 at 10.8 to 30 gal/A. Caution Fumigation must be before planting, so it is important that the planting row be directly over the fumigated soil if only the planting row is treated. Variations of a few inches can cause complete loss of control. Use highest rate on peat soils. Restricted-use pesticide. 5-day reentry..
  2. Telone II at 9 to 12 gal/A on mineral soils, 25 gal/A on peat soils. Caution Fumigation must be before planting, so it is important that the planting row be directly over the fumigated soil if only the planting row is treated. Variations of a few inches can cause complete loss of control. Restricted-use pesticide. 5-day reentry..
References:
Schwartz, HF. and Mohan, SK. 1995. Compendium of Onion and Garlic Diseases. St. Paul, MN: APS Press.
Content edited by: C.M. Ocamb and D.H. Gent on January 1, 2010
 
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