Fusarium basal plate rot - onions, garlic summary (2020) - 1 page
Scenario - an onion crop established using sets had been looking good until the onset
of warm weather in mid-July. Within a few days, a good portion of the crop had
begun to wilt, yellow and die. Problems seem more severe in low, flood-prone spots
in the field. When the damaged plants were lifted, a brown-red rot was found at the
connection between the bulb and the root system.
Diagnosis: Basal plate rot
Basal plate rot (Fusarium oxysporum f.sp. cepae) is a persistent soil-borne organism. It is
most likely introduced into non-contaminated fields on infested garlic cloves or onion sets. The disease tends to occur more frequently on garlic and Spanish-type onion varieties than on yellow cooking onion varieties.
The pathogen infects when soils become warm - so the problem usually shows up in mid-summer. Even in heavily contaminated fields the disease rarely occurs when soil temperatures are below 15°C.