Fusarium Wilt: Watermelon Disease & Prevention Techniques

What Is Fusarium Wilt?

Watermelon suffering from Fusarium WiltFusarium wilt is one of the most serious watermelon diseases. This post describes the cycle and symptoms of Fusarium wilt and offers management recommendations.

Symptoms & Signs Fusarium Wilt May Be Affecting Your Watermelon Crops

The fungus that causes Fusarium wilt in watermelon (Fusarium oxysporum fsp. niveum ,FON) is very specific and cannot infect closely related plants such as cucumber and muskmelon. FON forms resilient spores that remain viable in the soil for years, meaning Fusarium wilt may appear in a field that hasn’t had a suitable host for many seasons.

Is also means that the disease will not spread from plant to plant, only from spores in the soil. Any process that moves soil may be responsible for spreading this disease between or within fields. In addition, the organism that causes Fusarium wilt may be transmitted on seed; Fusarium wilt has been observed on watermelon transplants in greenhouses.

The first noticeable symptom is that one side of a plant wilts. This one-sided wilt is common in plants three to four weeks after they have been transplanted. Infected plants have white, healthy roots, but the vascular tissue is brown and discolored. In the field, infected plants often appear in clusters. Plants in areas of the field with high spore concentrations in the soil often develop symptoms before those plants in areas with relatively low spore populations, giving the appearance of disease spread.

Fusarium Wilt Prevention & Management Techniques

Ways To Prevent & Manage Fusarium Wilt In Watermelon Crops

Fusarium wilt is difficult to manage. Long rotations may lessen the survival rate of the fungus spores in the soil and decrease the severity of symptoms. Fumigation may help lessen the incidence and severity of Fusarium wilt. However, there are no fungicides currently labeled for treating Fusarium wilt.

Although no commercial watermelon varieties are completely resistant to Fusarium wilt, some varieties offer partial resistance, which will help lessen the impact of this disease (as is the case with various other soil pests and diseases).

The list below provides a timeline for Fusarium wilt management:

Winter / Off – Season

Long rotations of six years or more are necessary to keep inoculum from building up in the soil. Some cultivars offer partial resistance (See Purdue Extension publication ID-56, Midwest Vegetable Production Guide for Commercial Growers).

Greenhouse

Fusarium wilt may be seed-borne. Inspect seedlings for symptoms of Fusarium wilt. Use new transplant trays or sanitize trays well.

Vine Touch

Since symptoms are particularly likely at this stage, fields should be scouted for diseased plants.

Harvest

Do not save seed from fields where Fusarium wilt has been observed.

Further Studies, Reading & Resources On Fusarium Wilt

For more information, including cultivars that offer partial resistance to Fusarium wilt in watermelon, see Purdue Extension publication ID-56, the Midwest Vegetable Production Guide for Commercial Growers available at www.btny.purdue.edu/pubs/ID/ID-56/ or by visiting the Purdue Extension Education Store at www.ces.purdue.edu/new.

This post was written by Dan Egel, Extension Plant Pathologist, Southwest Purdue Agricultural Center (Purdue University)

Image via Growing Produce


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