Fusarium wilt—Fusarium oxysporum
Fusarium wilt affects relatively few woody ornamental species but can kill certain hosts, including albizia, date, palm, hebe, and pyracantha. Most forms of Fusarium oxysporum attack only herbaceous plants including aster, carnation, chrysanthemum, dahlia, and freesia. Fusarium wilt causes foliage to yellow, curve, wilt, then turn brown and die. Fusarium wilt symptoms often appear first on one side of a plant. Older leaves usually die first in infected plants, commonly followed by death of the entire plant. Plants infected when they are young often die. Cutting into infected wood may reveal that vascular tissue has turned brown, often all the way from the shoot to the soil line. Cross-sections of basal stems may reveal brown rings. Masses of spore-bearing stalks are sometimes visible on dead tissue and may look like small pink cushions.
Fusarium wilt results from infection through roots by hyphae that germinate from long-lasting survival structures in the soil. Plant with species from different genera rather than with plants previously infected there by Fusarium. Choose resistant cultivars if available. For herbaceous species, plant on raised beds. Provide proper sanitation and cultural care to reduce plant susceptibility to infection and damage. Avoid overwatering and provide good drainage. Avoid applying excessive fertilizer. Chronic branch dieback may develop in surviving trees; prune out any dead wood. Regularly inspect for possible hazards; affected trees may need to be removed. Soil solarization before planting may be effective.
Palm with yellow fronds from Fusarium oxysporum infection
Brown vascular discoloration of Fusarium wilt