Symptoms of Carnations with Fusarium Wilt
Fusarium of carnations is caused by the pathogen Fusarium oxysporum. The initial symptoms of carnations with fusarium wilt are a slow wilting of shoots accompanied by leaf discoloration that gradually lighten the color from light green to pale yellow. The wilting and chlorosis is generally more evident on one side of the plant than the other. As the disease progresses, the stems split, displaying a characteristic brown streaking or discoloration in the vascular tissue. Eventually, the root and stems rot and the plant dies. As the disease advances, small spores (microconidia) are produced and carried up through the plant into the vascular system. This, in turn, interferes with water and nutrient absorption. As the plant dies, the fungus bursts through the plant and forms structures called sporodochia, which become airborne and infect soil and plants nearby.
Treating Carnation Fusarium Wilt
The development of fusarium wilt of carnations is fostered by extended periods of high temps. It can be spread through infected wounds by soil, water, wind and contaminated clothing, equipment, and tools. Proper sanitation is the best control method. Sterilize tools and soil, and use clean gloves when handling the plants. Remove any diseased plants immediately. The use of potting soils that contain peat or coir fiber seem to increase the incidence of the disease, so avoid using them. Instead, use a soil that has been amended with compost or manure, which seems to retard the development of carnation fusarium wilt disease. Ideally, select a soilless, sterile potting medium. In the greenhouse, control of fungus gnats helps to prevent the spread of the disease. Also, in the greenhouse, be sure to properly sterilize potting benches. If the disease has been a problem in the past, solarize the ground for 4-6 weeks during the hottest part of the summer. This will be helpful in reducing not only the incidence of fusarium wilt of carnations, but also of other soil borne pathogens and weeds.
