Foliar Nematodes OF Chrysanthemum

Disease Information

Foliar Nematodes

(Aphelenchoidesritzema-bosi)

Hardy chrysanthemums that develop yellow-brown spots starting on the lower leaves and gradually moving up the stems may be infested with foliar nematodes. Nematodes are slender, unsegmented roundworms that are barely visible to the unaided eye. Foliar nematodes overwinter in the soil, in infested plant material. They swim up the film of water on the plants, created by spring rains, and enter leaves through the stomata. Nematodes can become dormant and survive for over a year in fallen leaves. Yellow-brown spots on the leaves eventually run together and cover the entire leaf, which dies, turns brittle, and falls. Severe infestations can kill entire plants. Foliar nematodes are easily confused with leaf spot ,but fungal leaf spots are most often black, not brown. They additionally infest hosta and ferns.

Management

 Remove infested plant material, along with the surrounding soil. Mulch plants in the spring to discourage nematodes from climbing up from the soil, and avoid spraying water on the leaves when watering. Foliar sprays with insecticidal soap may help reduce nematode populations.

 



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