Aphelenchoides spp. Foliar nematodes Damage.  Foliar nematodes pose a serious economic threat to ornamental plant production.  They are among the few plant- parasitic nematodes which live in and damage leaves, buds, and other soft above-ground plant parts rather than roots. Biology.   Aphelenchoides spp. are small nematodes (0.5mm - 1.0mm long) that attack aerial plant parts.  They enter and leave the host plants by natural openings, and must have free moisture on the leaf surfaces to move about.  Ecology.  Foliar nematodes spread by contact between plants in the presence of water. Symptoms.  The most distinctive field symptom of foliar nematodes is lesions- off color areas in foliage- that are bounded by the major veins in leaves.    Damage to other crops.  Foliar nematodes have broad host ranges and are capable of infecting hundreds of species of plants. Control.  Sanitation is imperative for control, as chemical control is costly and largely unavailable to home gardeners. Links and References.  Foliar nematodes in ornamental plants.  Rutgers Cooperative Extension.  Foliar nematodes as pests of ornamental plants.  University of Florida.   Foliar nematodes in nursery crops.  Florida Integrated Pest Management.