First Report of the Foliar Nematode Aphelenchoides ritzemabosi infecting chrysanthemum in Iran

During a nematode survey on cut flowers in the Pakdasht Region, Tehran Province, Iran, a species of foliar nematode belonging to the genus Aphelenchoides Fischer was detected in leaves of 10- to 11-month-old, greenhouse-grown (26 to 28°C) chrysanthemum (Dendranthema grandiflorum Kitam., cv. Puja) plants. Chrysanthemum leaves appeared discolored and slightly deformed. Diseased plants comprised approximately 40% of all plants in the greenhouse and occurred in scattered clumps along irrigation paths. Spots and blackish brown, irregular, necrotic areas occupied 5 to 50% of the leaf surface. Symptomatic tissue contained females, males, juveniles, and embryonated eggs of the nematode. All life stages of the nematode were detected in the mesophyll of younger and older infected leaves. The nematode population was extracted and quantified from symptomatic samples of 5 g of leaf tissues by modified Baermann funnel extraction and from 250 g of soil with a modification of the sugar centrifugal flotation method (1), counted, and identified. Morphological observations showed four incisures in the lateral field, excretory pore posterior to nerve ring, ovary single with oocytes in multiple rows, post-vulval uterine sac extending more than one-half of the vulva-anus distance, often containing sperm, tail elongate-conoid bearing a terminal peg with 2 to 4 minute processes. Males common (40% of females) posteriorly curved through 180° upon relaxation, tail conoid bearing a terminal peg with 2 to 3 processes. Measurements of 14 females and 11 males (body length = 987 ± 48 μm, a = 49.2 ± 4.4, b = 12.3 ± 1.1, c = 20.6 ± 2.8, V = 71 ± 1.7, T = 49 ± 2.3, stylet length = 12.6 ± 0.6 μm, tail length = 47.9 ± 5.2 μm; position of vulva = 70.8 ± 1.7%; spicules length = 22.8 ± 1.4 μm) conformed to the description of the chrysanthemum foliar nematode Aphelenchoides ritzemabosi (Schwartz) Steiner & Buhrer, (2). Voucher specimens have been deposited in the University of California Davis Collection. An average of 1,064 A. ritzemabosi per gram were found in the leaves of chrysanthemum, while only 48 nematodes were detected in the soil. To our knowledge, this is the first report of A. ritzemabosi infecting chrysanthemum plants in Iran.

Peer reviewed