Population Fluctuations of Rotylenchulus reniformis in Pineapple Fields and the Effect of the Nematode on Fruit Yield. B. S. SIPES, Assistant Professor, Department of Plant Pathology, University of Hawaii at Manoa, Honolulu 96822. D. P. SCHMITT, Professor, Department of Plant Pathology, University of Hawaii at Manoa, Honolulu 96822. Plant Dis. 78:895-898. Accepted for publication 13 June 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0895.

Population fluctuations of Rotylenchulus reniformis were studied in three pineapple fields on the island of Oahu, Hawaii, in nematicide-treated and untreated plots. Soil population densities of the nematode remained low (<200/250 cm3 of soil) for 6-9 mo after planting in all fields regardless of treatment. Nematode populations reached the carrying capacity in each pineapple field within 12 mo after planting. Numbers of R. reniformis decreased after flower induction but quickly resurged. Nematodes negatively affected yield. A single preplant application of 1,3-dichloropropene (337 L/ha) increased fruit yield in the first harvest over the untreated controls in all three fields. Postplant application of fenamiphos (I.I kg a.i./ha) resulted in highest yields by the second harvest (8% more in one field and 25% more in another field). Nematode control remains imperative for economical pineapple production in Hawaii, yet the long lag phase in nematode population development that follows a new planting of pineapple perhaps could be exploited to enhance long-term control.

Keyword(s): Ananas comosus, reniform nematode