EFFECT OF A SYSTEMIC ACQUIRED RESISTANCE INDUCER ON NEMATODES INFECTING PINEAPPLE

The effect of acibenzolar-s-methyl, a systemic acquired resistance inducer, on the reniform nematode, Rotylenchulus reniformis, and the root-knot nematode, Meloidogyne javanica, in pineapple was determined in the greenhouse. Foliar application of acibenzlar-s-methyl at 100 and 200mg/L water at pineapple planting, 1 month and 3 months after planting, reduced nematode egg production by 40%, as measured after 12 months compared to an untreated control. Pineapple treated with 100 mg acibenzolar-s-methyl/L water grew normally. Average shoot and dry root weights of treated pineapple were 549g and 29g in comparison to 579g and 32g in untreated plants. However, acibenzolar-s-methyl at 200mg/L water was phytotoxic resulting in stunting and lower pineapple shoot and root weights. To confirm the phytotoxicity of acibenzolar-s-methyl, another experiment was established using acibenzolar-s-methyl at concentrations ranging from 0, 50, 100, 200, and 400mg/L water. The results were similar to the first experiment in which acibenzolar-s-methyl at 200 and 400mg/L was phytotoxic. Foliar application of acibenzolar-s-methyl at 100mg/L water may activate intrinsic resistance of pineapple to R. reniformis and M. javanica as shown in a study with cowpea. The mechanisms of the induced resistance in pineapple are subject to further investigation but may be similar to the results obtained in cowpea which showed that acibenzolar-s-methyl did not pose direct toxicity on the nematodes or inhibit nematode root penetration but delayed nematode development and reduced fecundity.