| Abstract: | The fumigant nematicide, 1,3-dichloropropene (1,3-D VL; ‘Telone’ II) and a soluble liquid formulation, 1,3-D SL were tested in a pineapple field experiment to evaluate the vapor movement of the two formulations in soil gas as well as the movement and persistence of 1,3-D SL in soil profiles. Prior to planting, 1,3-D VL (407 kg ha?1) was hand-injected into the soil in two parallel rows per planting bed to approximate the practice of chisel injection. 1,3-D SL (407 kg ha?1) was applied with 6 mm of water by drip irrigation through a drip tube in the center of the bed. Post-plant applications of 1,3-D SL (113 kg ha?1) were made at three-month intervals during a two-crop cycle. 1,3-D concentrations in soil gas were lower at the plant line in the drip treatment compared with the 1,3-D VL treatment, owing to differences in application method and fumigant placement. 1,3-D in the vapor phase reached peak concentrations 24 h after injection in the 1,3-D VL treatment compared with a peak at 48 h in the drip treatment. Post-plant applications of 1,3-D SL resulted in a three-fold difference in peak 1,3-D soil gas concentrations between replicate applications, the concentration being inversely related to soil moisture at the time of sampling. Drip application of 1,3-D SL resulted in a relatively uniform distribution of 1,3-D across the bed and to a depth of 45 cm. There was no effect of formulation on downward movement of 1,3-D and persistence in soil profiles sampled two weeks and one month after application. Rainfall which occurred 9 days after pre-plant 1,3-D fumigation resulted in leaching of 1,3-D to a depth of 150 cm in soil profiles. Due to the short half-life of 1,3-D, significant penetration of 1,3-D in the soil was observed only when irrigation or rainfall occurred soon after application. |
