Sunn Hemp Cover Cropping and Solarization as Alternatives to Soil Fumigants for Pineapple Production

A field trial was conducted to compare the impacts of preplant treatments of 1) sunn hemp (SH) planted for 4 months, 2) solarization (Sol) for 2 months, 3) SH planted for 4 months followed by 2 months of Sol (SH+ Sol), or 4) fallow with weeds (C) on plant-parasitic nematodes, weeds and soil health conditions. Soil samples were also collected from a nearby commercial pineapple field planted at the same time but receiving plantation practices (PP) that included deep sub-soiling, 1 year bare fallow, followed by Telone (1,3-dichloropene) and several pre-emergence herbicide treatments (Ametryn, Bromacil, Diuron and Hexazinone) prior to planting. Pineapple slips were planted subsequently. At 3 months after pineapple planting, SH reduced numbers of reniform nematodes, but SH+Sol did not improve the reniform nematode suppressive effect as compared to SH. However, SH+Sol suppressed weeds more efficiently than SH or Sol alone. Nematode community analysis was used to evaluate soil health. Based on structure index, plantation practices severely disturbed nematode communities, but solarization disturbed soil health for less than 3 months. On the other hand, SH enriched soil nutrients as indicated by nematode enrichment index, enhanced populations of bacterial and fungal feeding nematodes at pre-plant as compared to C, and supported higher numbers of soil mesoarthropods than PP even up to 8 months after pineapple planting.