Weed Management in Watermelon (Citrullus lanatus) and Cantaloupe (Cucumis melo) Transplanted on Polyethylene-Covered Seedbeds1

Abstract

Studies were conducted from 1998 to 2001 in Tifton, GA, on weed management systems in transplanted cantaloupe and watermelon grown on polyethylene-covered seedbeds. Soil fumigants were metham (748 L/ha) and a nonfumigated control. All metham applications were sprayed in a 61-cm band and incorporated with a modified power tiller. Herbicide treatments were ethalfluralin (0.8 kg ai/ha) premergence (PRE), ethalfluralin plus halosulfuron (36 g ai/ha) PRE, ethalfluralin PRE followed by glyphosate (1.1 kg ai/ha) postemergence POST-SHIELDED, ethalfluralin plus halosulfuron PRE followed by glyphosate POST-SHIELDED, and a nontreated control. Premergence herbicides were directed to row middles not covered in polyethylene, without contacting the transplants. Glyphosate was applied to row middles using a hooded sprayer, just before vine running. Overall weed control was not improved with soil fumigation in either cantaloupe or watermelon, and there was no yield response in either crop. There may be minimal benefit in transplanted cantaloupe and watermelon on polyethylene-covered seedbeds from preplant soil fumigation for weed control, in the absence of other pests. Herbicide systems that included halosulfuron PRE or glyphosate applied POST-SHIELDED improved control of yellow nutsedge compared with ethalfluralin alone. Control of Texas panicum, southern crabgrass, Florida pusley, and smooth pigweed was not improved by halosulfuron or glyphosate. Polyethylene-covered seedbeds provide a mechanical barrier to weed infestation for many species. Integration of these weed control practices gives cantaloupe and watermelon growers effective options for weed management, particularly for a troublesome species such as yellow nutsedge.Nomenclature: Ethalfluralin; halosulfuron; metham; crowfootgrass, Dactyloctenium aegyptium (L.) Willd. #3 DTTAE; Florida pusley, Richardia scabra L. # RCHSC; smooth pigweed, Amaranthus hybridus L. # AMACH; southern crabgrass, Digitaria ciliaris (Retz.) Koel. # DIGSP; Texas panicum, Panicum texanum Buckl. # PANTE; yellow nutsedge, Cyperus esculentus L. # CYPES; cantaloupe, Cucumis melo L.; watermelon, Citrullus lanatus (Thunb.) Mansf.Additional index words: Alternatives to methyl bromide, fumigation, halosulfuron, metham, plasticulture.Abbreviations: POST, postemergence; PRE, premergence; PTO, power take off.