Impact of Fallow Programs and Fumigants on Nutsedge (Cyperusspp.) Management in Plasticulture Tomato

Abstract

With the loss of methyl bromide (MeBr) and high prices of alternatives, tomato growers are applying lower fumigant rates or adopting a reduced system. Without the broad-spectrum control provided by the complete fumigant system, a fallow weed program might be needed to avoid an increase in pest pressure with consecutive years of application of the reduced-fumigant system. Nutsedges are among the pests of interest due to their fast reproduction by underground structures and ability to spread and quickly infest a field. Field trials were conducted between February and December of 2011 in Balm, FL, to evaluate the impacts of fallow treatments, fumigants, and halosulfuron on nutsedge control. The trial design was a split–split plot with main, sub-, and subsubplots being fallow, fumigant, and herbicide treatment, respectively. Fallow treatments were spaced evenly throughout the fallow season and consisted of sequential combinations of cultivation (C) and/or glyphosate (G) applied at 2.24 kg ae ha−1; including: C, CC, G, GG, CG, GC, GCG, and NO (nontreated control). Fumigant treatments included a reduced-fumigant system of 1,3-dichloropropene plus chloropicrin 40:60 (1,3-D + pic) at 281 kg ha−1, a complete fumigant system of dimethyl disulfide plus chloropicrin 79:21 (DMDS + pic) at 545 kg ha−1, and no fumigant (NoFum). Herbicide treatments were either two POST applications of halosulfuron at 39 g ai ha−1(Hal) or no halosulfuron (NoHal). In general, the fallow weed treatment GCG was the most effective in reducing nutsedge shoot emergence through the plastic mulch. When the reduced-fumigant system 1,3-D + pic was combined with GCG fallow treatment and halosulfuron (GCG:1,3-D + pic:Hal), no differences were found between this combination and the complete fumigant system DMDS + pic with halosulfuron and combined with CC, G, GG, CG, GC or GCG. This study shows the importance of adding a fallow weed program and halosulfuron to either a reduced or complete fumigation system to minimize the reproduction and growth of nutsedges.