Author
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Webster, Theodore |
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Submitted to: Weed Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/3/2005 Publication Date: 11/1/2005 Citation: Webster, T.M. 2005. Patch expansion of purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus) with and without polyethylene mulch. Weed Science. 53:839-845. Interpretive Summary: Yellow nutsedge and purple nutsedge are exotic invasive weeds that have become naturalized within the US and are the most troublesome weeds of vegetable crops in many states in the Southern US. Several studies have identified potential short-term methyl bromide alternatives that include currently registered fumigants, but nutsedge control is variable. Also, many of these fumigant alternatives may only be short-term replacements for methyl bromide due to potential regulatory issues (e.g. questions surrounding environmental concerns, pesticide re-registration process, and worker protection standards). A greater understanding of the ecology of nutsedges in vegetable production systems will be an initial step in devising appropriate management strategies. The use of polyethylene mulch is common in fruiting vegetables and cucurbit production in the southeast US. Suppression of the establishment of many grass and broadleaf weeds is one of the more significant benefits of polyethylene mulch. However, nutsedges are capable of penetrating mulch. Field studies evaluated the influence of polyethylene mulch on growth patterns of single tubers of each species over time. Purple nutsedge growth was nearly doubled in black mulch relative to the non-mulched control. In contrast, yellow nutsedge growth was suppressed by black mulch, relative to the non-mulched control. The differences in response to black mulch will likely lead to purple nutsedge becoming a greater problem, relative to yellow nutsedge, in vegetable systems. Technical Abstract: Purple and yellow nutsedge are the most troublesome weeds of vegetable crops in the southeast US. Elimination of methyl bromide use will require alternative management programs to suppress nutsedge growth and interference in vegetables. Polyethylene mulch, an effective barrier for most weeds, is pierced by nutsedges. Field studies evaluated the influence of polyethylene mulch on growth patterns of single tubers of each species over time. Growth of purple nutsedge was similar among black mulch and non-mulched systems after 8 and 16 weeks after planting (WAP). However, purple nutsedge growth was nearly doubled in black mulch by the conclusion of the growing season relative to the non-mulched control; at 32 WAP there were 1550 shoots in the 16.1 m2 patch in black mulch and 790 shoots in the 8.1 m2 patch in non-mulched control. In contrast, yellow nutsedge growth was suppressed by black mulch. Compared to black mulch at 16 and 24 WAP, the non-mulched control possessed nearly three-times as many shoots and patches that were twice the size. The differences in response to black mulch will likely lead to purple nutsedge becoming a greater problem, relative to yellow nutsedge, in vegetable systems. The rapid expansion of a single purple nutsedge shoot to form a patch that is 22.1 m2 and containing 3440 shoots at 60 WAP illustrate the importance of managing this species. |
