By Nathan Boyd
Weed management can be a significant issue for many farms that grow peppers using a plasticulture production system. Nutsedge species can penetrate plastic mulches, and broadleaf weeds and grasses can emerge in the planting holes or in the rows between the raised, mulch-covered beds.
Fumigants are an important component of weed management. However, except for metam products, fumigants tend to be weak on broadleaf and grass weeds. There are very few registered herbicides for peppers that are effective on nutsedge. As a result, fumigation with combinations of chloropicrin and 1,3-dichloropropene or chloropicrin, 1,3-dichloropropene and metam combined with totally impermeable film mulches are recommended for nutsedge control.
ON THE BEDS
The use of pre-emergent herbicides is recommended for broadleaf and grass control on the beds. Dual Magnum (S-metolachlor), Reflex (fomesafen), Devrinol (napropamide) and Goal 2XL (oxyfluorfen) can all be applied on the bed top immediately prior to laying the plastic mulch. Keep in mind that Dual Magnum is a third-party registration, so a signed authorization and waiver of liability is required.
Dual Magnum and Reflex may suppress nutsedge species, especially yellow nutsedge, but neither product will provide adequate control on its own. If grasses are an issue, Dual Magnum is recommended over Goal as Goal tends to be less effective on many grass species.
A limited number of herbicides can be applied over the crop to control weeds that have already emerged. Grasses can be controlled with applications of Select (clethodim). League (imazosulfuron) can be safely applied when directed at the base of well-established pepper plants for control of some broadleaf weeds and nutsedge suppression.
IN THE ROW
There are many herbicide options for weed management in the row middles. Weeds that have emerged can be burned down with Aim (carfentrazone), Gramoxone (paraquat) or Reglone (diquat). Pre-emergent herbicide options include products such as Chateau (flumioxazin) or Dual Magnum.
In general, weeds in row middles are best controlled with tank mixes of more than one product. There are other herbicide options not listed in this article. Be sure to follow all label directions when applying herbicides.
Nathan Boyd is an associate professor at the University of Florida Institute of Food and Agricultural Sciences Gulf Coast Research and Education Center in Wimauma.
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