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Weed Management in Pepper1

Nathan S. Boyd, Ramdas Kanissery and Peter J. Dittmar 2

Peppers are present in the field in some area of Florida every month of the year. Over this period, variable climatic conditions influence the diversity of weed species present, as well as the severity with which weeds affect peppers. Growers should plan a weed–control program that integrates chemical, mechanical, and cultural methods to fit their weed problems and production practices.

Total-farm weed management is more complex than row-middle weed control because several different sites and possibly also several herbicide-label restrictions are involved. Often weed species in row middles differ from weeds on the rest of the farm, and this difference between weed species in different locations might dictate different approaches to weed management. Sites other than row middles where weeds are likely include roadways, fallow fields, equipment parking areas, well and pump areas, fencerows and associated perimeter areas, and ditches.

Disking is probably the least expensive weed control procedure for fallow fields. Where weed growth is mostly grasses, clean cultivation is not as important as in fields infested with nightshade and other disease hosts, including insects. In the latter situation, weed growth should be kept to a minimum throughout the year. If cover crops are planted, those crops should be plants that do not serve as hosts for pepper diseases and insects. Some perimeter areas are easily disked, but berms and field ditches are not, so some form of chemical weed control may have to be used on those areas.

Bare ground can lead to other serious problems, such as soil erosion and sandblasting of plants. However, where undesirable plants exist, some control should be practiced, if practical, and replacement of undesirable plant species with less troublesome ones, such as bahiagrass, might be worthwhile.

Certainly fencerows and areas around buildings and pumps should be kept weed free, if for no other reason than safety. Herbicides can be applied in these situations, provided care is exercised to keep the herbicide from drifting onto the pepper crop.

Use of rye as a windbreak is a common practice in the spring; however, in some cases, it can have adverse effects. If undesirable insects, such as thrips, build up on the rye, contact and systemic grass herbicides can be applied to kill the rye, eliminating it as a host, while the remaining stubble continues to serve as a windbreak.

The greatest row-middle weed problems confronting the pepper industry today are nightshade and dodder.

Nightshade has developed varying levels of resistance to some postemergence herbicides in different areas of Florida. Best control with postemergence (directed) contact herbicides is obtained when the nightshade is 4–6 in. tall, rapidly growing, and not stressed. Two applications of herbicide in about 50 gal. per acre, using a good surfactant, is usually necessary. With postdirected contact herbicides, several studies have shown that gallonage above 60 gal. per acre actually dilutes the herbicides and, therefore, reduces efficacy. Good leaf coverage can be obtained with a volume of 50 gal. or less per acre.

A good surfactant can do more to improve the wetting capability of a spray than increasing the water volume. Many adjuvants are available commercially. Some adjuvants contain more active ingredient than others, and herbicide labels may specify a minimum active ingredient rate for the adjuvant in the spray mix. Before selecting an adjuvant, refer to the herbicide label to determine the adjuvant specifications.

Keep in mind, however, that herbicide performance depends on weather, irrigation, soil type, proper selection for weed species to be controlled, and accurate application and timing. Obtain consistent results by reading the herbicide label and other information about proper application and timing of each herbicide. Use only labeled herbicides and use those herbicides in the proper formulation. Use of an herbicide that is not labeled for use on peppers—even if the herbicide may be labeled for row middles in crops that are closely related to peppers, such as tomatoes and eggplant —may damage peppers. When applying an herbicide for the first time in a new area, use only in a small trial area.

Crop destruction at the end of the season is important to prevent the spread of disease, viruses, and insects. Diquat (Reglone Dessicant®) can be sprayed for crop destruction. Use a minimum of 35 gal./A to increase crop coverage and improve complete plant death.

Table 1 contains herbicides that should be applied before planting. Table 2 contains chemical control of weeds after planting. Before applying an herbicide, carefully read and follow the label.

Tables

Table 1. 

Pretransplant chemical weed control in peppers.

Table 2. 

Posttransplant weed control in pepper

Footnotes

1. This document is HS199, one of a series of the Horticultural Sciences Department, UF/IFAS Extension. Original publication date January 1996. Revised August 2003, June 2005, May 2009, December 2012, December 2015, and January 2019. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication.
2. Nathan S. Boyd, associate professor, Gulf Coast Research and Education Center; Ramdas Kanissery, assistant professor, Southwest Florida REC; and Peter J. Dittmar, associate professor, Horticultural Sciences Department; UF/IFAS Extension, Gainesville, FL 32611.

The use of trade names in this publication is solely for the purpose of providing specific information, not a guarantee or warranty of the products named, and does not signify that they are approved to the exclusion of others of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label. Use pesticides safely. Read and follow directions on the manufacturer's label. The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other products of suitable composition.

Publication #HS199

Date: 1/17/2019

    Management

    Contacts

    • Nathan Boyd
    • Peter Dittmar