Weed Control in Sweet Potato1
Sweet potatoes are a long season crop. Control of weeds during the production can be difficult. Early season competition of weeds is extremely critical and a major emphasis on control should be made during this period. Growers must plan a total weed control program that integrates mechanical and cultural methods of weed control with the use of herbicides.
At the present time there are only three preemergence (to weeds) residual herbicides for sweet potatoes. Cultivation is also an effective way to manage weeds early in the season. Rolling cultivators either by themselves or behind hilling blades can uproot many annual weeds that have escaped the herbicide or have emerged since the last cultivation. Cultivation and hilling, while useful, will disrupt the efficacy of soil-applied herbicides. Fusilade may be applied at any time until 55 days of harvest and Poast or Select up to 30 days of harvest to control emerged grass weeds. These herbicides do not provide preemergence control.
Herbicide performance depends on weather, irrigations, soil type, proper selection for weed species to be controlled, and accurate application and timing (Table 1).
Before application of a herbicide: Carefully read and follow the label.
Tables
Chemical weed controls: sweet potato, yam.
Herbicide |
Labeled Crops |
Time of Application to Crop |
Rate (lbs. AI./Acre) |
|
Mineral |
Muck |
|||
Carfentrazone (Aim)
|
Sweet Potatoes |
Preplant Directed-hooded Row-middles |
0.031 |
0.031 |
Remarks: Aim may be applied as a preplant burndown treatment and/or as a post-directed hooded application to row middles for the burndown of emerged broadleaf weeds. May be tank mixed with other registered herbicides. May be applied at up to 2 oz (0.031 lb ai). Use a quality spray adjuvant such as crop oil concentrate (coc) or non-ionic surfactant at recommended rates. |
||||
Clethodim (Select) (Arrow) |
Sweet potatoes, yams (other tuberous corm vegetables) |
Postemergence | 0.1-0.25 | 0.1-0.25 |
Remarks: Control of emerged grasses. Always use a crop oil concentrate at 1% v/v in the finished spray volume unless tank mix instructions indicate otherwise. Do not apply within 30 days of harvest. Use 6 oz. to 16 oz. product to control actively growing grasses at recommended heights. For control of annual grasses, use 6 to 16 fl. oz/A, for perennial grasses, use 8 to 16 fl oz/A. |
||||
Clomozone (Command 3 ME) |
Sweet potato | Pretransplant Posttransplant |
0.48-0.56 | ---- |
Remarks: For control of annual grasses and broadleaf weeds, apply broadcast 1.3 pints/acre. Also, may be applied as a single application post transplant to the crop and prior to weed emergence at a maximum rate of 1.5 pints/acre. |
||||
Clomozone (Command 3 ME) |
Tuberous and corm vegetables (arracacha, cassava, tanier, yams) |
0.75-1.24 | ---- | |
Remarks: For control of grasses and broadleaf weeds apply 2 to 3.3 pints/acre broadcast. Try on trial basis only on arracacha, cassava and tanier. |
||||
DCPA (Dacthal) |
Sweet potato |
Posttransplanting or layby | 8-10.5 | ---- |
Remarks: Controls germinating annuals. Apply to moist soil or overhead-irrigate. Apply to weed-free field up to 6 weeks after transplanting. |
||||
Fluazifop (Fusilade) |
Sweet potato, yams |
Postemergence | 0.188 | 0.188 |
Remarks: Controls actively growing grass weeds. A total of 48 oz. product may be applied per season. Do not harvest within 55 days of application. Apply a crop oil concentrate or non-ionic surfactant in the spray mixture. Consult the label for specific rates and growth stage for best control. |
||||
Glyphosate (Roundup, Durango Touchdown, Glyphomax) |
Sweet potato |
Chemical fallow Preplant, preemergence, Pre-transplant |
03 - 1.0 |
---- |
Remarks: Roundup, Glyphomax and Touchdown have several formulations. Check the label of each for specific labeling directions. |
||||
Napropamide (Devrinol 50 DF) |
Sweet potato |
Postransplanting | 1-2 | ---- |
Remarks: Apply to soil surface immediately after transplanting. Will not control emerged weeds. |
||||
Pelarganic Acid (Scythe) |
Root and tuber vegetables, sweet potato, yam |
Preplant Preemergence Post-Directed |
3-10% v/v | 3-10% v/v |
Remarks: Product is a contact, nonselective, foliar herbicide. It has no residual activity. It may be tank mixed with soil residual herbicides. Consult the label for rates and timings. |
||||
Sethoxydim (Poast) |
Sweet potato |
Postemergence |
0.188 | 0.188 |
Remarks: For control of emerged annual and perennial grass weeds. Always add 1 qt oil concentrate per acre. Do not apply to drought-stressed grass weeds. Minimum time from application to harvest - 30 days. |
||||
Footnotes
This document is HS198, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Revised June 2005, October, 2006. Please visit the EDIS Web site at http://edis.ifas.ufl.edu.
William M. Stall, professor, Horticultural Sciences Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.
The use of trade names in this publication is solely for the purpose of providing specific information. It is 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.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal
Opportunity Institution authorized to provide research, educational
information and other services only to individuals and institutions
that function with non-discrimination with respect to race, creed,
color, religion, age, disability, sex, sexual orientation, marital
status, national origin, political opinions or affiliations.
For more information on obtaining other extension publications,
contact your county Cooperative Extension service.
U.S. Department of Agriculture, Cooperative Extension Service,
University of Florida, IFAS, Florida A. & M. University Cooperative
Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy,
Interim Dean.
