Weed Control in Potato 1
Weeds are a major problem in potato production in Florida. Weeds can reduce yields through direct competition for light, moisture and nutrients. Weeds also harbor insects and diseases that attack potatoes. Early-season competition of weeds is extremely critical; a major emphasis on control should be made during this period. Weeds present at harvest increase mechanical damage to the tubers and reduce harvesting efficiency by slowing the harvesting operation, leaving undug tubers in the ground and/or carrying them over the conveying chain.
Potatoes may be planted over a seven-month period in Florida. During this period, variable climatic conditions influence the diversity of weed species present and their severity. Growers should plan a total weed control program that integrates chemical, mechanical and cultural methods to fit their weed problems and production practices.
Cultivation is an effective way to manage weeds early in the season. Rolling cultivators behind the hilling blades can uproot many annual weeds that may have survived preplant herbicides. Cultivation and hilling, while useful, also disrupts the efficacy of several soil-applied herbicides. For cultivars that require several hilling operations during the season, one of several herbicides may be applied during or directly following the hilling and cultivation. This combination of practices can greatly enhance and extend weed control during the season.
Herbicide performance depends upon weather, irrigation, soil, proper selection for weeds species to be controlled, and accurate herbicide application and timing. Obtain consistent results by reading the herbicide label and other information concerning the proper application and timing of each herbicide. To avoid confusion between commercial formulations, suggested rates listed in Table 1 are stated in pounds of active ingredient per acre (lbs ai/acre). On marl and sandy soils with low organic matter, the lower rates should be applied. All herbicides listed below have been tested in research trials in Florida with successful results.
When applying a herbicide for the first time in a new area, use in a small, trial area first. Before application of a herbicide, carefully read and follow the label.
Tables
Chemical Weed Controls: Potatoes
Herbicide |
Labeled crops |
Time of Application to Crop |
Rates (lbs. AI./Acre) |
|
Mineral Soil |
Muck Soil |
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Carfentrazone (Aim) |
Potato (All) |
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. |
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Clethodim (Select 2 EC) (Arrow) (Select Max) |
Potato |
Postemergence |
0.09 - 0.25 |
0.09 – 0.25 |
Remarks: Postemergence control of actively growing annual grasses. Apply at 6-16 fl oz/acre (Select, Arrow) or 9-16 fl oz/acre (Select max). Higher rates are listed for perennial grasses. Use a crop oil concentrate for Select and Arrow, but a non-ionic surfactant may be used for Select Max. Do not apply within 30 days of harvest. |
||||
DCPA (Dacthal W-75) |
Potato |
Preemergence or early layby |
6.0 - 8.0 |
---- |
Remarks: Controls germinating annuals. Apply to moist soil. Note label precautions against replanting non-registered crops within 8 months. |
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EPTC (Eptam 7E) (Eptam 10G) |
Potato |
Postemergency or early layby; Preplant, Dragoff, Layby |
3.0 3.0 |
---- |
Remarks: Granular formulation may be applied preplant incorporated, at drag-off and incorporated or at layby and incorporated into clean cultivated soil. Emulsifiable formulation should not be applied on winter and early spring potatoes. Apply only after potatoes have emerged and true leaves have formed or at layby. There is a 45-day preharvest interval for application. |
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Flumioxazin (Chateau) |
Potato |
Preemergence |
0.048 |
---- |
Remarks: Chateau may be applied to potatoes at 1.5 oz product after hilling for the preemergence suppression of several broadleaf weeds. A minimum of 2 inches of soil must cover the potato at the time of application. Chateau should be tank-mixed with other labeled herbicides for broad spectrum weed control, especially the grass weeds. |
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S-Metolachlor (Dual 25G) |
Potato |
Preemergence Preplant incorporated Postplant incorporated |
0.95 - 1.9 |
---- |
Remarks: Applications must be made before crop emergence. Preemergence and postplant incorporated should be made after drag-off but before potato or weed emergence. May be tank mixed with Sencore/Lexone as preemergence treatment. When used alone, label states control of many grasses and broadleaf weeds including crabgrass, fall panicum, goosegrass, signalgrass, yellow nutsedge, galensoga, pigweed and Florida pusley. Note: Under prolonged cool, wet conditions, minor foliage injury has been seen. |
||||
S-Metolachlor+ Metribuzin (Boundary) |
Potato |
Preemergence |
1.5 to 2 pints |
---- |
Remarks: Boundary is a premix herbicide of s-metolachlor and metribuzin. The product contains 5.25 lbs of s-metolachlor and 1.25 lbs of metribuzin per gallon. Apply the product after planting but before potato emergence. This includes after drag-off. Do not incorporate. Post emergence applications to 'Atlantic' are precautioned against. |
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Metribuzin (Sencor DF) (Sencor 4) |
Potato |
Preemergence |
0.5 – 1.0 |
---- |
Remarks: Apply to soil surface after drag-off but before crop emergence. Do not incorporate. Use lower rate on sandy soil. |
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Metribuzin (Sencor DF) (Sencor 4) |
Potato |
Postemergence |
0.25 – 0.5 |
---- |
Remarks: Not to be used on early maturing white or red skinned varieties. Apply only if there have been 3 consecutive days of sunny weather. Treat before weeds are 1 inch tall. Do not apply within 60 days of harvest. Split applications of pre plus postemergence may be made. Do not use more than 1 lb. per season. |
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Paraquat (Gramoxone Inteon) (Firestorm) |
Potato |
Preemergence |
0.47 |
0.47 |
Remarks: Controls emerged weed seedlings. Apply after planting, but before potatoes emerge. Use a non-ionic spreader. |
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Pelargonic Acid (Scythe) |
Potato |
Preplant Preemergence Directed-shielded |
3-10% v/v |
3-10% v/v |
Remarks: Product is a contact, nonselective, foliar herbicide. There is no residual activity. May be tank mixed with soil residual herbicides. Consult label for rates and timings of applications. |
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Pendimenthalin (Prowl, Prowl H2O) |
Potato |
Preemergence Preemergence incorporated |
0.75 |
---- |
Remarks: May be applied after planting but before potatoes and weeds emerge or after drag-off. Most effective when incorporated by rainfall or mechanically into top 1 to 2 inches of soil within 7 days after application. Will not control established weeds. May also be applied early postemergence (from emergence to 6-inch stage of growth). Use this application on trial basis only. May be tank mixed with Sencore, Eptam. Label states not for use on peat or muck soils. |
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Rimsulfuron (Matrix) |
Potato |
Preplant Preemergence Directed-Shielded |
0.25-0.38 oz |
0.25-0.38 oz |
Remarks: Apply at a rate of 1 oz to 2 oz of product to clean soil following hilling or drag-off. Product must be activated by irrigation or rainfall within 5 days. Apply postemergence to actively growing small weeds after crop emergence. Add as non-ionic surfactant to postemergence applications. Do not apply within 60 days of harvest. Do not exceed 2.0 oz product per acre/growing season. Preemergence tank mixes of Matrix with Eptam, Prowl, Lorox or Dual are labeled. Postemergence tank mixes of Matrix plus Eptam are labeled. Note and follow rotational crop guidelines. |
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Sethoxydim (Poast) |
Potato |
Postemergence |
0.188 – 0.28 |
0.188 – 0.28 |
Remarks: Controls actively growing grass weeds. A total of 5 pts. product per acre may be applied in one season. Do not apply within 30 days of harvest. Apply in 5 to 20 gals. of water adding 2 pts. of crop oil concentrate per acre. Unsatisfactory results may occur if applied to grasses under stress. Use 0.188 lb ai (1 pt.) to seedling grasses and up to 0.28 lb ai (1.5 pts.) to perennial grasses emerging from rhizomes, etc. Consult label for grass species and growth stage for best control. |
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Footnotes
This document is HS194, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Revised in June of 2005 and April of 2009. Visit the EDIS Web site at http://edis.ifas.ufl.edu.
William M. Stall, professor, Chad M. Hutchinson, associate professor, Horticultural Sciences Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL.
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.
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