7 pp., 11 tablesThis profile of sweet potato production in Texas gives an overview of basic commodity information; discusses insect, disease and weed pests; and covers cultural and chemical control methods

Hall, Kent D.

Holloway, Rodney L.

Smith, Dudley

Texas A&amp;M Repository

This profile on sweet potato production in Texas gives an overview of basiccommodity information; discusses insect, disease and weed pests; and covers cul-tural and chemical control methods.Basic Commodity Information—1996-98 AverageState Rank: ..................................Texas is ranked fifth in total U.S. production.Percent U.S. Production: ..............10 percentAcres Planted: ..............................6,000 Acres Harvested: ..........................5,800Cash Value: ..................................$14,000,000Commodity DestinationNinety (90) percent of the crop goes to the fresh market, 10 percent goes to thecanner.Production RegionsSweet potatoes are grown almost exclusively in the eastern part of Texas, pri-marily in or near Van Zandt County. The Texas Department of Criminal Justicegrows sweet potatoes in an area near Huntsville and the production is limited toinmate consumption. In addition, there are a significant number of truck farmersin the eastern part of the state who grow and sell sweet potatoes predominatelyto friends and from roadside stands.  Cultural PracticesTexas sweet potato seed beds are usually established in early April using certi-fied or on-farm grown seed. One acre of bedded seed will usually produce enoughtransplants, or “slips,” for 100 acres of potatoes. Transplants are moved to thefield mid-May to late June, preferably into deep sandy loam, fine sandy loam orloamy fine sand soils. In many cases, pesticide applications will be made at thistime (planting). Fertilization is at a rate of 40 to 50 pounds of nitrogen, 20 to 45pounds of phosphorus and 85 to170 pounds of potassium per acre. A majority ofTexas sweet potatoes are the Beauregard variety; a few acres of “Jewell” also aregrown. The time from planting to harvest is between 120 to 135 days.TexasCropProfileSWEETPOTATOESE-223-00Prepared by Rodney L. Holloway, Kent D. Hall and Dudley T. Smith1In collaboration with James V. Robinson, George Philley and Marvin Baker21Extension Specialist, Extension Associate and Experiment Station Associate Professor, The TexasA&M University System.2Extension Entomologist, Extension Plant Pathologist and Extension Horticulturist, The Texas A&MUniversity System.Pest InformationInsectsFoliage feedersFrequency of occurrence: Foliage feedinginsects generally are not a problem in Texas sweetpotatoes but are considered occasional pests.Damage caused: Foliage feeding insects dam-age sweet potatoes by destroying plant stems andleaves. They can be very damaging in seed beds.Percent acres affected: Approximately 5 per-cent of sweet potato acreage, or 75 percent of beds,is affected.Pest life cycles: Generally, immature cut-worms, leaf hoppers, corn earworms, hornworms,loopers and armyworms will damage sweet potatofoliage. The other insect growth stages are notharmful.Timing of control: Foliage feeding insects aregenerally not treated in potato fields, but “slip”beds may occasionally need an insecticide applica-tion.Yield losses: Very seldom do foliage feedinginsects cause yield losses in field sweet potatoes.Regional differences: Because sweet potatoesare grown in a relatively small geographical areaof Texas, there are few regional differences.Cultural control practices: Use of resistantplant varieties may be an important tool to evadefoliage feeding insect damage, but there is no cur-rent research being conducted on this issue.Biological control practices: Biological con-trol could play a very important role in the man-agement of  foliage feeding insects in sweet pota-toes. Pests such as loopers can be impacted by nat-urally occurring viral agents and parasites, andpredators are known to prey on foliage feedinginsects.Postharvest control practices: Field sanita-tion and destruction of alternative hosts are impor-tant postharvest control measures.Soil pestsFrequency of occurrence: Sweet potato dam-age from soil insects generally is expected if no soilinsecticide is applied at planting. The soil insectcomplex includes flea beetle larvae, wireworms,the white grubs of June beetles and white fringebeetles.Damage caused: Soil inhabiting insects thatfeed on sweet potato roots and tubers cause qualityand yield losses.Percent acres affected: Approximately 85 per-cent of sweet potato acreage is affected by soilpests. Pest life cycles: Adult flea beetles feed on sweetpotato leaves, but more serious damage is causedby immatures feeding on the potato tuber, whichleaves a “scroll” looking blemish on the surface.Wireworms have a 1-year life cycle; immaturesfeed inside tubers and leave surface holes and sitesfor disease invasion. White grubs damage sweetpotatoes by causing surface damage and tuberscarring. White grubs are the immature stages of2Table 1: Chemical Controls for Foliar Insects.Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.Carbaryl (Sevin®) 2 ground 1 lb. a.i. per acre Apply when 40 percent  of plants are damaged. 1Use in IPMPrograms: The use of carbaryl can cause outbreaks of secondary pests such as spider mites.Resistance Would fit into resistant management scheme because of alternative chemistry but is a target of the Food Quality ProtectionManagement: Act of 1996.Efficacy Issues: Can produce 90+ percent  control of target pests.Endosulfan(Thiodan®) 25 ground 1 lb. a.i. per acre Apply when 40 percent  of foliage is damaged. 1Use in IPMPrograms: Used in conjunction with field scouting. No treatments unless pest is at damage threshold.ResistanceManagement: Offers chemistry alternatives to carbamates and synthetic pyrethroids.Table 2: Alternative Controls for Foliar Insects.Alternative EfficacyMethyl parathion Not as efficacious(PennCap M®)Permethrin Not as efficacious(Ambush®)beetles, most often June beetles. The white fringebeetle larvae cause damage similar to that of Junebeetle white grubs.Timing of control: The most effective controlmeasure is to apply soil insecticides at planting.Yield losses: Losses up to 75 percent  can resultfrom soil insect damage in sweet potatoes. Qualityalso can be significantly impacted.Regional differences: There may be someregional differences in the occurrence of soil pestsin the counties where small truck crop sweet pota-to production occurs. However, in the major Texassweet potato areas, there is little regional varia-tion. The sweet potato weevil is not found in themajor commercial sweet potato areas of Van Zandt,Smith and Wood counties. The weevil does occur inother parts of the state and the Texas Departmentof Agriculture actively monitors for this pest andmaintains a statewide quarantine program.Cultural control practices: Resistant plantvarieties have shown promise in contributing to areduction of soil insect damage. Crop rotation isimportant. Following a fallow season with sweetpotatoes, problems with some soil insects thatthrive on plant residues can result. To controlwhite fringe beetles, avoid planting sweet potatoesin fields known to have white fringe beetle popula-tions. Biological control practices: Some biologicalcontrol may occur with naturally occurring para-sites and predators, but this is undocumented.Postharvest control practices: Field sanita-tion can help reduce future soil insect pest prob-lems.Fungi and BacteriaPostharvest rotsFrequency of occurrence: The frequency ofoccurrence of postharvest rots depends on harvestand storage conditions, including length in storage.Damage caused: The occurrence of fungi andbacteria cause storage rot and decay.Percent acres affected: A total of 30 percent ofsweet potato acreage is infected by the fungi andbacteria that cause postharvest rots.Pest life cycles: Postharvest rots causal organ-isms survive in field soil, seed roots and usuallyinfects plants through wounds. Timing of control: Treat at harvest (curing)and when sweet potatoes are processed for freshmarket.Yield losses: Sweet potatoes can sustain heavydamage from postharvest rots.Regional differences: Generally there are noregional differences in postharvest rot occurrence.Cultural control practices: Careful handlingof sweet potatoes at harvest and during storagecan help prevent postharvest rot problems. Goodsanitation in fields and in storage houses also isvery important.Biological control practices: There are noneavailable.Postharvest control practices: Sanitation anda proper storage environment are important inpostharvest control of storage rots.3Table 3: Chemical Controls for Soil Insects.Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.Chlorpyrifos 85 ground 2 lbs. a.i. per acre Apply one application at planting or occasionally 1(Lorsban®) at mid season.Use in IPMPrograms: Used in fields with a history of soil insect damage. Not used in areas where soil pests are not a problem.ResistanceManagement: Typically not associated with a resistance management problem.Efficacy Issues: Lorsban is more effective than Diazinon.Table 4: Alternative Controls for Soil Insects.Alternative EfficacyDiazinon Not as affective as Lorsban.Endosulfan (Thiodan®) Used on about 1/3 of acreage in Methyl parathion (PennCap M®) some years.Carbaryl (Sevin)4Table 5: Chemical Control for Postharvest Rots.Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.Dicloran (Botran®) 1 ground 1 lb. a.i. Treat as harvested and when processed. 1per 100 gals. waterSeed root diseasesFrequency of occurrence: Seed root diseasesare an annual problem for sweet potato growers.Damage caused: Seed root diseases limit sweetpotato slip production.Percent acres affected: A total of 50 percent ofsweet potato acreage is infected by pathogens thatcause seed root diseases.Pest life cycles: Soil borne pathogens includediseases such as scurf, southern blight and rhizo-pus soft rot. Roots can be contaminated prior tostorage.Timing of control: To control root diseases, itis important to treat seed and slips prior to plant-ing.Yield losses: Uncontrolled soil borne diseasescan severely limit sweet potato slip production andestablishment.Regional differences: Seed root diseases aregenerally a problem in sweet potatoes statewide.Cultural control practices: Seed root diseaseoccurrence can be reduced with crop rotation, cleanslips, proper seed root handling and storage.Biological control practices: There are noneavailable.Postharvest control practices: Postharvestcontrol practices include the proper storage andcuring of roots.NematodesFrequency of occurrence: Most of Texas sweetpotato acreage has a problem with nematodes;usually the pest is the root knot nematode.Damage caused: Root knot nematodes causegalls on roots, blemishes on mature potatoes andoften a general stunting of vines.Percent acres affected: A total of 80 percent ofsweet potato acreage is affected by nematodes.Pest life cycles: The life cycle of most nema-todes is relatively short and is usually completedwithin 3 to 4 weeks. Root knot nematodes lifestages consist of an egg, four larval stages ( J1, J2,J3, and J4) and an adult stage. Table 6: Chemical Controls for Seed Root Diseases.*Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.Thiabendazole 5 seed root 4 lbs. a.i. per Apply at planting or bedding. 1(Mertect®) treatment 100 gals. of waterUse in IPMPrograms: Applied in plant bed for control of rhizopus soft rot, scurf and Plendodomus foot rot.Efficacy Issues: Possibly broader spectrum than some other registered materials.Dicloran (Botran®) 25 seed root Apply at planting. 1treatmentUse in IPMPrograms: Applied in plant bed for control of rhizopus soft rot, scurf and Plendodomus foot rot.Efficacy Issues: About equal to Mertect but not as broad spectrum.Dichloropropene + 10 soil treatment 10.8-17.1 gals. Treat prior to planting. 1chloropicrin per acre (Telone®)Use in IPMPrograms: Telone is applied to control of nematodes and Streptomyces soil pox. Efficacy Issues: Rate of Telone will vary according to soil type.*There are no alternative control measures.5Table 7: Chemical Controls for Nematodes.Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.Dichloropropene + 10 ground 10.8 to 17 gals. Apply 2 weeks prior to transplanting sweet 1chloropicrin formulation per acre potato slips.(Telone C-17®) Use in IPM Treating sweet potatoes in rows prior to planting is less expensive than broadcasting and often more effective. Less chemicalPrograms: is used with the row treatments.ResistanceManagement: Resistance management is not an issue.Efficacy Issues: Telone is highly effective but expensive and hard to apply.Aldicarb (Temik®) 25 ground 10 to 20 lbs. of 15G  Apply Temik to soil prior to transplanting  1formulation per acre. sweet potatoes.Use in IPMPrograms: NoneEfficacy Issues: Not as efficacious as Telone but gives satisfactory control.Ethoprop (Mocap®) 5 ground 2.4 to 3.2 lbs. of 10G  Apply prior to planting. 1formulation per acre.Use in IPMPrograms: Alternative to TemikResistanceManagement: Different chemistry from Telone and TemikEfficacy Issues: Much less efficacious than Temik and Telone.Oxamyl (Vydate®) 1 ground spray 2 to 3 gals.  Apply as soil is being bedded prior to planting. 1 formulation broadcastUse in IPM Vydate may be used where nematode populations are low.Programs:Resistance Vydate offers alternative chemistry to Aldicarb and Ethoprop.Management:Efficacy Issues: Not as efficacious as other compounds. Efficacy rating is a 4 on a scale of 1 to 5 where 1 is most effective.Table 8: Alternative Controls for Nematodes.Alternative EfficacyChloropicrin Efficacious, but could help if soil rot becomes a problem.Ethoprop (Mocap®) Not efficaciousTiming of control: Sweet potato nematicidesare soil applied prior to planting.Yield losses: Sweet potato yield losses fromnematodes can be as high as 75 percent.Regional differences: There are no regionaldifferences in sweet potato nematode problems.Cultural control practices: Good field sanita-tion should be practiced to lessen nematode prob-lems. Rotate the crop with nonhost plants.Biological control practices: There are noresistant sweet potato varieties currently beinggrown.WeedsAnnual grassesFrequency of occurrence: Annual grasses area constant threat to productive sweet potatoes.Damage caused: Annual grasses are a problemin sweet potatoes because of competition forresources such as space, nutrition and moisture.Percent acres affected: A total of 100 percentof sweet potato acreage is affected by annualgrasses.Pest life cycles: Annual grasses complete theirlife cycle in 1 year. Summer annuals germinate inthe spring, produce seeds and die in the fall.Winter annuals germinate in the fall, produceseeds and die in the spring or early summer.Timing of control: Pretransplant and poste-mergence applications of herbicides prevent harm-ful weed population buildup.Yield losses: Sweet potato yield can be seriouslyimpacted by weed competition. Heavy weed infes-tation can also slow or hamper harvest.Regional differences: There are no majorregional differences in weed problems in Texassweet potatoes.Cultural control practices: Cultivation is amajor part of sweet potato weed management.Cultivation practices include preseason fieldpreparation, bed construction and postemergencetillage prior to vine elongation.Biological control practices: Biological con-trol of weeds is probably not an important factor inTexas sweet potato production.Postharvest control practices: Postharvesttillage may help reduce the next season’s weedproblems.Broadleaf weedsFrequency of occurrence: Broadleaf weeds area constant threat to productive sweet potatoes.Damage caused: Broadleaf weeds damagesweet potatoes by competing with the crop forspace, nutrients and moisture.Percent acres affected: A total of 100 percentof sweet potato acreage is affected by broadleafweeds. Pest life cycles: The summer annual, winterannual and perennial plant groups all containbroadleaf plants that are at times consideredweeds.Timing of control: Broadleaf weeds are bestcontrolled when the plants are small or prior togermination.Yield losses: Sweet potato yields can be sub-stantially reduced if the broadleaf weeds are notcontrolled.Regional differences: There are no majorregional differences in broadleaf weed problems inTexas sweet potatoes.Cultural control practices: Tillage is a stan-dard preplant and postemergence weed controlpractice in Texas.Biological control practices: Natural biologi-cal control of weeds may be an important factor inTexas sweet potato production but this is generallyundocumented.Postharvest control practices: Postharvestcontrol of weeds can reduce the next season’s weedpressure.6Table 9: Chemical Controls for Annual Grasses.Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.Glyphosate 5 ground 0.75 lb. a.i. per acre Apply prior to planting. 1(Roundup®)Use in IPMPrograms: The use of preplant Roundup® can help reduce the need for in-season weed control.ResistanceManagement: Use carefully to avoid resistance.Efficacy Issues: Roundup® is not effective against woody plants at low rates.Clomazone 75 ground 0.75 to 1 lb.  Command is applied over the top of  newly 1(Command®) a.i. per acre transplanted sweet potato slips.  Use in IPMPrograms: Command is effective in controlling most annual grasses and small broadleaf weeds.Efficacy Issues: Not effective against nutsedge.Sethoxydim 2 ground 0.2 to 0.3 lb.  Postemergence 1(Poast®) a.i. per acreEfficacy Issues: Poast does not control sedges.Table 10: Alternative Control for Grasses.Alternative Efficacy EPTC EPTC will control nutsedge where Command will not.Rodney L. HollowayExtension Specialist2488 TAMUCollege Station, Texas 77843-2488979-845-3849rholloway@tamu.eduKent D. HallExtension Associate2488 TAMUCollege Station, Texas 77843-2488979-845-3849kd-hall@tamu.eduDudley SmithAssociate Professor, TAES2474 TAMUCollege Station, Texas 77843-2474979-845-4702George PhilleyExtension Plant PathologistP.O. Box 38TAMU Research and Extension Center FM 3053Overton, Texas 75684409-834-7140James V. RobinsonExtension EntomologistP.O. Box 38TAMU Research and Extension Center FM 3053Overton, Texas 75684903-834-6191Marvin BakerExtension HorticulturistP. O. Box 38TAMU Research and Extension Center FM 3053Overton, Texas 75684903-834-6191Table 11: Alternative Control for Broadleaf Weeds.Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.Clomazone 75 ground 0.75 to 1 lb. a.i.  Pretransplant incorporated 1(Command®) per acreEfficacy Issues: Command will not control nutsedge.“Texas Commercial Vegetable Production Guide,”Texas Agricultural Extension Service.E-10, “Vegetable and Herb Disease ControlProducts for Texas,” Texas Plant DiseaseHandbook. Texas Agricultural ExtensionService, http://agpublications.tamu.edu/pubs/eplant/.Texas Agricultural Statistics. USDA/NationalAgricultural Extension Service. 1997. ReferencesThe information given herein is for educational purposes only. Reference to trade names is made with the understanding that no dis-crimination is intended and no endorsement by the Texas Agricultural Extension Service is implied.State Contacts

Texas Crop Profile: Sweet Potatoes

Texas A&M University

This profile on sweet potato production in Texas gives an overview of basic
commodity information; discusses insect, disease and weed pests; and covers cul-
tural and chemical control methods.
Basic Commodity Information—1996-98 Average
State Rank: ..................................Texas is ranked fifth in total U.S. production.
Percent U.S. Production: ..............10 percent
Acres Planted: ..............................6,000 
Acres Harvested: ..........................5,800
Cash Value: ..................................$14,000,000
Commodity Destination
Ninety (90) percent of the crop goes to the fresh market, 10 percent goes to the
canner.
Production Regions
Sweet potatoes are grown almost exclusively in the eastern part of Texas, pri-
marily in or near Van Zandt County. The Texas Department of Criminal Justice
grows sweet potatoes in an area near Huntsville and the production is limited to
inmate consumption. In addition, there are a significant number of truck farmers
in the eastern part of the state who grow and sell sweet potatoes predominately
to friends and from roadside stands.  
Cultural Practices
Texas sweet potato seed beds are usually established in early April using certi-
fied or on-farm grown seed. One acre of bedded seed will usually produce enough
transplants, or “slips,” for 100 acres of potatoes. Transplants are moved to the
field mid-May to late June, preferably into deep sandy loam, fine sandy loam or
loamy fine sand soils. In many cases, pesticide applications will be made at this
time (planting). Fertilization is at a rate of 40 to 50 pounds of nitrogen, 20 to 45
pounds of phosphorus and 85 to170 pounds of potassium per acre. A majority of
Texas sweet potatoes are the Beauregard variety; a few acres of “Jewell” also are
grown. The time from planting to harvest is between 120 to 135 days.
Texas
Crop
Profile
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3-00
Prepared by Rodney L. Holloway, Kent D. Hall and Dudley T. Smith1
In collaboration with James V. Robinson, George Philley and Marvin Baker2
1Extension Specialist, Extension Associate and Experiment Station Associate Professor, The Texas
A&M University System.
2Extension Entomologist, Extension Plant Pathologist and Extension Horticulturist, The Texas A&M
University System.
Pest Information
Insects
Foliage feeders
Frequency of occurrence: Foliage feeding
insects generally are not a problem in Texas sweet
potatoes but are considered occasional pests.
Damage caused: Foliage feeding insects dam-
age sweet potatoes by destroying plant stems and
leaves. They can be very damaging in seed beds.
Percent acres affected: Approximately 5 per-
cent of sweet potato acreage, or 75 percent of beds,
is affected.
Pest life cycles: Generally, immature cut-
worms, leaf hoppers, corn earworms, hornworms,
loopers and armyworms will damage sweet potato
foliage. The other insect growth stages are not
harmful.
Timing of control: Foliage feeding insects are
generally not treated in potato fields, but “slip”
beds may occasionally need an insecticide applica-
tion.
Yield losses: Very seldom do foliage feeding
insects cause yield losses in field sweet potatoes.
Regional differences: Because sweet potatoes
are grown in a relatively small geographical area
of Texas, there are few regional differences.
Cultural control practices: Use of resistant
plant varieties may be an important tool to evade
foliage feeding insect damage, but there is no cur-
rent research being conducted on this issue.
Biological control practices: Biological con-
trol could play a very important role in the man-
agement of  foliage feeding insects in sweet pota-
toes. Pests such as loopers can be impacted by nat-
urally occurring viral agents and parasites, and
predators are known to prey on foliage feeding
insects.
Postharvest control practices: Field sanita-
tion and destruction of alternative hosts are impor-
tant postharvest control measures.
Soil pests
Frequency of occurrence: Sweet potato dam-
age from soil insects generally is expected if no soil
insecticide is applied at planting. The soil insect
complex includes flea beetle larvae, wireworms,
the white grubs of June beetles and white fringe
beetles.
Damage caused: Soil inhabiting insects that
feed on sweet potato roots and tubers cause quality
and yield losses.
Percent acres affected: Approximately 85 per-
cent of sweet potato acreage is affected by soil
pests. 
Pest life cycles: Adult flea beetles feed on sweet
potato leaves, but more serious damage is caused
by immatures feeding on the potato tuber, which
leaves a “scroll” looking blemish on the surface.
Wireworms have a 1-year life cycle; immatures
feed inside tubers and leave surface holes and sites
for disease invasion. White grubs damage sweet
potatoes by causing surface damage and tuber
scarring. White grubs are the immature stages of
2
Table 1: Chemical Controls for Foliar Insects.
Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.
Carbaryl (Sevin®) 2 ground 1 lb. a.i. per acre Apply when 40 percent  of plants are damaged. 1
Use in IPM
Programs: The use of carbaryl can cause outbreaks of secondary pests such as spider mites.
Resistance Would fit into resistant management scheme because of alternative chemistry but is a target of the Food Quality Protection
Management: Act of 1996.
Efficacy Issues: Can produce 90+ percent  control of target pests.
Endosulfan
(Thiodan®) 25 ground 1 lb. a.i. per acre Apply when 40 percent  of foliage is damaged. 1
Use in IPM
Programs: Used in conjunction with field scouting. No treatments unless pest is at damage threshold.
Resistance
Management: Offers chemistry alternatives to carbamates and synthetic pyrethroids.
Table 2: Alternative Controls for Foliar Insects.
Alternative Efficacy
Methyl parathion Not as efficacious
(PennCap M®)
Permethrin Not as efficacious
(Ambush®)
beetles, most often June beetles. The white fringe
beetle larvae cause damage similar to that of June
beetle white grubs.
Timing of control: The most effective control
measure is to apply soil insecticides at planting.
Yield losses: Losses up to 75 percent  can result
from soil insect damage in sweet potatoes. Quality
also can be significantly impacted.
Regional differences: There may be some
regional differences in the occurrence of soil pests
in the counties where small truck crop sweet pota-
to production occurs. However, in the major Texas
sweet potato areas, there is little regional varia-
tion. The sweet potato weevil is not found in the
major commercial sweet potato areas of Van Zandt,
Smith and Wood counties. The weevil does occur in
other parts of the state and the Texas Department
of Agriculture actively monitors for this pest and
maintains a statewide quarantine program.
Cultural control practices: Resistant plant
varieties have shown promise in contributing to a
reduction of soil insect damage. Crop rotation is
important. Following a fallow season with sweet
potatoes, problems with some soil insects that
thrive on plant residues can result. To control
white fringe beetles, avoid planting sweet potatoes
in fields known to have white fringe beetle popula-
tions. 
Biological control practices: Some biological
control may occur with naturally occurring para-
sites and predators, but this is undocumented.
Postharvest control practices: Field sanita-
tion can help reduce future soil insect pest prob-
lems.
Fungi and Bacteria
Postharvest rots
Frequency of occurrence: The frequency of
occurrence of postharvest rots depends on harvest
and storage conditions, including length in storage.
Damage caused: The occurrence of fungi and
bacteria cause storage rot and decay.
Percent acres affected: A total of 30 percent of
sweet potato acreage is infected by the fungi and
bacteria that cause postharvest rots.
Pest life cycles: Postharvest rots causal organ-
isms survive in field soil, seed roots and usually
infects plants through wounds. 
Timing of control: Treat at harvest (curing)
and when sweet potatoes are processed for fresh
market.
Yield losses: Sweet potatoes can sustain heavy
damage from postharvest rots.
Regional differences: Generally there are no
regional differences in postharvest rot occurrence.
Cultural control practices: Careful handling
of sweet potatoes at harvest and during storage
can help prevent postharvest rot problems. Good
sanitation in fields and in storage houses also is
very important.
Biological control practices: There are none
available.
Postharvest control practices: Sanitation and
a proper storage environment are important in
postharvest control of storage rots.
3
Table 3: Chemical Controls for Soil Insects.
Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.
Chlorpyrifos 85 ground 2 lbs. a.i. per acre Apply one application at planting or occasionally 1
(Lorsban®) at mid season.
Use in IPM
Programs: Used in fields with a history of soil insect damage. Not used in areas where soil pests are not a problem.
Resistance
Management: Typically not associated with a resistance management problem.
Efficacy Issues: Lorsban is more effective than Diazinon.
Table 4: Alternative Controls for Soil Insects.
Alternative Efficacy
Diazinon Not as affective as Lorsban.
Endosulfan (Thiodan®) Used on about 1/3 of acreage in 
Methyl parathion (PennCap M®) some years.
Carbaryl (Sevin)
4Table 5: Chemical Control for Postharvest Rots.
Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.
Dicloran (Botran®) 1 ground 1 lb. a.i. Treat as harvested and when processed. 1
per 100 gals. water
Seed root diseases
Frequency of occurrence: Seed root diseases
are an annual problem for sweet potato growers.
Damage caused: Seed root diseases limit sweet
potato slip production.
Percent acres affected: A total of 50 percent of
sweet potato acreage is infected by pathogens that
cause seed root diseases.
Pest life cycles: Soil borne pathogens include
diseases such as scurf, southern blight and rhizo-
pus soft rot. Roots can be contaminated prior to
storage.
Timing of control: To control root diseases, it
is important to treat seed and slips prior to plant-
ing.
Yield losses: Uncontrolled soil borne diseases
can severely limit sweet potato slip production and
establishment.
Regional differences: Seed root diseases are
generally a problem in sweet potatoes statewide.
Cultural control practices: Seed root disease
occurrence can be reduced with crop rotation, clean
slips, proper seed root handling and storage.
Biological control practices: There are none
available.
Postharvest control practices: Postharvest
control practices include the proper storage and
curing of roots.
Nematodes
Frequency of occurrence: Most of Texas sweet
potato acreage has a problem with nematodes;
usually the pest is the root knot nematode.
Damage caused: Root knot nematodes cause
galls on roots, blemishes on mature potatoes and
often a general stunting of vines.
Percent acres affected: A total of 80 percent of
sweet potato acreage is affected by nematodes.
Pest life cycles: The life cycle of most nema-
todes is relatively short and is usually completed
within 3 to 4 weeks. Root knot nematodes life
stages consist of an egg, four larval stages ( J1, J2,
J3, and J4) and an adult stage. 
Table 6: Chemical Controls for Seed Root Diseases.*
Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.
Thiabendazole 5 seed root 4 lbs. a.i. per Apply at planting or bedding. 1
(Mertect®) treatment 100 gals. of water
Use in IPM
Programs: Applied in plant bed for control of rhizopus soft rot, scurf and Plendodomus foot rot.
Efficacy Issues: Possibly broader spectrum than some other registered materials.
Dicloran (Botran®) 25 seed root Apply at planting. 1
treatment
Use in IPM
Programs: Applied in plant bed for control of rhizopus soft rot, scurf and Plendodomus foot rot.
Efficacy Issues: About equal to Mertect but not as broad spectrum.
Dichloropropene + 10 soil treatment 10.8-17.1 gals. Treat prior to planting. 1
chloropicrin per acre 
(Telone®)
Use in IPM
Programs: Telone is applied to control of nematodes and Streptomyces soil pox. 
Efficacy Issues: Rate of Telone will vary according to soil type.
*There are no alternative control measures.
5Table 7: Chemical Controls for Nematodes.
Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.
Dichloropropene + 10 ground 10.8 to 17 gals. Apply 2 weeks prior to transplanting sweet 1
chloropicrin formulation per acre potato slips.
(Telone C-17®) 
Use in IPM Treating sweet potatoes in rows prior to planting is less expensive than broadcasting and often more effective. Less chemical
Programs: is used with the row treatments.
Resistance
Management: Resistance management is not an issue.
Efficacy Issues: Telone is highly effective but expensive and hard to apply.
Aldicarb (Temik®) 25 ground 10 to 20 lbs. of 15G  Apply Temik to soil prior to transplanting  1
formulation per acre. sweet potatoes.
Use in IPM
Programs: None
Efficacy Issues: Not as efficacious as Telone but gives satisfactory control.
Ethoprop (Mocap®) 5 ground 2.4 to 3.2 lbs. of 10G  Apply prior to planting. 1
formulation per acre.
Use in IPM
Programs: Alternative to Temik
Resistance
Management: Different chemistry from Telone and Temik
Efficacy Issues: Much less efficacious than Temik and Telone.
Oxamyl (Vydate®) 1 ground spray 2 to 3 gals.  Apply as soil is being bedded prior to planting. 1 
formulation broadcast
Use in IPM Vydate may be used where nematode populations are low.
Programs:
Resistance Vydate offers alternative chemistry to Aldicarb and Ethoprop.
Management:
Efficacy Issues: Not as efficacious as other compounds. Efficacy rating is a 4 on a scale of 1 to 5 where 1 is most effective.
Table 8: Alternative Controls for Nematodes.
Alternative Efficacy
Chloropicrin Efficacious, but could help if soil rot becomes 
a problem.
Ethoprop (Mocap®) Not efficacious
Timing of control: Sweet potato nematicides
are soil applied prior to planting.
Yield losses: Sweet potato yield losses from
nematodes can be as high as 75 percent.
Regional differences: There are no regional
differences in sweet potato nematode problems.
Cultural control practices: Good field sanita-
tion should be practiced to lessen nematode prob-
lems. Rotate the crop with nonhost plants.
Biological control practices: There are no
resistant sweet potato varieties currently being
grown.
Weeds
Annual grasses
Frequency of occurrence: Annual grasses are
a constant threat to productive sweet potatoes.
Damage caused: Annual grasses are a problem
in sweet potatoes because of competition for
resources such as space, nutrition and moisture.
Percent acres affected: A total of 100 percent
of sweet potato acreage is affected by annual
grasses.
Pest life cycles: Annual grasses complete their
life cycle in 1 year. Summer annuals germinate in
the spring, produce seeds and die in the fall.
Winter annuals germinate in the fall, produce
seeds and die in the spring or early summer.
Timing of control: Pretransplant and poste-
mergence applications of herbicides prevent harm-
ful weed population buildup.
Yield losses: Sweet potato yield can be seriously
impacted by weed competition. Heavy weed infes-
tation can also slow or hamper harvest.
Regional differences: There are no major
regional differences in weed problems in Texas
sweet potatoes.
Cultural control practices: Cultivation is a
major part of sweet potato weed management.
Cultivation practices include preseason field
preparation, bed construction and postemergence
tillage prior to vine elongation.
Biological control practices: Biological con-
trol of weeds is probably not an important factor in
Texas sweet potato production.
Postharvest control practices: Postharvest
tillage may help reduce the next season’s weed
problems.
Broadleaf weeds
Frequency of occurrence: Broadleaf weeds are
a constant threat to productive sweet potatoes.
Damage caused: Broadleaf weeds damage
sweet potatoes by competing with the crop for
space, nutrients and moisture.
Percent acres affected: A total of 100 percent
of sweet potato acreage is affected by broadleaf
weeds. 
Pest life cycles: The summer annual, winter
annual and perennial plant groups all contain
broadleaf plants that are at times considered
weeds.
Timing of control: Broadleaf weeds are best
controlled when the plants are small or prior to
germination.
Yield losses: Sweet potato yields can be sub-
stantially reduced if the broadleaf weeds are not
controlled.
Regional differences: There are no major
regional differences in broadleaf weed problems in
Texas sweet potatoes.
Cultural control practices: Tillage is a stan-
dard preplant and postemergence weed control
practice in Texas.
Biological control practices: Natural biologi-
cal control of weeds may be an important factor in
Texas sweet potato production but this is generally
undocumented.
Postharvest control practices: Postharvest
control of weeds can reduce the next season’s weed
pressure.
6
Table 9: Chemical Controls for Annual Grasses.
Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.
Glyphosate 5 ground 0.75 lb. a.i. per acre Apply prior to planting. 1
(Roundup®)
Use in IPM
Programs: The use of preplant Roundup® can help reduce the need for in-season weed control.
Resistance
Management: Use carefully to avoid resistance.
Efficacy Issues: Roundup® is not effective against woody plants at low rates.
Clomazone 75 ground 0.75 to 1 lb.  Command is applied over the top of  newly 1
(Command®) a.i. per acre transplanted sweet potato slips.  
Use in IPM
Programs: Command is effective in controlling most annual grasses and small broadleaf weeds.
Efficacy Issues: Not effective against nutsedge.
Sethoxydim 2 ground 0.2 to 0.3 lb.  Postemergence 1
(Poast®) a.i. per acre
Efficacy Issues: Poast does not control sedges.
Table 10: Alternative Control for Grasses.
Alternative Efficacy 
EPTC EPTC will control nutsedge where 
Command will not.
Rodney L. Holloway
Extension Specialist
2488 TAMU
College Station, Texas 77843-2488
979-845-3849
rholloway@tamu.edu
Kent D. Hall
Extension Associate
2488 TAMU
College Station, Texas 77843-2488
979-845-3849
kd-hall@tamu.edu
Dudley Smith
Associate Professor, TAES
2474 TAMU
College Station, Texas 77843-2474
979-845-4702
George Philley
Extension Plant Pathologist
P.O. Box 38
TAMU Research and Extension Center FM 3053
Overton, Texas 75684
409-834-7140
James V. Robinson
Extension Entomologist
P.O. Box 38
TAMU Research and Extension Center FM 3053
Overton, Texas 75684
903-834-6191
Marvin Baker
Extension Horticulturist
P. O. Box 38
TAMU Research and Extension Center FM 3053
Overton, Texas 75684
903-834-6191
Table 11: Alternative Control for Broadleaf Weeds.
Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl.
Clomazone 75 ground 0.75 to 1 lb. a.i.  Pretransplant incorporated 1
(Command®) per acre
Efficacy Issues: Command will not control nutsedge.
“Texas Commercial Vegetable Production Guide,”
Texas Agricultural Extension Service.
E-10, “Vegetable and Herb Disease Control
Products for Texas,” Texas Plant Disease
Handbook. Texas Agricultural Extension
Service, http://agpublications.tamu.edu/
pubs/eplant/.
Texas Agricultural Statistics. USDA/National
Agricultural Extension Service. 1997. 
References
The information given herein is for educational purposes only. Reference to trade names is made with the understanding that no dis-
crimination is intended and no endorsement by the Texas Agricultural Extension Service is implied.
State Contacts


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Texas Crop Profile: Sweet Potatoes

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Texas Crop Profile: Sweet Potatoes

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