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Division of Agricultural Sciences and Natural Resources • Oklahoma State University

Warren RobertsExtension Vegetable Specialist

Bob CartwrightExtension Entomologist

Production RequirementsThe potato is a cool season crop and in Oklahoma it

is grown through the spring months and harvested in earlysummer. Fall potato production usually results in poor plantstands and low production, due to high soil temperatures atplanting and during early crop development. Potatoes growbest in ertile, well-drained, sandy loam soils. Planting on

poorly drained soils usually results in a poor plant stand, dueto seed piece decay and poor quality potatoes at harvest.Soils which blow or have poor water holding capacity shouldbe avoided. A good potato yield in Oklahoma is 200 to 250cwt/acre. High temperatures or insucient moisture in the latespring and early summer, while the potato tubers are ormingreduces yield. Under good management and weather condi-tions, yields o 300 cwt/acre are possible.

VarietiesSelect the potato variety best suited to your conditions

and market. Buyers contracting potato production or chippingwill designate the variety to be grown.

Red Skinned

Red LaSoda - Round to oblong, medium early, eyesmedium deep, high yield, resh market.

Viking - Round, medium maturity, relatively shallow eyes,resh market.

White Skinned

Kennebec - Oblong, late, eyes shallow, high specicgravity, good chipper, general purpose use.

Superior - Round, early, eyes moderately deep, reshmarket, and early chip processing.

Russet Skinned

Norgold Russet - Oblong to long, early, shallow eyes,early resh market russet.

Soil pH and FertilizerPotatoes grow well on a wide variety o soils and soil pH

can be as low as 5.0 with satisactory production. Potatoesare less susceptible to scab when soil pH is between 5.0 and5.5. I pH is too low apply dolomitic limestone. Based on OSU

soil test results the ollowing quantities o P2O

5and K

2O are

recommended.

Phosphorus per acre

When test shows 0-19 20-39 40-69 70-99 100 +Add Ibs/A P

2O

5150 100 75 50 0

Potassium per acre

When test shows 0-99 100-199 200-249 250-299 300 +Add Ibs/A K

2O 300 200 100 50 0

Nitrogen

Apply 75 Ibs/A N along with recommended P2O

5and K

2O

by either broadcast preplant incorporated or one hal broadcastand one hal with the planter in bands placed 3 to 4 inchesto each side and 1 to 2 inches below the seed piece. Topdress or irrigate on additional N when tubers begin to orm.Two or three N top dress applications o 30 to 40 Ibs/acreeach may be needed. Too much N can be detrimental anddecrease tuber quality, grade, and yield. Soils having a highamount o nitrate-N rom previous ertilization, green mature

crops, or rom livestock manure will require less N ertilizer.Potassium sulate is preerred to potassium chloride as thepotassium source, since skin color and specic gravity maybe adversely aected by potassium chloride.

Soil PreparationGood water penetration and aeration are musts or

proper growth and tuber ormation. Excessive tillage and landpreparation causes compaction and should be avoided. To beeective the soil should be plowed below any compacted layerwithin the normal root zone and then disk harrowed beoreplanting. Spike-tooth harrowing to break clods and level thesoil may be needed just prior to planting.

Seed and PlantingUse only certied seed tubers. Potato production costs

are too great to risk using noncertied seed. Certied seed ogood quality grown in the northern states normally producesthe largest yields, the highest quality tubers, and the ewestdisease problems. Pieces o large seed tubers are used or

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Oklahoma Cooperative Extension Fact Sheetsare also available on our website at:

http://osufacts.okstate.edu

Potato Production

Oklahoma Cooperative Extension Service 

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planting. Small whole tubers can be used with equal results.Seed pieces should be 11 / 

2to 2 ounces in size. Using smaller

seed pieces usually results in lower yields. Cut seed piecescan be suberized (healed over) beore planting, but plantingresh cut seed is a normal practice since growers usually lackthe time and space to store large quantities o cut seed beoreplanting. Treatment o seed pieces with ungicides may notalways be necessary as OSU researchers have shown thatsuch applications are likely to increase yield only when thecut seed pieces must be stored three or more days prior toplanting. Seed required to plant an acre depends upon seedpiece size and seed spacing. Distance between rows is com-

monly 36 inches.

Spacing o seed pieces within Seed needed per acre when seed36” rows pieces weigh an average o —

11 / 

2OZ 1

3 / 4

OZ 2 oz

(cwt/acre)8 inches 20.4 23.8 27.2

10 inches 16 3 19.0 21.812 inches 13.5 15.8 18.1

Planting should begin in early March in central Oklahomato promote early crop development and avoid extreme summertemperatures. There are several types o planters availablethat place the seed pieces in the soil and apply ertilizer and

systemic insecticides in one operation. Seed depth shouldbe about 4 inches below the top o the planted bed. Soil isridged over the row by throwing soil to the plants during earlycultivation, so that about 6 inches o soil cover the seed piecewhen tuber ormation occurs. Depth or hilling diers betweenvarieties.

CultivationPotatoes develop larger and more extensive root systems

in response to proper cultivation. Loose, riable soil improvestuber set and development o smooth, well-shaped and even-

colored potatoes. Cultivation may be necessary to controlweeds, keep soil hilled-up, and aid water penetration and soilaeration. Cultivate only when needed. Deep cultivation shouldbe avoided since many roots are destroyed. Extra cultivationsare expensive, increase soil compaction, and reduce yield. Bythe time plants reach ull bloom cultivation should cease.

Weed ControlWeeds should be controlled in potato elds, since they

cause many problems besides being hosts or insects anddiseases. An eective weed control program takes into account

the weed problem, cultivation, and herbicides. Fields contain-ing perennial weeds should be avoided. When herbicidesare used, the choice o which one or ones to use should betailored to the specic weed problems and when these weedsgerminate. Methods o application vary rom preplant incor-poration, post-plant and preemergence, to post-emergenceapplications. Various herbicides can be applied by groundrig, airplane, or through the sprinkler irrigation system. Forherbicide recommendations consult the most recent revisiono OSU Extension Fact Sheet HLA-6008, the latest edition othe Extension Agents’ Handbook, or Commercial VegetableInsect, Disease, and Weed Control (E-827).

IrrigationSoil moisture is probably the most important actor deter-

mining potato yield and quality. About 20 inches o water areneeded to produce a potato crop in central Oklahoma. Whenirrigation is practiced to supplement rainall it should be ap-plied in requent light amounts. Secondary growth and growthcracks occur when irrigation or rainall occurs ater moisturestress. The soil should be kept uniormly moist until tubershave reached ull size. For irrigation management decisions:1) the eective rooting depth o potatoes is two eet, 2) thesoil should not be allowed to dry below 65% o eld capac-ity, and 3) moisture levels above eld capacity will seriously

Disease Resistance of Recommended Potato Varietiesa

BacterialFungal Diseases Disease

FusariumSkin Color/ Seed Piece Early Verticillium CommonVariety Decay Blight wilt Scab BlacklegRed Skinned

Red LaSoda MRb MR (oliage) MS MS MSMR (tuber)

Viking _c

S (oliage) __ MR __

White Skinned *d

Kennebec MS (oliage) S S MSMS (tuber)

Superior * S S R __ 

Russet Skinned

Norgold S S (oliage) S R SRusset R (tuber)

a This variety disease resistance inormation was gathered rom several sources across the United States and is meant to serve only as a general guideline; the resistance or susceptibility o aparticular variety to a given pathogen may vary under Oklahoma conditions.b S = susceptible, MS = moderately susceptible, MR = moderately resistant, R = resistant.c _ indicates no inormation available.d indicates resistance to one or more strains o the ungus.

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aect yield and quality. On extremely sandy soils it is nearlyimpossible to prevent the soil rom drying below 65% o eldcapacity due to the low water holding capacity.

InsectsPotatoes should never be planted in elds that have been

in sod or grass the previous year. By avoiding this situation,one greatly decreases the chance o having wireworm andgrubworm problems. I potatoes are planted in soil that wasin sod the year beore, a soil insecticide should be used toprevent damage to the tubers rom these insects.

Once emerged, potatoes are susceptible to cutworms,fea beetles, and leafhoppers. Flea beetles and leafhoppersgenerally are not major problems in Oklahoma. Cutwormsare sporadic problems and can be severe in certain years.Treatment or cutworms is usually perormed at planting or just ater emergence.

Colorado potato beetles are the major insect problems.The adults overwinter in the soil and emerge about the sametime that the potatoes are emerging. They usually appear inmid-April and eed on the young oliage. Eggs are depositedon the lower third o the plant on the underside o the leaves.

The larvae appear in mid-May and can cause extensivedeoliation. Larvae are more easily controlled when they aresmall. They also do the least damage when they are small, socontrols should be timed to kill the majority o the small larvaepresent.

Colorado potato beetles can be controlled with systemicsoil insecticides or with oliar sprays. Crop rotation also aidsin reducing their numbers. Potato elds planted ater non-host crops (peanuts, wheat, sorghum, etc.) have ewer beetleproblems than elds planted to potatoes the previous year(s).Deoliation by Colorado potato beetles aects potato yieldsmost when the tubers are sizing. Early and late deoliation usu-ally does not decrease yields enough to warrant treatments.Late deoliation, ater tuber sizing, can be benecial rom the

standpoint o deoliation. The beetles can actually help in thedeoliation process and assist in killing the vines.Other potato insects include aphids, which transmit viruses

and can also stress the plants by sucking plant juices. Blisterbeetles can cause deoliation when they eed as they moveen masse across the eld; however, they are seldom plentiulenough to warrant treatment.

For specic insect control measures see the latest editiono the Extension Agents’ Handbook (E-832) or CommercialVegetable Insect, Disease, and Weed Control (E-827).

DiseasesA very common ungal disease o the oliage is early blight

(Alternaria ). Fusarium and Verticillium wilts are also causedby ungi. Blackleg, a bacterial disease, is characterized by ablackening o stems and a yellowing and curling o leaves.Tubers o the potato are also subject to attack by a varietyo pathogens. Various Fusarium  species and the blacklegbacterium cause tuber rots. Rhizoctonie solani  orms blacksclerotia on the surace o tubers, which gave rise to the name

black scur or this particular disease. Another ungal diseaseo the tuber surace is common scab (Streptomyces ).

Root-knot nematodes orm irregular bumps on the tu-bers. The potato plant is also susceptible to a variety o virusdiseases such as potato lea roll, rugose mosaic, and purpletop. A three to our year rotation helps avoid certain diseaseproblems. Non-parasitic diseases in Oklahoma potatoes arerepresented by sunscald, sunburn, and tipburn.

Descriptions and control measures or the above diseases

are available in OSU Extension Fact Sheet EPP-7635 IrishPotato Diseases: Prevention and Control. For specic diseasecontrol measures see the latest edition o the Extension Agents’Handbook (E-832) or Commercial Vegetable Insect, Diseaseand Weed Control (E-827).

Harvesting, Handling, and MarketingDigging potatoes begins in late June and continues to the

end o July. For best quality table stock potatoes, the tubersshould be ully matured beore digging. Vines may need to bekilled by vine beaters or chemicals to promote good skin set.However, since potatoes are edible at any time, the questiono when to dig must be decided by the grower. Considerations

include price, demand, market conditions, and expected yields.Early potatoes are sometimes dug beore optimum maturityto take advantage o certain limited market demands andhigh prices. Processors may require that a test or reducingsugars be made to determine i tubers are in the acceptablerange or chipping into light colored chips.

Potato harvesting is almost ully mechanized. The har-vester digs and loads the potatoes on trucks or transport toa shed where tubers are washed, graded, and sized or bulkmarketing or packed in bags or boxes. Due to high temperatureconditions during harvest, speed is very important in handlingthe potato crop rom digging to loading or shipment. Tubersbruise easily during harvest at temperature above 85°F andbelow 50° F. Soil condition, tuber condition, and harvester

operation are important actors that infuence bruising. Besidesbruising, other common market deects are rots, cracks, skin-ning, enlarged lenticels, heat sprouts, greening, and numerousdiseases.

Summer harvested potatoes are not stored or held anylonger than necessary beore marketing. The best temperatureor holding potatoes is 40 to 42° F. Oklahoma potatoes areusually sold on the open market at prevailing prices. Chippingpotatoes are normally sold at contract prices and may begraded or ungraded. B size and creamer potatoes are usuallysold to processors or canning.

Production Handbook Potato Association o America Handbook titled “Commer-

cial Potato Production in North America,” 40 pages. Availableat $2.50/copy rom the America Potato Journal, PICS Building,University o Maine at Orono, Maine 04469.

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The Oklahoma Cooperative Extension Service

Bringing the University to You!

• It provides practical, problem-oriented educationor people o all ages. It is designated to takethe knowledge o the university to those persons

who do not or cannot participate in the ormalclassroom instruction o the university.

• It utilizes research rom university, government,and other sources to help people make their owndecisions.

• More than a million volunteers help multiply theimpact o the Extension proessional sta.

• It dispenses no unds to the public.

• It is not a regulatory agency, but it does inormpeople o regulations and o their options in meet-ing them.

• Local programs are developed and carried out inull recognition o national problems and goals.

• The Extension sta educates people throughpersonal contacts, meetings, demonstrations,and the mass media.

• Extension has the built-in fexibility to adjust itsprograms and subject matter to meet new needs.Activities shit rom year to year as citizen groupsand Extension workers close to the problemsadvise changes.

The Cooperative Extension Service is the largest,most successul inormal educational organizationin the world. It is a nationwide system unded and

guided by a partnership o ederal, state, and localgovernments that delivers inormation to help peoplehelp themselves through the land-grant universitysystem.

Extension carries out programs in the broad catego-ries o agriculture, natural resources and environment;amily and consumer sciences; 4-H and other youth;and community resource development. Extensionsta members live and work among the people theyserve to help stimulate and educate Americans toplan ahead and cope with their problems.

Some characteristics o the Cooperative Extension

system are:

• The ederal, state, and local governmentscooperatively share in its nancial support andprogram direction.

• It is administered by the land-grant university asdesignated by the state legislature through anExtension director.

• Extension programs are nonpolitical, objective,and research-based inormation.

Oklahoma State University, in compliance with Title VI and VII o the Civil Rights Act o 1964, Executive Order 11246 as amended, Title IX o the Education Amendments o 1972, Americanswith Disabilities Act o 1990, and other ederal laws and regulations, does not discriminate on the basis o race, color, national origin, gender, age, religion, disability, or status as a veteran inany o its policies, practices, or procedures. This includes but is not limited to admissions, employment, nancial aid, and educational services.

Issued in urtherance o Cooperative Extension work, acts o May 8 and June 30, 1914, in cooperation with the U.S. Department o Agriculture, Robert E. Whitson, Director o CooperativeExtension Service, Oklahoma State University, Stillwater, Oklahoma. This publication is printed and issued by Oklahoma State University as authorized by the Vice President, Dean, andDirector o the Division o Agricultural Sciences and Natural Resources and has been prepared and distributed at a cost o 20 cents per copy. 0903