Sweet Potato Frank J. Dainello, Extension Horticulturist Department of Horticultural Sciences, Texas A&M University		Click photo to enlarge in new window.
VARIETIES Orange flesh- Beauregard, Jewel, Excel, Hernandez White flesh- Sumor, White Delight Gold flesh- Shore Gold
SOIL PREFERENCE Deep sandy loam, fine sandy loam or loamy fine sand (pH 5.0 - 7.5) underlain by a firm friable heavier soils.
OPTIMUM GROWING CONDITIONS Hot days and warm nights. Extremely heat tolerant, mean summer temperature above 72oF. Frost tolerant if soil temperature above 55oF.
ESTABLISHMENT METHODS: Transplants (slips) Optimum time= Soil temperature at planting depth > 65oF (150 days prior to anticipated 55oF soil temperature in fall). Slip rate /A= 15,680 - 19,600 Slip depth= 4 - 5 "(Cover several nodes) Slip spacing= 8 - 14 " in-row on 38 - 42 " wide raised beds.
FERTILITY/FERTILIZATION Rates presented as actual lbs/Acre N2, P2O5 and K2O (base actual rates on soil test results). Generalized rate lbs/A: 50 - 70 - 70 N- 40 - 80; 1/3 preplant sidebanned and the remainder 3-4 wks postplant as a top or sidedressing (do not apply within 60 - 80 days of anticipated harvest). P- 50 - 120; applied preplant K- 60 - 120; applied preplant. Lime- 0.5 - 1 ton; fall applied if need indicated by soil test. Starter solution- 1 cup of high phosphate solution/slip.
WATER/IRRIGATION 10 - 20 "; critical period; slip establishment, uniform distribution during growing season. Discontinue irrigation 2 - 3 weeks prior to anticipated harvest.
PEST MANAGEMENT MAJOR DISEASES CONTROL Scurf and black rot Mertect (seed roots only), long rotations (2 years) Stem rot and surface rot Botran, resistant varieties Soil pox or soil rot clean seed, Telone C-35 Leaf spots Headline, Quadris Nematodes Mocap, K-Pam, Temik, Telone II, Vydate MAJOR INSECTS CONTROL Sweet potato weevil Weevil free stock, Penncap M (24c), Sevin Wireworm and white grub diazinon, Lorsban, Mocap Sweet potato flea beetle endosulfan, Sevin Mite Vydate *NOTE* Always use clean fields and a minimum 3-yr rotations WEED CONTROL Preplant incorporated Devrinol, Eptam Preemergence Command (24c after transplanting), Dacthal (after transplanting), Devrinol (after transplanting) Postemergence Eptam, Fusilade, Poast, Select
* NOTE--The above is a partial listing of controls intended as examples. Some labels may have been revoked since the publication of this guide, Refer to product labels for specifics and use accordingly. Failure to do so may result in crop injury, death and/or citation for law violation. Humans, animals and the environment may also be adversely affected by misuse.
HARVEST Mechanical, can be hand harvested with potato plow or turn plow. Days after planting= 90 - 150, when a large percentage of U.S. No. 1 are present or foliage yellowing. Containers= crates Grades= U.S. Extra No. 1, U. S. No. 1, U.S. commercial, U.S. No. 2., Canner, Jumbo, Culls = based on root diameter, freedom from defects and uniformity. Packaging/handling= 50 lb crates / 40 lb cartons Anticipated yield/A= 400 - 800, 40 lb crates/boxes.
STORAGE/TRANSIT CONDITIONS 55 - 60oF at 85% RH with good ventilation (3 - 6 months); susceptible to chilling injury below 55oF if stored for prolonged periods. Store roots dry.
COMMENTS/PRODUCTION KEYS: Cure roots soon after harvest to prevent decay from wound injuries and to preserve root quality; cured by holding 7 - 10 days at 80 - 85oF at 85 - 90 % RH (increases root sugars). Exercise extreme care during harvest and handling to prevent bruising of roots (treat roots as if they were eggs). Vine removal facilitates harvest and reduces incidence of root injury; accomplished with shredders or flail choppers. Sweet potato storage roots will continue to grow and size until frost kills vines. Prevent harvested roots from sun exposure (as little as 30 minutes exposure during hot weather can cause sun scalding. Sweetpotato weevil populations can be reduced by plowing fields twice during the winter, use of weevil free stocks for plant production, cut slips above ground (do not pull slips), immediate post harvest crop destruction, and, clean storage areas. Wrap cartons etc. with perforated polyethylene to reduce moisture loss or drying during storage and transit. Excessive soil moisture at harvest can cause root souring. Excessive soil nitrogen can reduced yields and quality. Low pH (5.0 - 5.5) desirable to reduce soil rot. Weed control critical, especailly until plants cover rows.
Sources of Sweet Potato Slips.
Texas Cooperative Extension, Horticulture Crop Guides Series Revised November, 2003 http://aggie-horticulture.tamu.edu/extension/vegetable/cropguides/sweetpotato.html Prepared for Web delivery by Brooke Bludau, Amanda Zan, and Dan Lineberger