Sweet potato (Ipomoea batatas (L) Lam)
Convolvulaceae

Varieties
Co 3, Co CIP 1, Sree Nandini, Sree Vardhini, Kiran, Sree Bhadra, Sree Rethna, Gouri and Sankar are the popular varieties. Certain local cultivars like SP local, SP 4, SP 13, SP 18 and Musiri Thandel are also suited for cultivation in Tamil Nadu.

CO 3	CO CIP-1	Sweet Potato IGSP-14

Soil
Sweet potato can be grown in loamy soil with a pH range of 5.6 - 6.6.  It requires a warm and moist climate.

Season
June – July and September are highly suitable for planting.

Preparation of field
Plough the field to fine tilth.  The soil depth should be atleast 30 cm.  Form ridges and furrows at 60 cm apart.  Sweet potato can also be grown in beds.

Preparation of cuttings
The cuttings should be 10-15 cm in length with 2-3 nodes and to be collected from matured vines aged 3 months and above. Dip the vine cuttings in a solution by mixing 400 g of Azospyrillum in sufficient quantity of water.

Planting
Plant the terminal vine cuttings (80,000/ha) at 20 cm spacing.

Irrigation
Irrigate is done before planting, again on 3rd day and there after once in a week. Stop irrigation one week before harvest.

Application of fertilizers
Apply 25 t/ha FYM and 20:40:60 kg NPK/ha as basal and 20:40:60 kg NPK/ha after 30 days.  If 20 kg/ha Azospirillum is applied, apply only 2/3rd dose of N.  It is preferable to apply N and P in the form of DAP (Diammonium phosphate).

After cultivation
The field should be kept clean by hand weeding till vines are fully developed. Earthing up can be done on 25th, 50th and 75th day after planting. The vines are lifted and turned on 50th and 75th day after planting but before earthing up to prevent root formation at nodes and to make the originally formed roots larger. Spray Ethrel five times at 250 ppm at fortnightly intervals commencing from 15 days after planting.

Plant protection
Pests
Sweet potato weevil

• Remove previous sweet potato crop residues and alternate host i.e., Ipomoea sp. and destroy them.
• Use pest free planting materials.
  
• Dip the planting material in Fenthion 100 EC or Fenitrothion 50 EC.
  
• Rake up the soil and earth up at 50 days after planting.
• Drench the soil with Fenthion 100 EC at 2 ml/l. Spray any one of the  insecticides, if needed
  
• Harvest the crop immediately after maturity and destroy the crop residues.
  

Sweet potato weevil infestation

Diseases
Soft rot
Soft rot can be controlled by spot drenching with Carbendazim 1 g/lit.

Yield
About 20-25 t/ha of tubers in 110 – 120 days can be obtained.