Vine Removal and Desiccation
In preparation for harvest, it may be necessary to remove potato vines prior to harvesting the tubers. Vine removal can be done mechanically (flail beaters, rotary choppers) or by the application of chemical vine-killers. Mechanical beaters effectively remove potato tops, but should be adjusted to remove the tops without injuring any tubers near the soil surface. Organic growers prefer this method of top-killing.
When potatoes have excessive amounts of top growth, use a chemical vine-killer first, followed by mechanical removal to shred tops. This combination provides effective vine kill. Potato vines should be chemically killed approximately 21 days prior to harvest. This provides time to insure good skin set. Note, rapid vine desiccation (either chemical or mechanical) can cause stem-end discoloration in tubers.
With chemical vine-killers, use the lower application rates if plants are stressed (see the label). Good spray coverage is important for these chemicals to work effectively and the speed of vine desiccation varies greatly between the different chemicals.
CAUTIONS: When using chemical vine-killers, ALWAYS FOLLOW LABEL INSTRUCTIONS. The information provided below is very general and does not provide full label instructions regarding the application or full use of the materials.
- carfentrazone (Aim): 3.2 to 5.8 oz/A (7 dh; REI 12h) and spray adjuvant (NIS, MSO, or COC) is required (1-2% v/v). Suitable for seed and storage potatoes. Thorough coverage is essential. May be tank mixed or used sequentially with other desiccants (see labels for restrictions).
- diquat (Reglone): 1 to 2 pt/A (7 dh; REI 12h) and always use a spray adjuvant (0.1-0.5% v/v NIS). Suitable for seed and storage potatoes.
- glufosinate-ammonium (Rely): 3 pt/A (9 dh; REI 12h). Do NOT use on seed potatoes.
- paraquat (Firestorm or Parazone 3SL): 0.7 to 1.3 pt/A (9 dh; REI 24h) and always use either NIS (0.125% v/v) or COC (1.0% v/v). NOTE: paraquat is NOT registered as a vine desiccant for storage or seed potatoes. May ONLY be used for Fresh Market Potatoes. Potatoes must be harvested promptly and processed or consumed immediately.
- pyraflufen-ethyl (Vida): 2.75 to 5.5 oz/A (7 dh; REI 12h). Apply when vines are starting to senesce for best results. May be tank-mixed in sequence with other desiccant products.