Potato XXII – 17

Potato Vine Desiccants

Gary D. Franc

Vine desiccants are used aid tuber harvest. Vine desiccants kill the foliar portion of the potato plant, enabling more efficient movement of machinery and more efficient harvest in the absence of green vines. Complete vine death prior to harvest also reduces inoculum sources for late blight and early blight, decreasing the risk of tuber loss in storage. Vine desiccation encourages tuber skin-set, which reduces the potential for tuber injury during harvest. Adequate skin-set reduces the potential for disease loss from various tuber decays, including bacterial soft-rot, Fusarium dry rot, and early blight tuber decay. Vine desiccants should be applied at least 2 weeks prior to harvest, in order to promote adequate skin-set. Be aware that some labels only state the minimum time interval between application and harvest.

Product list for potato vine dessication:

Product	Product per Acre	When to apply	Remarks
(grouped by active ingredient)
Diquat Dibromide
Diquat	1-2 pt per acre	7 days before harvest	Do not apply to drought stressed potatoes. An additional application may be made 5 days after the first application (do not exceed a total 4 pt per acre).
Endothall
DES-I-CATE	1 ½-2 gal per acre	10 to 14 days before harvest	Treated potatoes must be harvested mechanically. Culling of harvested potatoes is allowed.
DESICATE II	1 ½-2 qt per acre	10 to 14 days before harvest	Treated potatoes must be harvested mechanically. Culling of harvested potatoes is allowed.
Sodium Chlorate
Defol 750	3.2 qt per acre	10 days before harvest	Do not apply under conditions of extreme heat during the middle of the day. Use 5 to 10 gal per acre of water for air applications and 10 to 20 gal per acre of water for ground applications.
Sodium Chlorate 5	1 to 2 ½ gal per acre	7 to 10 days before harvest	Do not feed treated foliage or graze treated fields. Use a minimum of 5 gal per acre of water for air applications and 20 gal per acre of water for ground applications.
Sulfuric Acid 93%
Sulfuric Acid (undiluted)	1 to 2 ½ gal per acre	7 to 10 days before harvest	Danger—corrosive: Causes irreversible eye damage and burns to skin. Specialized corrosion resistant equipment is needed. Currently, all applications are by commercial applicator. A second application is allowed 5 days after the initial application, if the vines are not dead. Do not harvest within 5 days of the last application.
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.

Categories: Potato, Vine desiccants, Tuber

Date: February 24, 2002