Potato Vine Killing or Desiccation

Revised! HS-925, a 3-page fact sheet by Chad M. Hutchinson and William M. Stall, describes mechanical, chemical, and combination methods of killing potato vines to ensure tuber maturity at harvest. Includes a table listing potato vine desiccants and references. Published by the UF Department of Horticultural Sciences, November 2007. HS925/HS181: Potato Vine Killing or Desiccation (ufl.edu)

Influence of Timing of Harvest in Relation to Haulm Killing and Planting Date on Potato Tuber Rot Caused by Phytophthora infestans

Killing potato haulms 2 to 3 weeks prior to harvesting tubers is recommended for the management of potato late blight to eliminate the foliage as a source of tuber blight inoculum. Some potato growers in the Columbia Basin of Washington and Oregon, however, harvest tubers within days of killing potato haulms or harvest tubers without killing potato haulms. The susceptibility of potato tubers harvested from green haulms to late blight is unknown. From 1996 to 1998, Russet Burbank and Ranger Russet seed tuber pieces were planted on three different dates and then harvested simultaneously to obtain daughter tubers at different levels of maturity as determined by physiological degree day (P-day) accumulation. Tubers from two trials in 1996 were harvested within 1 to 4 days of haulm killing, tubers from a single trial in 1997 were harvested 16 days after haulm killing, and tubers from two trials in 1998 were harvested 1 and 21 days after haulm killing. Tubers from each plot were divided into two samples; one sample was inoculated the day after harvest and the other sample was inoculated 6 months after harvest on the buds and periderm tissue with a US-8 isolate of Phytophthora infestans. Severity of tuber blight on tuber surfaces and internal tuber tissue was highly correlated. When tubers were harvested within 1 to 4 days after haulm kill, the youngest tubers had the highest percentage of skinning and the lowest percentage of tuber blight. These tests, however, were not designed to test the hypothesis that increased tuber skinning resulted in increased tuber rot. Severity of tuber blight was greater for Ranger Russet tubers than for Russet Burbank tubers. The correlation between the severity of tuber blight at harvest and after 6 months in storage was significant. In some cases, differences in susceptibility to tuber blight due to planting date were observed after 6 months in storage. When tubers were harvested within 1 to 4 days after vine killing, tubers from plants that had been growing longer were more susceptible to late blight tuber rot than tubers from plants that had been growing for a shorter period of time.

Potato Vine Killing or Desiccation

Proper tuber maturity at harvest is an important factor in producing high quality Florida fresh market potatoes. A mature tuber has improved skin-set, bruise resistance, and storage life. Vine killing not only benefits tuber appearance but can also limit tuber size and improve tuber release from the vine at harvest. Tubers naturally mature as the potato plant senesces. However, improved production methods cause potato vines to remain healthy and green longer into the season. Tuber maturation can be artificially induced by killing the potato vines. The three traditional methods for vine killing are mechanical, chemical, and combinations of the mechanical and chemical methods. This document is HS925, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: June 2003. HS925/HS181: Potato Vine Killing or Desiccation (ufl.edu)