Sep 6, 2017
Harvest conditions prompt Idaho Potato Commission to warn of blackspot bruise

The Idaho Potato Commission (IPC) is advising growers that an unusually warm harvest season may lead tubers to be especially susceptible to bruising. The IPC is giving producers tips on how tuber condition can affect a crop’s chances of falling victim to blackspot.

The article’s key points include:

  • Very green vines at the end of the season can make it difficult to kill the crop, increasing susceptibility to skinning injury, as well as blackspot bruise if tubers become dehydrated under the warm conditions forecast for the next few weeks.
  • Tubers under dead vines can become over-mature, and are also more susceptible to blackspot bruise.
  • Potatoes can become dehydrated when soil moisture content falls below 50 percent near or after vine kill.
  • Blackspot tends to show up more on the stem end compared to the bud end of the tuber due to differences in cell age and chemical content.

A PDF of the full report by Mike Thornton and Nora Olsen can be found at Tuber_condition_August_2017.

The authors caution that heading into summer maturity varies widely between some fields, with some still immature and quite green and some are showing a good deal of natural senescence due to the unusually warm temperatures, both of which can affect tuber susceptibility to bruising.

Other concerns include changes to tuber hydration when irrigation is stopped before vine kill and crop maturity at the time of vine kill. The optimal percentage of green vines to dead ones varies between varieties.



75 Applewood Dr. Ste. A
P.O. Box 128
Sparta, MI 49345


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