Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32S E P T E M B E R / O C T O B E R 2 0 1 6 12 POTATO GROWER Last year we conducted a survey to examine the number of blemishes to red and yellow fresh market pota- toes. One of the most common blemishes in North Dakota and Minnesota found was bruising/skin- ning of tubers. Of the tubers sam- pled, 36% from Minnesota and 35% from North Dakota had bruise and/or skinning. Additionally, lenti- cel spot was found on 33% of tubers from irrigated fields in Minnesota and on 14% of tubers from non-irri- gated fields in North Dakota. One of the takeaways from this study was that the improved han- dling of potatoes can improve qual- ity. As you prepare for harvest, it is important to train personnel about bruising and how to prevent it. This would include training operators about minimizing drops when load- ing and unloading trucks. Equipment should be properly maintained, with padded chains on harvesting and handling equipment and replacing worn chains. Properly adjust chain speed and timing for the conditions, allowing uniform flow of potatoes. Check the har- vester for places where bruising may occur and add padding to the spe- cific locations. When harvesting, keep drops to a minimum. Keep chains and machines full of potatoes to mini- mize bouncing, rolling, and single dropping. Sometimes slowing down the tractor speed can reduce bruis- ing of tubers. Dig potatoes when tuber pulp temperature is between 50 and 65 °F. Avoid walking on potatoes when putting on the tarp. When piling potatoes, use a stair- step manner to prevent potatoes from rolling down the face of the pile. In storage maintain proper conditions for wound healing and storage. In a year of excessive rain, there is a greater concern of bacterial rots which cause problems in quality and storability. Water-logged soils can cause lenticels to enlarge as they seek to obtain sufficient oxy- gen. The opening of the lenticel is an opportunity for bacteria to enter. Once bacteria are present in the lenticel they can multiply and cause rotting of the tuber or the bacteria can enter a latent phase. Lenticel spot (Figure 1) is a result of the latent phase which is typically the result of the lenticel closing and a corky layer being formed over the bacteria. Lenticel spot typically starts in the field and is enlarged in the storage and packaging process. Wounds caused by bruising (Figure 2) and mechanical damage at har- vest or during handling provide infection sites for bacteria. Careful handing can reduce wounds, which will reduce the risk of disease. Bacteria thrive in anaerobic condi- tions such as high carbon dioxide and when tubers are surrounded with a water film. When storing potatoes, maintain good ventilation to reduce carbon dioxide and mois- ture films. If washing tubers in a table stock operation, use clean water. After washing tubers, they should be dried quickly (if possible with forced hot air to remove the film of water on tubers) and then packed in well-aerated containers. Andy’s Advice: Careful Handling Of Potatoes Can Reduce Bruising And Bacterial Rot By Andy Robinson, Extension Potato Agronomist, NDSU/UMN