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M A R C H 2 0 1 6 POTATO GROWER 27 uneven stands. A more aggressive bacte- ria Dickeya dianthicola is found in the US since 1970. It has a wide host range and is generally more aggressive on potatoes than older species. Thats why it was considered necessary to identify common bacterial species associated with black leg and soft rots in potatoes grown in the Northern Plains. They processed 38 samples of tubers stems and water. They isolated Pectolytic bacte- ria isolated from 26 samples. 55 isolates were purified and characterized. They found P. carotovorum subsp. Carotovorum P. carotovorum subsp. Brasiliensis P. wasabiae and other Pectobacterium species and pectolytic bac- teria. Dr. Ishimaru intends to improve detec- tion and identification scheme and to continue monitoring for shifts in soft rot bacteria as well as the introduction of new species. Some recommendations for the man- agement of soft rot and stem rot were Prevention which means planting cer- tified seed crop rotation detection and diagnosis and reduce wounding. One has to control the environment by reducing water films and maintain cool storage temperatures. Sanitation is very important. That means cleaning and disinfection. Dr. Ishimaru included copper sprays in the management strategies. Use of resistant varieties is limited. The take home messages were that soft rots continue to affect crops in the Northern Plains potato growing region that common types of soft rot bacteria belong to the genus Pectobacterium and that Dickeya was not detected in any samples. A survey of soft rot bacteria could help identify introduction or spread of new species. The management of Pectobacterium and Dickeya species is similar. Nitrogen Response of New Potato Varieties Selected for Low Tuber Reducing Sugars Dr. Carl Rosen UMN indicated that reducing acrylamide content in fried potato products is a priority in the pota- to industry. Reducing sugars is usually the limiting factor for acrylamide in potatoes. Dr. Rosen tried to determine the Nitrogen N response of promising new varieties selected for low tuber reducing sugars. He evaluated varieties and N fer- tilizer rate effects on tuber reducing sug- ars over an eight month storage period. Two new varieties Easton and Dakota Russet were compared with Russet Burbank. Dr. Rosen found that the newer varieties tended to be more N efficient than Russet Burbank with lower glucose and lower potential for acrylamide produc- tion. He concluded that the variety selection had more effect than N man- agement for lowering reducing sugars. Dakota Russet and Easton had better tuber bulking than Russet Burbank. Easton was the highest yielding variety. University of Minnesota Potato Breeding Program Dr. Tom Michaels UMN indicated that some of their research objectives were to breed new varieties for chip and fry pro- cessing and red and white fresh market. They also want to develop capacity for producing disease free seed stock. They compared two hydroponic production systems One conventional in deep water with an airstone and one without an airstone. The unexpected discovery was that when no airstone supplied oxy- gen the plants adapted and produced many more roots. Dr. Michaels expect- ed that to mean a higher production at lower cost. Can Enhanced Efficiency Fertilizers reduce nitrogen N loss with prof- itable yield in potatoes Ms. Upasana Ghosh NDSU stated rea- sons to manage Nitrogen in potatoes The high N demand. Leaching in sandy soils. Shallow root system of potatoes. Enhanced efficiency fertilizers can have urease inhibition or nitrification inhi- bition andor controlled- or slow- release of N. Some results of her research were that 200 lba Urea and 250 lba of ESN gave the highest yield in her trial. One of Ms. Ghoshs conclu- sions was that ESN maintained yield as well as effectively mitigated N loss. Simulated Glyphosate Drift in Red Norland Seed Potato Fields Affects Daughter Tubers Ms. Amanda Crook NDSU emphasized the risk of the increased use of glyphosate close to seed potato fields. Ms. Crook used an ELISA test to measure the glyphosate residue in tubers of crops exposed to glyphosate. She determined that drift during early bulking resulted in a higher residue in the tuber than drift during tuber initiation. Previous research had indicated that later drift resulted in less emergence from the seed potatoes planted from that crop. She now confirmed the hypothesis that later glyphosate drift results in less emer- gence because the residue is higher in the tuber than when drift occurs during tuber initiation. Ms. Crook emphasized that the problem is self-eliminating in seed potatoes because daughter tubers from seed out of a contaminated crop do not show any effect after planting.