J U L Y / A U G U S T 2 0 1 7 18 POTATO GROWER Dakota and Minnesota. Trials are locat- ed at Big Lake, Minnesota; Park Rapids, Minnesota; Oakes, North Dakota; Grand Forks, North Dakota; and Inkster, North Dakota. Big Lake, Minnesota We are studing the effects of chloropi- crin fumigation and nitrogen rates on red skinned potatoes. We would like to determine if a lower nitrogen rate can be effectively used for skin set and high yield. We are studying ESN on red pota- toes and different mixtures with urea in irrigated red potato production. Park Rapids, Minnesota We are testing Zidua as a herbicide for weed control and for cultivar sensitivity. Other herbicides we are testing are Eptam and Sonalan tank combination and metribuzin formulations. Oakes, North Dakota We are evaluating various fertilizers and their effects on potato yield and quality. Nelson Geary, a Masters student is studying the effects of planting back Russet Burbank seed with dicamba and glyphosate in the seed piece to deter- mine the effects of these herbicides on potato production and effects of herbi- cides in seed. Grand Forks, North Dakota We are conducting a rotational study with spring wheat, dry bean and canola to determine the effects of crop rotation on potato yield and quality. This work is supported by the NPPGA and Canola growers. Inkster, North Dakota We are testing products on seed and in- furrow for starter fertilizers. We are also looking at the effects of plant growth hormones on stem number, tuber size profile and production. Nutrient Management Re- search on Irrigated Potatoes Dr. Carl Rosen, UMN In 2017, five studies conducted at the Sand Plain Research Farm in Becker, Minnesota and one at Central Lakes College irrigation farm at Staples are outlined. Most are continuation of studies initiated last year. The overall goal of this research is to improve nutri- ent management for potato production on irrigated sandy soils. The objectives and brief descriptions of these studies are as follows: Validation of a Nitrogen and Irrigation Model for Potato Production in Minnesota Rationale: Nitrate leaching during pota- to production continues to be a concern to the public and the industry. This is a major challenge because potatoes require high amounts of available nitro- gen to optimize yield, but because nitrate is so mobile keeping it in the root zone is difficult. Unpredictable rainfall can leach nitrate during the growing season; however, the amount leached is hard to measure. One approach to help manage nitrogen dur- ing the season is to use various models that take into account crop growth, water inputs and outputs and nitrogen inputs and outputs. A number of these models exist such as APEX, DSSAT, and EPIC, but they have not been tested or validated for potatoes grown under Minnesota conditions. This research is part of a larger MDA project in collabo- ration with Dr. David Mulla to develop a useable irrigation and nitrogen model for crop production in Minnesota. The overall objective is to obtain potato yield, nitrogen budgets, and water budg- ets under Minnesota conditions to vali- date selected models. These models can potentially be used to help guide N fer- tilizer and irrigation decisions during the growing season. The study will be conducted at the Sand Plain Research Farm in Becker, Minnesota. Two irriga- tion treatments will be tested. One using the checkbook method and the other using plant and soil sensors to measure plant stress and soil water potential. Six N treatments will be imposed within each irrigation treat- ment: 1) starter N only, 2) 160 lb N/A as soluble N, 3) 160 lb N as ESN, 4) 240 lb N/A as soluble N, 5) 240 lb N/A as ESN, 6) N based on sensor measurements. Data generated from this study on N uptake, N leaching and water move- ment will be used to help validate selected models listed above. Nitrogen Response, Disease Incidence, and Soil Microbial Activity in Potato Cropping Systems as Affected by Fumigation This is a collaborative project being con- ducted by NDSU and UMN at the Sand Plain Research Farm in Becker. Fumigation is routinely used by potato growers to control soil-borne diseases. While the use of fumigation temporarily reduces disease incidence, it also elimi- nates the populations of beneficial soil organisms. Therefore, once fumigation is used, repeated applications are neces- sary every time potatoes are grown in