J U L Y / A U G U S T 2 0 1 7 20 POTATO GROWER 0.5B) is a product devised to facilitate even application of B by combining it in fertilizer granules with K, which, being required in high quantities, is easier to distribute evenly. The objectives of this study were to: (1) evaluate Russet Burbank potato response to Aspire relative to K without B (KCl), (2) evaluate the effectiveness of Aspire relative to KCl blended with sup- plementary granular B (Granubor), and (3) compare the effectiveness of a single pre-planting application of K to split pre-planting and emergence applica- tions for both Aspire and KCl (without B). Evaluation of Polyhalite as a Potassium, Magnesium, Calcium and Sulfur Source for Potato Yield and Quality Polyhalite is a sulfate form of potassi- um, calcium and magnesium manufac- tured by Sirius Minerals. The objective of this third year study is to evaluate polyhalite on tuber yield and quality of Russet Burbank potatoes. Treatments will compare muriate of potash (MOP) with and without S, Ca, and Mg or in blends of polyhalite with MOP based on potash recommendations for Russet Burbank potatoes in Minnesota. The study will be conducted at Becker, Minnesota on a low S, K, Mg, and Ca soil. Petioles samples will be collected during the season and analyzed for nitrate-N, P, K, Ca, Mg, and S. Soil sam- ples to the 6-inch depth will be collect- ed before planting and after harvest and analyzed for K, Ca, Mg, and SO4-S. Effect of Late-season Boron Applications on Potato Quality Boron is an important essential element that plays a significant role in the integrity of the plant cell wall, where it binds pectins together, and in calcium absorption and sugar transport. In these roles, boron availability is vital to tuber internal quality and storability, as well as yield. The amount of boron needed by plants is relatively low. Generally, 2 lbs B/A is recommended as a preplant application on low B testing soils. However, B is susceptible to leaching and may be at low levels by tuber bulk- ing. Boron at higher applications rate such as 4 lbs B/A can be toxic and actu- ally has herbicidal effects at these rates. Circumstantial evidence suggests that late season boron can enhance tuber maturity by promoting stem detach- ment and lowering reducing sugars such as glucose. However, replicated trials evaluating late season boron applications have not been conducted in the Upper Midwest. The overall objective of this study is to determine the effect of late season boron applications on tuber quality of Alpine potatoes. The study will be con- ducted at the Sand Plain Research Farm in Becker, Minnesota. The soil is Hubbard loamy sand, which is typical of the soil used for irrigated potato produc- tion in many parts of the state. In 2017, Red Norland potatoes were selected to determine if B would have any effect on red color and Alpine pota- toes were selected to determine if it would assist abscission of stems on the tuber at harvest. Six treatments will be evaluated: a control (no B), 2 lb B/A pre- plant as a broadcast soil application, and four foliar B treatments at various rates a timing depending on cultivar. At harvest, total tuber yield, final tuber set, graded yield, tuber specific gravity, and internal disorders will be recorded at final harvest. For Red Norland, skin color will be evaluated and for Alpine, tubers will be collected and evaluated for the presence or absence of stems as well as sugar analysis. Evaluation of Bed Planted Potatoes for Improved Nitrogen Use Efficiency This project will explore innovative planting configurations to allow potato roots to intercept more water and nutri- ents than typical row crop configura- tions. Rather than high density single rows planted with wide spacing between rows, the potential for using lower density plantings within narrow rows will be investigated. The study will be conducted at the Central Lakes College irrigation farm in Staples, Minnesota. Treatments will include five plant populations planted in seven row beds spaced 1.7 ft between rows and six single rows spaced 3 ft. between rows. Only one N rate will be used in this study. At 55 days after emergence whole plants from each plot will be har- vested and separated in to tubers and vines. Biomass, tuber number, N con- centrations and total N uptake will be determined. Similar measurements will be made at final harvest. Suction tubes will be installed in a subset of treat- ments to determine if there are differ- ences in nitrate leaching.