In recent years there has been an increase in the amount of sugarbeet fields that have exhibited boron deficiency symptoms. This nutrient has an essential role in promoting cell wall formation, carbohydrate metabolism, and has been associated with sugar translocation. Boron deficiency symptoms in sugarbeets first occur as a white netted chapping of the upper blade surfaces or wilting of crops. Later, if the deficiency becomes severe, transverse (crosswise) cracking of the petioles develops and the new leaves in the growing point may turn black. Correcting or preventing the deficiency can improve yield and sugar content.
There are several factors that affect availability including organic matter, clay content and soil moisture. Alkaline soils have a reduced uptake because of high pH. The soil types that are most frequently deficient in boron are sandy soils, organic soils and fine-textured lake-bed soils. Boron deficiency frequently develops during drought periods when soil moisture is inadequate for maximum growth. Boron is one of the most leachable micronutrients. Sandy soils that are low in organic matter naturally suffer from excessive leaching.
In the last two years, Michigan State University Sugarbeet Advancement program has taken foliar nutrient tests on all the varieties in three different variety trials. The results appear to indicate that some varieties may have marginally low levels of boron compared to other varieties within the same trial. Further testing of these varieties is needed to determine responsiveness of boron applications. As a general recommendation, boron should be applied in the starter fertilizer in a 2-by-2 placement. Boron should never be applied in direct contact with seed because it can be toxic. Band application rates should be less than 0.5 lbs/acre to reduce chance of depressed root growth in the boron rich zone.
Foliar applications can also be effective in supplying boron needs of the sugarbeet plant. However, foliar applications will need to be put on early. Generally, two applications before mid-June would be the preferred foliar application method. Two applications are preferred because boron does not transfer well from old to new growth. There are several boron products available, usually ranging from 10 to 20 percent active. Follow labeled directions for application rates. These products can be antagonistic when applied with glyphosate, but are generally safe when tank-mixed with fungicides.
Supplying boron at planting or by early foliar applications will likely reduce or eliminate deficiencies. If sugarbeet producers have concerns about adequate nutrient sufficiency or confirming symptoms that are seen, a foliar nutrient analysis should be performed.