Foliar boron was applied at 20% bloom stage of irrigated canola and increased
yield at two of three sites. The treated area showed up in NDVI images at two of
three sites located on sandy soils. With the frequent rainfall in recent years, foliar
boron applied to irrigated canola at 20% bloom especially on sandy soils during
wet years has shown increased yields by 4-5 bu/ac. The response that has
been observed in recent years during high rainfall summers may disappear if canola
relies more on subsoil moisture uptake and irrigation water. Plant tissue levels below 20 ppm boron are indicated as a potential threshold for application of foliar boron at early flowering with the first fungicide application to irrigated canola. Earlier work showed that the soil test was not effective for predicting the potential for a yield response with foliar application.