Magnesium, Calcium, and Boron Nutrition of the Strawberry in Relation to Black Root Disease

Abstract

An experiment was conducted in order to study the effects of all possible combinations of three different concentrations of the elements magnesium, calcium, and boron upon strawberry plants of the variety Senator Dunlap growing in sand culture. The effect of these treatments on the contents of the three elements was determined by spectrographic analysis.Increasing the concentration of magnesium in the culture solution tended to increase the accumulation of magnesium and to decrease the accumulation of calcium by the plants. Increasing the concentration of boron in the culture solution tended to increase the accumulation of boron by the plants and to decrease their yield of fruit. All plants growing in a culture solution containing 0.5 p.p.m. of boron developed both a foliar symptom characteristic of boron toxicity, namely, a marginal chlorosis of the leaves, and certain symptoms characteristic of strawberry black root disease, namely, gradually extending necrotic areas upon the crowns and roots. The fact that the foliar chlorosis symptomatic of boron toxicity in strawberry appeared upon plants supplied with a relatively low concentration of boron is confirmation of the low boron requirement of the strawberry. The fact that the typical foliar symptom of boron toxicity was in all cases accompanied by certain symptoms characteristic of black root disease, namely necrosis of crown and roots, seems to suggest that the latter, in this instance, were also symptomatic of boron toxicity.