Bitter pit in the apple variety Cleopatra in Tasmania in relation to calcium and magnesium

Abstract

When spray treatments were applied to half-trees of Cleopatra apples, it was shown that magnesium nitrate increased the incidence of pit and calcium nitrate decreased it. There was a suggestion that borax decreased the effectiveness of the calcium nitrate treatment. Magnesium or calcium nitrate, with or without borax, did not affect the potassium, magnesium, phosphorus, or nitrogen content of the fruit cortex. Calcium nitrate in 1959 increased the calcium content but magnesium nitrate had no effect. There was no significant difference in the content of potassium, magnesium, or phosphorus between 1958 and 1959, but the calcium content was 3.3 times as high in 1958. Pit incidence was low in 1958 and high in 1959. No significant difference in content of these four elements could be demonstrated between sound and pitted fruits. The results support the view that calcium is the critical element in pit incidence and that magnesium may play an important part.