RELATIONSHIPS BETWEEN SOIL FACTORS AND MAGNESIUM DEFICIENCY IN APPLE

Foliar sprays are commonly applied to English orchards to counteract the effects of magnesium deficiency: a more permanent solution of the problem would lie in increasing the magnesium content of soils, so that the trees take up more magnesium via their roots.
However, while soil treatments can be effective on very sandy soils they tend to be uncertain in their effects on most other soils.
The study of this problem is bedevilled by variation in symptom expression over comparatively short distances on apparently uniform land, where exchangeable magnesium varies little, either horizontally or vertically.
This may cause untreated trees to show less symptoms than treated trees a few metres away.

Soils from three experiments showing such variation were examined in an attempt to discover the factors affecting deficiency symptoms.
Soil magnesium treatments had been applied in two of the experiments, but not in the third, and attention was concentrated on potassium and phosphate, which have been shown in pot experiments to affect leaf magnesium (Allen, unpublished work).

Some of the treatments and the soils have previously been described (Allen, 1971).

Symposium on Mineral Nutrition and Fruit Quality of Temperate Zone Fruit Trees

M. ALLEN

https://doi.org/10.17660/ActaHortic.1980.92.36