Pests and Diseases Viewer

Magnesium Deficiency



P_magndef

Magnesium Deficiency

Usually appear in

Spring to Summer


Back to Pests and Diseases


Caused By:-     Insufficient Magnesium in soil.

Description

The effects of manganese deficiency is not a pest as such, but is a symptom that there is something wrong, usually with soil nutrients. It can occur on trees and shrubs, as well as on many herbaceous plants. It can easily be mistaken for a virus or nitrogen deficiency, but in nitrogen deficiency the younger leaves are mostly affected All plants need magnesium for the production of chlorophyll, it is the central atom in the chlorophyll molecule C 55H 72O 5N 4Mg, hence the the effect of yellowing of the leaves(chlorosis). Usually starting with leaf tissue between the veins. The leaf veins are usually greener, including the smallest ones. These are the last part of the leaves to go yellow. The Cholorosis begins with older leaves and spreads to younger growth. Can be confused with virus, or natural ageing in the case of tomato plants. Severely affected foliage may develop scorching at the leaf center between the veins.
Magnesium deficiency is more often found where soils where there is a high pottasium, as this can cause Mg to become unavailable to the growing plant and or quick draining soils as magnesium can be easily washed out of light soils in wet seasons This is why it is most often seen in tomatoes followed by potatoes, chrysanthemums and fruits like apples, currants and gooseberries. The reason for this is that all these crops like high levels of potassium to produce high yields and potassium can lock up magnesium in the soil.
See also BORON DEFICIENCY, CALCIUM DEFICIENCY, IRON DEFICIENCY, MANGANESE DEFICIENCY, MOLYBDENUM DEFICIENCY, NITROGEN DEFICIENCY, PEAR BORON DEFICIENCY, PHOSPHORUS DEFICIENCY, POTASSIUM DEFICIENCY.


Control

Mg deficiency can be rectified in the short term by applying a foliar feed fortnightly, with epsom salts diluted at a rate of 200g per 10 litres of water (8oz per 2.5 gal) as plants can quickly absorb magnesium through the leaves. In the longer term add dolomitic limestone if soil pH allows, or other Mg containing rocks such as potassium magnesium sulfate. Reduce usage of potash fertilisers as this may be contributing to the problem. Excess magnesium sulphate solution can be watered into the soil. Usually good composted material supplies all the nutrients necessary for plants.


Back to top