Manganese deficiency in tomato plants

Manganese is important for allowing plants to harness the energy of the sun (photosynthesis). Soil shortages are rare, but manganese can be unavailable to plant roots in alkaline conditions. Ericaceous (acid-loving) plants are particularly vulnerable when growing in alkaline soils or potting composts.

Tomatoes are very susceptible to manganese deficiency. Interveinal areas develop yellowish gold spots giving the leaf a speckled appearance. All veins, including the very small ones, and a small frame around the veins, remain green. Petioles and the stems can develop similar Symptoms. Few flowers or fruit will develop if the deficiency is severe.

Role of manganese in tomato plants

Manganese is required for chlorophyll formation and oxide-reduction reactions in cells. It is also involved in the synthesis of ascorbic acid (Vitamin C).

Establishment - Ensure good shoot growth
Vegetative Growth - Ensure growth is not limiting

While considered a micronutrient, manganese is essential to the growth and vitality of African Violets. It plays an important role in the function of photosynthesis, thus contributing to those processes which give African Violets their deep, green leaves.

Cause of manganese deficiency

The most common cause of Manganese Deficiency is either a lack of available manganese in the soil or a pH imbalance in the soil which is inhibiting the absorption of manganese and other nutrients. However, it may also be caused by an excess of potassium or phosphorus.

Symptoms

The leaves show a light interveinal chlorosis developed under a limited supply of Mn. The early stages of the chlorosis induced by manganese deficiency are somewhat similar to iron deficiency. They begin with a light chlorosis of the young leaves and netted veins of the mature leaves especially when they are viewed through transmitted light. As the stress increases, the leaves take on a gray metallic sheen and develop dark freckled and necrotic areas along the veins. A purplish luster may also develop on the upper surface of the leaves.

While rarely seen, transient deficiencies can occur during wet seasons or in sandy or peaty soils of a high pH. Manganese is not very mobile in the plant and deficiencies are best prevented by using foliar sprays. Temporary Mn deficiency is known as ‘growth mottle’ and is seen during flushes of rapid plant growth.

Prevention and control

Prevention can be achieved by improving soil structure. Do not over-lime. Apply chelated iron and manganese treatments, such as Sequestrene, to the soil around the plant roots.