What is Molybdenum Deficiency in plants?

Although only required in very small amounts, Molybdenum (Mo) deficient plants develop very pronounced symptoms on their leaves. This trace element plays a crucial role in various biochemical processes, including nitrogen (N) metabolism and the conversion of nitrate to ammonia.

Relatively immobile, once taken up by the roots Molybdenum does not readily translocate to other parts of the plant – so symptoms tend to appear in older leaves. Zinnias may show reduced flower production and leaf discoloration, while Poinsettias are very sensitive to trace element imbalances and will exhibit a range of leave symptoms.

What are the symptoms of Molybdenum Deficiency?

Leaf yellowing – a common symptom is interveinal chlorosis, where the area between the leaf veins turns yellow, while the veins remain green and is particularly noticeable in older leaves.
Stunted growth – reduced plant growth, including shorter stems and smaller overall plant size.
Leaf curling – or distorted shape.
Poor flower development – fewer flowers (and fruits) which may be smaller and lower quality.
Necrosis – in severe cases, dead spots may appear on the leaves.
Reduced N uptake – necessary for converting nitrate (NO3-) to ammonia (NH4+), molybdenum deficient plants may struggle to take up/utilise Nitrogen, leading to reduced protein synthesis.

Molybdenum Deficiency in Ribes

How should you manage Molybdenum Deficiency?

Regular growing media testing is essential to monitor nutrient levels, including molybdenum. Leaf analysis can also be used to diagnose deficiencies in Poinsettia.
To avoid a deficiency and optimise plant growth, we recommend including our Micromax® Premium fine granular in growing media mixes giving a long-lasting supply of essential trace elements for up to 16 months.
To rectify a deficiency, we recommend applying our water soluble Micromax WS TE mix – containing all the essential trace elements, in the correct proportions and in chelated form.
Plants exhibiting Molybdenum deficiency need a boost, to restore healthy growth and leaf colour. Peters® Professional Foliar Feed (27+15+12 +TE) addresses the plant’s nutritional needs and contains the unique M77 chelating formula – ensuring nutrient remain readily available for fast and easy uptake so plants quickly recover normal growth. Due to poor movement within the plant, in cases of severe deficiency foliar applications can provide a quick remedy during critical growth stages.

Molybdenum Deficiency in Caryopteris

Did you know?

It’s essential to address molybdenum deficiency promptly to ensure healthy plant growth. ICL’s Angelaweb 3.0 is a great tool to help produce a crop nutrient plan.
Required in very small quantities, it is easy to apply too much Molybdenum in a fertiliser application, causing toxicity. This is particularly true at low growing media pH – as the symptoms can be similar to those of deficiency. Molybdenum toxicity may interfere with the uptake/ utilisation of other essential nutrients, leading to imbalances in the plant.
pH impact: Molybdenum availability in the root zone is influenced by growing media pH. It is less soluble (available to plants) at lower pHs, commonly found in peat based growing media. Peat free growing media inherently have a higher pH – reducing the chance of Molybdenum deficiency. Water quality should also be considered, as hard or soft water can affect the pH of the growing media.