Rare Micronutrient Deficiencies of Crops
Molybdenum Deficiency of Peanut (Arachis Hypogaea L.)
Description of Symptoms
Symptoms of molybdenum deficiency resemble those of nitrogen deficiency, i.e. overall chlorosis, stunted growth, and low yields (Plate 1 and Plate 2).
Climatic Conditions Likely to Produce Molybdenum Deficiency
The condition is often seen in high-rainfall areas with high temperatures (more than 33oC) and coarse, acidic soils.
Soil Conditions Likely to Produce Molybdenum Deficiency
Molybdenum deficiency is found in peanut growing in sandy soils, and in very acidic soils (pH lower than 5.5). It is also found in soils with a very high iron content, and in peat soils with a very low iron content. It is found in soils to which excessive phosphate fertilizer has been applied, and in soils with high levels of calcium, manganese, iron and copper.
Diagnosis by Soil Analysis
Soil with 0.02 mg/L or less of water soluble molybdenum (Mo) (about 3.5 mg/kg or less of total molybdenum in soils, or 0.4 mg/kg or less of exchangeable Mo in soils) probably cannot supply enough to support normal peanut growth and yield.
Diagnosis by Plant Analysis
In peanut, a level of molybdenum in plant tissue of 0.3-5 mg/kg is considered adequate for normal growth.
How to Correct Molybdenum Deficiency
The problem of molybdenum deficiency can be easily solved by applying this element, usually in the form of ammonium molybdenum or sodium molybdenum salt.
The quantities needed for the crop are very small. As little as 300 to 600 mg/ha of ammonium molybdenum can correct the disorder.
Liming materials (eg. calcium carbonate) should be applied to acidic soils to increase the soil pH to 6.0 to 6.5.
Alternatively, a foliar spray of 0.01-0.05 % ammonium molybdenum solution should be applied repeatedly every 10 days untill the deficiency is corrected. The total quantity is about 1000 L/ha.
Information from Dr. Zueng-Sang Chen, National Taiwan University
Molybdenum Deficiency of Cauliflower (Brassica Oleracea L. Var. Botrytis)
Description of Symptoms
Leaves are concave and sometime chlorotic (Plate 3 and Plate 4. The curd is small and discolored (Plate 5).
Soil Conditions Likely to Produce Molybdenum Deficiency
The condition is usually found in soils with a low pH (less than 5.0). The molybedum content of the plant is shown in Table 1.
How to Correct Molybdenum Deficiency
The soil pH should be maintained at about 5.5 - 6.5. The deficiency can be corrected by a basal application of 1 kg/ha sodium molybdenum.
Information from Dr. Susumu Eguchi, Ferro Enamels (Japan) Ltd.
Copper Deficiency of Tomato (Lycopersicon Esculentum Mill.)
Description of Symptoms
Copper deficiency in tomato produces symptoms of reduced or stunted growth of shoots. (Plate 6). Young leaves are distorted, and there is necrosis of the apical meristem. The upper leaves and stem wilt.
How to Correct Copper Deficiency
The condition can be corrected by applying a foliar spray of 0.1% copper sulfate pentahydrate (CuSO4.5H2O) solution with lime. The pH of the soil, and any nutrient solution used, should be adjusted to 5.5-6.5.
Information from Dr. Byoung-Choon Jang, National Institute of Agricultural Science and Technologyy, Korea
Index of Images
Plate 1 Peanut in Taiwan with Molybdenum Deficiency(Left: Normal Peanut; Right: Acid Soil PH 4.5)
Plate 2 Same Plants As in Plate 1, Showing Root System and Peanut Pods
Plate 3 Molybdenum Deficiency of Cauliflower (Var. Nozakiwase) in Japan, 25 Days after Transplanting. Leaves Are Concave and Chlorotic.
Plate 4 Deficiency Symptoms 45 Days after Transplanting. Leaves Are Concave and Elongated.
Plate 5 Effect of Molybdenum Application. on the Left Is a Normal Cauliflower, Grown in Soil to Which Molybdenum Has Been Applied, and the PH Adjusted to 6.5. on the Right Is a Cauliflower Deficient in Molybdenum, Grown in an Acid Soil with a PH of 4.3, Japan. the Curd Is Very Small and Dark Brown in Color.
Plate 6 Tomato Plants in Korea with Copper Deficiency. They Were Grown in a Plastic Greenhouse by Hydroponic Culture, without Copper Nutrition.
Table 1 Molybdenum Deficiency of Cauliflower
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