Integrated Pest Management CROP NUTRIENT DEFICIENCIES & TOXICITIES Plant Protection Programs College of Agriculture, Food and Natural Resources Published by MU Extension, University of Missouri-Columbia $3.00 IPM1016 This publication is part of a series of IPM Manuals prepared by the Plant Protection Programs of the University of Missouri. Topics covered in the series include an introduction to scouting, weed identification and management, plant diseases, and insects of field and horticul- tural crops. These IPM Manuals are available from MU Extension at the following address: Extension Publications 2800 Maguire Blvd. Columbia, MO 65211 1-800-292-0969 CONTENTS Authors Gene Stevens, Department of Agronomy, University of Missouri-Delta Center How nutrient disorders develop . .3 Peter Motavalli, Soil Science Program, Visual symptoms . .4 University of Missouri-Columbia Sulfur-nitrogen . .5 Peter Scharf, Department of Agronomy, Zinc-magnesium-iron-manganese . .5 University of Missouri-Columbia Others . .5 Manjula Nathan, Department of Agronomy, University of Missouri-Columbia Nutrient deficiency in corn . .6 David Dunn, Soil Test Laboratory, Nutrient deficiency and University of Missouri-Delta Center toxicity in soybeans . .7 Nutrient deficiency in rice . .8 Credits Unless otherwise credited in the captions, the Nutrient deficiency in cotton . .9 photographs were provided by the authors. Many of the symptom descriptions were taken from MU Nutrient deficiency in wheat . .10 publication G9132, Signs of Crop Hunger, by Marshall Christy. Nutrient deficiency in alfalfa . .11 Plant tissue testing . .12 Five steps in plant tissue testing . .12 On the World Wide Web Sampling plant tissue . .12 Updates to this publication will be posted on the Submitting samples for testing . .14 World Wide Web at: Interpreting the test report . .14 http://muextension.missouri.edu/xplor/agguides/ pests/ipm1016.htm Diagnosing nitrogen need from plant color .15 Measuring greenness . .15 Radiometry . .16 Aerial imagery . .16 Production Other field quick tests . .17 MU Extension and Agricultural Infomation Dale Langford, editor Table 1. Essential plant nutrients . .3 Dennis Murphy, designer and illustrator Table 2. Environmental conditions associated with crop nutrient deficiency .12 Table 3. Guide for plant sampling of College of selected agronomic crops . .13 Agriculture Food and Table 4. Guide for plant sampling of Natural selected vegetables, fruits and trees . .13 Resources Plant analysis submission form . .18 © 2002 University of Missouri the largest amounts. Micronutrients (iron, copper, manganese, zinc, boron, molybdenum, chlorine and nickel) are required in relatively smaller CROP NUTRIENT amounts in plants. Other mineral elements that are beneficial to some plants but are not consid- ered essential include sodium, cobalt, vanadium, DEFICIENCIES selenium, aluminum and silicon. A deficiency occurs when an essential element is not available in sufficient quantity to AND TOXICITIES meet the needs of the growing plant. Nutrient toxicity occurs when an element is in excess of plant needs and decreases plant growth or qual- ity. Nutrient deficiency or toxicity symptoms oil fertility is one of several factors, often differ among species and varieties of plants. including light, moisture, weeds, insects, Sand diseases, that affect crop yield (Figure 1). An important part of crop farming is being able to identify and prevent plant nutrient HOW NUTRIENT deficiencies and toxicities. This publication provides background information on the nature DISORDERS and development of crop nutrient disorders under DEVELOP the growing conditions commonly encountered in Missouri. It is a guide to identifying crop nutrient problems through observable symptoms on crop he occurrence of nutrient deficien- plants. Information is provided on effects of cies or toxicities is a result of soil, climatic conditions on plant nutrient availability, Tcrop, climatic, and cultural factors. and the results of soil and plant tissue testing. These factors interact to influence the availabil- Plants require 14 mineral elements for ity of nutrients to crop plants over the course of normal growth and reproduction. Each of these a growing season. nutrients has a function in plants and is required Soil properties influence the form, amount, in varying amounts in plant tissue (see Table 1). retention and movement of soil nutrients. The Macronutrients (nitrogen, phosphorus, potassium, effects of soil properties on water availability also calcium, magnesium and sulfur) are required in influence nutrient availability, because water is Table 1. Essential plant nutrients. essential for chemical reactions, biological activ- ity, and the transport and absorption of nutrients Chemical Relative % by roots. Among the critical soil chemical prop- Name symbol in plant* Function in plant Nutrient category erties affecting soil nutrient availability are soil pH Nitrogen N 100 Proteins, amino acids (a measure of the acidity or alkalinity of a soil) and Primary Phosphorus P 6 Nucleic acids, ATP macronutrients soil cation exchange capacity (a measure of the Potassium K 25 Catalyst, ion transport capacity of the soil to retain positively charged Calcium Ca 12.5 Cell wall component nutrient ions). Some important physical proper- Secondary Magnesium Mg 8 Part of chlorophyll macronutrients ties affecting nutrient availability are soil texture Sulfur S 3 Amino acids (the proportion of sand, silt and clay-sized parti- Boron B 0.2 Cell wall component cles in a soil), clay mineralogy (the type of soil Chlorine Cl 0.3 Photosynthesis reactions clay), and soil structure (the physical arrange- Copper Cu 0.01 Component of enzymes ment of soil particles). Iron Fe 0.2 Chlorophyll synthesis The soils of Missouri vary widely in their Micronutrients inherent soil fertility and suitability for crop Manganese Mn 0.1 Activates enzymes production. Information about the specific soil Molybdenum Mo 0.0001 Involved in N fixation resources on your farm can be obtained by Nickel Ni 0.001 Component of enzymes consulting your regional extension specialist or Zinc Zn 0.03 Activates enzymes your county Farm Service Agency office or by *Relative amounts of mineral elements compared to nitrogen in dry shoot tissue. May using the Center for Agricultural Resource and vary depending on plant species. Potential yield VISUAL Insects and diseases SYMPTOMS Weeds Improper crop variety utrient disorders may appear in Poor soil structure many ways in a plant, including Lack of moisture Lack Poor stand Poor Low fertility Low Nstunting or reduced growth, off- colored leaves (often white, yellow or purple); abnormally shaped leaves, stems, and roots; and a breakdown of certain parts of the plant, includ- ing the root system. “Chlorosis” is a type of defi- ciency or toxicity symptom characterized by yellowing that can be generalized over the whole plant, localized over individual leaves or isolated between some leaf veins (interveinal chlorosis). “Necrosis” is a type of deficiency or toxicity symp- tom characterized by death of plant tissue some- times in spots. Yield and quality of grain or fiber Figure 1. Low soil fertility is only one of several factors that can limit crop yields. may suffer when nutrition is inadequate. When inspecting plants for symptoms of Environmental Systems (CARES) Web site nutrient disorders, compare plants displaying (www.cares.missouri.edu).The parent material of symptoms with normal ones and examine new some soils may contain a large amount of certain and older leaves. Nutrient deficiencies generally plant nutrients (e.g., potassium, calcium and appear first in the oldest leaves when nitrogen, magnesium) and, therefore, the possibility of a phosphorus, potassium, and magnesium are limit- plant response to additional fertilizer sources of ing. These nutrients move from one part of the those nutrients may be reduced. In addition, plant to another as needed. certain soils have natural soil physical and chem- Younger leaves and terminal buds show a ical restrictions that can limit potential crop deficiency when sulfur, iron, calcium, zinc copper, productivity. A prior knowledge of your soil boron, manganese or chlorine are limiting. These resources will help you to develop a successful nutrients do not readily move about in the plant. nutrient management program. As a deficiency becomes more severe, visual Primary and secondary macronutrients are symptoms may spread to the whole plant, leaves often limiting factors for crop production in may become more chlorotic or bleached in appear- Missouri depending on soil conditions and prior ance, or stunting, deformity and death of plant management. Most soils in Missouri have suffi- parts may become more extensive. Deficiencies of cient amounts of micronutrients to supply plant certain nutrients, such as sulfur and phosphorus in needs for crop production, but individual crop corn, may also be visible only early in the growing species may have special micronutrient require- season because of immature root development or ments, and soil properties may vary. cold weather, and then become less apparent as the Factors such as soil pH and moisture can plant matures and the weather warms up. affect the solubility of nutrients or interfere with Symptoms of nutrient toxicity vary, depend- the ability of plant roots to absorb nutrients ing on the element and the crop. Essential nutri- (Figure 2). Deficiencies of micronutrients occur ents that can be toxic to plants include manganese, most often