Plant Issues
"Plant diseases are shifty enemies"
- E. C. Stakman
- E. C. Stakman
introduction
There are many variables that can produce issues in plants, from strong winds to not enough air movement, animals, pests and diseases, nutrient deficiencies or abundances, sun exposure, under- or over-watering, and physical damage caused by humans and pets, among others. This page will help to guide you through the many issues that can pop up in your garden, and give you some great ideas about how to eradicate and prevent them using tried and true methods.
Plant Pathology
Plant pathology, also called Phytopathology, is the science of plant diseases, which are series of responses of plant cells and tissues to a pathogen or environmental factors that result in undesirable changes in form, function or health of plant parts (or sometimes the entire plant). These diseases are generally broken up into two distinct groups: infectious and noninfectious. Infectious diseases of plants are caused by pathogens, a group of disease-causing agents including fungi, bacteria, viruses, viroids, phytoplasmas, spiroplasmas, nematodes, parasitic plants, and protozoa. Noninfectious diseases, on the other hand, are caused by environmental factors. This group of disease-causing agents is also known as abiotic plant diseases, and includes factors such as air pollution, drought, nutrient deficiencies, mineral toxicities, freezing temperatures, pesticide toxicities, light issues, and improper cultural practices (the ways in which we care for our plants in their environments).
Infectious diseases of plants
Infectious diseases of plants follow a general path called the disease cycle. In the first step, inoculation, a pathogen comes into contact with a host plant. Individual units of pathogens are called propagules, and are carried to plants via wind currents, irrigation or rain water, or insect or animal activity (including humans). For propagules to stay viable, the environment must be conducive to their survival so that they stay alive long enough to reach the host. The second step, penetration, marks the moment the pathogen enters the host plant, either through a damaged area or opening or by making its own entry point.
Infection occurs next, when the inoculum (the pathogen) establishes contact with the internal tissues of the host plant, and begins the parasitic relationship. During this stage, the pathogen grows and multiplies, invading more and more tissues and feeding on the plant for energy. Some pathogens will also release enzymes or growth regulators that will begin to affect the health and appearance of the host. The time that passes between the infection event and the point at which the plant shows outward symptoms of infection is called the incubation period. Infections can be systemic (throughout the entire plant) or localized (in certain areas). When the population of the invader is increasing quickly within the plant, it is said to colonize the host. The next logical step after the pathogen has colonized its host is for it to disseminate and spread to other plants. In this step of the disease cycle, plants send their progeny out of the plant, and the cycle starts again when they travel via water, wind, or animal action to the next host plant.
Pathogens can cause a wide range of symptoms due to their abilities, which include affecting the permeability of cell membranes in the host plant, attacking roots (interfering with water absorption), and increasing the respiration rate in infected plant cells (drying out plants in the process). They can also interfere with photosynthesis by attacking leaves and sometimes defoliating entire plants. Some pathogens infect the vascular system of the host, plugging it up and interfering with the transport of water and nutrients. Two more effects pathogens can have on plants are altering synthesis of proteins and enzymes and disrupting the metabolism of genetic materials (DNA/RNA) in infected host plants.
Infection occurs next, when the inoculum (the pathogen) establishes contact with the internal tissues of the host plant, and begins the parasitic relationship. During this stage, the pathogen grows and multiplies, invading more and more tissues and feeding on the plant for energy. Some pathogens will also release enzymes or growth regulators that will begin to affect the health and appearance of the host. The time that passes between the infection event and the point at which the plant shows outward symptoms of infection is called the incubation period. Infections can be systemic (throughout the entire plant) or localized (in certain areas). When the population of the invader is increasing quickly within the plant, it is said to colonize the host. The next logical step after the pathogen has colonized its host is for it to disseminate and spread to other plants. In this step of the disease cycle, plants send their progeny out of the plant, and the cycle starts again when they travel via water, wind, or animal action to the next host plant.
Pathogens can cause a wide range of symptoms due to their abilities, which include affecting the permeability of cell membranes in the host plant, attacking roots (interfering with water absorption), and increasing the respiration rate in infected plant cells (drying out plants in the process). They can also interfere with photosynthesis by attacking leaves and sometimes defoliating entire plants. Some pathogens infect the vascular system of the host, plugging it up and interfering with the transport of water and nutrients. Two more effects pathogens can have on plants are altering synthesis of proteins and enzymes and disrupting the metabolism of genetic materials (DNA/RNA) in infected host plants.
Fungi & FUngus-Like Organisms
Of the 100,000 species of fungus that exist, 10,000 can cause plant diseases, and almost all plant species can be affected by types of disease-causing fungi. Fungi are commonly classified according to which plants they infect, indicated by the abbreviations f. sp. (which stands for forma specialis). For example a fungus species, Fusarium oxysporum, that only feeds on celery plants is called Fusarium oxysporum f. sp. apii. Fungi grow and search for food sources within the host using hyphae. or long, branching structures that release the enzymes needed to digest plant tissues. Fungi use hyphae to form networks called mycelium and multiply using spores produced at or near the surface of host tissues. They have haustoria, or specialized structures that pierce and penetrate the host plant's internal tissues, absorbing nutrients for their own growth. Fungi will go dormant during times of the year that have weather non-conducive to fungal spread, and will use structures such as sclerotia (compact masses of hyphae), rhizomorphs (root-like masses of hyphae) or thick-walled spores that are more resilient to harsher conditions. The following list includes important groups of fungal pathogens that can attack garden and crop plants.
Phytophthora
This group of fungus-like organisms can infect soil or the leaves of plants. The genus name phytophthora is derived from the Greek words for plant (phyton) and destroy (phthora), and Phytophthora is commonly known as "The Plant Destroyer". Since their formal discovery in 1875 by Henrich Anton de Bary, approximately 210 species have been described, and scientists estimate that 100-500 more undiscovered species exist. These organisms are very similar to fungi in many aspects, though they have a completely different evolutionary history (they're a great example of convergent evolution). There are two main types of phytophthora: soil borne and foliar. Soil-borne phytophthora cause root rots, trunk lesions, and fruit rots (if splashed up from the soil onto nearby fruits). Examples of soil-borne phytophthora include Phytophthora cinnamomi, Phytophthora citrophthora, and Phytophthora parasitica. Foliar phytophthora infect leaves, branches, and trunks. They can form cankers, and do well in environments with high soil moisture, high relative humidity, free moisture on foliage, and cool temperatures. Examples include Phytophthora infestans, and Phytophthora ramorum (also known as Sudden Oak Death, or SOD). The list below includes many of the more commonly-found species of phytophthora:
This group of fungus-like organisms can infect soil or the leaves of plants. The genus name phytophthora is derived from the Greek words for plant (phyton) and destroy (phthora), and Phytophthora is commonly known as "The Plant Destroyer". Since their formal discovery in 1875 by Henrich Anton de Bary, approximately 210 species have been described, and scientists estimate that 100-500 more undiscovered species exist. These organisms are very similar to fungi in many aspects, though they have a completely different evolutionary history (they're a great example of convergent evolution). There are two main types of phytophthora: soil borne and foliar. Soil-borne phytophthora cause root rots, trunk lesions, and fruit rots (if splashed up from the soil onto nearby fruits). Examples of soil-borne phytophthora include Phytophthora cinnamomi, Phytophthora citrophthora, and Phytophthora parasitica. Foliar phytophthora infect leaves, branches, and trunks. They can form cankers, and do well in environments with high soil moisture, high relative humidity, free moisture on foliage, and cool temperatures. Examples include Phytophthora infestans, and Phytophthora ramorum (also known as Sudden Oak Death, or SOD). The list below includes many of the more commonly-found species of phytophthora:
Phytophthora cactorum
This species causes rhododendron root rot, which affects Rhododendrons, Azaleas, Orchids, and causes bleeding cankers in hardwood species of trees. |
Phytophthora capsici
Affects plants that are in the Gourd family (Cucurbitaceae), like cucumbers and squashes. |
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Phytophthora cinnamomi
This is one of the more commonly-seen garden invaders on this list. It causes what is called Cinnamon Root Rot, and affects forest and fruit trees as well as woody ornamentals, including Arborvitae, Azalea, Chamaecyparis, Dogwood, Forsythia, Fraser Fir, Hemlock, Japanese Holly, Juniper, Pieris, Rhododendron, Taxus, White Pine, American Chestnut, Banksia, and Eucalyptus.
This is one of the more commonly-seen garden invaders on this list. It causes what is called Cinnamon Root Rot, and affects forest and fruit trees as well as woody ornamentals, including Arborvitae, Azalea, Chamaecyparis, Dogwood, Forsythia, Fraser Fir, Hemlock, Japanese Holly, Juniper, Pieris, Rhododendron, Taxus, White Pine, American Chestnut, Banksia, and Eucalyptus.
Phytophthora citricola
This species infects citrus trees, causing root rot and stem cankers. |
Phytophthora fragariae
Affects strawberry plants, causing Red Root Rot. |
Phytophthora infestans
This species causes the devastating disease known as Potato Blight, and is responsible for the Great Famine of Ireland (1845-1852). |
Phytophthora kernoviae
First seen in the UK in 2003, this species affects Beech, Rhododendron, and Oak trees. |
Phytophthora lateralis
This species causes Cedar Root Disease in the pacific-northwest native tree Port Orford Cedar. |
Phytophthera megakarya
This is one of the Cocoa Black Pod disease species, and affects mainly Cocoa crops. |
Phytophthora multivora
Affects many different plants, once thought to be a variant of Phytopthora citricola. |
Phytophthora nicotianae
Infects Tobacco and Onion plants. |
Phytophthora palmivora
This species causes fruit rot in Coconut and Betel Nut plants. |
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Phytophthora ramorum
This is a very infectious, quick-spreading species that affects over 60 plant genera and has over 100 host species; it causes the disease known as Sudden Oak Death.
This is a very infectious, quick-spreading species that affects over 60 plant genera and has over 100 host species; it causes the disease known as Sudden Oak Death.
Phytophthora quercina
Causes Oak Death. |
Phytophthora sojae
This species causes root rot in Soybean plants. |
Armillaria
This genus includes 10 species of fungi, and are long-lived and form large colonies. They are considered to be the largest fungi in the world. The largest known organism of this genus stretches across 3.4 square miles in Oregon's Malheur National Forest and is estimated to be 2,500 years old. Some species in this genus exhibit bioluminescence. These organisms form colonies of mushrooms at the base of plants, and commonly cause root rot issues in Almond, Walnut, Apple, Citrus, Grape, Peach, Strawberry, and a variety of ornamental plants.
This genus includes 10 species of fungi, and are long-lived and form large colonies. They are considered to be the largest fungi in the world. The largest known organism of this genus stretches across 3.4 square miles in Oregon's Malheur National Forest and is estimated to be 2,500 years old. Some species in this genus exhibit bioluminescence. These organisms form colonies of mushrooms at the base of plants, and commonly cause root rot issues in Almond, Walnut, Apple, Citrus, Grape, Peach, Strawberry, and a variety of ornamental plants.
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Fusarium & Verticillium
Fusarium and Verticillium are two similar fungi which cause vascular issues and wilting in host plants. Both of these soil pathogens cause affected plants to have wilting in shoots and leaves, yellowing or browning leaves and stems (usually on one side). and death of branches or the entire plant. Fusarium is a large genus with between 396 and 440 species, many of which are not harmful to plants and are part of the soil biome. Those that are harmful, however, cause Fusarium Wilt, a systemic
Fusarium and Verticillium are two similar fungi which cause vascular issues and wilting in host plants. Both of these soil pathogens cause affected plants to have wilting in shoots and leaves, yellowing or browning leaves and stems (usually on one side). and death of branches or the entire plant. Fusarium is a large genus with between 396 and 440 species, many of which are not harmful to plants and are part of the soil biome. Those that are harmful, however, cause Fusarium Wilt, a systemic
Fusarium oxysporum f. sp. fragariae
Affects strawberry plants, among others. |
Fusarium oxysporum f. sp. lactucae
This species affects lettuce crops. |
Fusarium brachygibbosum
This species affects Watermelon, Almond, Wheat, Spurge, and Corn. |
Fusarium lactis
This is an important inoculum causing internal fruit rot in Pepper plants. |
Fusarium equiseti
This species causes wilt diseases in Watermelon. Grape, Cucumber, Tomato, Cowpea, Bean, and Potato plants, among others. |
Verticillium is also a commonly encountered genus in the garden and causes the disease known as Verticillium Wilt. These fungi are commonly found in garden soils, and affect many different types of crops and ornamentals. With this disease, plants will exhibit symptoms such as faded green, yellow or brown foliage, scattered wilting of foliage and branches, dying branches (usually on one side of the plant at first), and wilting of flowers and fruits.
Verticillium dahliae
This species affects around 300 species, including Brussels Sprouts, Cabbage, Mint, Pepper. Potatoes, Pumpkin, Tomato, Watermelon, and Canteloupe, among others. |
Verticillium albo-atrum
This Verticillium affects a wide range of hosts, including Potato, Alfalfa, Tomato, Sunflower. Strawberry, Rose, Mint, Impatiens, Hemp, Geranium, Fuchsia, Elm, and Dahlia. |
Verticillium alfalfae
This fungus affects mainly Alfalfa plants, as its name suggests. |
Verticillium isaacii
This species is found mostly in Artichoke, Spinach and Lettuce. |
Verticillium longisporum
This species of Verticillium commonly affects Canola, but can also cause issues in Cabbage, Broccoli, Mustard and Cauliflower. |
Verticillium nonalfalfae
This species causes Verticillium Wilt in Hops, Kiwi, Spinach, and plants in the Solanaceae family. It also infects Tree of Heaven plants, and is used as a control for the spread of this invasive species. |
Verticillium theobromae
This species affects mainly Banana and Plaintain crops. |
Verticillium zaregamsianum
This Verticillium species mainly affects Lettuce crops. |
Taphrina
This fungus commonly affects Stone Fruit Trees. Oaks. and Poplar Trees, and causes twisted leaves, blisters on leaves. and fruit infections.
This fungus commonly affects Stone Fruit Trees. Oaks. and Poplar Trees, and causes twisted leaves, blisters on leaves. and fruit infections.
Peach Leaf Curl is caused by this fungus.
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Taphrina can cause Witch's Brooms to form on affected plants.
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Taphrina causes leaf blisters on the foliage of infected plants.
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Powdery Mildew
This issue affects many different types of plants, including ornamentals, fruit trees, strawberries, vegetables, forest species, cereals, and weeds. Affected plants will have patches of white or grey powder on them that continue to grow over time. This is a very common occurrence in vegetable and fruit gardens.
This issue affects many different types of plants, including ornamentals, fruit trees, strawberries, vegetables, forest species, cereals, and weeds. Affected plants will have patches of white or grey powder on them that continue to grow over time. This is a very common occurrence in vegetable and fruit gardens.
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Downy Mildew
Similar to Powdery Mildew, the visible symptoms of this type of fungal infection appear on the leaves of infected plants. The difference is that the white, gray, or purple fungal growth appears on the undersides of leaves, and the topsides appear mottled in color.
Similar to Powdery Mildew, the visible symptoms of this type of fungal infection appear on the leaves of infected plants. The difference is that the white, gray, or purple fungal growth appears on the undersides of leaves, and the topsides appear mottled in color.
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Rusts
Bacteria
Viruses
viroids
phytoplasmas
spiroplasmas
nematodes
parasitic plants
protozoa
Noninfectious diseases of plants (Abiotic plant disorders)
Nutrient issues
Plants absorb vital water and nutrients through their root systems. If the soil your plant has its roots in is deficient in minerals and nutrients, it can cause issues, such as stunted growth, discolored leaves, and less flowering. On the other end of the spectrum, if there is an abundance of certain nutrients in the soil, this can also damage the plant, burning roots and discoloring foliage. Sorting out which minerals your plant is having difficulty with can be a tiring process, but it is vital to the health of your garden. There are seventeen vital nutrients essential to plant growth, three airborne and fourteen pulled from the soil.
Nitrogen
This element is used to create amino acids, proteins, enzymes and chlorophyll and plays an important role in photosynthesis, metabolism, protoplasm reactions. Nitrogen also is a component of nucleic acids (the backbone of DNA), and is essential for many plant growth and development processes. Plants take up nitrogen primarily as nitrite, because in this form it is mobile, moving with soil water to plant roots where it is absorbed. Plants can also technically absorb nitrogen as ammonium, but in this form it is often strongly bound to soil particles and cannot move as easily to roots. Nitrogen that originates in fertilizers added to soil is converted to nitrite by soil microorganisms, though a lot of nitrogen is lost through soil leaching. Several species of soil microbes are categorized as nitrogen-fixing, meaning that they take nitrogen from the air and make it available to the plants they have a symbiotic relationship with.
Symptoms of nitrogen deficiency begin in older tissues because nitrogen is mobile within plants, who send the nitrogen present in older tissue to younger tissues of the plant. Nitrogen deficiency can cause slowed growth, stunting, and a yellow-green foliage color (chlorosis). Tips and leaf margins will turn brown and dry out. Plants will die prematurely eventually if the deficiency is not corrected. Nitrogen in excess will cause excessive vegetative growth, even if the plant should be in a flowering phase. Foliage will turn a darker green and transpire excessively. Maturity can be delayed, as vegetative growth is favored over flowering, and therefore sexual maturity. Fruiting also suffers due to a lack of flowers.
This element is used to create amino acids, proteins, enzymes and chlorophyll and plays an important role in photosynthesis, metabolism, protoplasm reactions. Nitrogen also is a component of nucleic acids (the backbone of DNA), and is essential for many plant growth and development processes. Plants take up nitrogen primarily as nitrite, because in this form it is mobile, moving with soil water to plant roots where it is absorbed. Plants can also technically absorb nitrogen as ammonium, but in this form it is often strongly bound to soil particles and cannot move as easily to roots. Nitrogen that originates in fertilizers added to soil is converted to nitrite by soil microorganisms, though a lot of nitrogen is lost through soil leaching. Several species of soil microbes are categorized as nitrogen-fixing, meaning that they take nitrogen from the air and make it available to the plants they have a symbiotic relationship with.
Symptoms of nitrogen deficiency begin in older tissues because nitrogen is mobile within plants, who send the nitrogen present in older tissue to younger tissues of the plant. Nitrogen deficiency can cause slowed growth, stunting, and a yellow-green foliage color (chlorosis). Tips and leaf margins will turn brown and dry out. Plants will die prematurely eventually if the deficiency is not corrected. Nitrogen in excess will cause excessive vegetative growth, even if the plant should be in a flowering phase. Foliage will turn a darker green and transpire excessively. Maturity can be delayed, as vegetative growth is favored over flowering, and therefore sexual maturity. Fruiting also suffers due to a lack of flowers.
Potassium
This nutrient affects membrane permeability and impacts stomatal opening and closing. It also helps regulate internal water relations, cell division, starch and protein synthesis, and sugar translocation. The presence of potassium increases size and quality of fruits and vegetables and increases plants' resistance to disease. Potassium is taken up into plant roots and exists in plant tissues as a simple ion. Potassium is abundant in soils, but a lot of it is unavailable to plants due to it being tightly bound to soil minerals.
Symptoms of potassium deficiency are slowed growth and leaf tip, marginal burn, and necrosis starting in mature leaves and eventually moving to new growth. If plants do not get enough potassium, they can have weak stalks, small fruits, and seeds will be shriveled. In excess, potassium causes issues like light green foliage and deficiencies in magnesium (Mg) and Calcium (Ca).
This nutrient affects membrane permeability and impacts stomatal opening and closing. It also helps regulate internal water relations, cell division, starch and protein synthesis, and sugar translocation. The presence of potassium increases size and quality of fruits and vegetables and increases plants' resistance to disease. Potassium is taken up into plant roots and exists in plant tissues as a simple ion. Potassium is abundant in soils, but a lot of it is unavailable to plants due to it being tightly bound to soil minerals.
Symptoms of potassium deficiency are slowed growth and leaf tip, marginal burn, and necrosis starting in mature leaves and eventually moving to new growth. If plants do not get enough potassium, they can have weak stalks, small fruits, and seeds will be shriveled. In excess, potassium causes issues like light green foliage and deficiencies in magnesium (Mg) and Calcium (Ca).
Phosphorus
This element is a constituent of proteins, phospholipids, enzyme systems, and nucleic acids and is important for energy systems (ATP) within a plant. Phosphorus is essential in the process of creating growth early on in a plant's life, and contributes to root and formation, while also playing an important role in photosynthesis. Phosphorus is absorbed by plants in many forms, depending mostly on soil pH, and is more often than not tied up in insoluble compounds. Phosphorus fertilizer uptake is more efficient if there is also nitrogen present in the soil. A deficit of phosphorus can cause issues such as slowed and stunted growth, dark green or purple color (caused by anthocyanins) on foliage, and dying leaf tips. It can also cause interveinal chlorosis, delayed maturity, and poor fruit or seed set. Excess phosphorus can interfere with micronutrient uptake and can look like a zinc (Zn) deficiency.
This element is a constituent of proteins, phospholipids, enzyme systems, and nucleic acids and is important for energy systems (ATP) within a plant. Phosphorus is essential in the process of creating growth early on in a plant's life, and contributes to root and formation, while also playing an important role in photosynthesis. Phosphorus is absorbed by plants in many forms, depending mostly on soil pH, and is more often than not tied up in insoluble compounds. Phosphorus fertilizer uptake is more efficient if there is also nitrogen present in the soil. A deficit of phosphorus can cause issues such as slowed and stunted growth, dark green or purple color (caused by anthocyanins) on foliage, and dying leaf tips. It can also cause interveinal chlorosis, delayed maturity, and poor fruit or seed set. Excess phosphorus can interfere with micronutrient uptake and can look like a zinc (Zn) deficiency.
Calcium
Calcium regulates cell membrane permeability, integrity, and acidity and promotes cell elongation. It is also a critical component of plant cell walls and membranes. Calcium has limited mobility in plants, so young plant parts will begin to show symptoms first. It is often applied as a foliar feeding on celery, apples, pears, and cherries. Excess calcium leads to a high soil pH, and a deficit will affect plants by reducing terminal growth of shoots and roots, which results in plant death. Calcium deficits also cause blossom end rot in tomatoes, peppers, and melons and pit rot in apples and pears. Calcium deficit in young lettuce and cabbage plants can burn leaf tips. An excess amount of calcium interferes with micronutrient availability.
Calcium regulates cell membrane permeability, integrity, and acidity and promotes cell elongation. It is also a critical component of plant cell walls and membranes. Calcium has limited mobility in plants, so young plant parts will begin to show symptoms first. It is often applied as a foliar feeding on celery, apples, pears, and cherries. Excess calcium leads to a high soil pH, and a deficit will affect plants by reducing terminal growth of shoots and roots, which results in plant death. Calcium deficits also cause blossom end rot in tomatoes, peppers, and melons and pit rot in apples and pears. Calcium deficit in young lettuce and cabbage plants can burn leaf tips. An excess amount of calcium interferes with micronutrient availability.
Magnesium
This nutrient is a constituent of chlorophyll and is required for many enzymatic reactions. It can also aid mobility and the efficiency of phosphorus. Magnesium is used frequently to fertilize celery and citrus, and is essential for the photosynthetic process. It is a mobile nutrient within plants, easily transferring from older plant material to younger shoots in times of deficit. When there is not enough magnesium present to support plant functioning, gardeners will find marginal and interveinal necrosis in leaves (beginning in more mature leaves and moving to newer tissues), and leaves will begin to curl upward along margins. Leaves will appear to have a Christmas tree shape of green inside yellowing leaf parts towards the edges. An excess of magnesium can interfere with calcium (Ca) uptake.
This nutrient is a constituent of chlorophyll and is required for many enzymatic reactions. It can also aid mobility and the efficiency of phosphorus. Magnesium is used frequently to fertilize celery and citrus, and is essential for the photosynthetic process. It is a mobile nutrient within plants, easily transferring from older plant material to younger shoots in times of deficit. When there is not enough magnesium present to support plant functioning, gardeners will find marginal and interveinal necrosis in leaves (beginning in more mature leaves and moving to newer tissues), and leaves will begin to curl upward along margins. Leaves will appear to have a Christmas tree shape of green inside yellowing leaf parts towards the edges. An excess of magnesium can interfere with calcium (Ca) uptake.
Sulfur
This element is necessary for creating amino acids and proteins within plants, in addition to being a constituent of vitamins B1 and H. It also activates enzyme systems and is found in aromatic oils produced by some plants that impart a characteristic sulfur smell and taste of onion, garlic, mustard, and cabbage relatives. Sulfur is mainly taken up by plants as sulfate, which is mobile and taken up alongside water molecules. It is supplied by organic matter, where soil microorganisms transform it into a usable form. It can also be taken in through stomata as a constituent of air pollution, but prolonged exposure in this form can cause damage to plants. Sulfur is also supplied to plants via fertilizers in many different forms, including superphosphate, ammonium phosphate, magnesium phosphate, gypsum, and others. Sulfur deficiency can cause stunted growth, yellow-green or light-green leaf color (sometimes affecting older leaves first, but this is not true in all cases). It also causes leaf spotting and can mimic zinc or nitrogen deficiencies. Plants that are deficient in sulfur have a lower protein content, and deficiencies are most common in highly leaches soils in humid climates.
This element is necessary for creating amino acids and proteins within plants, in addition to being a constituent of vitamins B1 and H. It also activates enzyme systems and is found in aromatic oils produced by some plants that impart a characteristic sulfur smell and taste of onion, garlic, mustard, and cabbage relatives. Sulfur is mainly taken up by plants as sulfate, which is mobile and taken up alongside water molecules. It is supplied by organic matter, where soil microorganisms transform it into a usable form. It can also be taken in through stomata as a constituent of air pollution, but prolonged exposure in this form can cause damage to plants. Sulfur is also supplied to plants via fertilizers in many different forms, including superphosphate, ammonium phosphate, magnesium phosphate, gypsum, and others. Sulfur deficiency can cause stunted growth, yellow-green or light-green leaf color (sometimes affecting older leaves first, but this is not true in all cases). It also causes leaf spotting and can mimic zinc or nitrogen deficiencies. Plants that are deficient in sulfur have a lower protein content, and deficiencies are most common in highly leaches soils in humid climates.
Iron
Essential for the formation of chlorophyll, iron is also important for respiration, photosynthesis, nitrogen fixation, and cell division. Deficiencies cause interveinal chlorosis in young plant parts. In severe deficiencies, it can cause twig dieback, reduced growth and death. Soils in the western US are commonly low in iron, caused by poor aeration, poor pH, high manganese concentrations, and lime present in the soil. Turf grass, certain trees, and ornamentals are especially susceptible to deficiencies in iron. Excesses mimic phosphorus or manganese deficiencies.
Essential for the formation of chlorophyll, iron is also important for respiration, photosynthesis, nitrogen fixation, and cell division. Deficiencies cause interveinal chlorosis in young plant parts. In severe deficiencies, it can cause twig dieback, reduced growth and death. Soils in the western US are commonly low in iron, caused by poor aeration, poor pH, high manganese concentrations, and lime present in the soil. Turf grass, certain trees, and ornamentals are especially susceptible to deficiencies in iron. Excesses mimic phosphorus or manganese deficiencies.
Manganese
This nutrient is an important enzyme catalyst in many metabolic plant functions and works with iron to create chlorophyll. Manganese also plays a role in chloroplast structure and promotes pigment and vitamin C synthesis. Commercial citrus growers commonly use foliar-applied manganese alongside zinc. Deficiency causes interveinal and marginal chlorosis on young leaves, and is common in tree crops. Excess manganese mimics and induces iron deficiency symptoms, and causes lack of foliar color, bronzing leaf margins, and necrotic areas.
This nutrient is an important enzyme catalyst in many metabolic plant functions and works with iron to create chlorophyll. Manganese also plays a role in chloroplast structure and promotes pigment and vitamin C synthesis. Commercial citrus growers commonly use foliar-applied manganese alongside zinc. Deficiency causes interveinal and marginal chlorosis on young leaves, and is common in tree crops. Excess manganese mimics and induces iron deficiency symptoms, and causes lack of foliar color, bronzing leaf margins, and necrotic areas.
Zinc
This element is an important building block of enzymes and hormones, notably auxins that regulate growth and development. It also plays a role in the synthesis of chlorophyll. It is taken up by plants as a zinc cation, and is the micronutrient that is most often deficient in western soils. Plants that usually require zinc fertilization include citrus, grapes, nuts, other tree fruits, beans, onions, tomatoes, corn, rice, and cotton. Deficiencies in zinc ca cause interveinal chlorosis in young leaves, rosetting of terminal leaves, reduced fruit bud formation, and twig dieback after the first year.
This element is an important building block of enzymes and hormones, notably auxins that regulate growth and development. It also plays a role in the synthesis of chlorophyll. It is taken up by plants as a zinc cation, and is the micronutrient that is most often deficient in western soils. Plants that usually require zinc fertilization include citrus, grapes, nuts, other tree fruits, beans, onions, tomatoes, corn, rice, and cotton. Deficiencies in zinc ca cause interveinal chlorosis in young leaves, rosetting of terminal leaves, reduced fruit bud formation, and twig dieback after the first year.
Boron
This element plays a role in the differentiation of meristem cells and regulates sugar metabolism within plants. Boron also plays a role in pectin formation and facilitates the movement of calcium within plant tissues. It is taken up by plants as an orthoborate ion, and is not remobilized in plants once assimilated. Plants require a continuous supply of boron at growing points to develop well. Boron deficiencies in soil are common in intensive cropping areas, and are first noted in younger plant stems. Boron deficiencies can cause death, distortion or stunting of terminal growth, witches' broom growth, and thickened, curled, wilting, chlorotic leaves. It can also cause soft, necrotic growth on fruits and tubers, and reduced flowering and cell differentiation errors. Excess boron is rarely found, but does occur in inland deserts with high boron-contaminated water. Excess boron has been found in these situations to cause marginal necrosis on grape leaves.
This element plays a role in the differentiation of meristem cells and regulates sugar metabolism within plants. Boron also plays a role in pectin formation and facilitates the movement of calcium within plant tissues. It is taken up by plants as an orthoborate ion, and is not remobilized in plants once assimilated. Plants require a continuous supply of boron at growing points to develop well. Boron deficiencies in soil are common in intensive cropping areas, and are first noted in younger plant stems. Boron deficiencies can cause death, distortion or stunting of terminal growth, witches' broom growth, and thickened, curled, wilting, chlorotic leaves. It can also cause soft, necrotic growth on fruits and tubers, and reduced flowering and cell differentiation errors. Excess boron is rarely found, but does occur in inland deserts with high boron-contaminated water. Excess boron has been found in these situations to cause marginal necrosis on grape leaves.
Copper
Copper plays a role in enzymatic reactions important in carbohydrate and protein metabolism and also participates in chlorophyll and vitamin A synthesis. It is taken up by plants as copper ions or as cupric ions, and is not commonly needed as a fertilizer in California other than in situations where gardeners are growing tree crops in sandy or organic soils. Copper can be highly toxic to plant life, so fertilizing with copper should only be done if the need has been well-established. Not enough copper can cause stunted growth and terminal dieback of shoots in trees. It can also cause poor foliage pigmentation, wilting, death of leaf tips, gum pockets, and sandy rinds on citrus fruit. Excess copper can cause reduced growth and necrosis.
Copper plays a role in enzymatic reactions important in carbohydrate and protein metabolism and also participates in chlorophyll and vitamin A synthesis. It is taken up by plants as copper ions or as cupric ions, and is not commonly needed as a fertilizer in California other than in situations where gardeners are growing tree crops in sandy or organic soils. Copper can be highly toxic to plant life, so fertilizing with copper should only be done if the need has been well-established. Not enough copper can cause stunted growth and terminal dieback of shoots in trees. It can also cause poor foliage pigmentation, wilting, death of leaf tips, gum pockets, and sandy rinds on citrus fruit. Excess copper can cause reduced growth and necrosis.
Chlorine
This micronutrient is required for photosynthesis and influences cell membrane permeability (it prevents desiccation). It is taken up by plants as a negatively charged ion and moves well through soil. Chlorine deficiencies are uncommon. but cause wilting of leaves followed by chlorosis, and branching of lateral roots and leaf bronzing. An excess of chlorine can cause poor growth and marginal leaf necrosis.
This micronutrient is required for photosynthesis and influences cell membrane permeability (it prevents desiccation). It is taken up by plants as a negatively charged ion and moves well through soil. Chlorine deficiencies are uncommon. but cause wilting of leaves followed by chlorosis, and branching of lateral roots and leaf bronzing. An excess of chlorine can cause poor growth and marginal leaf necrosis.
Molybdenum
This nutrient is required for nitrogen use; it converts nitrogen into amino acids and plays a role in nitrogen fixation as well. It is taken up by plants as molybdate, and many of the deficiency symptoms mimic nitrogen deficiency symptoms because of the role molybdenum plays in the usability of nitrogen. Deficiency causes stunting of plants and reduced fruit yields, as well as lack of vigor and chlorosis in foliage. Leaves will also exhibit symptoms such as marginal scorching, cupping, and rolling of leaves.
This nutrient is required for nitrogen use; it converts nitrogen into amino acids and plays a role in nitrogen fixation as well. It is taken up by plants as molybdate, and many of the deficiency symptoms mimic nitrogen deficiency symptoms because of the role molybdenum plays in the usability of nitrogen. Deficiency causes stunting of plants and reduced fruit yields, as well as lack of vigor and chlorosis in foliage. Leaves will also exhibit symptoms such as marginal scorching, cupping, and rolling of leaves.
Nickel
This recently-discovered micronutrient is an important enzyme component and plays a role in nitrogen metabolism, especially during stages of seed germination. It is not fully understood how plants take up this element, but deficiencies cause leaf tip necrosis and excesses induce iron and zinc deficiencies and chlorosis symptoms.
This recently-discovered micronutrient is an important enzyme component and plays a role in nitrogen metabolism, especially during stages of seed germination. It is not fully understood how plants take up this element, but deficiencies cause leaf tip necrosis and excesses induce iron and zinc deficiencies and chlorosis symptoms.
