Miscellaneous

Types Of Plant Lodging: Treating Plants Affected By Lodging

Types Of Plant Lodging: Treating Plants Affected By Lodging


By: Bonnie L. Grant, Certified Urban Agriculturist

High yield cereal crops must pass numerous tests as they go from seedling to harvested product. What is lodging? There are two forms: root lodging and stem lodging. Overall, lodging is the displacement of stems or roots from their vertical and proper placement. It can cause lower yields and diminish nutrient density.

Causes of Plant Lodging

The causes of plant lodging are legion. High nitrogen levels, storm damage, soil density, disease, sowing date, overpopulation, and seed type are all contributing factors to lodging in cereal crops. The most common plants affected by lodging are corn, but other cereal and grain crops are also at risk.

The two types of plant lodging can occur coincidentally or singly but their effect on the crop reduces overall health and harvest. Certain seed types, such as semi-dwarf cereals, may be less at risk than standard seed.

The primary causes of plant lodging are over-crowding, wet soil, and excess nitrogen in soil.

High plant populations and overly wet soil cause root lodging where roots are displaced from soil. Wet soil is unstable and does not afford an adequate foot hold for young roots.

Over populated fields prevent plants from growing tillers, which become crown roots – the main anchors for the plant.

High nitrogen levels create an environment that encourages stem and leafy growth, but the rapid rate can cause weak and skinny stems that are too feeble to hold themselves up. This is known as the stem lodging effect on plants.

Lodging Effect on Plants

Excess moisture or nitrogen and heavily populated fields are not the only reasons for plant lodging. The two types of plant lodging can also be caused by storm damage, which weakens stems and roots.

Plants in shade or that grow excessively tall are also at risk for stem lodging. Weeds and fungal diseases are other conditions that affect shoots and roots.

No matter the cause, the cereal becomes weaker and tends to form seed earlier. Yield is lower and the nutrient content is adversely affected. Corn yields are most affected if lodging occurs at the ear emergence stage. From a strictly mechanical perspective, stem lodged plants are harder to harvest and there is more waste. Stems are more susceptible to stalk rots as are disturbed roots.

Preventing Plant Lodging

New strains of cereal grains have been developed with semi-dwarf genes introduced. This minimizes lodging but also lowers yield.

Setting seed farther apart, amending soil for proper drainage, delaying nitrogen fertilization, and plant growth regulators are all methods to reduce the loss from lodging.

Plants affected by lodging should not receive nitrogen until the root system has had time to tiller and form crown roots. This means no fertilizer until the grain is three to four weeks old.

Unfortunately, there’s little you can do to control Mother Nature, so wind and rain will always be a contributing factor to lodging. However, the new strains and some good agronomic practices should be beneficial in trimming the numbers of plants affected.

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Lodging

bending of the stalk of a plant (stalk lodging) or the entire plant (root lodging).

Stalk lodging is caused by the large load of lush growth on the lower part of the stalk. It is caused by overgrowth, a high nitrogen level, abundant watering, and shading. Lodging also occurs in fields with climbing weeds and fungal diseases that afflict the shoots and roots of plants. Bread grains most often lodge at the end of the milk stage and the beginning of the dough stage, at which time the weight of undeveloped matter is greatest. In this period, walls of stalk cells may partially decompose to form seeds, as a result of which the straw becomes weaker. Root lodging occurs when the roots are poorly anchored in the soil because of excess moisture. The grain of lodged plants forms abnormally it is sickly, its nutrient content is lower than normal, and its yield drops. The mechanized harvesting of lodged plants is difficult, and harvest losses increase.

Steps to prevent lodging include raising varieties resistant to lodging observing norms for sowing rate and depth using optimal doses of nitrogen fertilizer in combination with phosphorus, potassium, and microfertilizers and treating crops with growth inhibitors (for example, chlorocholine chloride).

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Chernobyl: Capping a Catastrophe

A 32,000-ton arch that will end up costing $1.5 billion is being built in Chernobyl, Ukraine, to all but eliminate the risk of further contamination at the site of the 1986 nuclear reactor explosion.

Dr. Mousseau said that for years he pursued the Chernobyl research largely out of personal interest. But that changed after the nuclear accident at the Fukushima plant in Japan in 2011. While the two accidents were different — at Chernobyl the reactor exploded, while at Fukushima cores melted down and there was an explosion outside the reactor itself — the result was basically the same: radioactive contamination over a wide area.

“No one really expected there’d be another nuclear disaster on this scale,” he said. “But it’s clear now after Fukushima that all of this has some broad relevance.”

Dr. Mousseau has expanded his work to include similar studies in Japan — he’s made about 10 trips there. Already, he said, he is seeing some Chernobyl-like effects in the contaminated area around the Fukushima plant, but he needs to gather data for at least a few more years before he can be confident about the impact.

“If we find the same sort of dose response in both places,” he said, “that provides incredible strength to the hypothesis that it is indeed radiation that is leading to these negative impacts.”


When should I clean my tools and containers?

  • In the fall before you put them away for the winter.
  • In the spring before you use them if you didn’t clean them in the fall.
  • After working with an infected plant and before moving onto the next plant.
  • After you use your tools at another garden site and before you use them at home.

How to clean with effective disinfectants

Clean items well before disinfecting

Dirt and debris left on tools will interfere with the disinfection process and reduce its effectiveness, so remove all visible soil and plant debris.

  • Washing with water and soap or detergent will remove grease and grime.
  • Use a stiff brush to remove dirt especially from rough surfaces.
  • A hard spray of water or a pressurized sprayer will remove caked-on dirt from tools and get into tight spaces like between the tines of a tiller.
    • Consider removing parts like the tines to clean and spray thoroughly (see your equipment manual).
  • Most wood used for planters naturally repels bacteria and fungi, but it can get dirty.
    • Wash wooden planters with warm, soapy water, let dry and oil or wipe with a wood preservative.

Caution about disinfectants: Chemicals used to disinfect can have harmful fumes and burn skin. Read the label, use as directed, and wear personal protective equipment like goggles and gloves when the label recommends doing so.

  • Always store out of reach of children and vulnerable adults, and in a dry location with stable temperature.
  • Never mix disinfectants with other chemicals.
  • If used improperly, disinfectants can cause harm to the user. If poisoning is suspected, call 911 or the Poison Control Hotline 1-800-222-1222.

Active ingredient .1% alkyl dimethyl benzyl ammonium saccharinate

There are various products that contain the above active ingredient, so check the product label. One product is Lysol® All-Purpose Cleaner*. Research has shown that this formulation will eliminate bacteria, fungi and viruses from tools. This product dose not corrode metal and will not damage fabric. Do not use on polished wood, painted surfaces or acrylic plastics.

Usually comes ready-to-use

Best used on:

  • Small hand tools like pruners, loppers, trowel, tree saws, pole pruners.
  • Small pots and saucers, plant labels, clips, ties.
  • Hard-to-reach areas like tines and blades, and ornate implements like trellises, plant stands, hanging baskets.

How to use:

  • Clean all visible dirt and debris from tools including crevices.
  • Dip tool, spray directly on a tool or soak tool for 2 minutes.
  • Let air dry.
  • Tip: Some experts pruning multiple trees advise having two pruning tools on-hand. They let one soak in the disinfectant while making cuts with the other. When they move to the next plant, they switch pruners.

*Lysol® is a registered trademark of Reeckitt Benckiser Group plc. The use of trade names is for clarity and educational purposes only and does not imply endorsement of a particular brand or product.

Bleach (5.25% Sodium hypochlorite)

Bleach is a common, inexpensive household product.

  • It can damage fabric.
  • It corrodes metal and not recommended for pruning and cutting tools that require a sharp edge as it can create pits and nicks in the metal.
  • Dispose of bleach after use by pouring it down the sink.

Do NOT pour it in your garden as it can harm plants and beneficial soil organisms.

Make a 10% bleach solution

  • Mixing one part bleach with 9 parts of water in a plastic container large enough to immerse all or part of the item.
  • NEVER mix bleach with anything except water or laundry detergent as dangerous, toxic gases may be generated that can be harmful to your health and others around you.

Best used for:

  • Large hand tools such as shovels, spades, rakes.
  • Stakes, poles, simple trellises, tomato cages, large containers and pots.

How to use:

  • Clean all visual dirt and debris from tools.
  • Dip, douse or spray tools with the 10% bleach solution. This will kill fungi, bacteria, and viruses within seconds.
  • Turn taller items over in the bucket to make sure all parts are treated.
  • Allow tools and equipment to dry completely.
  • Rub metal items with a few drops of linseed oil, Tung oil or mineral oil. Do not use motor oil as it may transfer to plants. If rust does develop, use steel wool or wire brush to remove and re-oil.

Rubbing alcohol (isopropyl alcohol, 70% concentration)

Alcohol is flammable, so take precautions. According to the Center for Disease Control, isopropyl alcohol in concentrations of 70% or more will disinfect surfaces for bacteria, fungi and viruses.

Alcohol might NOT effectively disinfect pruning tools used on apple trees infected with fire blight.


Pests and Disease

Stunting is also a symptom of many types of plant disease. Healthy plants in good growing condition are less susceptible to disease, but pathogens can spread throughout your garden, so be sure to identify any problems.

The most common plant diseases are caused by fungi, notes the University of Kentucky. Besides stunting, symptoms of a fungal infection include wilting, leaf spots, rotted fruit and thick, curled leaves. Some fungal diseases include powdery mildew, downy mildew, sooty mold, root rot and crown rot. Make sure you remove and destroy any affected plant parts to prevent the spread of disease. In some cases, treating the plants with a fungicide may help control the infection.

Insects and other pests can also damage plants and, depending on the severity of the infestation, can cause stunted growth. Nematodes, small roundworms, may also attack plants and cause stunted growth. Other symptoms include yellowing of the plant, decline, loss of vigor and death. Good cultural practices will usually control nematodes, but you can also apply a nematocide if necessary.

Maureen Malone has been a professional writer since 2010 She is located in Tucson, Arizona where she enjoys hiking, horseback riding and martial arts. She is an outdoor lover who spends her weekends tending her raised garden and small orchard of fruit trees.


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Features Agronomy The effects of plant hormones

Plant hormones are chemicals in plants that regulate almost all aspects of plant growth and development. Hormones play a critical role in how plants respond to biotic and abiotic factors, including sunlight, soil conditions, soil water and nutrients. Hormones are naturally occurring in plants, but some specific hormones can be made synthetically for application to crops.

April 9, 2018 By Ross H. McKenzie PhD P.Ag.

The lodging shown in this cereal crop lodging could potentially be reduced with the use of plant growth regulators. Plant hormones are chemicals in plants that regulate almost all aspects of plant growth and development.

Plant hormones are grouped into five classes depending on their chemical makeup: abscisic acid, auxins, cytokinins, ethylene and gibberellins. These hormones control or influence all aspects of plant growth and reproduction, including seed germination, growth of roots, stems and leaves, plant flowering, seed development, seed fill and seed dormancy.

In Western Canada, we presently use two types of plant growth regulators (PGRs) that are commercially available. The first type are ethylene-releasing agents (for example, Ethrel, with the active ingredient ethephon) registered for use with wheat. When applied at the flag leaf growth stage (GS 38), an ethylene-releasing agent decreases plant height and increases stem wall thickness. The second type of PGR is the gibberellin inhibitor, which reduces stem elongation, shorten the crop and reduce lodging. In Western Canada, Manipulator (active ingredient chlormequat chloride) is registered for use on wheat.

Plant hormones are frequently interactive to assist crops to respond to varying environmental conditions. As we learn more about how crops grow and how hormones influence crop growth and yield, the more we can use science to improve crop growth and production.

Abscisic acid
The principal effect of abscisic acid is inhibition of cell growth. Abscisic acid concentration increases in developing seeds to promote dormancy. Abscisic acid is relatively high in seed but just before the seed germinates, abscisic acid level decreases. During germination and early seedling growth, abscisic acid level continues to decrease. When plants start to produce shoots and leaves, abscisic acid levels increase. As levels continue to increase, growth in older, mature plant parts is slowed and terminated.

Plants produce abscisic acid in response to water stress. Abscisic acid is made in drought-affected leaves and roots and developing seeds. Abscisic acid travels to the stomata to prevent water loss through the stomata.

Auxins
Auxins are responsible for many aspects of plant growth, including cellular elongation and stimulating shoot growth. Auxins are responsible for the way plants grow towards light, a process called phototropism. Auxins regulate which cells elongate to control plant growth direction. Auxin is manufactured mostly in the shoot tips, and in parts of developing flowers and seeds. Auxins maintain dominance of the main shoot over the growth of tillers and buds, and maintain dominance of main root growth over lateral root growth. Auxins control plant aging and senescence and play a role in seed dormancy. However, plant roots are very sensitive to auxin levels, which can inhibit root growth.

Synthetic auxins, such as 2,4-D, are used as herbicides to kill many types of broad-leaved plants. This herbicide works by causing the cells in the tissues that carry water and nutrients, to divide and grow without stopping, causing plants to literally growth themselves to death.

Cytokinins
Cytokinins and auxins tend to work together. The ratio of these two hormone groups affect growth throughout a plant’s lifecycle. Normally, both are relatively even in concentration in plants. When cytokinin levels are lower than auxin levels, the plant is in vegetative growth. As cytokinin levels increase and auxin levels decrease, the plant transitions into reproductive growth stage. Higher cytokinin level can cause plants to have shorter internodal spacings.

Ethylene
Ethylene is a gaseous hydrocarbon that often occurs in larger amounts when plants respond to biotic or abiotic stress. Ethylene can diffuse from its site of origin into the air to affect surrounding plants. Roots, senescing flowers and ripening seed can produce large amounts of ethylene. Ethylene production can be promoted by auxins.

Gibberellins
Gibberellin hormones play a number of roles. They are present in plant shoots and seeds. Initially, gibberellins cause seeds to initiate germination. Gibberellins help to control the transition from vegetative to the reproductive growth. Gibberellins play an important role in stem strength and promote stem elongation between nodes on the stem. Increased gibberellin levels will elongate the internodes to increase stem length. A reduction of gibberellin reduces stem length between internodes to cause dwarf plants. This results in less space between nodes on a stem and leaves are clustered closer together.

Canola
Canola growers are constantly striving to achieve higher yields by maximizing their plant populations, which increase competition among neighboring plants for sunlight. Hormones respond to increased sunlight competition by stimulating increased stem elongation. Increased competition can cause plants to put more energy into stem elongation growth versus expanded leaf area. This causes taller plants with thinner stems and reduced leaf area development, ultimately causing reduced yields rather than increased yield.

Increased inter-plant competition can increase gibberellin and auxin levels, coupled with reduced ethylene levels. In theory, the application of ethephon, or a growth retardant, could be used to regulate shoot morphology and growth. In the future, canola breeders may need to include dwarf characteristics in new canola varieties to reduce plant height and increase leaf area to increase canola yield potential.

Canola yield is strongly affected by water and nutrient availability and is also influenced by several plant hormones. An optimum level of ethylene is needed for reproductive development in canola. Ethylene can play a role in seed development and maturity in canola. The number of seeds per pod in canola is affected by gibberellin. An increase or decrease in ethylene production from normal levels during flowering can cause abortion of seed and seed loss.

Pea
Ethylene controls stem elongation in pea. When germinating pea seedlings encounter a surface soil crust, the ethylene hormone increases in response to this abiotic stress by inhibiting cell elongation and in turn, promotes the pea stems to be shorter and thicker. This gives the pea shoot greater strength to effectively push and break through the crusted soil to successfully emerge.

Pea cultivars in Western Canada are typically semi-dwarf and semi-leafless at growth. The development of pea leaves and tendrils is strongly controlled by plant hormones. Shorter stem length is caused by gene mutation that decreases the efficiency gibberellin. The mutation results in lower levels of gibberellin in the stem resulting in pea plants with shorter internodes and reduced stem length. A semi-leafless pea has stipule leaves that surround the main stem, but does not have leaflets. Tendrils are more pronounced, causing the intertwining of tendrils among plants to keep plants upright. This causes the pea to remain more upright as it grows and matures, which makes harvesting easier. During the development of leaves and tendrils, which originate from the apical bud (growing point), leaflets form in areas with low auxin levels and tendrils form in areas with high auxin.

Wheat
In recent years, cereal crop breeding has used dwarfed wheat varieties with altered or a modified sensitivity to gibberellins. Research has shown that wheat with reduced levels of growth-active gibberellins have shorter stems that reduce lodging and can improve grain yield.

Plant growth regulating chemicals can be applied to control lodging of taller wheat genotypes. Recent research in Western Canada has shown the effects of PGR application but results are greatly affected, by application rates and the crop growth stage of application. There are even varietal differences in response to PGR application.

Various types of PGR products are used in Europe with cereal grains. The most common inhibitors of gibberellins are chlormequat chloride (Cycocel), trinexapac-ethyl (PrimoMaxx or Moddus) and paclobutrazol (Cultar) (Kurepin et al. 2013). Most are applied at earlier growth stages to reduce lodging and increase grain yield. Later applications have been shown to reduce grain yield.

There have been promising advances in understanding of abscisic acid, ethylene and cytokinin hormones in signaling response pathways in plants and the interactions between them that can impact crop growth and yield. Researchers are realizing that changing the ratios and relative abundance of hormone concentrations in plants may be a better strategy than changes in the concentration of a single hormone to improved crop response to stress or to achieve optimum crop yield.

Research is noting that crop response to abiotic or biotic stresses often cause overlapping hormone responses. Crop breeding and crop management for particular abscisic acid:ethylene and abscisic acid:cytokinin ratios or relative abundances may be an appropriate strategy in the future.

As researchers develop a greater knowledge and understanding of plant hormones on crop growth, crop breeding and management practices can be developed to further enhance crop production and yield.