Amaranth is a versatile plant grown for its nutritious leaves and edible seeds. However, like any crop, amaranth is susceptible to pest problems if not properly cared for. In this article, we will discuss common amaranth pests, prevention methods, and control solutions to help you keep your amaranth plants healthy and thriving.
An Overview of Common Amaranth Pests
Some of the most prevalent pests that affect amaranth plants include:
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Aphids – These tiny sap-sucking insects can spread quickly, causing yellowing, stunted growth, and sticky residue on leaves.
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Spider Mites – Tiny arachnids that feed on plant juices causing spotty yellow leaves and webbing.
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Cutworms – Caterpillars that chew through amaranth stems at the base, killing seedlings.
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Flea Beetles – Small jumping beetles that chew tiny holes in amaranth leaves
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Whiteflies – Sap-sucking insects that cause yellowing leaves and stunted growth.
Keeping on top of pest prevention is key to avoiding infestations that can quickly get out of hand.
Preventing Pests through Cultural Practices
The best defense is a good offense when it comes to stopping amaranth pests before they start. Here are some tips:
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Crop Rotation – Rotating amaranth plantings to different beds each season prevents pests from accumulating in the soil.
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Companion Planting – Interplanting amaranth with pest-deterring plants like marigolds, garlic, and basil can confuse and repel pests.
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Remove Debris – Clearing away dead leaves and plants deprives overwintering pests of habitat.
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Solarization – Covering beds in clear plastic during hot months raises soil temperatures, killing pests and pathogens.
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Row Covers – Floating row covers form a protective barrier against flying and crawling insects.
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Proper Spacing – Giving amaranth proper spacing reduces humidity levels that breed fungal diseases.
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Daily Habits – Rotating location, aerating soil, and properly timed watering discourages pests.
Control Methods for Existing Infestations
If prevention fails and pests take hold, safer, organic methods should be employed to get infestations under control:
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Insecticidal Soap – Potassium salts in insecticidal soap disrupt soft-bodied pests like aphids.
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Neem Oil – Derived from the neem tree, this oil coats and suffocates insects while deterring feeding.
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Diatomaceous Earth – Microscopic diatom fossils abrade the waxy coating of soft-bodied insects, causing dehydration.
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Kaolin Clay – This white mineral powder deters pests from landing and feeding on sprayed plants.
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Bacillus thuringiensis – A bacterial insecticide that poisons pests when ingested while sparing beneficial insects.
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Beneficial Insects – Releasing predatory insects like ladybugs and lacewings to feed on amaranth pests.
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Horticultural Oils – Light oils smother soft-bodied insects and mites while safe for plants.
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Insect Traps – Yellow sticky traps or pheromone traps lure and catch problematic pests.
An Ounce of Prevention
While amaranth is susceptible to pest problems, the good news is there are many effective ways to deter infestations from taking hold in the first place. Focus on cultural practices like crop rotation, debris removal, and row covers as your first line of defense. Catching issues early and using organic treatments can help get minor pest outbreaks under control before major damage occurs. With some diligence and preventative care, you can keep your amaranth plants flourishing and pest-free all season long.
Also in: Identify common weeds
Redroot pigweed, rough pigweed
Common amaranth is an introduced annual found as a casual weed on cultivated land and in waste places. It is considered to be a native of North America but is now distributed worldwide. Common amaranth has come into the UK from many different sources including with birdseed. It is more frequent in the warmer drier regions of Britain like East Anglia. It prefers loose friable soils rich in nitrogen.
Mature plants have been used as animal feed but young plants eaten in large quantities can be poisonous to livestock. The green leaves contain oxalates and high levels of nitrate. Sheep, swine and cattle, particularly young calves have been affected. Nevertheless, in many parts of the world it is used as a green vegetable and the seeds are ground to make flour.
Common amaranth plants and residues may have an allelopathic effect on the germination and growth of other plants. It accumulates high levels of caesium 137 and strontium 90 and may be used for bioremediation of contaminated soil.
Common amaranth flowers from July to September. The flowers are primarily wind pollinated but some insect pollination can occur. Seed matures from August to October. The minimum time for seed development is 30 days from flowering. The average seed number per plant is 117,400 but a large plant may have 229,175 seeds. Closely spaced plants have fewer seeds. The 1,000 seed weight ranges from 0.340 to 0.439 g. Seeds on plants that mature earlier in the season are heavier than seeds on plants that mature later. Seeds can be retained in the inflorescence overwinter.
Common amaranth seed is dormant when shed. The level of dormancy is affected by time of emergence and the growing conditions experienced by the parent plant. Fresh seed from distinct populations of common amaranth may differ in their germination characteristics but the differences are reduced during dry storage. Dormancy is lost after a 2-3 months of dry storage. The tough seedcoat does not rupture easily and, while water uptake is not prevented, seed germination is hindered by it. Anything that weakens the seedcoat will aid germination. In laboratory studies, the minimum germination temperature was 10°C. Maximum germination occurred at 35 to 40°C. A temperature of 40°C will produce some germination of ripe seeds soon after harvest. The optimum germination temperature becomes lower as the seed after-ripens. Nitrogen is thought to promote germination but there is some disagreement on the effect of light.
In the field, common amaranth seeds do not germinate until temperatures begin to rise in late spring or summer. The main period of seedling emergence occurs from May to August but some seedlings can appear in April. Seedlings emerge best from between 5 and 30 mm deep in soil. Below 40 mm, seed germination is much less. Although seedling emergence decreases with increasing burial depth, fatal germination does not occur and deeply buried seeds remain ungerminated. Germination is better in a clay than a sandy soil. Cultivation increases seedling emergence. There is some confusion about whether leaving seeds on the soil surface promotes or inhibits germination.
Common amaranth is a C4 plant in terms of carbon fixation during photosynthesis. It grows best at higher temperatures and light levels. The seedlings are frost sensitive.
Common amaranth seed sown in the field and followed over a 5-year period in winter wheat and spring barley showed an annual decline of around 40%. Emerged seedlings represented 8% of the seedbank. Seed buried in soil at 20, 56 and 107 cm deep gave germination of 11, 36 and 48% respectively after 10 years but none after 16 years. In some burial experiments seeds were able to germinate after 40 years, in others viability was lost after just 5 years. After 30 months dry storage at low temperatures, seeds still retained full viability.
Common amaranth seeds are dispersed by wind, water, on farm machinery, in manure, sewage sludge and in compost. It has been found as a contaminant of lettuce seed. It is a constituent of wild birdseed sold in the UK and is spread by birds and animals. Common amaranth seed has been recovered from irrigation water. Seed stored in water for 33 months gave 9% germination when tested.
Some common amaranth seeds were still viable after 2 weeks of windrow composting at temperatures of 50 to 65°C, but after 4 weeks all had been killed. Seeds are said to survive digestion by cows, sheep and horses. Apparently-viable seeds have been found in samples of cow manure. In silage, ensiling for 8 weeks or a combination of ensilage and 24 hrs of rumen digestion killed most seeds. Rumen digestion alone left 27% of seeds still able to germinate. In pig slurry dried to aid transport, common amaranth seeds survived drying for up to 15 minutes at 50°C but did not survive 3 minutes at 75 or 100°C. In dry soil, heating seeds to 60 or 70°C for up to 7 days had little effect on seed viability. In moist soil, viability was gradually reduced over 7 days to around 5%. At 50°C the viability was reduced to 44% but at 40°C there was little effect.
Control is achieved by repeated surface cultivations and the prevention of seeding. Small seedlings are easily controlled by hoeing, rotary cultivations and flaming.
Common amaranth seed is susceptible to soil solarization but seedlings are relatively tolerant of ultraviolet-B radiation.
A thick mulch of cover crop residue spread over the soil surface reduces seedling emergence in the field. In greenhouse tests in the USA, corn gluten meal (CGM) applied as a surface and incorporated treatment to soil sown with common amaranth seed has been shown to reduce common amaranth development by up to 99% at application rates of 324, 649 and 973g per m2. Corn gluten hydrolysate (CGH), a water-soluble material derived from CGM, was found to be more active than CGM when applied to the soil surface.
A number of fungi have been evaluated as biological control agents. The seeds are eaten by many species of birds, rodents and insects. In Canada, pre-dispersal seed predation by micro-moth larvae reduces seed production by up to 40%.
7 Pests You Probably Have In Your Garden (And What To Do)
FAQ
How do you control amaranthus?
What are the pests of amaranth plants?
What pesticides to use on amaranth?
How to care for an amaranth plant?
How do I get rid of pests in my amaranth plant?
If you already have a pest infestation in your amaranth plants, here are some methods you can use to control them: 1. Insecticidal Soap Insecticidal soap is a safe and effective way to control aphids, spider mites, and other soft-bodied insects. Simply spray the affected areas of the plant with the soap solution. 2. Neem Oil
Are amaranth plants immune to pests?
Amaranth is a popular plant with edible leaves and seeds. It is also known as pigweed, redroot, and love-lies-bleeding. However, amaranth plants are not immune to pest infestations. In this article, we will discuss some common amaranth plant pests and how to prevent and control them. 1. Aphids
Can amaranth be planted from seed?
Amaranths are propagated from seed and can be planted either by transplanting or direct seeding. Certified seeds with special attributes, such as tolerance/resistance to pest and diseases and high yielding should be used. Indirect seeding, seeds are either broadcasted or sown in rows at 0.5 to 1.0 g per m2 of bed.
Can amaranth grow in poor soil?
Amaranth grows well in average soils and will even grow adequately in poor soils. Though very rich soils might hinder flowering and seed production, only dense clay mixtures will likely be unsuitable for amaranth. Amaranth plants have average needs for water, requiring no more than one inch per week.