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Add to My Garden Brazilian joyweed
Alternanthera brasiliana
Also known as: Purple joyweed, Metal weed, Bloodleaf, Calico plant
The brazilian joyweed is a flowering plant native to Central and South American forests and grown as an ornamental plant. Locals gather this plant for food and medicine as well. The brazilian joyweed is designated an environmental weed in some parts of Australia. 
Every week
Water
Partial sun
Sunlight
Care Guide for Brazilian joyweed
Water
Brazilian joyweed should be grown in well-drained soils that are consistently moist. Gardeners should water Brazilian joyweed before its soil fully dries out to keep the soil damp. Once established, it can be heat and drought-tolerant.
Fertilization
Brazilian joyweed's blooms can be encouraged with a high phosphorous fertilizer. It can be treated every three weeks with liquid fertilizer. If using granular fertilizer, it should be fed monthly.
Pruning
Trim the diseased, withered leaves once a month.
Potting Suggestions
Needs excellent drainage in pots.
Sunlight
Partial sun, Full sun, Full shade
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Brazilian joyweed
Water
Every week
Sunlight
Partial sun
Hardiness Zones
10 to 11
Planting Time
Spring, Fall
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Brazilian joyweed
Water
Every week
Sunlight
Partial sun
Hardiness Zones
10 to 11
Planting Time
Spring, Fall
Download
Brazilian joyweed
Water
Every week
Sunlight
Partial sun
Hardiness Zones
10 to 11
Planting Time
Spring, Fall
Download
Questions About Brazilian joyweed
Watering 
Pruning 
Sunlight 
Temperature 
Fertilizing What is the best way to water my Brazilian joyweed?
When watering the Brazilian joyweed, you should aim to use filtered water that is at room temperature. Filtered water is better for this plant, as tap water can contain particles that are harmful to its health. The reason that the water should be at room temperature or slightly warmer is that the Brazilian joyweed comes from a warm environment, and cold water can be somewhat of a shock to its system. Also, you should avoid overhead watering for this plant, as it can cause foliage complications. Instead, simply apply your filtered room temperature water to the soil until the soil is entirely soaked. Soaking the soil can be very beneficial for this plant as it moistens the roots and helps them continue to spread through the soil and collect the nutrients they need.
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What should I do if I water my Brazilian joyweed too much or too little?
Both overwatering and underwatering will be detrimental to the health of your Brazilian joyweed, but overwatering is a far more common issue. When this species receives too much water, its stems and leaves may begin to wilt and turn from green to yellow. Overwatering over a prolonged period may also lead to diseases such as root rot, mold, and mildew, all of which can kill your plant. Underwatering is far less common for the Brazilian joyweed, as this plant has decent drought tolerance. However, underwatering remains a possibility, and when it occurs, you can expect to find that the leaves of your Brazilian joyweed have become brittle and brown.
It is crucial that you notice the signs of overwatering as soon as possible when caring for your Brazilian joyweed. Some of the diseases that arise from overwatering, such as root rot, may not be correctable if you wait too long. If you see early signs of overwatering, you should reduce your watering schedule immediately. You may also want to assess the quality of soil in which your Brazilian joyweed grows. If you find that the soil drains very poorly, you should replace it immediately with a loose, well-draining potting mix. On the other hand, if you find signs that your Brazilian joyweed is receiving too little water, all you need to do is water more regularly until those signs have subsided.
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How often should I water my Brazilian joyweed?
If your plant is in a pot. The most precise way to decide whether your Brazilian joyweed needs water is to plunge your finger into the soil. If you notice that the first two to three inches of soil have become dry, it is time to add some water.
If you grow your Brazilian joyweed outdoors in the ground, you can use a similar method to test the soil. Again, when you find that the first few inches of soil have dried out, it is time to add water. During the spring and early fall, this method will often lead you to water this plant about once every week. When extremely hot weather arrives, you may need to increase your watering frequency to about twice or more per week. With that said, mature, well-established the Brazilian joyweed can show an admirable ability to withstand drought.
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How much water does my Brazilian joyweed need?
When it comes time to water your Brazilian joyweed, you should not be shy about how much water you give. With the first two to three inches of soil dry, this plant will appreciate a long and thorough watering. Supply enough water to soak the soil entirely. The amount of water you add should be enough to cause excess water to flow through the drainage holes at the bottom of your pot. If you don’t see excess water draining from the pot, you have likely underwatered your plant. But do not let the water accumulate inside the soil, which will be very dangerous to the plant as well. Alternatively, a lack of water draining through the pot could indicate poorly draining soils, which is detrimental to the health of this plant and should be avoided. If the plant is outside, 1 inch of rain per week will be sufficient.
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How should I water my Brazilian joyweed at different growth stages?
The water needs of the Brazilian joyweed can change depending on growth stages as well. For example, when your Brazilian joyweed is in the first few years of its life, or if you have just transplanted it to a new growing location, you will need to give more water than usual. During both of those stages, your Brazilian joyweed will put a lot of energy towards sprouting new roots that will then support future growth. For those roots to perform their best, they need a bit more moisture than they would at a more mature phase. After a few seasons, your Brazilian joyweed will need much less water. Another growth stage in which this plant may need more water is during the bloom period. Flower development can make use of a significant amount of moisture, which is why you might need to give your Brazilian joyweed more water at this time.
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How should I water my Brazilian joyweed through the seasons?
The Brazilian joyweed will have its highest water needs during the hottest months of the year. During the height of summer, you may need to give this plant water more than once per week, depending on how fast the soil dries out. The opposite is true during the winter. In winter, your plant will enter a dormant phase, in which it will need far less water than usual. In fact, you may not need to water this plant at all during the winter months. However, if you do water during winter, you should not do so more than about once per month. Watering too much at this time will make it more likely that your Brazilian joyweed will contract a disease.
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What's the difference between watering my Brazilian joyweed indoors and outdoors?
It is most common to grow the Brazilian joyweed indoors for any gardener that does not live in temperate and tropical regions. Those gardeners should consider the fact that soil in a container can dry out a bit faster than ground soil. Also, the presence of drying elements such as air conditioning units can cause your Brazilian joyweed to need water on a more frequent basis as well. if you planted it outside. When that is the case, it’s likely you won’t need to water your Brazilian joyweed very much at all. If you receive rainfall on a regular basis, that may be enough to keep your plant alive. Alternatively, those who grow this plant inside will need to water it more often, as allowing rainwater to soak the soil will not be an option.
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Common Pests & Diseases
Common issues for Brazilian joyweed based on 10 million real cases
Leaf beetles
Leaf beetles are a class of colored insects 1 to 2 cm in size. They gnaw on leaves and petals resulting in small, round holes scattered over the surface.
Solutions: For less serious cases: Remove beetles, nymphs, and eggs. Remove all life stages of the beetles and kill them by placing them in a bucket of warm, soapy water. This can be done more easily by placing the bucket under affected leaves and shaking the plant. This method is most effective in the afternoon when leaf beetles are more active. Always dispose of insects in a sealed bag or container to avoid escape and spread. To treat more serious infestations: Apply organic insecticides. Use naturally-derived insecticides before moving on to synthetic insecticides. Neem oil and pyrethrum are naturally-derived insecticides that should be applied following label instructions. Apply synthetic insecticides. Examples of insecticides effective for leaf beetles include carbaryl, permethrin, and bifenthrin. Apply insecticides according to label instructions.
Caterpillars
Caterpillars are fleshy moth or butterfly larvae that come in an array of colors, patterns, and even hairstyles. They chew on leaves and flower petals, creating large, irregular holes.
Solutions: Even though caterpillars are diverse, they all chew on plant parts and can cause significant damage if present in large numbers. For severe cases: Apply insecticide. For an organic solution, spray plants with a Bacillus thuringiensis (Bt), which specifically affects the larval stage of moths and butterflies. Be sure to coat plants, since caterpillars need to ingest Bt for it to be effective. This will not harm other insects. Spray a chili extract. Chili seeds can be cooked in water to make a spicy spray that caterpillars don't like. Spray this mixture on the plants, but be aware it will also be spicy to humans. Introduce beneficial insects. Release beneficial insects to the garden that eat caterpillars, such as parasitic wasps. For less severe cases: Hand pick. Using gloves, pick off caterpillars on plants and dispose of them in a bucket of soapy water. Dust plants with diatomaceous earth. This powder is harmless to humans but irritates caterpillars. Therefore, it will make it difficult for caterpillars to move and eat.
Brown spot
This infection can cause brown spots or patches to appear on the plant.
Solutions: In minor cases of brown spot, there isn’t any need to treat the disease. However, if much of the foliage is affected and defoliation occurs, the plant will benefit from getting rid of the infection. It is recommended to start by applying organic treatment options, working up to the more potent synthetic, chemical fungicides if necessary. Organic options won’t kill the fungus, but will prevent it from spreading. Dissolve ½ teaspoon of baking soda and one teaspoon of liquid soap in a gallon of water. Using a spray bottle, spray on tops and bottoms of leaves until the mixture drips off. Repeat every two weeks until existing spots stop enlarging and new spots no longer appear. Spray a copper-based fungicidal soap on the leaves, coating the top and bottom leaf surfaces. Reapply as directed on the product label. Copper penetrates the leaf surface and prevents germination of spores so the fungus cannot spread. Apply an all-purpose fungicide to the entire plant, following the label instructions carefully.
Scars
Any light-colored markings that appear on stems but which do not enlarge or multiply are simply scars that have healed.
Solutions: Each source of scarring requires a different approach to help your plant recover. Protect the trunk and leaves from physical damage like scrapes. If pests or disease are the cause of scarring, isolate the plant from others to avoid further spread. Some pests can be removed with organic remedies such as a soft cloth and soapy water solution or diluted isopropyl alcohol spray. Stop sunburn by moving your plant away from direct sunlight and making sure it has the water it needs. Frequent leaf or bud loss may be due to insufficient light or nutrients.
Yellow spot
Leaf spot can show up as yellow or white spots on the leaves.
Solutions: Diseases Fungicides can prevent the transmission of spores, but they may not treat the established infection. The first step is removing and disposing of all infected plant parts. Then apply recommended chemicals. For bacterial infections, apply a spray containing copper or streptomycin. For fungal infections, consult the local cooperative extension for recommendations on which fungicides will work best. Nutrient deficiency Apply a liquid fertilizer via foliar application to fix the deficiency quickly. Follow label directions regarding dosing instructions and application notes, such as not using before the rain or when temperatures are out of the recommended range. Incorrect watering Determine the water requirements for your specific plant, and follow accordingly. Some plants like consistently moist soil, and others like the soil to dry out slightly before being watered. Pests Thoroughly apply an insecticidal soap, an organic product like neem oil, or an appropriate chemical insecticide to the plant.
Powdery Mildew
Powdery mildew is a white mold that appears on leaves. It can be wiped away.
Solutions: As powdery Mildew spores are transported by the wind, it can be tricky to put a complete stop to the spread of the fungus. Luckily, there are several easy treatments for plants that are exhibiting symptoms: If powdery Mildew seems to be impacting isolated leaves or stems, they can simply be trimmed away and disposed of. Disinfect pruning tools after doing this. Remove any plant debris from the ground around the infected plants and dispose of it in the garbage. Then, cover the soil with a thick layer of mulch to limit reinfection. Milk sprays have been found to be useful in controlling powdery Mildew. Make up a spray consisting of 60% water and 40% milk and spray on the affected plants. This can also be used as a preventative measure. In cases where powdery Mildew is more widespread, plants can be sprayed with a mild sulfur- or copper-based fungicide or a non-toxic solution made from baking soda and soap. Sprays can help areas that have been recently infected, though they are less effective against well-established infections. If possible, try transplanting the plants to a sunnier location. Though powdery Mildew does fine in hot, dry conditions, it is unable to reproduce without some humidity. Putting plants in more direct sunlight can help stop the spread of the fungus. Trimming around closely-packed plants can help improve airflow, which also prevents the reproduction of the fungus.
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Leaf beetles
Leaf beetles are a class of colored insects 1 to 2 cm in size. They gnaw on leaves and petals resulting in small, round holes scattered over the surface.
Overview
Leaf beetles range in size from 1.5 mm to 2 cm. Both adult beetles and their larvae eat the leaves of many different types of plants. There are over 35,000 different species of leaf beetles, in a variety of colors including gold, green, yellow-striped, and red striped. Some of these have been mistaken for ladybirds because of their shape and coloring. They can be oval, round, or elongated in shape. These insect pests are most active in spring and summer.
If not controlled, leaf beetles can do a lot of damage to vegetable crops and ornamental plants. They feed on the leaves, flowers, stems, roots, and fruits of different plants. They can fly, which means it's easy for them to move from one plant to another. Some species of leaf beetles only target one specific crop, while others will target many different types of plants. Although a lot of the damage that they cause is cosmetic, an infestation can weaken a plant and leave it prone to other more problematic diseases.
Symptom Analysis
The first signs of a leaf beetles infestation are small visible holes in leaves. Leaves then become discolored and dark beetle droppings can be seen. As the leaves turn yellow and brown, they will drop off the plant onto the ground. Some leaves will appear skeletonized with only the veins still remaining.
Infestation begins in spring, when the adult beetles emerge from the soil and lay their eggs on the leaves of plants. When these eggs hatch, the young nymphs start munching on the leaves as they grow up. Once leaf beetles are large and mature, they'll fall to the ground and pupate in the soil over winter before starting the cycle all over again.
Leaf beetles also eat holes in fruits and vegetables. These can be seen as small round holes that sometimes have a larger brown area surrounding them.
Solutions
For less serious cases:
- Remove beetles, nymphs, and eggs. Remove all life stages of the beetles and kill them by placing them in a bucket of warm, soapy water. This can be done more easily by placing the bucket under affected leaves and shaking the plant. This method is most effective in the afternoon when leaf beetles are more active. Always dispose of insects in a sealed bag or container to avoid escape and spread.
To treat more serious infestations:
- Apply organic insecticides. Use naturally-derived insecticides before moving on to synthetic insecticides. Neem oil and pyrethrum are naturally-derived insecticides that should be applied following label instructions.
- Apply synthetic insecticides. Examples of insecticides effective for leaf beetles include carbaryl, permethrin, and bifenthrin. Apply insecticides according to label instructions.
Prevention
To prevent infestations of leaf beetles, follow these practices.
- Regularly check for beetles. To prevent large pest infestations, be proactive about frequently checking plants for pests and removing them quickly.
- Clear debris. Clear weeds and debris to remove areas where these beetles may overwinter and hide.
- Attract natural predators. Birds and other insects, such as wasps and ladybugs, are effective natural predators of leaf beetles. Encourage them to visit by including a diverse array of plants to provide habitat and food. Also, avoid applying broad-spectrum herbicides that can harm and kill beneficial insects.
- Plant aromatic herbs like mint, garlic, or rosemary, as these can repel leaf beetles.
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Caterpillars
Caterpillars are fleshy moth or butterfly larvae that come in an array of colors, patterns, and even hairstyles. They chew on leaves and flower petals, creating large, irregular holes.
Overview
Caterpillars can cause problems for home gardeners. If not managed, these insects can defoliate a plant in just a matter of days. However, home gardeners face a challenge because these caterpillars eventually turn into beautiful butterflies and moths, which are important for pollination and the general ecosystem.
There are thousands of different species of caterpillars and many will only target certain plants. If caterpillars are posing a problem, they can be removed by hand, or gardeners can use insect-proof netting to protect their valuable plants.
Symptom Analysis
Caterpillars are the larvae of butterflies and moths. During the warmer months, butterflies and moths that visit gardens will lay their eggs on the underside of leaves.
When the tiny eggs hatch, the young larvae emerge and start feeding on the leaves of the plant. Depending on how many larvae have hatched, they can easily defoliate the plant in a very short period of time. Caterpillars will shed their skin as they grow, around 4 or 5 times during this feeding cycle.
Symptoms of caterpillars eating plants appear as holes in the leaves. The edges of the leaves may be eaten away as well, and flowers can be affected as well.
Some are easy to see, but others need to be searched for. This is because their bodies are often camouflaged to look like part of the plant. Gardeners need to look carefully along the stems of the plant as well as under the leaves. Also, look for tiny white, yellow, or brown eggs that can be found in groups on the underside of leaves.
Once the caterpillar is fully grown, it transforms into a pupa or chrysalis. Then, after a period of time that varies according to the species, a butterfly or moth will emerge from the pupa and the cycle begins again.
Solutions
Even though caterpillars are diverse, they all chew on plant parts and can cause significant damage if present in large numbers.
For severe cases:
- Apply insecticide. For an organic solution, spray plants with a Bacillus thuringiensis (Bt), which specifically affects the larval stage of moths and butterflies. Be sure to coat plants, since caterpillars need to ingest Bt for it to be effective. This will not harm other insects.
- Spray a chili extract. Chili seeds can be cooked in water to make a spicy spray that caterpillars don't like. Spray this mixture on the plants, but be aware it will also be spicy to humans.
- Introduce beneficial insects. Release beneficial insects to the garden that eat caterpillars, such as parasitic wasps.
For less severe cases:
- Hand pick. Using gloves, pick off caterpillars on plants and dispose of them in a bucket of soapy water.
- Dust plants with diatomaceous earth. This powder is harmless to humans but irritates caterpillars. Therefore, it will make it difficult for caterpillars to move and eat.
Prevention
Prevention may require less effort than attempts to eradicate infestations that have already begun. Here are our top steps for prevention:
- Monitor plants. Check plants regularly for caterpillar eggs on leaves. If they do not belong to an endangered species, they should be squished.
- Use insect netting. Cover plants with insect netting to prevent butterflies and moths from laying eggs on plants.
- Apply diatomaceous earth. Apply DE to plants early in the season and reapply after rain.
- Encourage plant diversity. This will attract predatory insects including parasitic wasps.
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Brown spot
This infection can cause brown spots or patches to appear on the plant.
Overview
Discolored spots on the foliage of plants are one of the most common disease problems people observe. These spots are caused by fungal and bacterial diseases, with most infections related to a fungal pathogen.
Brown spot can occurs on all houseplants, flowering ornamentals, vegetable plants, and leaves of trees, bushes, and shrubs. No plants are resistant to it, and the problem is worse in warm, wet environments. It can occur at any point in the life stage as long as leaves are present.
Small brownish spots appear on the foliage and enlarge as the disease progresses. In severe cases, the plant or tree is weakened when the lesions interrupt photosynthesis or cause defoliation.
Symptom Analysis
In most cases, brown spot only affects a small percentage of the whole plant, appearing on a small amount of the leaves. A small infection only puts minor stress on the plant. However, if left untreated and the disease progresses over numerous seasons, it will severely impact the health and productivity of the infected specimen.
- Sporulation begins (reproduction of the fungal spores), and tiny spots appear on leaves.
- Placement is often random and scattered as diseases are spread through raindrops.
- May appear on lower leaves and the interior of the plant where humidity is higher.
- Brown spots enlarge and grow large enough to touch neighboring spots to form a more prominent blotch.
- Leaf margins may turn yellow.
- Tiny black dots (fruiting bodies of the fungi) appear in the dead spots.
- Blotches grow in size until the entire leaf is brown.
- The leaf falls off the plant.
Severe Symptoms
- Partial or complete premature defoliation
- Reduced growth
- Increased susceptibility to pests and other diseases
Disease Cause
Brown spot, or leaf spot, is a common descriptive term given to several diseases affecting the leaves of plants and trees. Around 85% of diseases exhibiting leaf spots are due to fungus or fungus-like organisms. Sometimes brown spot is caused by a bacterial infection, or insect activity with similar symptoms.
When conditions are warm and the leaf surfaces are wet, fungal spores being transported by wind or rain land on the surface and cling to it. They do not rupture the cell walls but grow in the space between the plant plasma membrane and the plant cell wall. As the spores reproduce, they release toxins and enzymes that cause necrotic spots (i.e., dead tissue) on the leaves, allowing the fungi to consume the products released when the cells degrade.
Solutions
In minor cases of brown spot, there isn’t any need to treat the disease. However, if much of the foliage is affected and defoliation occurs, the plant will benefit from getting rid of the infection. It is recommended to start by applying organic treatment options, working up to the more potent synthetic, chemical fungicides if necessary.
Organic options won’t kill the fungus, but will prevent it from spreading.
- Dissolve ½ teaspoon of baking soda and one teaspoon of liquid soap in a gallon of water. Using a spray bottle, spray on tops and bottoms of leaves until the mixture drips off. Repeat every two weeks until existing spots stop enlarging and new spots no longer appear.
- Spray a copper-based fungicidal soap on the leaves, coating the top and bottom leaf surfaces. Reapply as directed on the product label. Copper penetrates the leaf surface and prevents germination of spores so the fungus cannot spread.
- Apply an all-purpose fungicide to the entire plant, following the label instructions carefully.
Prevention
Like many other diseases, it is easier to prevent brown spot than cure it, and this is done through cultural practices.
- Clear fall leaves from the ground before winter to minimize places where fungi and bacteria can overwinter.
- Maintain good air movement between plants through proper plant spacing.
- Increase air circulation through the center of plants through pruning.
- Thoroughly clean all pruning tools after working with diseased plants.
- Never dispose of disease plant material in a compost pile.
- Avoid overhead watering to keep moisture off of the foliage.
- Keep plants healthy by providing adequate sunlight, water, and fertilizer.
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Scars
Any light-colored markings that appear on stems but which do not enlarge or multiply are simply scars that have healed.
Symptom Analysis
Scars form when the plant repairs wounds. They can be the result of people or pets passing by and scraping the plant. Once the underlying issue is resolved, the plant will heal but a scar may remain.
Pests and pathogens can also cause scarring. Insects may attack the plant for a meal, resulting in extensive scarring when a few invaders turn into an infestation. Diseases such as fungus and bacteria can weaken the plant, causing brown spots, mushy areas, or blisters that lead to scars.
Scars occur on stems when a leaf or bud has been lost and the plant has healed. The harder tissue is like a scab that protects a wound.
On other occasions, scars can signal problems from environmental conditions, such as overexposure to sunlight or heat. It might surprise you to know that plants can suffer from sunburn, even desert dwellers like cactus!
Solutions
Each source of scarring requires a different approach to help your plant recover.
- Protect the trunk and leaves from physical damage like scrapes.
- If pests or disease are the cause of scarring, isolate the plant from others to avoid further spread. Some pests can be removed with organic remedies such as a soft cloth and soapy water solution or diluted isopropyl alcohol spray.
- Stop sunburn by moving your plant away from direct sunlight and making sure it has the water it needs.
- Frequent leaf or bud loss may be due to insufficient light or nutrients.
Prevention
Preventing some sources of scarring is easier than others, but all start with careful attention to your plants once you decide to bring them home.
- Review specific guidelines for your plant, including soil drainage, watering, and fertilizer requirements.
- Inspect plants before planting and use sterile pots and fresh potting soil or media to limit transfer of fungi or bacteria.
- Once established, check your plants regularly for signs of scarring or the presence of pests, as it is better to catch problems as early as possible.
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Yellow spot
Leaf spot can show up as yellow or white spots on the leaves.
Overview
Yellow spot is a common condition that affects all types of plants -- flowering ornamentals, trees, shrubs, herbs, and vegetable plants -- worldwide. Yellow spots may appear because of dozens of potential causes and occur in various environmental and climatic conditions, but fortunately, most are easy to address. The most common causes of yellow spots include diseases, nutrient deficiency, watering problems, and pests.
In most cases, yellow spots can be treated without permanent damage to the plant. However, in some fungal disease cases, nothing can be done to treat the disease after infection, and the plant will ultimately perish from the disease.
Due to this, the most critical aspect of addressing yellow spots on plants is correctly determining the cause.
Symptom Analysis
Symptoms occur on varying parts of the plant, depending upon the cause. Smaller spots tend to be indicative of younger infections or newly developing problems.
- Small yellow spots appear on leaves
- Spots can occur on the lower or upper leaf surfaces, or both
- Raised, rounded, or sunken spots with fringed or smooth edges
- Spots may grow together, causing leaves to become totally discolored
- Stunted growth
- Premature leaf drop
Disease Cause
The vast majority of yellow spot diseases are caused by fungal pathogens. However, there are some situations in which bacteria, environmental conditions, or other issues may be blamed.
Diseases are typically host-specific, so they may only affect plants within the same family. That said, just about every single species of plant is vulnerable to at least one disease that causes yellow spot. The most common problems are leaf blight, leaf septoria, powdery mildew, and downy mildew, to name a few.
All plants need specific nutrients from the soil to survive. When these nutrients become depleted or unavailable for plant uptake due to particular conditions, deficiencies occur, and yellow spots are seen.
- Nitrogen is an integral component of chlorophyll.
- Iron is needed in the enzymes that make chlorophyll.
Yellow spots may also appear because of incorrect watering, mainly underwatering, or infestations of sap-sucking pests such as aphids.
- Too little water inhibits photosynthesis. Too much water pushes oxygen out of the soil and the roots cannot take in nutrients or even water from the soil.
- Insect problems can cause yellow spots directly by damaging leaf tissue when feeding, or they may introduce pathogens.
Solutions
Diseases
Fungicides can prevent the transmission of spores, but they may not treat the established infection. The first step is removing and disposing of all infected plant parts. Then apply recommended chemicals.
For bacterial infections, apply a spray containing copper or streptomycin.
For fungal infections, consult the local cooperative extension for recommendations on which fungicides will work best.
Nutrient deficiency
Apply a liquid fertilizer via foliar application to fix the deficiency quickly. Follow label directions regarding dosing instructions and application notes, such as not using before the rain or when temperatures are out of the recommended range.
Incorrect watering
Determine the water requirements for your specific plant, and follow accordingly. Some plants like consistently moist soil, and others like the soil to dry out slightly before being watered.
Pests
Thoroughly apply an insecticidal soap, an organic product like neem oil, or an appropriate chemical insecticide to the plant.
Prevention
Depending on the type of plant and which specific disease is causing yellow spot, problems may be avoided by taking the following preventative steps:
- Plant resistant varieties
- Avoid planting susceptible varieties close together - space susceptible plants further apart from one another so it’s more difficult for the fungal spores to find new plant hosts.
- Water wisely - water from below rather than splashing water on foliage. This can reduce the spread of both bacterial and fungal pathogens responsible for yellow spot.
- Prune - prune as a way of getting rid of affected leaves but also to control the spread of yellow spot to new plants. Pruning can also improve air circulation to limit disease spread.
- Rotate crops - many diseases, including downy mildew, can live in the soil over the winter and produce problems for many years. Rotate annual crops to new locations each year so that they aren’t growing anywhere in which plants in the same family were grown within the last three to four years.
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Powdery Mildew
Powdery mildew is a white mold that appears on leaves. It can be wiped away.
Overview
Powdery Mildew is a common disease and the scourge of many home gardeners. It affects a large variety of plants including many varieties of vegetables. The disease is easy to identify but not always easy to get rid of once it has started to infect plants.
Powdery Mildew thrives in warm, humid conditions and can quickly spread from plant to plant. Although this disease will not kill the plants, a severe infestation will inhibit plant growth and fruit production.
Symptom Analysis
Powdery Mildew appears as pale yellow spots on leaves. These spots then become white and look powdery. The fungus spreads quickly both on the top and underside of the leaves and on the plant stems.
These white, powdery spots will join up and soon, almost the entire surface of the leaf appears white. Eventually, the edges of the leaf will turn brown and dry and start to die.
In severe infections, even the flower buds will turn white and become disfigured. Fruit will ripen prematurely and be inedible.
Disease Cause
Powdery Mildew is caused by a fungus. There are many different genera of fungus diseases that cause powdery Mildew. The fungal spores overwinter inside leaf buds and on plant material that has dropped to the soil below. As the weather warms up, these spores are then carried onto the plant by water, wind, and insects. Powdery Mildew can also be more severe in areas that experience warm, dry climates, even though the spores require some humidity to germinate.
Solutions
As powdery Mildew spores are transported by the wind, it can be tricky to put a complete stop to the spread of the fungus. Luckily, there are several easy treatments for plants that are exhibiting symptoms:
- If powdery Mildew seems to be impacting isolated leaves or stems, they can simply be trimmed away and disposed of. Disinfect pruning tools after doing this.
- Remove any plant debris from the ground around the infected plants and dispose of it in the garbage. Then, cover the soil with a thick layer of mulch to limit reinfection.
- Milk sprays have been found to be useful in controlling powdery Mildew. Make up a spray consisting of 60% water and 40% milk and spray on the affected plants. This can also be used as a preventative measure.
- In cases where powdery Mildew is more widespread, plants can be sprayed with a mild sulfur- or copper-based fungicide or a non-toxic solution made from baking soda and soap. Sprays can help areas that have been recently infected, though they are less effective against well-established infections.
- If possible, try transplanting the plants to a sunnier location. Though powdery Mildew does fine in hot, dry conditions, it is unable to reproduce without some humidity. Putting plants in more direct sunlight can help stop the spread of the fungus.
- Trimming around closely-packed plants can help improve airflow, which also prevents the reproduction of the fungus.
Prevention
There are a few ways to prevent a powdery Mildew infection from occurring in the first place:
- Preemptive chemical controls, including fungicides and non-toxic solutions, can help prevent powdery Mildew from becoming established on plants.
- When placing new plants, allow enough space between each one to provide adequate air circulation.
- Water at the base of plants rather than from overhead.
- Many mildew-resistant strains of common garden plants are available. Consider these in areas that have a Mediterranean climate.
- Powdery Mildew can form tiny, round black structures, called cleistothecia, as the growing season draws to a close. These hardy, dry structures help the fungus survive winter. Raking away debris over the winter can remove stowaway cleistothecia and will help prevent plants from being reinfected.
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Distribution Map
Habitat
Wilderness, cultivated land, coastal districts, ravine slopes, creeks
Native
Cultivated
Invasive
Potentially invasive
Exotic
No species reported
More Info
Plant Type
Herb
Flower Color
White
Bloom Time
Late spring, Early summer
Leaf Color
Red
Orange
Purple
Name story
Large purple alternanthera||Purple joyweed
Brazilian joyweed got its name from its purple flowers. The name Alternanthera was derived from the Latin 'alterno', meaning ‘to alternate', and the Greek word 'anthera' which refers to plant's anthers. The coin indicates that the plants in this genus are alternatively fertile and sterile.
Usages
Garden Use
Brazilian joyweed and its popular cultivars are grown for their uniquely-colored foliage, which ranges from green to purple to burgundy, and bushy, easy-to-care-for growth habit. These plants are best grown in masses and used along borders, as hedging or in containers, especially in wildlife and naturalistic gardens.
Scientific Classification
Phylum
Vascular plants Class
Dicotyledons Order
Pinks, cacti, and allies Family
Amaranth Genus
Joseph's coat Species
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Add to My Garden Brazilian joyweed
Alternanthera brasiliana
Also known as: Purple joyweed, Metal weed, Bloodleaf, Calico plant
Every week
Water
Partial sun
Sunlight
Care Guide for Brazilian joyweed
Water
Brazilian joyweed should be grown in well-drained soils that are consistently moist. Gardeners should water Brazilian joyweed before its soil fully dries out to keep the soil damp. Once established, it can be heat and drought-tolerant.
Fertilization
Brazilian joyweed's blooms can be encouraged with a high phosphorous fertilizer. It can be treated every three weeks with liquid fertilizer. If using granular fertilizer, it should be fed monthly.
Pruning
Trim the diseased, withered leaves once a month.
Potting Suggestions
Needs excellent drainage in pots.
Sunlight
Partial sun, Full sun, Full shade
Tips, advice, and instructions for over 13,000 species that you will find nowhere else
Brazilian joyweed
Alternanthera brasiliana
Water
Every week
Sunlight
Partial sun
Hardiness Zones
10 to 11
Planting Time
Spring, Fall
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Questions About Brazilian joyweed
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Common Pests & Diseases
Common issues for Brazilian joyweed based on 10 million real cases
Leaf beetles
Leaf beetles are a class of colored insects 1 to 2 cm in size. They gnaw on leaves and petals resulting in small, round holes scattered over the surface.
Solutions: For less serious cases: Remove beetles, nymphs, and eggs. Remove all life stages of the beetles and kill them by placing them in a bucket of warm, soapy water. This can be done more easily by placing the bucket under affected leaves and shaking the plant. This method is most effective in the afternoon when leaf beetles are more active. Always dispose of insects in a sealed bag or container to avoid escape and spread. To treat more serious infestations: Apply organic insecticides. Use naturally-derived insecticides before moving on to synthetic insecticides. Neem oil and pyrethrum are naturally-derived insecticides that should be applied following label instructions. Apply synthetic insecticides. Examples of insecticides effective for leaf beetles include carbaryl, permethrin, and bifenthrin. Apply insecticides according to label instructions.
Learn More ![more]()
Caterpillars
Caterpillars are fleshy moth or butterfly larvae that come in an array of colors, patterns, and even hairstyles. They chew on leaves and flower petals, creating large, irregular holes.
Solutions: Even though caterpillars are diverse, they all chew on plant parts and can cause significant damage if present in large numbers. For severe cases: Apply insecticide. For an organic solution, spray plants with a Bacillus thuringiensis (Bt), which specifically affects the larval stage of moths and butterflies. Be sure to coat plants, since caterpillars need to ingest Bt for it to be effective. This will not harm other insects. Spray a chili extract. Chili seeds can be cooked in water to make a spicy spray that caterpillars don't like. Spray this mixture on the plants, but be aware it will also be spicy to humans. Introduce beneficial insects. Release beneficial insects to the garden that eat caterpillars, such as parasitic wasps. For less severe cases: Hand pick. Using gloves, pick off caterpillars on plants and dispose of them in a bucket of soapy water. Dust plants with diatomaceous earth. This powder is harmless to humans but irritates caterpillars. Therefore, it will make it difficult for caterpillars to move and eat.
Learn More ![more]()
Brown spot
This infection can cause brown spots or patches to appear on the plant.
Solutions: In minor cases of brown spot, there isn’t any need to treat the disease. However, if much of the foliage is affected and defoliation occurs, the plant will benefit from getting rid of the infection. It is recommended to start by applying organic treatment options, working up to the more potent synthetic, chemical fungicides if necessary. Organic options won’t kill the fungus, but will prevent it from spreading. Dissolve ½ teaspoon of baking soda and one teaspoon of liquid soap in a gallon of water. Using a spray bottle, spray on tops and bottoms of leaves until the mixture drips off. Repeat every two weeks until existing spots stop enlarging and new spots no longer appear. Spray a copper-based fungicidal soap on the leaves, coating the top and bottom leaf surfaces. Reapply as directed on the product label. Copper penetrates the leaf surface and prevents germination of spores so the fungus cannot spread. Apply an all-purpose fungicide to the entire plant, following the label instructions carefully.
Learn More ![more]()
Scars
Any light-colored markings that appear on stems but which do not enlarge or multiply are simply scars that have healed.
Solutions: Each source of scarring requires a different approach to help your plant recover. Protect the trunk and leaves from physical damage like scrapes. If pests or disease are the cause of scarring, isolate the plant from others to avoid further spread. Some pests can be removed with organic remedies such as a soft cloth and soapy water solution or diluted isopropyl alcohol spray. Stop sunburn by moving your plant away from direct sunlight and making sure it has the water it needs. Frequent leaf or bud loss may be due to insufficient light or nutrients.
Learn More ![more]()
Yellow spot
Leaf spot can show up as yellow or white spots on the leaves.
Solutions: Diseases Fungicides can prevent the transmission of spores, but they may not treat the established infection. The first step is removing and disposing of all infected plant parts. Then apply recommended chemicals. For bacterial infections, apply a spray containing copper or streptomycin. For fungal infections, consult the local cooperative extension for recommendations on which fungicides will work best. Nutrient deficiency Apply a liquid fertilizer via foliar application to fix the deficiency quickly. Follow label directions regarding dosing instructions and application notes, such as not using before the rain or when temperatures are out of the recommended range. Incorrect watering Determine the water requirements for your specific plant, and follow accordingly. Some plants like consistently moist soil, and others like the soil to dry out slightly before being watered. Pests Thoroughly apply an insecticidal soap, an organic product like neem oil, or an appropriate chemical insecticide to the plant.
Learn More ![more]()
Powdery Mildew
Powdery mildew is a white mold that appears on leaves. It can be wiped away.
Solutions: As powdery Mildew spores are transported by the wind, it can be tricky to put a complete stop to the spread of the fungus. Luckily, there are several easy treatments for plants that are exhibiting symptoms: If powdery Mildew seems to be impacting isolated leaves or stems, they can simply be trimmed away and disposed of. Disinfect pruning tools after doing this. Remove any plant debris from the ground around the infected plants and dispose of it in the garbage. Then, cover the soil with a thick layer of mulch to limit reinfection. Milk sprays have been found to be useful in controlling powdery Mildew. Make up a spray consisting of 60% water and 40% milk and spray on the affected plants. This can also be used as a preventative measure. In cases where powdery Mildew is more widespread, plants can be sprayed with a mild sulfur- or copper-based fungicide or a non-toxic solution made from baking soda and soap. Sprays can help areas that have been recently infected, though they are less effective against well-established infections. If possible, try transplanting the plants to a sunnier location. Though powdery Mildew does fine in hot, dry conditions, it is unable to reproduce without some humidity. Putting plants in more direct sunlight can help stop the spread of the fungus. Trimming around closely-packed plants can help improve airflow, which also prevents the reproduction of the fungus.
Learn More ![more]()
Keep your leafy friends healthy and happy.
Diagnose your plant, and learn how to prevent and treat plant diseases.
Leaf beetles
Leaf beetles are a class of colored insects 1 to 2 cm in size. They gnaw on leaves and petals resulting in small, round holes scattered over the surface.
Overview
Leaf beetles range in size from 1.5 mm to 2 cm. Both adult beetles and their larvae eat the leaves of many different types of plants. There are over 35,000 different species of leaf beetles, in a variety of colors including gold, green, yellow-striped, and red striped. Some of these have been mistaken for ladybirds because of their shape and coloring. They can be oval, round, or elongated in shape. These insect pests are most active in spring and summer.
If not controlled, leaf beetles can do a lot of damage to vegetable crops and ornamental plants. They feed on the leaves, flowers, stems, roots, and fruits of different plants. They can fly, which means it's easy for them to move from one plant to another. Some species of leaf beetles only target one specific crop, while others will target many different types of plants. Although a lot of the damage that they cause is cosmetic, an infestation can weaken a plant and leave it prone to other more problematic diseases.
Symptom Analysis
The first signs of a leaf beetles infestation are small visible holes in leaves. Leaves then become discolored and dark beetle droppings can be seen. As the leaves turn yellow and brown, they will drop off the plant onto the ground. Some leaves will appear skeletonized with only the veins still remaining.
Infestation begins in spring, when the adult beetles emerge from the soil and lay their eggs on the leaves of plants. When these eggs hatch, the young nymphs start munching on the leaves as they grow up. Once leaf beetles are large and mature, they'll fall to the ground and pupate in the soil over winter before starting the cycle all over again.
Leaf beetles also eat holes in fruits and vegetables. These can be seen as small round holes that sometimes have a larger brown area surrounding them.
Solutions
For less serious cases:
- Remove beetles, nymphs, and eggs. Remove all life stages of the beetles and kill them by placing them in a bucket of warm, soapy water. This can be done more easily by placing the bucket under affected leaves and shaking the plant. This method is most effective in the afternoon when leaf beetles are more active. Always dispose of insects in a sealed bag or container to avoid escape and spread.
To treat more serious infestations:
- Apply organic insecticides. Use naturally-derived insecticides before moving on to synthetic insecticides. Neem oil and pyrethrum are naturally-derived insecticides that should be applied following label instructions.
- Apply synthetic insecticides. Examples of insecticides effective for leaf beetles include carbaryl, permethrin, and bifenthrin. Apply insecticides according to label instructions.
Prevention
To prevent infestations of leaf beetles, follow these practices.
- Regularly check for beetles. To prevent large pest infestations, be proactive about frequently checking plants for pests and removing them quickly.
- Clear debris. Clear weeds and debris to remove areas where these beetles may overwinter and hide.
- Attract natural predators. Birds and other insects, such as wasps and ladybugs, are effective natural predators of leaf beetles. Encourage them to visit by including a diverse array of plants to provide habitat and food. Also, avoid applying broad-spectrum herbicides that can harm and kill beneficial insects.
- Plant aromatic herbs like mint, garlic, or rosemary, as these can repel leaf beetles.
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Caterpillars
Caterpillars are fleshy moth or butterfly larvae that come in an array of colors, patterns, and even hairstyles. They chew on leaves and flower petals, creating large, irregular holes.
Overview
Caterpillars can cause problems for home gardeners. If not managed, these insects can defoliate a plant in just a matter of days. However, home gardeners face a challenge because these caterpillars eventually turn into beautiful butterflies and moths, which are important for pollination and the general ecosystem.
There are thousands of different species of caterpillars and many will only target certain plants. If caterpillars are posing a problem, they can be removed by hand, or gardeners can use insect-proof netting to protect their valuable plants.
Symptom Analysis
Caterpillars are the larvae of butterflies and moths. During the warmer months, butterflies and moths that visit gardens will lay their eggs on the underside of leaves.
When the tiny eggs hatch, the young larvae emerge and start feeding on the leaves of the plant. Depending on how many larvae have hatched, they can easily defoliate the plant in a very short period of time. Caterpillars will shed their skin as they grow, around 4 or 5 times during this feeding cycle.
Symptoms of caterpillars eating plants appear as holes in the leaves. The edges of the leaves may be eaten away as well, and flowers can be affected as well.
Some are easy to see, but others need to be searched for. This is because their bodies are often camouflaged to look like part of the plant. Gardeners need to look carefully along the stems of the plant as well as under the leaves. Also, look for tiny white, yellow, or brown eggs that can be found in groups on the underside of leaves.
Once the caterpillar is fully grown, it transforms into a pupa or chrysalis. Then, after a period of time that varies according to the species, a butterfly or moth will emerge from the pupa and the cycle begins again.
Solutions
Even though caterpillars are diverse, they all chew on plant parts and can cause significant damage if present in large numbers.
For severe cases:
- Apply insecticide. For an organic solution, spray plants with a Bacillus thuringiensis (Bt), which specifically affects the larval stage of moths and butterflies. Be sure to coat plants, since caterpillars need to ingest Bt for it to be effective. This will not harm other insects.
- Spray a chili extract. Chili seeds can be cooked in water to make a spicy spray that caterpillars don't like. Spray this mixture on the plants, but be aware it will also be spicy to humans.
- Introduce beneficial insects. Release beneficial insects to the garden that eat caterpillars, such as parasitic wasps.
For less severe cases:
- Hand pick. Using gloves, pick off caterpillars on plants and dispose of them in a bucket of soapy water.
- Dust plants with diatomaceous earth. This powder is harmless to humans but irritates caterpillars. Therefore, it will make it difficult for caterpillars to move and eat.
Prevention
Prevention may require less effort than attempts to eradicate infestations that have already begun. Here are our top steps for prevention:
- Monitor plants. Check plants regularly for caterpillar eggs on leaves. If they do not belong to an endangered species, they should be squished.
- Use insect netting. Cover plants with insect netting to prevent butterflies and moths from laying eggs on plants.
- Apply diatomaceous earth. Apply DE to plants early in the season and reapply after rain.
- Encourage plant diversity. This will attract predatory insects including parasitic wasps.
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Brown spot
This infection can cause brown spots or patches to appear on the plant.
Overview
Discolored spots on the foliage of plants are one of the most common disease problems people observe. These spots are caused by fungal and bacterial diseases, with most infections related to a fungal pathogen.
Brown spot can occurs on all houseplants, flowering ornamentals, vegetable plants, and leaves of trees, bushes, and shrubs. No plants are resistant to it, and the problem is worse in warm, wet environments. It can occur at any point in the life stage as long as leaves are present.
Small brownish spots appear on the foliage and enlarge as the disease progresses. In severe cases, the plant or tree is weakened when the lesions interrupt photosynthesis or cause defoliation.
Symptom Analysis
In most cases, brown spot only affects a small percentage of the whole plant, appearing on a small amount of the leaves. A small infection only puts minor stress on the plant. However, if left untreated and the disease progresses over numerous seasons, it will severely impact the health and productivity of the infected specimen.
- Sporulation begins (reproduction of the fungal spores), and tiny spots appear on leaves.
- Placement is often random and scattered as diseases are spread through raindrops.
- May appear on lower leaves and the interior of the plant where humidity is higher.
- Brown spots enlarge and grow large enough to touch neighboring spots to form a more prominent blotch.
- Leaf margins may turn yellow.
- Tiny black dots (fruiting bodies of the fungi) appear in the dead spots.
- Blotches grow in size until the entire leaf is brown.
- The leaf falls off the plant.
Severe Symptoms
- Partial or complete premature defoliation
- Reduced growth
- Increased susceptibility to pests and other diseases
Disease Cause
Brown spot, or leaf spot, is a common descriptive term given to several diseases affecting the leaves of plants and trees. Around 85% of diseases exhibiting leaf spots are due to fungus or fungus-like organisms. Sometimes brown spot is caused by a bacterial infection, or insect activity with similar symptoms.
When conditions are warm and the leaf surfaces are wet, fungal spores being transported by wind or rain land on the surface and cling to it. They do not rupture the cell walls but grow in the space between the plant plasma membrane and the plant cell wall. As the spores reproduce, they release toxins and enzymes that cause necrotic spots (i.e., dead tissue) on the leaves, allowing the fungi to consume the products released when the cells degrade.
Solutions
In minor cases of brown spot, there isn’t any need to treat the disease. However, if much of the foliage is affected and defoliation occurs, the plant will benefit from getting rid of the infection. It is recommended to start by applying organic treatment options, working up to the more potent synthetic, chemical fungicides if necessary.
Organic options won’t kill the fungus, but will prevent it from spreading.
- Dissolve ½ teaspoon of baking soda and one teaspoon of liquid soap in a gallon of water. Using a spray bottle, spray on tops and bottoms of leaves until the mixture drips off. Repeat every two weeks until existing spots stop enlarging and new spots no longer appear.
- Spray a copper-based fungicidal soap on the leaves, coating the top and bottom leaf surfaces. Reapply as directed on the product label. Copper penetrates the leaf surface and prevents germination of spores so the fungus cannot spread.
- Apply an all-purpose fungicide to the entire plant, following the label instructions carefully.
Prevention
Like many other diseases, it is easier to prevent brown spot than cure it, and this is done through cultural practices.
- Clear fall leaves from the ground before winter to minimize places where fungi and bacteria can overwinter.
- Maintain good air movement between plants through proper plant spacing.
- Increase air circulation through the center of plants through pruning.
- Thoroughly clean all pruning tools after working with diseased plants.
- Never dispose of disease plant material in a compost pile.
- Avoid overhead watering to keep moisture off of the foliage.
- Keep plants healthy by providing adequate sunlight, water, and fertilizer.
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Scars
Any light-colored markings that appear on stems but which do not enlarge or multiply are simply scars that have healed.
Symptom Analysis
Scars form when the plant repairs wounds. They can be the result of people or pets passing by and scraping the plant. Once the underlying issue is resolved, the plant will heal but a scar may remain.
Pests and pathogens can also cause scarring. Insects may attack the plant for a meal, resulting in extensive scarring when a few invaders turn into an infestation. Diseases such as fungus and bacteria can weaken the plant, causing brown spots, mushy areas, or blisters that lead to scars.
Scars occur on stems when a leaf or bud has been lost and the plant has healed. The harder tissue is like a scab that protects a wound.
On other occasions, scars can signal problems from environmental conditions, such as overexposure to sunlight or heat. It might surprise you to know that plants can suffer from sunburn, even desert dwellers like cactus!
Solutions
Each source of scarring requires a different approach to help your plant recover.
- Protect the trunk and leaves from physical damage like scrapes.
- If pests or disease are the cause of scarring, isolate the plant from others to avoid further spread. Some pests can be removed with organic remedies such as a soft cloth and soapy water solution or diluted isopropyl alcohol spray.
- Stop sunburn by moving your plant away from direct sunlight and making sure it has the water it needs.
- Frequent leaf or bud loss may be due to insufficient light or nutrients.
Prevention
Preventing some sources of scarring is easier than others, but all start with careful attention to your plants once you decide to bring them home.
- Review specific guidelines for your plant, including soil drainage, watering, and fertilizer requirements.
- Inspect plants before planting and use sterile pots and fresh potting soil or media to limit transfer of fungi or bacteria.
- Once established, check your plants regularly for signs of scarring or the presence of pests, as it is better to catch problems as early as possible.
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Yellow spot
Leaf spot can show up as yellow or white spots on the leaves.
Overview
Yellow spot is a common condition that affects all types of plants -- flowering ornamentals, trees, shrubs, herbs, and vegetable plants -- worldwide. Yellow spots may appear because of dozens of potential causes and occur in various environmental and climatic conditions, but fortunately, most are easy to address. The most common causes of yellow spots include diseases, nutrient deficiency, watering problems, and pests.
In most cases, yellow spots can be treated without permanent damage to the plant. However, in some fungal disease cases, nothing can be done to treat the disease after infection, and the plant will ultimately perish from the disease.
Due to this, the most critical aspect of addressing yellow spots on plants is correctly determining the cause.
Symptom Analysis
Symptoms occur on varying parts of the plant, depending upon the cause. Smaller spots tend to be indicative of younger infections or newly developing problems.
- Small yellow spots appear on leaves
- Spots can occur on the lower or upper leaf surfaces, or both
- Raised, rounded, or sunken spots with fringed or smooth edges
- Spots may grow together, causing leaves to become totally discolored
- Stunted growth
- Premature leaf drop
Disease Cause
The vast majority of yellow spot diseases are caused by fungal pathogens. However, there are some situations in which bacteria, environmental conditions, or other issues may be blamed.
Diseases are typically host-specific, so they may only affect plants within the same family. That said, just about every single species of plant is vulnerable to at least one disease that causes yellow spot. The most common problems are leaf blight, leaf septoria, powdery mildew, and downy mildew, to name a few.
All plants need specific nutrients from the soil to survive. When these nutrients become depleted or unavailable for plant uptake due to particular conditions, deficiencies occur, and yellow spots are seen.
- Nitrogen is an integral component of chlorophyll.
- Iron is needed in the enzymes that make chlorophyll.
Yellow spots may also appear because of incorrect watering, mainly underwatering, or infestations of sap-sucking pests such as aphids.
- Too little water inhibits photosynthesis. Too much water pushes oxygen out of the soil and the roots cannot take in nutrients or even water from the soil.
- Insect problems can cause yellow spots directly by damaging leaf tissue when feeding, or they may introduce pathogens.
Solutions
Diseases
Fungicides can prevent the transmission of spores, but they may not treat the established infection. The first step is removing and disposing of all infected plant parts. Then apply recommended chemicals.
For bacterial infections, apply a spray containing copper or streptomycin.
For fungal infections, consult the local cooperative extension for recommendations on which fungicides will work best.
Nutrient deficiency
Apply a liquid fertilizer via foliar application to fix the deficiency quickly. Follow label directions regarding dosing instructions and application notes, such as not using before the rain or when temperatures are out of the recommended range.
Incorrect watering
Determine the water requirements for your specific plant, and follow accordingly. Some plants like consistently moist soil, and others like the soil to dry out slightly before being watered.
Pests
Thoroughly apply an insecticidal soap, an organic product like neem oil, or an appropriate chemical insecticide to the plant.
Prevention
Depending on the type of plant and which specific disease is causing yellow spot, problems may be avoided by taking the following preventative steps:
- Plant resistant varieties
- Avoid planting susceptible varieties close together - space susceptible plants further apart from one another so it’s more difficult for the fungal spores to find new plant hosts.
- Water wisely - water from below rather than splashing water on foliage. This can reduce the spread of both bacterial and fungal pathogens responsible for yellow spot.
- Prune - prune as a way of getting rid of affected leaves but also to control the spread of yellow spot to new plants. Pruning can also improve air circulation to limit disease spread.
- Rotate crops - many diseases, including downy mildew, can live in the soil over the winter and produce problems for many years. Rotate annual crops to new locations each year so that they aren’t growing anywhere in which plants in the same family were grown within the last three to four years.
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Powdery Mildew
Powdery mildew is a white mold that appears on leaves. It can be wiped away.
Overview
Powdery Mildew is a common disease and the scourge of many home gardeners. It affects a large variety of plants including many varieties of vegetables. The disease is easy to identify but not always easy to get rid of once it has started to infect plants.
Powdery Mildew thrives in warm, humid conditions and can quickly spread from plant to plant. Although this disease will not kill the plants, a severe infestation will inhibit plant growth and fruit production.
Symptom Analysis
Powdery Mildew appears as pale yellow spots on leaves. These spots then become white and look powdery. The fungus spreads quickly both on the top and underside of the leaves and on the plant stems.
These white, powdery spots will join up and soon, almost the entire surface of the leaf appears white. Eventually, the edges of the leaf will turn brown and dry and start to die.
In severe infections, even the flower buds will turn white and become disfigured. Fruit will ripen prematurely and be inedible.
Disease Cause
Powdery Mildew is caused by a fungus. There are many different genera of fungus diseases that cause powdery Mildew. The fungal spores overwinter inside leaf buds and on plant material that has dropped to the soil below. As the weather warms up, these spores are then carried onto the plant by water, wind, and insects. Powdery Mildew can also be more severe in areas that experience warm, dry climates, even though the spores require some humidity to germinate.
Solutions
As powdery Mildew spores are transported by the wind, it can be tricky to put a complete stop to the spread of the fungus. Luckily, there are several easy treatments for plants that are exhibiting symptoms:
- If powdery Mildew seems to be impacting isolated leaves or stems, they can simply be trimmed away and disposed of. Disinfect pruning tools after doing this.
- Remove any plant debris from the ground around the infected plants and dispose of it in the garbage. Then, cover the soil with a thick layer of mulch to limit reinfection.
- Milk sprays have been found to be useful in controlling powdery Mildew. Make up a spray consisting of 60% water and 40% milk and spray on the affected plants. This can also be used as a preventative measure.
- In cases where powdery Mildew is more widespread, plants can be sprayed with a mild sulfur- or copper-based fungicide or a non-toxic solution made from baking soda and soap. Sprays can help areas that have been recently infected, though they are less effective against well-established infections.
- If possible, try transplanting the plants to a sunnier location. Though powdery Mildew does fine in hot, dry conditions, it is unable to reproduce without some humidity. Putting plants in more direct sunlight can help stop the spread of the fungus.
- Trimming around closely-packed plants can help improve airflow, which also prevents the reproduction of the fungus.
Prevention
There are a few ways to prevent a powdery Mildew infection from occurring in the first place:
- Preemptive chemical controls, including fungicides and non-toxic solutions, can help prevent powdery Mildew from becoming established on plants.
- When placing new plants, allow enough space between each one to provide adequate air circulation.
- Water at the base of plants rather than from overhead.
- Many mildew-resistant strains of common garden plants are available. Consider these in areas that have a Mediterranean climate.
- Powdery Mildew can form tiny, round black structures, called cleistothecia, as the growing season draws to a close. These hardy, dry structures help the fungus survive winter. Raking away debris over the winter can remove stowaway cleistothecia and will help prevent plants from being reinfected.
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Distribution Map
Habitat
Wilderness, cultivated land, coastal districts, ravine slopes, creeks
Map
Native
Cultivated
Invasive
Potentially invasive
Exotic
No species reported
More Info
Plant Type
Herb
Flower Color
White
Bloom Time
Late spring, Early summer
Leaf Color
Red
Orange
Purple
Name story
Large purple alternanthera||Purple joyweed
Brazilian joyweed got its name from its purple flowers. The name Alternanthera was derived from the Latin 'alterno', meaning ‘to alternate', and the Greek word 'anthera' which refers to plant's anthers. The coin indicates that the plants in this genus are alternatively fertile and sterile.
Usages
Garden Use
Brazilian joyweed and its popular cultivars are grown for their uniquely-colored foliage, which ranges from green to purple to burgundy, and bushy, easy-to-care-for growth habit. These plants are best grown in masses and used along borders, as hedging or in containers, especially in wildlife and naturalistic gardens.
Scientific Classification
Phylum
Vascular plants Class
Dicotyledons Order
Pinks, cacti, and allies Family
Amaranth Genus
Joseph's coat Species
Brazilian joyweed Related Plants
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