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Marigolds are common companion plants, which appear to repel many pest insects. They are fairly resistant to insect issues, but diseases in marigold plants are an occasional problem. The most prevalent diseases are fungal and affect stems, leaves, and roots. Marigold plant diseases are relatively easy to diagnose and treat, however. In fact, most can be cured by using different cultural methods.
Among the most common marigold diseases are blights, rots, and mildews. Usually, these types of diseases show up when conditions are wet and warm, and fungal spores are rampant. In most cases, simply discontinuing overhead watering can stop the formation and spread of spores. As mentioned, fungal marigold plant diseases occur most often. These might be Aster yellows, wilt, and stem rot, collar rot, flower bud rot, and damping off when in the seedling phase. Fungicide applications can help in controlling diseases of marigold caused by fungus along with avoiding overhead irrigation. Powdery mildew is another fungal disease that affects all kinds of plants. It is recognized by a powdery white film on leaves and other surfaces. Spraying a mixture of baking soda, water, and a touch of dish soap is an effective weapon. Correct timing when watering plants will allow the moisture to dry on foliage and is another effective strategy to avoid fungal diseases like this. Additionally, ensure that you have correct drainage in your containers and beds.
African marigolds are a popular choice for gardens thanks to their vibrant colors and ability to repel certain insects However, these hardy annuals can still fall victim to some tricky pests that can damage their flowers and stunt plant growth. As an avid gardener, I want to keep my marigold bed looking its best all season long So over the years, through trial and error, I’ve learned how to identify and treat the most common marigold pests effectively. Here is my guide to the usual suspects and how to outsmart them naturally so your flowers can thrive.
Aphids
These tiny pear-shaped insects seem to love sucking the sap right out of marigold stems and leaves. The worst part is they leave behind a clear sticky residue called honeydew which can attract even more pests.
How to Identify
Look for tiny teardrop-shaped bugs clustered on stems and the undersides of leaves. They may be green, yellow, black or peach colored Leaves can appear wrinkled or curled as a result of their damage.
Organic Treatments
I’ve had great success controlling aphids by spraying leaves with a strong jet of water to knock them off. Insecticidal soap or neem oil also suffocate them on contact. Finally, ladybugs love to munch on aphids, so I always welcome them to my garden. Their larvae can devour up to 60 aphids a day!
Spider Mites
Spider mites are members of the arachnid family and attack plants by sucking sap using their needle-like mouths. They get their name from the fine webs they leave behind on leaves.
How to Identify
Check the undersides of leaves for the tiny red or yellow mites themselves, which are practically invisible to the naked eye. Their webbing and speckled yellow leaf damage are better indicators. Leaves may also appear bronzed or dried out when infestations are high.
Organic Treatments
I find insecticidal soap or neem oil sprayed generously on leaves to be effective. Introducing predatory mites like Phytoseiulus persimilis also helps reduce populations. They’re available online or from garden centers.
Whiteflies
If tiny white moth-like insects take flight when you brush against your marigolds, you likely have whiteflies. They feed on sap like aphids and excrete honeydew.
How to Identify
Carefully look through the upper and lower leaves for whiteflies themselves or their pinhead-sized yellow eggs. Leaves may turn yellow or dry out when they are present.
Organic Treatments
I hang up yellow sticky traps around plants to capture adults. Spraying the leaves with insecticidal soap or neem oil coated in a light horticultural oil helps smother eggs and nymphs. Releasing mini wasps also naturally controls them.
Caterpillars
Marigolds attract certain visiting caterpillars like the cabbage looper, corn earworm and tobacco budworm. They munch on leaves and can completely defoliate plants if not controlled.
How to Identify
Chewed leaves and green caterpillars with stripes are a dead giveaway. Look for them on the underside of leaves or inside developing buds. Frass (caterpillar poop) is another clear sign!
Organic Treatments
I handpick any caterpillars I spot and drop them into soapy water. Spraying Bacillus thuringiensis (Bt) bacteria onto leaves is also very effective at killing young larvae. Encouraging parasitic wasps and birds naturally helps too.
Thrips
These tiny slender insects rasp leaf surfaces and suck out the contents, leaving behind silver patches. They also can transmit plant viruses.
How to Identify
Leaves with a sandpaper-like texture or silver streaks are signs of thrips damage. You may be able to spot the dark or straw colored thrips on close inspection inside curled leaves or unopened buds.
Organic Treatments
Spraying insecticidal soap directly on thrips provides good control. Releasing predatory mites or minute pirate bugs can help reduce their numbers naturally over time too.
By inspecting plants frequently and taking action at the first signs of infestation, I can usually get pests under control before they destroy my marigolds. I prefer to use organic sprays and introduce beneficial insects whenever possible to create a naturally balanced garden ecosystem. Vigilance and prompt treatment help ensure my marigolds stay strong and keep blooming beautifully all season long! What are your best tips for protecting marigolds from pesky invaders? I’d love to hear what has worked for you.
Controlling Diseases of Marigold
Hindsight is 20/20, but prevention is a crucial part of the strategy.
- Most marigold plant diseases will be due to fungal spores, so correct watering is key.
- Removing infected plant material can also help limit the spread of disease.
- Amend soil with well-rotted compost. If you have heavy clay soil, add sand or other grit to loosen the soil.
- Use containers that drain well and avoid using saucers, which can catch water and cause root rot.
- Use pathogen free potting mixes or sterilize your soil before planting marigolds. If you had an infected plant in the past, use bleach to clean containers before installing any new plant species.
- Choose French and dwarf varieties of marigold, rather than the African species.
Fortunately, problems with marigolds are rare and easily fixed, leaving you with happy plants and a season of golden blooms.
Other Diseases in Marigold Plants
While many issues can be caused by inadequate nutrients, nutrient excesses in soil can also lead to many plant ailments. Leaf burn, where the tips of leaves and new growth yellow and die, is the result of surplus boron, manganese, or molybdenum. When using fertilizer, be certain your soil needs the amount of nutrients it contains. Soil levels for boron should be 55 parts per million, manganese 24 ppm, and molybdenum just 3 ppm. It may be necessary to perform a soil test to determine what nutrients are already in the soil. Marigolds are not tolerant of low pH soils. This causes manganese or iron toxicity, which will cause leaves to brown and speckle. If pH is too low, you will need to amend the soil with lime for the next years plants. Bacterial leaf spot is another disease in marigold plants. Unfortunately, the entire plant must be destroyed to prevent spreading the disease.
7 Pests You Probably Have In Your Garden (And What To Do)
FAQ
What is the common disease in marigold?
What is the best pesticide for marigolds?
What diseases affect African marigolds?
One of the most common diseases that affect African marigolds is powdery mildew. This fungal disease appears as a white powdery substance on the leaves, stems, and flowers of the plant. Powdery mildew thrives in humid conditions and can quickly spread from plant to plant.
What causes dark spots on African marigold leaves?
Leaf spot is another common disease that affects African marigolds caused by various fungal pathogens. It appears as dark spots on the leaves of the plant and can spread rapidly if left untreated. Identification: Look for circular or irregularly shaped spots on the leaves of the African marigold plant.
Why are my African marigolds turning yellow?
These diseases are often spread by insects such as aphids or through contaminated tools or plant material. Identification: Symptoms of viral diseases in African marigolds include yellowing or mottling of leaves, stunted growth, distorted flowers, and overall poor plant vigor.
What pests eat African marigolds?
One of the most common pests that attack African marigolds is aphids. These small insects feed on the sap of the leaves, causing them to wilt and turn yellow. To prevent aphids from infesting your marigolds, it is essential to keep your garden clean and tidy.