Parsley has so many benefits for our health, beauty, and food that seeing white spots on their leaves can induce a panic attack. Relax. Let’s see what these are and what we can do.
What spots on parsley can be due to 1) excess minerals, 2) fresh weevil eggs, 3) powdery mildew, 4) downy fungus, 5) celery mosaic virus, 6) insect attacks, or 7) pathogenic infections. Fortunately, there are solutions for each.
This article summarizes the benefits of parsley as well as details the causes and solutions to different types of white spots that you can see on parsley leaves.
Parsley (Petroselinum crispum) is an herb grown from seeds for its culinary, medicinal, cosmetic, as well as ornamental benefits. It has been cultivated by various civilizations at least since the 16th century. Today, it is one of the most widely-used herbs in the USA.
Parsley grows almost anywhere, even on rocks, cliffs, and old walls. That’s why the name comes from the old Greek word for rock (petros) and celery (selinum). There are at least three types of Petroselinum crispum cultivated as a vegetable crop in the USA:
- The common or curly-leaved parsley: The P. c. var. crispum is the curled-leaf, bright green parsley with finely cut leaves with a toothed leaf margin.
- The flat, plain or Italian parsley: The P. c. var. neapolitanum is the flat-leafed, dark green, parsley that is hardier and has a stronger flavor than the curled-leaf variety.
- The turnip-rooted or Hamburg parsley: The P. c. var. tuberosum is the turnip-rooted parsley with large, edible roots that are used as a vegetable.
Parsley is a rich source of nutrients. You’ve got vitamins A, B, and C. You’ve also got minerals such as iron, calcium, and magnesium. That’s why – for thousands of years – parsley has been used as a detoxifier, a blood purifier, and a diuretic.
A regular diet containing parsley can boost metabolism, stimulate the appetite and aid digestion. Here are other benefits that you can enjoy from your parsley plants:
- Medicinal uses: Aside from preventing cancer and improving bone health, parsley leaves can be infused in water and used as a digestive tonic as well as to improve blood circulation. Parsley root decoctions can be used as a mild laxative or to treat kidney ailments while root juice can reduce swelling. Leaves can be applied as a poultice to treat bites, stings, and wounds.
- Cosmetic applications: Leaves soaked in water can be used as a hair tonic and conditioner. The infusion can also be added to skin lotion to alleviate dry skin conditions. Chewing on raw parsley leaves can serve as an effective breath freshener. Parsley also looks great as an edging plant along sidewalks and flower beds.
- Culinary benefits: Parsley leaves can be used raw in salads or sandwiches as dressings, or added to egg, vegetable, or meat dishes and as a flavor enhancer in soups and stews.
Factoid: For more than 2,000 years, parsley was used for ceremonial, religious, or medicinal reasons until Charlemagne used it to flavor cheeses.
Aside from being a long-term popular herb, parsley is so useful that parsley growers feel quite alarmed when white spots appear on the leaves of their parsley plants.
The thing is, several types of white spot issues have been identified, and they’re not all caused by the same things. While some white spots can be caused by bacteria, fungi, or insects, many cases are simply minerals in soil or water.
- Hard water contains high levels of dissolved minerals such as magnesium and calcium. This happens when water passes through such natural subsoil deposits as chalk, gypsum, or limestone, all of which dissolve as bicarbonates, carbonates, and sulfates of magnesium or calcium.
- Potting soil can accumulate build-ups of salt from watering or from fertilizer. The highest salt build-ups in soil can come from sodium chloride, potassium chloride, ammonium nitrate, potassium nitrate, ammonium sulfate, calcium nitrate, potassium sulfate, as well as anhydrous ammonia.
- In water, sodium (salt) cannot be easily removed by boiling or filtration. More expensive processes are required, such as distillation, reverse osmosis, or ion exchange. So, in most cases, salt in household water remains dissolved there.
- Some plants can get rid of excess salt from water or soil by extruding these on leaf surfaces using their salt glands, cuticles, or bladders. This is a natural method of increasing the plant’s salt tolerance in high-saline contexts.
According to a 1999 report title Tolerance of vegetable crops to salinity from the U.S. Salinity Laboratory, umbellifers (which include carrots, celery, dill, fennel, and parsley) were first cultivated from wild stock that grew naturally in the marshy areas of Abyssinia, Algeria, Egypt, and Sweden.
In other words, today’s parsley crops may have ancestral origins from halophytes, plants that grew in the wild by tidal waters, in brackish marshes, and near the sea.
We can take a leap and say that the parsley in your garden may not be true halophytes as they have been grown away from salty water for centuries. However, despite modifications of ancestral DNA, celery has most likely retained the ability to extrude excess salt on its leaves.
- When plants are watered with hard water, the water evaporates and the remaining minerals show as white deposits or spots on the leaves.
- Some plants can eliminate excess salt from their systems by pushing it out of their leaves. Parsley originated from plants that grew in salty water, which are able to extrude excess salt on their leaves to increase salt tolerance.
- You can see these extrusions as white spots that look like round, bumpy pinpricks on the leaves of plants.
- Wiping: Wipe the leaves with a weak vinegar solution.
- Rinsing: Leach the salt deposits from soil by repeated rinsing or watering.
- Cleaning: Use fresh soil after cleaning your pots thoroughly.
Another explanation for white spots that you see on your parsley are eggs or larva of insects such as the carrot weevil.
In cold weather, carrot weevils hide under plant debris, sod, or under rocks or wood, or about an inch under topsoil around parsley plants. In warmer weather, they lay fresh eggs that you can see as white spots on green leaves.
Starting from around the middle of May until the end of June, adult carrot weevils begin to lay eggs on parsley plants that have at least four leaves.
These eggs are white or yellow during the first day and, in about five days, blacken as they get ready to hatch.
To effectively to prevent white spot on parsley due to weevil eggs the following are all valid approach:
- Plowing or tilling: At the end of the crop season, plow the parsley field. For parsley grown in pots or plots, till the soil. This will force the adult weevils to walk away and overwinter in nearby sites if they have not started their diapause (resting) stage.
- Remove winter covers: At the same time, removing annual weeds such as henbit and chickweed can deprive weevils of winter cover.
- Apply insecticide: For larger crops, the use of organophosphates such as Azinphos-methyl (Guthion 50WP) can be 100% effective for 30 days, but this efficacy depends on the timing of the application.
Factoid: The most popular types of fresh-market parsley are the curled-leaf and Italian flat-leaf types, which are grown exclusively for their green leaves or tops.
Some white spots on green parsley leaves are actually mildew from fungi.
For instance, powdery mildew is a white fungus that is caused by the fungal infection of Erysiphe heraclei or the more common Sphaerotheca fuliginea, for example.
Plants infected with fungi can show white, powdery spots on leaves and stems. This is a major problem in some potted plants, including kitchen herbs and indoor gardens.
- Powdery mildew occurs increasingly on parsley during hot summer periods.
- Poor air circulation among overcrowded plants promotes spore development.
To remove powdery mildew from a plant it is important to:
- Air circulation: Keep plants separated for enough air to circulate between them.
- Spray: Spray some fungicide such as captan or Bordo Mix (Bordeaux mixture) on potted parsley as well as on other plants growing nearby. The mildew issue can also be treated with copper fungicide at the first sign of infection.
- Re-spray: Repeat the spray after one week, and again until the infection disappears.
A good spray that helps controlling powdery midlew is the one below
Factoid: Parsley can be stored up to 12 days with no changes in flavor, except when the leaves are damaged.
The white sporulation indicates spores that are in active production on young leaves. The leaves begin to curl and are gradually covered by white or light-gray fungus.
This is different from white spots that show on the upper leaf surface, which is caused by the fungus Plasmopara petroselini.
Also known as “powdery mildew,” this fungal disease is triggered by a combination of high humidity and low soil moisture. The pathogen spreads quickly in cool, wet conditions. The wind spread the spores.
While water is not necessary for the spores to germinate, water helps spores to swell, release, and disperse. With at least 72 hours of leaf wetness, symptoms can develop on parsley in about 9 days after infection.
However, P. petroselini spores require water to germinate and infect the plant. Later, the spots enlarge and turn yellow until the leaves drop off.
Moreover, spores can also spread due to irrigation, wind-driven rain, as well as by machine and human movements such as wet boots.
The risk of downy mildew can be reduced by using the following practices:
- Clean seeds: Treat parsley seeds with a warm-water thiram soak (not permitted for organic production).
- Apply approved fungicides: Do not use on parsley seeds any fungicides that are approved for parsley foliar applications. Do not use broad-spectrum disinfectants or biocides.
- Water in the morning: To prevent long periods of leaf wetness, do not water late in the day.
- Remove infected leaves: Inspect plants regularly for early symptoms and remove infected plants.
- Keep clean: Clean or disinfect boots and equipment after and between use.
One cause of white spots on parsley leaves is the celery mosaic virus that causes a “mosaic” of white spots that can also show as yellow, light or dark green.
Some sources note that CMV is rare and often confused with Apium virus Y, which can be transmitted by aphids and gardening tools or farm equipment.
This virus infection has been found to begin in plants such as dill, carrots, and celery and spread to other plants.
Overlapping crops are one of the triggers of this pathogen, which is often spread by aphids as they feed on an infected plant, even if only for a few seconds.
Parsley plants can also be affected by other types of mosaic viruses:
- BCMV – Bean Common Mosaic Virus, seed-borne or spread by aphids
- BYMV – Bean Yellow Mosaic Virus, seed-borne or spread by aphids
- CMV – Cucumber Mosaic Virus, spread by aphids
- TMV – spread by seeds and by direct contact
Cutting out the infected parts of your parsley plant can only slow down the spread of the virus to other plants. The infection will not be cured and any plant with the mosaic virus will always remain infected.
Here what can be done to prevent the fungal problems causing white spot on yor parsley:
- Start over: Since fungicides and chemicals are ineffective, the best way to address this issue is to toss out all infected plants, weeds, and soil (do not compost) and, after three months, start over with transplants or seeds from a reputable source.
- Wash frequently: Since the virus can spread via tools, equipment, and human activity, it is recommended that you frequently wash all hands, tools, pots, stakes, ties, etc. Even better, you can disinfect with a solution of one part bleach and 4 parts water.
- Work when it’s dry: Since viruses spread easily when the plants are wet, do not work in your garden or farm when on damp days or conditions.
Insects such as aphids, whitefly, thrips, leafhoppers, and so on that feed on parsley can leave small, white spots on parsley leaves.
- Here are some photos of whitefly eggs on a parsley plant: photo 1, photo 2.
- Here is a photo of bug eggs, probably bird’s nest fungus, on parsley leaves: photo 3
- Here is a picture of butterfly eggs on a parsley leaf: photo 4
- Here is a photo of black swallowtail eggs on parsley leaves: photo 5
- Here is a photo of aphids on the parsley leaves: photo 6
- To compare, here is a photo of parsley leaves with fungal infection: photo 7
- Mites seem to be attracted to dusty leaves.
- Aphids, leafhoppers, and whiteflies are attracted to the color yellow, as well as to plants with soft, new tips or leaves, as these are easy for them to feed on.
- Thrips are attracted to the juicy parts of plants, particularly to colors such as blue or yellow.
- Overfeeding with fertilizer nutrients can overstimulate growth of plants, thus making them more vulnerable to insects. For instance, the plant may grow excessive or vigorous new foliage, buds, and tips, which can attract insects.
Since these insects are considered as minor pests, using an insecticide spray on herb plants is not recommended.
The 7 steps to remove the insects responsible for the white spots on parsley are:
- Water: Hose or spray of leaves and remove dead or infested leaves.
- Cut down on fertilizer: Apply fertilizer according to recommended dosages, but you can dilute as necessary. Flush out any excess fertilizer from the slow, and henceforth use slow-release fertilizers.
- Identify the insect: To identify the actual insect causing the white spots, examine the underside of the leaves.
- Use earth, soap or oil: One solution is to apply either insecticidal soap or some horticultural oil or neem oil. You can also try and apply some diatomaceous earth.
- Use hydrogen peroxide: Thoroughly water the soil around the parsley plant with a mix of 1 part 35% hydrogen peroxide and 10 parts water.
- Use dish soap: You can wipe or spray the leaves with a mix of water and a few drops of dish soap. When aphids reappear, repeat the soapy water solution once every two or three days for about two weeks.
- Fire: If the parsley plant has a serious attack of mites, it is best to dispose of the plant altogether. To make sure that viral or bacterial content are killed, use fire so the insects have no possibilities to spread in nearby plants.
Factoid: Do not over fertilize your parsley plants with nitrogen. This can reduce the flavor of the leaves.
White spots caused by bacteria or bio-pathogens first show on older leaves that become thin, weak, and easily disintegrate when touched,
These spots eventually turn into brown spots near the leaf margins, as well as at the top or bottom of leaves.
The white spots on the leaves of parsley can be caused by bacterial leaf spotting due to microscopic single-celled organisms. These are frequently observed in humid and cool environments.
Five are the solutions to address a pathogenic infection on parsley resultng in white spotted leaves. These are:
- Spray: Spray a copper fungicide or a natural solution as soon as you first notice the first signs of bacterial infection.
- Work dry: Reduce long periods of wetness by irrigating when dew is normally on the leaves.
- Water quickly: Use a drip irrigation system instead of watering from above. Short and heavy watering is better than long, light watering. After watering, let the plant dry.
- Drain soil: To reduce humidity, increase soil drainage as much as possible.
- More light and air: Make sure that each plant is exposed to enough air and sunlight each day.
Factoid: Later cuts of parsley may have better flavor compared to the first cuts. At the same time, younger plants have more intense flavor in the leaves.
The white spots on your parsley leaves can be caused by non-pathogenic sources such as excess salts or mineral deposits in soil or water. This is easily solved by wiping the leaves and leaching the soil of excess minerals or by using soft water for irrigation.
White spots can also mean that insects are attacking or laying eggs or larva on the leaves. Insect attacks by weevils, thrips, leafhoppers, aphids, whitefly, and so on can be resolved by reducing fertilizer or by applying neem oil, diatomaceous earth, or insecticidal soap.
The more serious causes are pathogenic infections from viruses and bacteria. In most cases, it is best to dispose of all infected soil and plants by burning (do not compost), and to start over.
And that’s it! Now you know the different causes and solutions for the white spots on your parsley leaves.
Oh, yes. Before I forget: you can eat parsley leaves after cleaning them of non-pathogenic or insect damage. However, when white spots are caused by bacteria or viruses, it’s best to burn everything, even infected plants growing nearby.
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