Parsnip Leaf Spot Problems – Learn About Leaf Spot On Parsnips

Parsnip Leaf Spot Problems – Learn About Leaf Spot On Parsnips

By: Amy Grant

Parsnips are grown for their sweet, earthy tap roots. Biennials that are grown as annuals, parsnips are as easy to grow as their cousin, the carrot. One such disease, parsnip leaf spot results in exactly what it sounds like – parsnips with spots on the leaves. While leaf spots on parsnips do not infect the root of the plant, parsnips with leaf spots will be more susceptible to other diseases and pest injury than healthy plants.

What Causes Spots on Parsnips?

Leaf spot on parsnips is usually caused by the fungi Alternaria or Cercospora. The disease is favored by warm, wet weather where leaves are moist for lengthy periods of time.

Parsnips with spots on their leaves may also be infected with another fungus, Phloeospora herclei, which is primarily observed in late summer or early autumn crops in the United Kingdom and New Zealand.

Symptoms of Parsnip Leaf Spot

In the case of leaf spot due to Alternaria or Cercospora, the disease shows as small to medium spots on the leaves of the parsnip plant. At onset they appear yellowish in color and later turn brown, merge together, and result in leaf drop.

Parsnips with leaf spots as a result of the fungus P. herclei begin as small, pale green to brown spots on foliage that also merge to form large necrotic regions. Infected tissue is a grayish/brown. As the disease progresses, leaves die and fall prematurely. Severe infections result in tiny black fruiting bodies that ooze spores, creating characteristic white patches on foliage.

Control for Parsnip Leaf Spot

In the case of P. herclei, the fungus overwinters on infected debris and certain weeds. It is spread by splashing water and direct contact. There is no chemical control for this fungus. Management includes removal of infected plants and debris, weed control, and wide row spacing.

With leaf spot as a result of Alternaria or Cercospora, fungal sprays can be applied at the first sign of infection. Since sustained leaf wetness fosters the spread of the disease, allow for wide row spacing to permit air circulation so that leaves can dry more rapidly.

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Parsnips in the Garden

Parsnips are cool season vegetables that prefer sunny locations and fertile, deep, well-drained soils. Incorporate plenty of organic matter and an all-purpose fertilizer into the area before planting. Plant seeds Вј-ВЅ inch deep. Thin seedling parsnips to 3 inches apart in row with rows 12-18 inches apart. Plant two to three weeks before the last frost. Parsnips taste best when plants have been exposed to several weeks of cool, frosty weather. Avoid water or fertilizer stress during growth. Irrigation should be frequent and uniform to ensure good growth. Control insect and diseases throughout the year. Harvest parsnips when the leaves reach full size.

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I can't believe no one has brought up honey parsnips yet. My mom used to make these for us all the time when I was growing up. It was one of the few vegetables I would eat. Probably because I loved honey.

Making them is really simple. You just mix together some water, honey and butter in a bowl. Then you throw in the parsnips and coat them. Put everything into a glass baking dish and bake at 375 for about 30 minutes until they are soft.

The amount of ingredients depends on the number of parsnips you are using, but generally I use about 1/2 cup of both water and honey and a tablespoon of butter for 6 parsnips. I usually cut up the parsnips, too, but I don't see why you couldn't leave them whole.

If anyone tries this, let me know what you think. cardsfan27 September 19, 2011

I would like to add parsnips to my garden next year, but I have never tried to plant them before.

Does anyone know of any good varieties of parsnip seeds? I used to eat parsnips a lot when I was younger, but it seems like they aren't as common now. I don't really remember if there were different types of parsnips or if they were all basically the same.

When I actually go to plant them, are there any suggestions for the best time of year to plant them and any special considerations I should think about? How long does it usually take for them to get to the point where you can pull them up, and how will you know when they are ready? Izzy78 September 18, 2011

@drtroubles - Like the article briefly mentions, it is probably not a good idea to pick anything that looks like a parsnip.

Carrots and parsley are all in the same family of plants as parsnips, and all of their leaves look the same. The underground roots can even look the same in some plants. The problem is that for every edible plant, there are quite a few poisonous ones.

Poison hemlock is definitely the most famous, but there are even wild carrots that can make you very sick. It's best to just leave it to the professionals and know that you are getting something from the supermarket or your garden that won't hurt you. drtroubles September 18, 2011

If you want to grow parsnips you can use them in so many easy recipes. One of my favorites is curried parsnip soup. It really hits the spot in the winter and is really filling, despite the fact it is basically a vegetable soup.

One thing I am curious about is, does anyone know if you can eat wild parsnips? Or is it best to just to stick to the ones you grow in your garden?

I noticed a few weeks ago that there are wild parsnips in the field behind my house, and it would be nice if I could just pick those every year and not have to bother with taking up space in my garden. popcorn September 18, 2011

My grandmother used to make roasted parsnips in the winter and occasionally would treat us to mashed parsnips covered in butter. I always loved her parsnips as they were what I would describe as a hearty vegetable.

When I was really young I remember watching my grandma planting parsnips in her backyard. She liked to make sure she had a good supply for the family because when it came time, parsnips roasted in the winter were a favorite of everyone.

Nowadays I don't really have as many parsnips as I would like. I am thinking that a trip to the supermarket should be in order. I just hope I can make my parsnips taste as good as my grandma did.

Why Do Parsnips Fork?

Though they’re absolutely edible, you still wouldn’t want to miss the happiness in pulling out perfect roots at harvest time. The key to perfect harvests is to find out what caused the problem in the first place so you can rectify it in the next growing season.

Here are some reasons why your parsnips might be forked:

Unsuitable Soil Structure

Parsnips, like most root vegetables, like to grow in light, friable soil. Loamy or sandy soil, rich in organic material, is perfect to start your parsnips with. If you’re getting forked parsnips, one of the most common reasons is heavy, compacted soil or a rocky one. With heavy soil or rocks obstructing their development, roots find it challenging to grow straight down into the soil and turn out short and branched.


Prevent distorted roots by tilling and sifting the garden bed to about 12 inches, removing any stones, sticks, or large solid structures that you find along the way. If you have heavy clay soil, amend it with aged-compost and sand to improve soil structure to promote straight parsnips. If you don’t have the best soil in your garden, another solution is to grow your veggies in a raised bed prepared with packed soil and sand.

Too Much Nitrogen

It might be hard to believe, but incorrect fertilization can also result in forked parsnips. The use of high-nitrogen fertilizers, especially right after you’ve sown the parsnip seeds, can also result in the deformities that are bothering you. Parsnips don’t need as much nitrogen as most of your other garden plants.


For organic fertilization of your parsnip crop, select well-aged manure. Fresh manure has a higher content of nitrogen, which can result in forking and branching of roots. If you’re incorporating synthetic fertilizers, choose a low-nitrogen feed, for example, 5-10-10 fertilizer.


Transplanting parsnips can also be one of the causes of deformities. Transplanting root vegetables, especially those with long taproots, is never a good idea. That’s because root vegetables are very sensitive to such disturbances.


Avoid transplanting parsnips. Sow the seeds directly in the garden or container as soon as the soil temperatures are higher than 50°F. Leave them growing in the same spot until they’re ready for harvest to avoid disturbing the roots.

Insufficient Spacing

Oddly shaped roots can also result from the inadequate spacing between the plants. Tight plantings can result in twisted and forked parsnips instead of the straight ones you’re looking for.


Once the seedlings develop their first true set of leaves, thin them to 3 to 4 inches apart. This will allow plenty of space for each root to develop freely, without being obstructed by its neighbors.


Weeds in your garden bed is another common reason for deformed roots. Since weeds have their own underground root system that competes for nutrients against your crop, it’s not surprising to find forked parsnips in a weedy garden.


Keep your garden weed-free throughout the growing season, so the unwanted roots don’t disturb the development of your parsnips.

Root-Knot Nematodes

Root-knot nematodes can also result in knotty, forked parsnip roots. They are microscopic worms that feed on the plants, leaving galls on the roots. These galls or knots prevent the plant from accessing water and nutrients to its fullest capacity, stunting the growth.


Select root-knot nematode-resistant parsnip seeds to prevent the problem right from the start. With certified nematode-free parsnip seeds, you can be sure you won’t find this disease in your crop. Also, since root-knot nematodes are less active during the winters, overwintering parsnips is also a good idea to prevent the damage done by these pests.


  • 1 Symptoms
  • 2 Phototoxic species
    • 2.1 Apiaceae
    • 2.2 Rutaceae
    • 2.3 Moraceae
  • 3 Prevention
  • 4 Treatment
  • 5 History
  • 6 See also
  • 7 References
  • 8 External links

A reaction typically begins within 24 hours of exposure and peaks at 48–72 hours after exposure. [6] Initially, the skin turns red and starts to itch and burn. Large blisters (or bullae) form within 48 hours. [7] The blisters may leave black, brown, or purplish scars that can last for several years. This hyperpigmentation of the skin is caused by the production of melanin triggered by the furanocoumarins.

Although media reports have suggested that eye exposure to the agent can lead to temporary or permanent blindness, the risk of permanent blindness is not supported by existing research. [8]

Phytophotodermatitis can affect people of any age. In children, it has been mistaken for child abuse. [9]

Plants associated with phytophotodermatitis mainly come from four plant families: [2] [10] the carrot family (Apiaceae), the citrus family (Rutaceae), the mulberry family (Moraceae), and the legume family (Fabaceae).

Apiaceae Edit

The carrot family Apiaceae (or Umbelliferae) is the main family of plants associated with phytophotodermatitis. Of all the plant species that have been reported to induce phytophotodermatitis, approximately half belong to the family Apiaceae. [11]

False bishop's weed (Ammi majus), the world's major source of the linear furanocoumarin xanthotoxin, has been used since antiquity to treat vitiligo [2] but accidental or inappropriate use of this plant can lead to phytophotodermatitis. [12] Despite this danger, A. majus continues to be cultivated for its furanocoumarins, [13] which are still used for the treatment of skin disease.

Numerous species in the family Apiaceae are cultivated as food products, some of which exhibit phototoxic effects. In particular, celery, parsnip, and parsley have been reported to cause phytophotodermatitis among agricultural workers, grocery workers, and other occupational food handlers. [14] [15] [16] [17] [18] [19] [2]

A number of phototoxic plant species in the carrot family have become invasive species, including wild parsnip (Pastinaca sativa) [20] [21] and the tall hogweeds of the genus Heracleum, [22] [23] namely, Persian hogweed (Heracleum persicum), Sosnowsky's hogweed (Heracleum sosnowskyi), and giant hogweed (Heracleum mantegazzianum). In particular, the public health risks of giant hogweed are well known. [24]

Other plant species in the family Apiaceae that are associated with phytophotodermatitis include blister bush (Notobubon galbanum), cow parsley (Anthriscus sylvestris), wild carrot (Daucus carota), various species of the genus Angelica (e.g., Korean angelica Angelica gigas), and most (if not all) species of the genus Heracleum (esp. the tall invasive hogweeds and the cow parsnips, Heracleum sphondylium and Heracleum maximum).

Rutaceae Edit

The citrus family Rutaceae is the second most widely distributed family of plants associated with phytophotodermatitis.

Numerous citrus fruits in the family Rutaceae exhibit phototoxic effects. Of these, perhaps the best known is lime. [25] [26] [27] [28] Phytophotodermatitis associated with limes is sometimes colloquially referred to as "lime disease," [29] [30] not to be confused with Lyme disease.

In the family Rutaceae, the most severe reactions are caused by the essential oil of the bergamot orange (Citrus bergamia). [2] [31] Bergamot essential oil has a higher concentration of bergapten (3000–3600 mg/kg) than any other citrus-based essential oil, even lime oil, which contains 1700–3300 mg/kg of bergapten. [32]

Other plant species in the family Rutaceae that are associated with phytophotodermatitis include burning bush (Dictamnus albus), [33] common rue (Ruta graveolens), [34] [35] [36] [37] and other plants in the genus Ruta.

Moraceae Edit

The mulberry family Moraceae is often associated with phytophotodermatitis. Multiple species in the genus Ficus are known to exhibit phototoxic effects. Of these, the common fig (Ficus carica) is well known and thoroughly documented.

Like Ammi majus in the family Apiaceae, the common fig has been used since antiquity to treat vitiligo [38] but the milky sap of fig leaves can cause phytophotodermatitis if used accidentally or inappropriately. [39] [40] [41] [42] [43] [44] A literature search revealed 19 cases of fig leaf-induced phytophotodermatitis reported between 1984 and 2012. [44] In Brazil, several hospitals reported more than 50 cases of fig leaf-induced burn in one summer. [43] In most cases, patients reportedly used the leaves of the fig plant for folk remedies, tanning, or gardening.

Other plant species in the family Moraceae that are associated with phytophotodermatitis include Ficus pumila [45] [46] and Brosimum gaudichaudii. [47] Like Ficus carica, the South American species Brosimum gaudichaudii has been shown to contain both psoralen and bergapten.

The first and best line of defense against phytophotodermatitis is to avoid contact with phototoxic substances in the first place:

  • Avoid contact with the plant family Apiaceae, citrus fruits, and other biological agents known to have phototoxic effects. Do not incinerate phototoxic plants and agents since this will serve to disperse the phototoxic substances more widely. [48]
  • In outdoor situations where contact with phototoxic plants is likely, wear long pants and a long-sleeve shirt. Wear gloves and protective eyewear before handling such plants.
  • If protective clothing is not available, apply sunscreen to exposed areas. This will provide some measure of protection if contact is made.
  • After an outdoor activity, take a shower or a bath as soon as possible. Wash your clothing and then wash your hands after handling the dirty clothes.

A second line of defense is to avoid sunlight, so as not to activate a phototoxic substance:

  • If you come in contact with a phototoxic substance, immediately wash the affected area with soap and cold water, and avoid any further exposure to sunlight for at least 48 hours. Heat and moisture can worsen the skin reaction, [24] which is why it’s important to wash the affected area with soap and cold water.
  • Stay indoors, if possible. Be sure to avoid light shining through windows.
  • If staying indoors is not an option, cover the affected area with sun protective clothing.
  • In lieu of sun-protective clothing, apply sunscreen[49] to the affected areas after washing.

Phytophotodermatitis is triggered by long wavelength ultraviolet light (called UVA) in the range of 320–380 nanometers, [6] so the best sun-protective clothing and sunscreen products will block these wavelengths of UVA radiation.

In 2011, the U.S. Food and Drug Administration (FDA) established a "broad spectrum" test for determining a sunscreen product's UVA protection. [50] Sunscreen products that pass the test are allowed to be labeled as "Broad Spectrum" sunscreens, which protect against both UVA and UVB rays.

There is no equivalent test or FDA-approved labeling for sun-protective clothing. Some clothing is labeled with an Ultraviolet Protection Factor (UPF) but test results from Consumer Reports [51] suggest that UPF is an unreliable indicator of UV protection.

Many different topical and oral medications may be used to treat the inflammatory reaction of phytophotodermatitis. A dermatologist may also prescribe a bleaching cream to help treat the hyperpigmentation and return the skin pigmentation back to normal. If the patient does not receive treatment, the affected sites may develop permanent hyperpigmentation or hypopigmentation. [6]

The photosensitizing effects of plants have been known since antiquity. In Egypt around 2000 B.C., the juice of Ammi majus "was rubbed on patches of vitiligo after which patients were encouraged to lie in the sun." [2] In A.D. 50, the Greek physician Dioscorides observed that pigment would return to patches of vitiligo if "cataplasmed with ye leaves or ye boughes of ye Black Figge," [38] an apparent reference to Ficus carica, the common fig. These ancient practices acknowledged the hyperpigmentation effects now known to accompany phytophotodermatitis.

One of the earliest reports of plant-based dermatitis was given by Chaumton in 1815, who noted that the outer rind and root of cow parsnip (a common name for any Heracleum species of plant) contained an acrid sap sufficiently strong to inflame and ulcerate the skin. [52] Similarly in 1887 Sornevin reported that Heracleum sphondylium caused dermatitis. However, neither of these early reports recognized the crucial role of ultraviolet radiation.

"Berloque dermatitis" [3] (from the French word "berloque" meaning trinket or charm) is a term coined by Rosenthal in 1925 to describe the pendant-like streaks of pigmentation observed on the neck, face, and arms of patients. [53] [2] He was unaware that, in 1916, Freund had correctly observed that these pigmentation effects were due to sun exposure after the use of Eau de Cologne, a perfume infused with bergamot oil. [54] It is now known that bergamot oil contains a significant amount of bergapten, [2] a linear furanocoumarin that gets its name from the bergamot orange.

In 1937, dermatitis from Heracleum mantegazzianum was reported by Miescher and Burckhardt who suspected the possibility of light sensitization. [55] A few years later, Kuske confirmed this hypothesis. [56] [57] In 1942, Klaber introduced the term "phytophotodermatitis" to emphasize that both plants and light were required to affect a reaction. [58] [28]

Darrell Wilkinson, a British dermatologist, gave an accurate description of the disease in the 1950s. [59] In 1961, Efremov reported 357 cases of phytophotodermatitis from Heracleum dulce (sweet cow parsnip). He "noted the requirement for sunlight in evoking the dermatitis since inunction of the juice of the plant without exposure to sunlight was harmless." [60] Between 1962 and 1976, numerous reports of phytophotodermatitis from giant hogweed (Heracleum mantegazzianum) were reported. By 1980, the photosensitizing effects of various plant species had become well known (as evidenced by the comprehensive work of Mitchell and Rook [61] ).

Watch the video: How I Plant Parsnips