Parsley

Description

Parsley, Petroselinum crispum is an herbaceous biennial or perennial plant in the family Apiaceae grown for its leaves which are used as a herb. Parsley is an aromatic plant with an erect growth habit and possesses branched, hollow stems and dark green flat or curled leaves which are arranged alternately on the stems. The leaves form a rosette on younger plants. The plant produces small, yellow flowers on umbels. Parsley can reach 30–100 cm (12 –39 in) in height depending on the variety being grown and is commonly grown as an annual, harvested after one growing season. Parsley may also be referred to as garden parsley and likely originates from the Mediterranean.


Uses

Parsley leaves are used fresh or dried as a culinary herb. Fresh leaves are also commonly used as a garnish. The taproot of some cultivars is edible and may be eaten as a vegetable. Essential oil can be extracted from the parsley flowers and is used as a flavoring.


Propagation


Basic requirements
Parsley plants will grow best when planted in bright sunlight or partial shade. Plants grow best at temperatures between 7 and 16°C (45–61°F) in a well-draining loam which is high in organic matter. It will grow optimally when the soil pH is between 4.9 and 8.2.

Propagation
Parsley if propagated from seed, either by direct seeding or sowing indoors to produce transplants. Seeds should be sown in the spring when the soil has warmed. Soaking the seeds overnight prior to planting will aid germination. Seeds should be planted no more than 6 mm (0.25 in) deep using 10 to 15 seeds per inch of row space. Seeds should be kept moist and not allowed to dry out. after emergence, seedlings should be thinned to a final spacing of 10–15 cm (4–6 in) apart, leaving 30–60 cm (12–24 in) between rows. Parsley should be left in the ground for a second year if the collection of seed is desired.

General care and maintenance
Parsley is generally very easy to care for. Keep plants productive by clipping the branches to promote new growth. Remove any flower stalks as they form during the first year of growth to prevent the plant going to seed, retaining the flavor of the leaves. Weeds should be removed from around parsley plants by carefully cultivating the soil. A layer of mulch applied around the plants can help suppress weeds. Fertilizer may be applied to the soil before planting seeds and during the growing season, plants can be side dressed with nitrogen to keep plants productive. Parsley can be overwintered successfully by protecting the plants with a frame or layer of straw. Leaves can be continually harvested over the winter months.

Harvesting
Parsley is usually ready for harvest about 75 days after sowing, when the plants have reached approximately 20 cm (~8 in) in height. In the home garden, parsley leaves can be harvested as required or whole plants can be harvested and dried for longer storage. If the whole plant is cut, plant growth is usually sufficient to allow for 3 cuttings per year.


References

Anderson, C. R. Parsley. University of Arkansas Division of Agriculture. Available at: http://www.uaex.edu/publications/PDF/.... [Accessed 04 March 15]. Free to access.

Brobst, J. E. (2012). Essential facts for parsley Petroselinum crispum . The Herb Society of America. Available at: http://www.herbsociety.org/herbs/docu.... [Accessed 04 March 15]. Free to access.

CABI Crop Protection Compendium. (2008). Petroselinum crispum (parsley) datasheet. Available at: http://www.cabi.org/cpc/datasheet/38808. [Accessed 04 March 15]. Paid subscription required.


Common Pests and Diseases

Damping-off
Pythium spp.
Rhizoctonia solani

Symptoms
Soft, rotting seeds which fail to germinate; rapid death of seedling prior to emergence from soil; collpase of seedlings after they have emerged from the soil caused by water-soaked reddish lesions girdling the stem at the soil line
Cause
Fungi
Comments
Damping-off diseases favor conditions which slow seed germination; fungi can be spread in water, contaminated soil or on equipment
Management
Avoid planting parsley in poorly draining, cool, wet soil; planting in raised beds will help with soil drainage; plant high quality seed that germinates quickly; treat seeds with fungicide prior to planting to eliminate fungal pathogens

Rust
Puccinia spp.
Uromyces spp.
Nyssopsora spp.

Symptoms
Light green discolored lesions on leaves which become chlorotic; yellow-orange pustules on underside of leaves; stems bend and become swollen or distorted; plants may be stunted
Cause
Fungi
Comments
Some species infect only parsley while others have alternative hosts which may provide a reservoir for the disease; disease emergence is favored by high humidity
Management
Plant in well-draining soils to reduce humidity around plants; apply appropriate systemic fungicide

Septoria leaf spot
Septoria petroselini

Symptoms
Small, angular, gray-brown spots with defined red-brown margins on leaves; black fungal fruiting bodies may be visible on surface of lesions; leaves becoming chlorotic and necrotic
Cause
Fungus
Comments
Disease spread via infected seed, by contaminated irrigation water and by equipment or people moving through wet plants
Management
Control of disease is reliant on cultural control methods and good sanitation practices: use pathogen free seeds or treat seeds with fungicide prior to planting; rotate crops; plow plant debris into soil; if disease is present avoid working with infected plants when foliage is wet; apply appropriate protective fungicides

Alternaria leaf blight
Alternaria petroselini

Symptoms
Brown-black necrotic lesions on leaves which may have chlorotic margins; lesions expand and coalesce causing the death of leaves and petioles; dark necrosis on crown and upper region of taproot; damping-off of seedlings
Cause
Fungus
Comments
Disease spread primarily by planting infected seed
Management
Plant only pathogen-free seed; apply appropriate foliar fungicide; rotate crops to non-umbelliferous varieties fro a period of 2-4 years if soil-borne fungi

Powdery mildew
Erisyphe heraclei

Symptoms
Powdery growth on leaves, petioles flowers stalks and bracts; leaves becoming chlorotic; severe infections can cause flowers to become distorted
Cause
Fungus
Comments
Fungus can spread long distances in air; disease emergence is favored by high humidity and moderate temperatures; infection is most severe in shaded areas
Management
Plant tolerant varieties; avoid excess fertilization; protective fungicide applications provide adequate protection; sulfur application can be used in infection occurs early in season

Cercospora leaf blight
Cercosporidium punctum

Symptoms
Small, necrotic flecks on leaves which develop a chlorotic halo and expand into tan brown necrotic spots; lesions coalesce and cause leaves to wither, curl and die
Cause
Fungus
Comments
Disease can be introduced through infested seed and spread by wind or water splash; symptoms usually occur on younger foliage first
Management
Plant only pathogen-free seed; rotate crops; plow crop debris into soil ofter harvest; apply appropriate fungicide sprays

Crater spot
Rhizoctonia solani

Symptoms
Small, water-soaked lesions on crowns or petioles in contact with soil; collapse of petioles; petioles drying; lesions develop a sunken appearance and a dry, firm texture
Cause
Fungus
Comments
Disease emergence is favored by warm, moist conditions and practices which introduce soil contact with crowns and petioles
Management
Destroy crop debris or plow deeply into soil; avoid planting seeds too deep to prevent petioles coming into contact with soil; apply appropriate protective fungicides at plant bases; rotate crops with non-hosts such as grains to prevent disease building up in the soil

Armyworm
Pseudaletia unipuncta

Symptoms
Singular, or closely grouped circular to irregularly shaped holes in foliage; heavy feeding by young larvae leads to skeletonized leaves; shallow, dry wounds on fruit; egg clusters of 50-150 eggs may be present on the leaves; egg clusters are covered in a whitish scale which gives the cluster a cottony or fuzzy appearance; young larvae are pale green to yellow in color while older larvae are generally darker green with a dark and light line running along the side of their body and a pink or yellow underside
Cause
Insect
Comments
Insect can go through 3–5 generations a year
Management
Organic methods of controlling armyworms include biological control by natural enemies which parasitize the larvae and the application of Bacillus thuringiensis; there are chemicals available for commercial control but many that are available for the home garden do not provide adequate control of the larvae

Aphids (Willow-carrot aphid)
Cavariella aegopodii

Symptoms
Small soft bodied insects on underside of leaves and/or stems of plant; usually green or yellow in color; if aphid infestation is heavy it may cause leaves to yellow and/or distorted, necrotic spots on leaves and/or stunted shoots; aphids secrete a sticky, sugary substance called honeydew which encourages the growth of sooty mold on the plants
Cause
Insect
Comments
Distinguishing features include the presence of cornicles (tubular structures) which project backwards from the body of the aphid; will generally not move very quickly when disturbed; willow-carrot aphid will also attack parnip, carrot and celery
Management
If aphid population is limited to just a few leaves or shoots then the infestation can be pruned out to provide control; check transplants for aphids before planting; use tolerant varieties if available; reflective mulches such as silver colored plastic can deter aphids from feeding on plants; sturdy plants can be sprayed with a strong jet of water to knock aphids from leaves; insecticides are generally only required to treat aphids if the infestation is very high - plants generally tolerate low and medium level infestation; insecticidal soaps or oils such as neem or canola oil are usually the best method of control; always check the labels of the products for specific usage guidelines prior to use

Cutworms
Agrotis spp.
Peridroma saucia
Nephelodes minians
and others

Symptoms
Stems of young transplants or seedlings may be severed at soil line; if infection occurs later, irregular holes are eaten into the surface of fruits; larvae causing the damage are usually active at night and hide during the day in the soil at the base of the plants or in plant debris of toppled plant; larvae are 2.5–5.0 cm (1–2 in) in length; larvae may exhibit a variety of patterns and coloration but will usually curl up into a C-shape when disturbed
Cause
Insects
Comments
Cutworms have a wide host range and attack vegetables including asparagus, bean, cabbage and other crucifers, carrot, celery, corn, lettuce, pea, pepper, potato and tomato
Management
Remove all plant residue from soil after harvest or at least two weeks before planting, this is especially important if the previous crop was another host such as alfalfa, beans or a leguminous cover crop; plastic or foil collars fitted around plant stems to cover the bottom 3 inches above the soil line and extending a couple of inches into the soil can prevent larvae severing plants; hand-pick larvae after dark; spread diatomaceous earth around the base of the plants (this creates a sharp barrier that will cut the insects if they try and crawl over it); apply appropriate insecticides to infested areas of garden or field if not growing organically

Root knot nematode
Meloidogyne spp.

Symptoms
Galls on roots which can be up to 3.3 cm (1 in) in diameter but are usually smaller; reduction in plant vigor; yellowing plants which wilt in hot weather
Cause
Nematode
Comments
Galls can appear as quickly as a month prior to planting; nematodes prefer sandy soils and damage in areas of field or garden with this type of soil is most likely
Management
Plant resistant varieties if nematodes are known to be present in the soil ;check roots of plants mid-season or sooner if symptoms indicate nematodes; solarizing soil can reduce nematode populations in the soil and levels of inoculum of many other pathogens

Carrot motley dwarf (CMD)
Carrot redleaf virus (CRLV)
+ Carrot mottle virus (CMoV)

Symptoms
Yellow and red leaves; stunted plant growth
Cause
Viruses
Comments
Disease transmitted by aphids; both viruses must be present to cause carrot motley dwarf
Management
Avoid planting coriander in close proximity to overwintered carrot fields