U UNIVERSITY of
2007 Florida Plant Disease Management Guide: Parsley1
Richard Raid and Pam Roberts2
Specific Common Diseases
Alternaria Leaf Spot (Alternaria radicina)
Symptoms: Infections begin with the appearance
of small brown flecks on parsley leaflets. Lesions
may develop yellow halos as they expand in size and
number. The disease is usually most prevalent on the
oldest leaves and lesions attacking the petiole may
render the entire leaflet brown and appearing
Cultural Controls: Controls for Altemaria leaf
spot should include planting in fields where parsley
or carrots have not been planted for several years. The
pathogen is sometimes associated with infected seed,
so purchase high quality seed from a reputable
source. Old plantings should be destroyed and
disked in to avoid spread of inoculum to younger
Chemical Controls: Early buildup of Altemaria
leaf spot may preclude multiple cuttings of this crop.
In such cases, fungicidal sprays may be effective and
economical. Scout fields regularly for early
detection. Strobilurin fungicides offer the best
efficacy in controlling this disease. See PPP-6.
Damping-off (Pythium spp. and Rhizoctonia
Symptoms: Seedlings may die at random or in
rapidly lengthening sections of freshly seeded rows.
Lesions may be observed well up on the petioles as
well as at the soil line. Entire plantings may be lost
unless adequate control measures are practiced.
Cultural Controls: Plant parsley on raised beds
in well-drained soil.
Chemical Control: Ridomil Gold, applied as a
band over seeded rows at the time of planting, may
assist in the control of diseases incited by Pythium
spp. This compound does not control Rhizoctonia.
Root Rots (Fusarium spp. and Rhizoctonia
Symptoms: Initial symptoms of root decay are
the progressive yellowing and browning of older,
lower leaves. Plants may wilt during mid-day.
Ultimately, the entire plant may turn yellow, then
necrotic, and die. Inspections of root systems may
reveal a reddish discoloration and deterioration of
1. This document is PDMG-V3-43, one of a series of the Department of Plant Pathology, 2006 Florida Plant Disease Management Guide, Florida Cooperative
Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Reviewed January 2007. Please visit the EDIS Web site at
2. R.N. Raid, professor, Plant Pathology Department, Everglades Research and Education Center--Belle Glade, FL; P.D. Roberts, assistant professor, Plant
Pathology Department, Southwest Florida Research and Education Center--Immokalee, FL; Florida Cooperative Extension Service, Institute of Food and
Agricultural Sciences, University of Florida, Gainesville, FL 32611.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and
other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex,
sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service,
University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry
2007 Florida Plant Disease Management Guide: Parsley 2
small feeder roots. Longitudinal, reddish cankers
frequently develop on the taproots. Exterior cortical
tissues appear dry and rotted. With Fusarium, a
reddish discoloration of the internal vascular system
may also be observed, extending well up into the
crown. On an annual basis, this is easily the most
devastating disease of parsley in Florida.
Cultural Controls: Avoid planting parsley in
fields previously planted to this crop. Crop rotations
should exceed five years to be effective. Fallow
flooding during the offseason may assist in reducing
the impact of this disease, but cannot be relied on
solely if parsley is planted in consecutive years.
Excessive seeding densities should be avoided, as
this has been observed to increase disease incidence.
Chemical Controls: Soil fumigation may assist
in reducing the effects of these organisms but is
Septoria Leaf Spot (Septoria petroselini)
Symptoms: Lesions appear as sunken brown
foliar spots with gray centers. As lesions age, minute
black specks (fungal pycnidia embedded in the leaf
tissues) may be observed under low magnification.
These black specks distinguish Septoria leaf spot
from the leaf spot caused by Alternaria radicina.
Cultural Controls: Septoria may survive for up
to 2 years on infected seed. Plant seed that has been
certified as being free of Septoria or store seed
suspected as being infected for a period of two or
more years. This reduces the viability of the
pycnidia, rendering the pathogen incapable of
infection. Avoid the use of overhead irrigation, as
the pathogen is rain splash disseminated. Also, if an
outbreak has been detected, the movement of
equipment or workers through the field while the
canopy is wet should be minimized.
Chemical Controls: Scout fields for early
detection. The use of recently registered strobilurin
fungicides should assist in reducing the impact of this
disease. See PPP-6.