Carrot Diseases A

Lecture To ToT trainees ( FFS) By

Mr. Allah Dad Khan Provincial Coordinator

IPM KPK MINFAL Pakistan

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

Soft rot rwinia carotovoraErwinia chrysanthemi Pseudomonas marginalis

Symptoms

• Sunken dull orange lesions on taproot which causes tissue to collapse and become soft

• Cause• Bacteria

Black rot Alternaria radicina

• Symptoms• Damping-off of seedlings; root

and crown necrosis; blighted foliage; lower portion of petioles black and necrotic; black ring around petiole attachment black, sunken lesions on taproot

• Cause• Fungi

Bacterial leaf blight Xanthomonas campestris

Symptoms

• Small, angular, yellow spots on leaves which expand into irregularly shaped, brown, water-soaked lesions with a yellow halo; centers of lesions dry out, become brittle; leaves may become curled or distorted; flower stalks may develop elongated lesions that exude a bacterial ooze; infected umbels may be blighted

• Cause• Bacterium

Alternaria leaf blight Alternaria dauci

Symptoms

• Green-brown water-soaked lesions on leaves which enlarge and turn dark brown or black; lesions may coalesce causing leaves to yellow and die; lesions may be present on petioles

• Cause• Fungus

Cercospora leaf blight Cercospora carotae

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

Downy mildew Peronospora umbellifarum

Symptoms• Yellow spots on upper surface of leaves;

white fluffy growth on underside of leaves; lesions become darker as the mature

• Cause• Fungus• Comments• Disease affects young, tender leaves;

disease emergence and spread is favored by prolonged leaf wetness

• Management• Plant pathogen-free seed; do not

overcrowd plants; rotate crops with non-umbelliferous varieties

• Symptoms

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

Cavity spot Pythium spp.

• Symptoms• Sunken, elliptical, gray lesions across the root; outer

layer of root ruptures and develops dark, elongated lesions; small vertical cracks may form on the cavities

• Cause• Fungi• Comments• Fungi can persist in soil for several years and

disease outbreaks are associated with wet soils; flooded soil increases the number of cavities formed

• Management• Some cultural practices can control the disease:

avoid planting in fields/areas known to previously had carrot spot; do not over-fertilize plants; application(s) of appropriate fungicide can provide adequate control

Root-knot nematodes (Stubby root nematodes, Needle nematodes)Meloidogyne spp.

Paratrichodorus spp.Longidorus africanus

Symptoms

• Forked, distorted or stunted taproots; reduced stand; reduced yield

• Cause• Nematodes

Sclerotinia Rot - White MoldSclerotinia sclerotiorum

Common ScabStreptomyces scabies