Fusarium oxysporum f. sp. batatas

1. SWEET POTATO STEM ROT
COLLEGE OF AGRICULTURAL TECHNOLOGY
(Affiliated to Tamil Nadu Agricultural University, Coimbatore-3)
Kullapuram (Po),Via Vaigai, Dam, Theni-625 562
STUDENT
Miss. SIVASHANKARI K
ID. NO. 2015021119
COURSE TEACHER
Dr. PARTHASARATHY S
Asst. Professor (Plant Pathology)

2. Occurence
 This disease was first reported in Kayapa,
Nueva Vizcaya in 2011 with 30 to 85 percent
disease incidence in affected villages .
 This disease fairly spread through the
movement of infected planting materials.

3. Symptoms
 Initial symptoms on sweet potato are
interveinal yellowing of the leaves followed
by complete yellowing of the lower, older
leaves during the rapid growth stage.
 Leaves later wilt and abscise, stunting results
and eventually death of the plant.

4. Symptoms
 Necrosis of the stem vascular bundles occurs with
brown to purple discoloration; this may be
accompanied by rupturing of the cortex of the stem.
 The vines may turn tan to light brown. Diseased
plants may manage to produce storage roots, but
these usually have some discoloured, infected
vascular tissues.

5. Symptoms
 Rot may follow in storage or the disease may
be transmitted to the next field generation by
infected cuttings.

6. Symptom
@conservazione degli alimenti

7. Stem rot
@Shell’s feed and garden supply

8. Discolouration of vascular bundle
@forestryimages.org

9. Pathogen
 Mostly microconidia are
produced by the fungus.
 They are hyaline, one
celled, ovoid to broadly
ovate.
 The macroconodia are
fusiform, hyaline, 2-5
septate. @biologydiscussion.com

10. Systematic position
Kingdom: Fungi
Division: Ascomycota
Class: Sordariomycetes
Order: Hypocreales
Family: Nectriaceae
Genus: Fusarium
Species: F. oxysporum
Subspecies: F. o. f. sp. batatas
Trinomial name: Fusarium oxysporum f. sp. batatas
W. C. Snyder & H. N. Hansen, (1940)

11. Mode of spread
 The fungus mainly survives and spreads
through runners used for propagation.
 It can also subsists as chlamydospores in
diseased vines left in the field.
 The thin walled conidia are also known to
survive at least from one season to the next.

12. Favourable condition
 The pathogen can infect sweet potato at
temperatures at which the crop can grow.
 The optimum for infection is 30°C, maximum
38°C.

13. Management
Cultural control
 Soil solarization under a plastic film for 98
days reduced or eliminated F. oxysporum f. sp.
batatas to a depth of 20 cm.
 Crop rotation can reduce the incidence of
disease.

14. Chemical control
 Before planting the sets should be dipped in a
0.2 per cent suspension of Aretan or Agallol.
 The dipping of seed roots and vine cuttings in
fungicides such as benzimidazole or
thiabendazole.

15. Reference
 Singh. R. S., 2016 Third edition, Diseases of
vegetable crops, CBS Publishers, New Delhi.
Saha. L. R., 2009, Handbook of Plant
Diseases, Kalyani Publisher, New Delhi.