Grey Blight in Horticultural Crops

Grey Blight in Horticultural Crops

1. COLLEGE OF AGRICULTURAL TECHNOLOGY (Affiliated to Tamil Nadu Agricultural University, Coimbatore-3) Kullapuram (Po), ViaVaigai Dam, Theni-625 562 Grey Blight in Horticultural crops Student Course teacher K. Harish Dr. Parthasarathy . S 2015021045 Asst. Professor., (Plant Pathology)

2. Grey blight Kingdom: Fungi Division: Ascomycota Class: Sordariomycetes Subclass: Xylariomycetidae Order: Xylariales Family: Sporocadaceae Genus: Pestalotiopsis Species : P. theae , P. mangifera

3. GREY BLIGHT IN MANGO

4. Occurrence World : Asia, Africa, Australia and South Pacific areas. India : Tamil Nadu, Kerala, Karnataka and Andhra pradesh . Hosts: Mango.

5. Economic Importance The results showed that mango was 100% prevalent in the study area. Incidence and severity varied across farmer’s field and market places. The disease incidence under farmer’s fields ranged from 41-72.1% on leaf and from 36.2-74% on fruit

6. Symptoms Brown spots develop on the margin and at the tip of the leaf lamina. They increase in size and become dark brown. Black dots appear on the spots which are acervuli of the fungus. Survive on mango leaves for over a year. Spreads through wind borne conidia. Heavy infectionis noticed during the monsoon when the temperature is 20-25˚C and high humidity

7. Black dots appear on the spots which are acervuli of the fungus.

8. Pathogen Character : Acervuli seen as minute black dots on affected portion. Mycelium is colored and septate . Conidia five celled middle three cells are colored and the end cells are hyaline Slender 3-5 appendages are produced at the apex of the spore.

9. Mode of survival and spread Survive on mango leaves for over a year. Spreads through wind borne conidia.

10. Favourable conditions Heavy infection is noticed during the monsoon when the temperature is 20-25˚C and high humidity.

11. Management Remove and destroy infected plant parts. Spraying copper oxychloride 0.25 Mancozeb 0.25% or Bordeaux mixture 1.0%.

12. Grey blight of tea Pestalotiopsis theae .

13. Economic Importance Higher inci-dences and more severe damage by gray blight were found in Japanese tea variety Yabukita than the Korean local variety. In Yabukita , Pestalotiopsis longiseta was more frequently observed on the diseased leaves than P. theae but vice versa in the Korean local variety. This indicates that there was the varietal difference in the distribution of fungal species of gray blight pathogens. Both varieties were most severely damaged during the third harvest period with weather conditions of high temperature and humidity favorable to the disease.

14. PATHOGEN CHARACTER Acervuli seen as minute black dots on affected portion. Mycelium is colored and septate . Conidia five celled middle three cells are colored and the end cells are hyaline Slender 3-5 appendages are produced at the apex of the spore.

15. Life cycle The tiny, black spots on the lesions contain the fungal spores. Rain splash transports the spores from one plant or site of infection to another. If the spores land on a leaf, they germinate to start a new leaf spot or a latent infection .

16. Symptoms Small, oval, pale yellow-green spots first appear on young leaves. Often the spots are surrounded  by a narrow, yellow zone. As the spots grow and turn brown or gray, concentric rings with scattered, tiny black dots become visible and eventually the dried tissue falls, leading to defoliation. Leaves of any age can be affected.

17. Grey blight of tea

18. Mode of survival and spread Survive on mango leaves for over a year. Spreads through wind borne conidia.

19. Favourable conditions Heavy infection is noticed during the monsoon when the temperature is 20-25˚C and high humidity.

20. Management Remove and destroy infected plant parts. Spraying copper oxychloride 0.25 Mancozeb 0.25% or Bordeaux mixture 1.0%.

21. Grey blight in coconut Pestalotia palmarum

22. Occurrence World : Asia, Africa, Australia and South Pacific areas. India : Tamil nadu , Kerala, Karnataka and AP. Hosts: Coconut

23. Pathogen Character Pestalotiopsis palmarum  is the causative agent of a  fungal disease  of bananas, coconut and Date palms. The fungus causes leaf spots , petiole / rachis   blights and sometimes bud rot of palms. Unlike other leaf spot and blight diseases and also diseases ,  Pestalotiopsis palmarun  attacks all parts of the leaf from the base to the tip. Whereas most diseases only infect the leaf blade or the leaf petiole.

24. Symptoms The initial symptom appears as yellowish brown spots with grey brown margins, usually they are oval in shape and measures approximately 1-5 cm long. As the disease advances the spots coalesce to form larger irregular necrotic patches with greyish white center . The symptoms are noticed in leaflets of the outer whorl and give a blighted appearance. In advanced stages the tips and margins of the leaf lets dry and shrivel giving a burnt appearance.

25. Grey blight symptoms

26. EPIDEMIOLOGY The disease is noticed in farms with poor nutritional status. Deficiency of potassium and excess of nitrogenous fertilizers favour the disease incidence

27. Mode of survival and spread Primary spread and secondary spread through conidia from infected plants

28. Favourable conditions Heavy infection is noticed during the monsoon when the temperature is 20-25˚C and high humidity.

29. Management Balanced nutrient management. Remove the severely affected older leaves and burn. Spray the trees with Bordeaux mixture 1% or propiconazole (Tilt) 0.3%. Regular application of potassium chloride was reported to reduce the disease incidence.