Integrated disease management of chilli

Chilli diseases and their management

1. Integrated disease management of chilli SUDEEP PANDEY PALB 6306

2. INTRODUCTION Chilli ( capsicum annum L. And capsicum frutescens ) Family solanaceae India ranks first in export of chilies but is only 2.5 to 3 per cent of the total production. The pungency in chillies due to an alkaloid ‘ capsium ’.

3. FUNGAL DISEASES DISEASE PATHOGEN Alternaria rot Alternaria tenui Anthracnose, Fruit rot and die back Colletotrichum capsici Damping off Pythium aphanidermatum Frog eye leaf spot Cercospora capsici Fusarium wilt of chilli Fusarium oxysporum f.sp capsici Phytophthora Phytophthora capsici Powdery mildew Leveillula taurica

4. DISEASE PATHOGEN Bacterial leaf spot Xanthomonas campestris pv. vesicatoria Bacterial wilt Ralstonia solanacearum DISEASE PATHOGEN Chilli mosaic CMV- Cucumber mosaic virus Leaf curl Tobacco leaf curl virus DISEASE PATHOGEN Root knot nematode Meloidogyne spp. BACTERIAL DISEASES VIRAL DISEASES NEMATODE DISEASES

5. FUNGAL DISEASES AT DIFFERENT PLANT STAGES

6. BACTERIAL DISEASES AT DIFFERENT PLANT STAGES

7. VIRAL DISEASES AT DIFFERENT PLANT STAGES

8. Damping off   S ymptoms: Pre-emergence: seed generally fail to germinate, become soft and mushy then turn brown, shrink and finally degenerate. Post-emergence stage: the infected tissues become discolored, water soaked and soon collapse.

9. ETIOLOGY Pythium spp ( Pythium ultimum , Pythium debaryanum , Pythium aphanidermatum ) Primary source :oospores in soil or plant debris. Secondary source: zoospores through irrigation water. .

10. Anthracnose, Die-back and Ripe fruit rot of chilies : Symptoms: The pathogen cause two different type of symptoms on two different parts of the host. Die back Fruit rot

11. Die back: Necrosis of the tender twigs from the tip backwards. Flowers drop and dry up. The entire branch or the entire top of the plant may wither away. The twigs are water soaked to brown, become grayish white or straw colored in advance stage of the disease.

12. Ripe fruit rot: Circular to elliptical sunken spots with black margins and marked with concentric rings on mature fruits. Badly diseased fruits turn straw colored from normal red. On this discolored area, numerous black dots ( acervuli ) are present. The diseased fruit may drop off prematurely.

13. ETIOLOGY Colletotrichum capsici . Primary source: infected seeds and diseased crop debris Secondary source : conidia dispersed by rain splash and wind .

14. Bacterial spots of chillies : Symptoms : Small, circular to irregular, water soaked area which appear as definite spots on the lower surface Color change from dark green to purplish grey with a black center. A narrow yellow halo may surrounded the spot. When the spots are too many, the intervening tissues become dry and brown and the whole leaf dies.

15. Etiology Xanthomonas campestris pv . Vesicatoria . The bacterial cells are single ,straight rods 0.2-0.8*0.6-2.0 µm in size. They are gram negative and motile by a single polar flagellum. These bacterial are strict aerobes and optimum temperature for growth is 25-27°c . It is a seed borne bacteria . Spattering rains are the chief means of local dissemination of bacterial cells

16. Leaf curl Symptom : Curling of the leaves, and thickening and swelling of veins. Abaxial and adaxial curling of leaves accompanied by puckering and blistering of interveinal areas and thickening and swelling of veins. Stunted plant growth due to shortened internodes and leaves greatly reduced in size. Flower buds abcise before attaining full size and anthers do not contain pollen grains.

17. Causal agent: Tobacco leaf curl virus The genome consists of a single circular ssdna . The disease is transmitted by white fly , Bemisia tabaci . This vector spread the maximum disease during the month of August to October .

18. Frog eye leaf spot Leaf lesions are brown and circular with small to large light grey centers and dark brown margins. The lesions may enlarge to 1cm or more in diameter and some times coalesce. Stem, petiole and pod lesions also have light grey centers with dark borders, but they are typically elliptical. Severely infected leaves drop off prematurely resulting in reduced yield.

19. Etiology Cercospora capsici Primary sources of infection are infected seeds, volunteer plants and infected plant debris. Secondary spread is through air-borne conidia.

20. Fusarium Wilt Fusarium oxysporum fsp capsici The leaves turn yellow and die. Initial slight yellowing of the foliage and wilting of the upper leaves that progress in a few days into a permanent wilt with the leaves still attached. By the time above - ground symptoms are evident, the vascular system of the plant is discolored, particularly in the lower stem and roots.

21. Phytophthora Blight Phytophthora capsici Plants suffering from this condition often wilt and die, leaving brown stalks and leaves small. Poor quality fruits Affected areas are often borded with a white mold .

22. Powdery mildew Leveillula taurica It affects on the lower leaf surface, where the lesions are covered with a white to gray powdery growth. Disease progress from the older leaves to younger leaves and defoliation is a prominent symptom which reduces in size and number of fruits.

23. Bacterial wilt: Ralstonia solanacearum . Symptoms : This disease wilted plant without yellowing of leaf due to the entry through natural root wounds or wounds created by insects and nematodes.

24. Mosaic Viruses Symptoms Mottling of yellow and green colour on the leaves. Curled margins Depression, raised areas and puckering on the leaf blade. Stunting Less flowering, retarded fruit shape and size.. 

25. Causal agent -   Chilli mosaic virus. It is a rigid rod and 102 to 339 x 17 nm . Mode of spread and survival The virus is sap transmissible . Rubbing together of a diseased and a healthy leaf may result in the development of the disease on healthy plants. The vectors of the virus are Aphis evonymi , A.Gossypii , A.spiraecola , Lipaphis erysimi , Myzus persicae and Rhopalosiphum maydis

26. Root knot Nematode Plants show wilting which leads to death of plant. If the effected plant pulled out from the soil, the roots can be seen to be distorted, swollen and bearing knots (galls). So, infested roots rot and affected plants will die.

27. Integrated disease management of chilli : Integrated of following practices manage the diseases effectively economically and in a most environment friendly manner. Cultural practices Field sanitation Cropping system: 2-3 rows of maize or sorghum as border crop to restrict the spread of vector. Seed: Use certified seed of varieties for different areas. Seeds obtained from a disease free crop.

28. Sowing : Thin sowing to avoid over crowding, light sandy soil for nurseries or use of pure time sand sawdust mixture for raising seedlings. Under well drained conditions seedling can be transplanted into loam soil also. Thinning and weeding: Weeds serve carriers of plant pathogens and high plant density favor development. Remove the weeds once before and then after the irrigation. Rouge out the mixture and stray diseased plant as their serve as foci of infection.

29. Irrigation: Provide only need-based light irrigations, high humidity and frequent irrigations favour disease development. Varietal: Resistant/tolerant genotypes . resistant/tolerant genotypes against major diseases: G-4, G-5, pusa jwala , pant C-1, NP-46 and JCA 196.

30. Chemical: The common seed protectants are use for seed treatment such as thiram or captan @ 3g/kg of seeds for the better control of damping off. Soil drenching with captan or thiram @ 0.2-0.5%. For the management of anthracnose chilli -spray of captafol @ 0.2% followed by copper oxychloride @ 0.25% and carbendazim @ 0.1% , two spray at 10-15 days interval, 35-45 days after transplanting.

31. The strobilurin fungicides azoxystrobin ( quadris ), trifloxystrobin (flint), and pyraclostrobin ( cabrio ) have been labeled for the control of anthracnose fungus in chillies crop. Spray twice at 10-15 days interval with 2.5g mancozeb or 1g carbendazim /lit of water for the controlling of cercospora leaf spot. Spray twice at 10-15 days interval with chlorothalonil ( kavach ) 0.1% for cercospora leaf spot.

32. Seed treatment with agronsan GN @ 2.5g/kg of seeds and ceresan @ 2.5 g/kg of seeds were used for bacterial leaf spot of chilli . Protect the crop in nursery bed from insect vectors (white fly) by spraying metasystox or rogor @ 1 ml/ litre of water at 10 days interval. Good control of the disease has been reported by three sprayings with ziram o. 25% captan 0.2% or miltox 0.2%.

33. Fungal Diseases Disease Control Damping off ( Pythium aphanidermatum, Rhizoctonia solani, Fusarium spp., and Phytophthora spp. ):- Seed treatment with Captan or Thiram @ 2g/kg seed. Nursery bed treatment with Formalin. Drenching nursery bed with mixture of Dithane M-45 0.25% and Bavistin 0.1%. Ripe fruit rot, Dieback and Anthracnose ( Colletotrichum capsici ):- Seed treatment with Thiram or Dithane M-45 @ 2g/kg seed. Spray Dithane M-45 0.25% or Blitox 0.1% or Bavistin 0.1%. Fruit rot ( Phytophthora capsici ):- seed treatment with Thiram or Dithane M-45 @ 2g/kg seed. Spray Dithane M-45 0.25% or Blitox 0.1% or Bavistin 0.1%. Powdery mildew ( Leveillula taurica ):- Spray Karathane 0.2% at 15 days interval. Leaf spot ( Cercospora capsici) Seed treatment with Thiram @ 2g/kg seed. Spray Bordeaux mixture 1% or Bavistin 0.1% at 15 days interval. Blight (Alternaria solani):- dark and leathery spots appear on the leaves and defoliation occur Spray Dithane M-45 (0.2%) and repeat after 10 days interval.

34. Conclusions: The cultivated chilli suffers from number of fungal, bacterial and viral disease. Among the fungal diseases damping off and anthracnose are the major devastating diseases causing considerable yield loss. Environmental play an effective role for development of these diseases. Disease perpetuate through plant debris in soil, special fruiting body, volunteer host and weeds year to year. The disease can be managed effectively and eco-friendly by cultural practices and applying economic chemicals.