Diseases of Grape

For UG course

1. DISEASES OF GRAPE Anurag Kerketta CHRS, Jagdalpur

2. DISEASES OF GRAPE B. N.- ( Vitis vinifera). F.- Vitaceae. In India, grapes are grown under tropical as well as subtropical climate. The commercial cultivation of grapes has begun only during the last four decades. Maharashtra, Karnataka, Andhra Pradesh and Tamil Nadu are the states growing grapes.

3. Diseases Powdery mildew - Uncinula necator. Downy mildew - Plasmopara viticola. Anthracnose - Elsinoe ampelina (Gloeosporium amphelphagum) Black rot - Guignardia bidwellii. Bacterial canker - Xanthomonas campestris pv. Viticola.

4. Minor diseases Brown leaf spot - Cercospora viticola Rust - Phakopsora vitis Coniothyrium blight - Coniothyrum diplodiella Alternaria blight - Alternaria vitis Drechslera leaf spot - Drechslera rostrata

5. 1. POWDERY MILDEW: Powdery mildew is an endemic disease. The disease has been reported from the American continent. In India, the disease is most common in Maharashtra, Gujarat, Andhra Pradesh, Karnataka and Tamil Nadu. Economic Importance The disease causes extensive damage in whole of Europe and Western USA. French grapevine industry also suffered huge losses due to the epidemics of this disease during 1850-55. The disease not only reduces the yield and lower the fruit quality but wine prepared from infected fruits often develops off-flavor (Ough and Berg, 1979).

6. Causal organism : Uncinula necator (I.S: Oidium tuckeri ) Classification: Kingdom – Fungi. Phylum – Ascomycota. Class – Ascomycetes . Order – Erysiphales . Family - Erysiphaceae . Genus – Uncinula Species - necator

7. Symptoms The disease attacks the vines at any stage of their growth. All the aerial parts of the plant are attacked. Cluster and berry infections usually appear first. Floral infection results in shedding of flowers and poor fruit set. Early berry infection results in shedding of affected berries. Powdery growth is visible on older berries and the infection results in the cracking of skin of the berries. Often infected berries develop a net-like pattern of scar tissues.

8. Powdery growth mostly on the upper surface of the leaves. Malformation and discolouration of affected leaves. Leaf lesions appear late and doesn’t cause much damage .

9. Characteristics of pathogen The mycelium is ectophytic and produces bilobate or multilobate appressoria. The conidiophores are simple, multiseptate and erect bearing a chain of 3-4 conidia. Under Indian conditions, perfect stage of the fungus is not found. When the mating types are present cleistothecia can form on all infected tissues during later part of the growing season.

10. Disease cycle

11. It survives as dormant mycelia and as Cleistothecia on the shoots and buds from season to season. The disease spreads by the air- borne conidia/ oidia .

12. Epidemiology/ Favourable conditions The disease occurs in severe form from Oct- Nov in North India and Feb- June in South India. Disease is favoured by warm sultry weather and retarded by sunshine. Warm winter temperature from 20 to 33.5ºC has been found to be the cause for epidemic. Disease development is adversely affected by rain.

13. Management Cultural practices: The use of training systems which allow proper air circulation through the canopy and prevent excess shading helps in reducing the disease. Orchard sanitation is also important in reducing the disease pressure during the growing season. Grow resistant varieties like Chholth Red, Chholth white, Skibba Red, Skibba White, etc. Chemical control: Fungicides like Sulphur, Dinocap, Benomyl, Triadimefon, Penconazole, Mycobutanil and Flusilazole are used commercially although not as extensively as sulphur, to control the disease. The use of fungicides for control of powdery mildew should begin during early stages of vine development. Spray schedules at an interval of 7-10 days are usually required for effective control by sulphur. Dinocap is to be given at an interval of 10-14 days while; sterol biosynthesis inhibiting fungicides are commonly used at 14-21 days schedule. For effective control, the fungicide spray should start just after bud burst. The fungicides should be sprayed alternatively and the same fungicide should not be sprayed continuously..

14. 2. DOWNY MILDEW Causal Organism: Plasmopara viticola Classification Kingdom - Chromista Division - Oomycota Class - Oomycetes Order - Peronosporales Family - Peronosporaceae Genus - Plasmopara Species - viticola

15. Symptoms Symptoms appear on all aerial and tender parts of the vine. Symptoms are more pronounced on leaves, young shoots and immature beries. Irregular, yellowish, translucent spots on the upper surface of the leaves. Correspondingly on the lower surface, dirty white, powdery growth of fungus appears. Affected leaves become, yellow and brown and gets dried due to necrosis Premature defoliation. Dwarfing of tender shoots.

16. Infected leaves, shoots and tendrils are covered by whitish growth of the fungus. White growth of fungus on berries which subsequently becomes leathery and shrivels. Infected berries turn hard, bluish green and then brown. Later infection of berries results in soft rot symptoms. Normally, the fully grown or maturing berries do not contact fresh infection as stomata turn non-functional. No cracking of the skin of the berries.

17. Mycelium is intercellular with spherical haustoria, coenocytic, thin walled and hyaline. Sporangiophores arise from hyphae in the sub- stomatal spaces and sometimes they emerge directly through the cuticle. On young berries of grapevine they emerge through the lenticels. Sporangiophore branching is almost at right angles to the main axis and at regular intervals. Secondary branches arise from lower branches. From the apex of each branch 2-3 sterigmata arise and bear sporangia singly. The sporangia are thin walled, oval or lemon-shaped. Asexual spores: Zoospores are pear shaped, biflagellate borne in sporangia Characteristics of pathogen

18. Disease cycle

19. The most favourable temperature for germination of sporangia is between 10-23ºC. Disease development is favoured during rainy season when there is heavy dew, relative humidity is above 80% and temperature is between 23 and 27ºC. Epidemiology/ Favourable conditions

20. Regulatory measures: Restriction on the movement of planting material at regional, national or international level should be imposed, since the pathogen spreads through dormant cuttings (planting materials). Cultural practices: All infected plant material and pruned parts must be removed and burnt before bud sprouting, so as to reduce primary inoculum. Even during growing season plant debris must be avoided in and around the field. Careful attention should be paid to spacing of vines, row direction and placement of wind breaks, which will ensure maximum air drainage and minimum leaf wetness duration. To encourage air movement within the plant canopy, practices such as, removal of leaves around berry clusters, trellis designs and pruning systems which allow more air movement be followed during the early development of vines. Careful disbudding and training of veins should be practiced to maximize distance between soil and foliage. Management

21. Biological control: Erwinia herbicola, a saprophytic bacterium, used as liquid culture and sprayed on vines which inhibits P. viticola upto 75%. Chemical control: After pruning, the vines should be sprayed with Bordeaux Mixture 1.0% or Difolatan 0.2% or Copper oxychloride 0.3% or Chlorothalonil 0.2%. When the flushes are formed, spraying with Difolatan 0.2% or Chlorothalonil 0.2% or Metalaxyl 0.2% or Copper oxychloride (%) are effective. It may be repeated at weekly or fortnightly intervals depending up on severity and weather conditions. When the non-systemic fungicide is used during humid and rainy period spraying should be repeated for every two or three days.

22. ANTHRACNOSE / BIRDS EYE SPOT Anthracnose is a widespread disease in all grape growing regions of the world. The disease is known in Europe since ancient times, however, in India, the disease was first recorded in 1903 near Poona and is now widely prevalent in Rajasthan, Uttar Pradesh, Punjab, Haryana, Andhra Pradesh, Karnataka and Tamil Nadu. Under north Indian conditions, the disease appears only during rainy season. In the southern part of the country, the berries escape infection because the crop matures before the onset of rains.

23. Symptoms The fungus attacks shoots, tendrils, petioles, leaves, veins and stems and also inflorescence and berries. Numerous spots occur on the young shoots. These spots may unite to girdle the stem and cause death of the tips and may also cause die-back symptoms. Spots appear on the new shoots and fruits also. Spots on petioles and leaves cause them to curl or become distorted. On berries, characteristic round, brown sunken spots resembling “Birds Eye” and hence the name of the disease.

24. On the leaves it appears as small, irregular, dark brown spots. The central tissue turn grey and falls off. The disease appears as dark red spots on the berry. Later these spots are circular, sunken and ashy grey and in late stages these spots are surrounded by a dark margin which gives it the bird’s eye appearance.

25. Causal Organism: The anthracnose of grapes is caused by Gloeosporium ampelophagum (Pars.) Sacc. {Elsinoe amphelina (de bary) Shear –perfect stage}. Classification Kingdom - Fungi Division - Ascomycota Class - Loculoascomycetes Order - Dothideales Family - Elsinoaceae Genus - Elsinoe Species - ampelina Etiology

26. Characteristics of pathogen Conidial stage is Sphaceloma ampelina de Bary . Conidia are formed in pink acervuli . They are hyaline, single celled, oblong or ovoid . Perithecia ( Pseudothecia ) are small and unconspicuous . Asci are globular and ascospores are hyaline, 3-celled. OR Anamorph – Gloeorporium ampelophagum, produce hyaline, single celled conidia. Teleomorph - Elsinoe ampelina, Produces hyaline 4 celled ascospores

27. Disease cycle Survives as dormant mycelium in the infected stem-cankers. Secondary spread is by means of conidia formed in the leaf and other plant parts which are easily disseminated by wind and splashed rain. Continuous drizzle of rain for 2-3 days encourages the disease. No infection can take place in the absence of rain. Wind associated with warm atmosphere (temp.) and heavy rains favour the disease spread.

28. Epidemiology Warm wet weather Low lying and badly drained soils.

29. Management Cultural practices: Training of vines should be such that water splashes should not reach the foliage, canes and branches during rainy season. Ground level canes and branches should be removed. All cankerous canes should be pruned and destroyed by burning. This will help in reducing the primary inoculum during the growing season. Chemical control: Spray vineyards at the time of leaf emergence with Thiophanate methyl (0.1%), bitertanol (0.1%), benomyl (0.1%), carbendazim (0.1%), or Bordeaux mixture (1.0%). At least four sprays of fungicides should be given during rainy season at fortnightly intervals. Care should be taken not to spray the same fungicide regularly.

30. Varietal Resistance: The Muscadine grapes seems to be immune, Champane highly resistant, Concord moderately resistant and most varieties are highly susceptible. Variety Delight is tolerant whereas, Bharat Early and Hussaini are resistant.

31. BLACK ROT The disease after its introduction in France during 1880‟s, it spread to all grape growing areas of Europe. In India, the disease has been observed in Madurai district. Black rot is more distructive in warm and humid areas than in the cooler and drier ones. The disease has been recently observed on certain purple varieties and it is less common on the seedless and Pachha draksha varieties.

32. Symptoms The disease on fruit begins to show as light, brownish, soft, circular spots which increase in size and the entire berry is discoloured . The decaying berries begin to shrivel within a week and are transformed into hard, black, shriveled mummies. On the leaf, circular red spots appear and later the margins become black. Minute black dots representing fruiting bodies of the fungus are arranged in a ring near the outer edge.

33. Causal Organism: Guignardia bidwelli Classification Kingdom - Fungi Division - Ascomycota Class - Loculoascomycetes Order - Dothideales Family - Botryosphaeriaceae Genus - Guignardia Species - bidwelli

34. Characteristics of pathogen The mycelium is hyaline when young and it becomes brown after full maturity. Perithecia are globose , ostiole not prominent. Asci are clavate , thick walled. Each Ascus contains 8 ascospores. Ascospores are bicelled but cells are unequal in size. Ascospores are hyaline, sub-ovoid or elliptical, slightly flattened on one side .

35. Disease cycle Perithecia develop on mummified grape berries and the Ascospores are discharged when mummies are wet. Ascospores produce germ tube and penetrate directly through the cuticle. Primary infection occurs on young leaves and fruit pedicles. Pycnidia are rapidly produced. Pycnidiospores spread through meteoric water. They may survive the winter and germinate in the following season.

36. Epidemiology Frequent rains and humid climate are conducive for disease development. Management Diseased berries and leaves should be collected and destroyed. Spraying of Bordeaux Mixture 1.0% or Ferbam 0.2% or Captan 0.2%, Chlorothalonil 0.2% should be done when the new shoots are 15-25cm long and repeated before bloom, 10-15 days after bloom.

37. MINOR DISEASES

38. Brown Leaf Spot Brown leaf spot is caused by Cercospora viticola. Classification Kingdom - Fungi Division - Deuteromycota Class - Deuteromycetes Order - Moniliales Family - Dimatiaceae Genus - Cercospora Species – viticola .

39. This is normally prevalent in neglected gardens, during July- Dec in the grapes growing areas . Dark brown, angular spots appear on leaves and young shoots. Sometimes young shoots dry up. The disease spreads through wind- borne conidia.

40. High humidity favours the disease. Keeping the garden in healthy and robust (vigorous) conditions by proper manuring and cultural operations keeps away the disease. Mancozeb 0.25% or Bordeaux mixture 1.0% or benomyl 0.05% spray is quite effective. Varieties like Australia No.2, Champach and Champion are resistant