himanshu Walia 2.pptx disease of grapees

Grapes

1.                                       Submitted to – Dr. Neha Neghi Submitted by- Himanshu 2621069 Tushar Verma 2621086                                                                                                Faculty of Agriculture  Maharishi Markandeshwar (Deemed to be university)Mullana (Ambala) Diseases of Grapevine

2. Diseases of Grapevine 1. Downy mildew Causal organism : Plasmopara viticola Symptoms : Disease occurs on all tender organs of the vine. Characteristic small yellow translucent spots are seen on under surface of leaves followed by development of downy growth (white fluffy growth) of the fungus. White coloured fruiting bodies of the fungus may be observed on the upper surface which usually becomes dirty grey in colour. Several such spots may coalesce among them forming larger necrotic patches. The infected shoots, tendrils and young leaves are seen covered with fruiting structures. In severe infections fruits and flowers are killed and drop off. At later stages of disease development, berries wither, turn brown, shrivelled and scattered easily from the branch. Young fruits exhibit brownish spots covered with downy growth of the fungus. Such fruits may also appear dull green to brown and become wrinkled

3. Etiology P. Viticola is a biotroph / obligate parasite. The hyphae are coenocytic , thin-walled, hyaline and the mycelium grows intercellularly producing vasicular haustoria . The sporangiophores arise from stomata or immerse directly through rupture of host cuticle. The branching of sporangiophores occurs at right angle, at the apex of each branch 2-3 sterigmata are formed on which thin-walled hyaline sporangia are formed. Disease cycle
The pathogen overwinters by means of oospores formed in diseased tissues. The wild species of Vitis also harbour the pathogen. The sporangia or zoospores are splashed or blown to wet vine surface and cause infection.

4. Control Field sanitation.
Spray the vine with copper oxychloride ( Blitox 50 WP) @ 0.3% after pruning.
Cut ends after pruning may be protected with Bordeaux paste.
Search for chemical control of this disease led to discovery of Bordeaux
mixture in 1885 by Millardet .
Resistant varieties- Amber Queen, Champion red and Sultana.
Spray azoxystrobin (0.1%), mancozeb (0.25%).
Biocontrol agent- Fusarium proliferatum is antagonistic to this pathogen.

5. 2. Powdery mildew Causal organism : Uncinula necator Symptoms The fungus causes ash grey to White powdery growth on green tissues of grapevine. The leaves developed small, yellow green blothes 2-10 mm in diameter within irregular outline on upper surface of leaves. The leaves are covered with ash grey to whitish growth on both the sides in severe cases or at later stage of the crop/plant/vine growth. The chains of conidia that develop from the powdery mildew hyphae give the infected vine tissue a characteristic powdery or dusty appearance. Severely affected vines emit a musty (damp smell) odour mid to late season. The affected shoots remain stunted and are covered with ash grey to white powdery growth with distorted leaves that curl upwards. Veins of underside of the leaves turn brown when infected. If flower clusters are infected, the flowers may wither and drop without fruit set. Severely infected leaves give the vine a wilted appearance as such leaves fall down prematurely in hot weather.
The immature berries and bunch stalks are also covered with white powdery growth. Infected berries develop irregular shape, crack, split and rot. Black patches on green immature shoots develops into reddish brown patches on mature canes. Late in the season the fruiting bodies cleistothecia are also found on infected areas.

6. Etiology U. Necator is an obligate parasite. It produces superficial mycelium on host surface. The hyphae are hyaline and septate. Conidia are born in chain on conidiophores which are simple, erect and septate. Cleistothecia are rarely formed which are globose with several asci and coiled appendages. Disease cycle It overwinters inside dormant buds of grapevine in the form of cleistothecia . Ascospores released from cleistothecia serve as primary source of inoculum while conidia produced as a result of infection by ascospores cause secondary infection Favorable conditions Temperature: 68-70°F.
Relative humidity: 40-100% Control Pruning and training of vines to reduce shading and increase air circulation.
Spray propiconazole (Tilt) @ 0.1% or Karathane @ 0.25%.

7. 3. Anthracnose Causal organism: Gloeosporium ampelophagum (imperfect stage)
Elsinoe amphelina (perfect stage/ascus stage) Symptoms The disease affects the green parts of the plant including flower and fruits in the form of small, irregular dark brown spots. These spots are grey in the center surrounded by dark brown border. Later the centre of the spots fall off resulting in a symptom called shot hone. Similar small, isolated, light brown spots also develop on shoots and tendrils. Such spots may elongate to form elliptical and sunken lesions. On the berries, characteristic brown brownish sunken spots develop resembling bird’s eye. Hence called bird’s eye spot. These spots are light brown in the beginning. They become grey at the centre usually surrounded by yellowish or purplish margins. The affected fruits may crack with scabbish appearance.

8. Etiology The fungus produces fruiting body on affected areas of the host which are called pseudothecium . Pseudothecium is an ascocarp resembling a perithecium but whose asci are not regularly organised in a Hymenium and are bitunicate . These bitunicate asci expand when they take up water and release the enclosed spores ( ascospores ) suddenly to dispense them. The pseudothecium have uniloculate ascomata . Disease cycle Fungus survive in a canker of uncut vines or on pruned twigs in form of mycelium or pseudothecia . Control Pruning and distruction of affected plant parts followed by painting of pruned parts with a paste of ferrous sulphate in sulphuric acid to kill the deep seated mycelium.
Spray the vines with copper oxychloride 0.2% or Bavistin 0.2% on leaves emergence. Repeat the spray 3-4 times during May (1 week), July, 2 nd and 3 rd week of August and September.
Resistant varieties: Banglore blue, Isabella, Golden muscat , Himrod , Large white, Golden queen and Muscat.