Link; Davidiella tassiana De Not. The skin of the fruit turns black and shrivels and becomes covered with characteristic pink acervuli. Galls can develop from undifferentiated flower buds, stamen tissues, and various other tissues. The secondary infection may be caused by conidia disseminated by rain splash and irrigation water. Authors should make clear whether they are using sensu lato or sensu stricto. Management: Select good quality seeds.
The disease is mainly spread through air-borne uredospores. Cankers on fruits are the same as in leaves except that yellow hallow is absent. Sheath blight: Rhizoctonia solani Symptoms: The fungus affects the crop from tillering to heading stage. Insect transmission: About 150 species of insects are known to transmit from one plant to other. Epidemiology: The disease is more common on close plantations. Remove the volunteer sunflower plants.
Secondary infection takes place through wind splashed rain. Rust: Puccinia sorghi Symptoms: Circular to oval, elongated, brown powdery pustules are scattered over both surface of the leaves. Removal and destruction of the alternate host and diseased plant debris. The head finally withers and droops down with heavy fungal mycelial nets. The decaying stems are covered by whitish mycelial growth. Downy mildew: Plasmopara viticola Symptoms: The disease is usually first observed as small translucent, pale yellow spots with indefinite borders on the upper surface of leaves.
The rotten tissues contain large number of black or dark brown, thick walled sclerotia. The margin of the affected area becomes raised. Bilaĭ Fusarium tricinctum Corda Sacc. Management Hot water treatment: Soak the seeds in water at 26-30°C for 5hrs to induce dormant mycelium to grow. Free water from dew, irrigation or rain on leaf are more important for pathogenesis. Uredospores and dormant mycelium survive on stubbles and straws and also on weed hosts and self- sown wheat crops. Management: Avoid monoculturing of groundnut.
Management: Plant healthy setts taken from disease free area. Use of resistant varieties are recommended to control the diseases. The secondary spread of sclerotia is aided by irrigation water, human agency, implements, cattle etc. The earliest symptoms on leaves are round pin point, black spots on the main veins of the lamina, usually close to the leaf margin. Mode of Spread and Survival: The fungus survives on collateral hosts like Erianthus fulvus and Saccharum spontaneum. In addition, leaf hopper, Proutista moesta also involves in the transmission. Favourable Conditions: Clipping of tip of the seedling at the time of transplanting, heavy rain, heavy dew, flooding, deep irrigation water, severe wind, temperature of 25-30 °C and application of excessive nitrogen, especially late top dressing.
Other quality characters of grain such as colour, appearance and degree of acceptability in partially attacked ears were inferior to those from cockled and healthy ears Paruthi et al. Powdery mildew Podosphaera leucotrigha Symptoms: The disease appears soon after the buds develop into new leaves and shoots. Tilletia aegilopis Golovin; Tilletia brevifaciens G. These shootlets are much thicker than main axis from which they arise. Philosophical Transactions of the Royal Society of London 42:634-641. .
Winter; Puccinia tritici-duri Viennot-Bourgin Leptosphaeria leaf spot Phaeosphaeria herpotrichoides De Not. Winter Loose smut Ustilago tritici Pers. The final molt to adulthood occurs only after the seed gall has formed. Rust pustules Uredia apper on leaves at early stage of crop and at maturity they turn to brown or orange Telia. The stem inflorescence and capsules are also shown dark brown lesions with concentric rings. Management: In the field the distal bud should be removed when all the hands have opened to prevent infection. These spots enlarge in size and become dark brown and angular.
Avoid continuous cropping of wheat in the same field. Avoid deep sowing of seeds. Follow crop rotation with non-host crops. Apply the recommended doses of fertilizers. Table 4: Important diseases caused by viruses Name of the Diseases Diagnostic Symptoms Management Yellow dwrf of rice C. For nematodes forming seed galls, one generation is produced per year; more than one generation per year can be produced for nematodes that form leaf galls and more stages may be found in the gall.