BP Singh

140 P. C. Agarwalsoybean (P. manshurica); downy mildew of grapes (Plasmoparaviticola)i downy mildew of sunflower (P. halstedii).RustRust fungi are host specific, symptoms appear on leaf- stem,leaf sheath, ear, and even pod. Symptoms may appear initially assmall flecks, round or elongated; scattered all over the leaf surfaceor in the form of stripes on stem or leaf sheath. Colour of thesepustules may be either pale yellow, orange, brown, red or black.Examples: Wheat stem rust (Puccinia graminis f. sp. tritici); wheatleaf rust (Puccinia reco1tdifa); brown rust of barley (Puccinia hordei);linseed rust (Melampsora lini); sugarbeet rust (Uromyces betae);maize rust (Puccinia polysora); safflower rust (P. carthami); onion,leek and garlic rust (P. allii).SmutThere are three basic types of smuts, which are distinguishedby the way in which they infect a host plant. (a) Corn smut: spores(Ustilago maydis) can penetrate the plant and cause disease at anygrowing point (local ,infection); including the tasset leaves andalso developing corn (maize) kernels; (b) Covered smut: infectsyoung barley, oat or wheat seedlings (seedling infection); (c) Loosesmut (like loose smut of wheat and barley-Ustilago nuda) infects theovary of cereal plants when plant is flowering. (floral infection).In case of pearl millet smut (Tolyposporium penicillariae) only fewgrains are replaced by spore mass. The smut sari are projected,green at initial stage then turns brown in colour. Examples: Headsmut of sorghum (Sorosporium reillianum); loose smut of oat(Ustilago avenae); covered smut of barley (U. hordei); loose smutof wheat (U. tritid).In case of leaf smuts symptoms are restricted to leaf and leafsheath, in the form of greyish black, slightly swollen bands, stripesor elongated, linear spots. Leaves may shred along the infectedportions which contain spore mass of the fungus, ultimately thespore masses are released in the air and soil. Examples : Smut(En tyloma oryzae); flag smut of wheat (Urocystis tritici); Onion smut(U. cepulae).BuntLike ear smuts, in case of bunts, the symptoms are onlyvisible at the time of heading. In hill bunt of wheat (Tilletia caries