The Gazetteers Department

Besides the damage done by the pests, the crops in the district also suffer from various plant diseases. The following are the important diseases of crops in the district.

Cereals.—Jowar: Grain smut : Sphacelotheca Sorghi is a grain smut of jowar locally known as kani or danekani. It is a seed borne sporadic disease. The disease cannot be recognised until the earheads come out. The affected earheads do not form normal grains but form sacs in place of grains. The affected ovaries turn into conical porcelain white sori which contain black powder. This black powder consists of millions of spores of the fungus. The disease occurs from September to November and affects the kharif jowar. It also affects the rabi jowar. Its source of infection is the threshing yard. It can be controlled by treating the seed with sulphur (200—300 mesh fine) at the rate of 0.028 kg of sulphur to 6.804 kg of seed.

Loose Smut: Sphacelotheca cruenta is a loose smut of jowar locally known as kajali. It is a seed borne disease of jowar prevalent in the district. The symptoms of the disease are nearly the same as those of the grain smut of jowar with the difference that in case of loose smut, wall of sorus gets ruptured and black mass of powder is exposed, giving blackish appearance to the affected earheads. The disease affects kharif jowar from September to November as also rabi jowar. Its source of infection is the threshing yard where the diseased and healthy earheads get mixed up. The disease can be controlled in the same way as the grain smut of jowar.

Sphacelotheca sorghi is a sugary disease of jowar locally known as chikta. It is an air borne disease disseminated by aphids. The disease is detected when sugary secretions are noticed oozing out from the affected ovaries. The oozing drops on the leaves which get sticky to the touch. Hence the disease is named as chikta. The disease affects jowar crop at any time during the period of its growth. It also causes reduction in yield to the extent of five per cent. The disease is brought under check by controlling aphids, through the use of insecticides.

Wheat: Puccinia graminis tritici, locally known as tambera, haldya or gerwa is a rust disease of wheat. It is by far the most destructive disease of wheat and causes damage to the tune of 60 per cent to 75 per cent. It is an air borne disease. The disease appears in the form of reddish brown elongated linear eruptive spots known as pustules mostly on stems and also on leaves. When rubbed, brownish red powder smears the thumb. It contains spores called uredo spores. Later in the season, the endho-phytic mycelium gives second type of black coloured sori or black pustules either at the same erupted spots or side by side. The black pustules contain blackish powder consisting of spores called teleuto spores, which means last spores. As the name signifies, teleuto stage appears at maturity of the crop. The disease is also known as a black stem rust on account of the black colour of the powder. The disease is prevalent from November to February. Infection spreads through spores carried by wind and rain.

The best way to avoid the occurrence of this disease is to grow resistant varieties for irrigated crop.

Ustilago tritici locally known as kani or kajali is a loose smut of wheat. It is a seed borne disease confined to the wheat crop of the district. Loose blackish powder is formed in place of grains, which consists of the spores of the fungus. The infection being inside the seed, dressing with fungicides is ineffective and hence a special method has been evolved to sterilise the seed before sowing.

Pulses.—Tur: (Fusarium oxysporum) locally known as mar is the wild disease of tur. Its attack is generally of a mild nature, the extent of loss in yield being one to two per cent. The disease is soil borne. Affected plants appear sickly, their leaves drop down and they ultimately wither and die. If roots of affected plants are split open, they exhibit brown discoloration of vascular tissue. The disease is of seasonal occurrence and may break out any time during the growth of the crop. The method of controlling this disease is to grow resistant varieties of tur.

Groundnut: Tikka (cercospora arachidicola, Cercospora peisonata) is an air borne disease of groundnut. The disease usually appears on crops when they are 1^l/2 months old. Conspicuous round purplish brown spots, which later on increase in size and become blackish, are seen on the leaves. A yellow halo is also found round the spot. These give an appearance of tikka on leaves. In case of cercospora personata, spots are round and small in size whereas in case of cercospora arachidicola spots are larger in size and of severe intensity.

Infected plant debris provides the source of infection. Affected leaves shed and shedding becomes the striking feature of the disease. The disease can be controlled by spraying the crop in the third week of July with 5: 5: 50 bordeaux mixture or any copper fungicide containing 50 percent metallic copper. If required a second spraying in the month of August and a third one in the third week of September may be given. Dusting with 200 to 300 mesh sulphur at the rate of 15 to 20 lbs. per acre also controls the disease.

Cotton: Anthracones (kawadi).—The disease affects the crop at the seedling stage and also at the boll forming stage. It is a seed borne disease of cotton caused by a fungus parasite. The infected seeds and plant debris provide the source of infection. The disease causes a boll rot resulting in the development of short immature, weak and discoloured lint. This disease can be controlled by treating the seed with organo mercurial compound containing one per cent organic mercury at the rate of 0.057 kg. for 6.804 kg. of seed.

Remularia aresla' locally known as dahiya or dahya is gray mildew of cotton. When it assumes serious proportions, it causes damage to the tune of 50 per cent or more. The disease manifests itself when small greyish white spots first appear on lower leaves. Gradually, these spots grow in size and coalesce giving whitish appearance to the entire leaf. When the attack is severe, white spots appear on both the sides of leaves resulting into defoliation of the plant. The disease generally occurs in the last week of August and continues till November. The spores of the fungus are propagated by wind from diseased to healthy crop. Dusting of 200—300 mesh fine sulphur at the rate of 16.783 kg. 22.68 kg per hectare before the appearance of disease is the only effective measure for controlling the disease.

Xanthomonas malvacearum (karpa), the blackarm or angular leaf spot is a minor disease of cotton. The disease first appears as small water soaked area on leaves which are angular in shape The spots later coalesce involving greater part of the leaf. The stem and the bolls also get affected. The disease extends to the edges of mid and literal veins when it is known as blackarm. Mature bolls when attacked open prematurely and the lint from such bolls bears yellow stains. Such lint fetches low market value. The disease affects dry cotton between July and December and irrigated cotton from July to March. Primary infection on seedlings occurs through bacteria carried in the fuzz on the seed but the secondary source of infection is through splashing rain drops carried by the wind.

Seed borne infection can be controlled by seed disinfection through fungicides but the secondary infection cannot be controlled by any direct method. Breeding for resistance is therefore, the only practicable method.

Grapes : Uncimula necator is powdery mildew of grapes. It is an air borne disease locally known as " bhuri". It affects grapes of all varieties. The disease appears in the form of whitish patches on both the sides of leaves. Affected blossoms fail to set in fruit. Young berries drop when affected in the early stage of their growth. They crack when affected in the advanced stage. The disease normally occurs between November and January. The spores are carried by wind from a diseased to a healthy crop which provides the source of infection. The disease can be effectively controlled by dusting sulphur (200 to 300 mesh) in the third week of November, December and January.

Plasmopara Viticola is a downy mildew of grapes. It is locally known as kevada and affects all varieties of grapes. Yellow oily spots appear on the upper surface of leaves, and simultaneously on the back side, there is a downy growth. Due to the early attack, the blossoms get blighted and berries drop down exhibiting mummified condition. The disease can be controlled by spraying bordeaux mixture 5: 5: 50 in the third week of May and October and in the first week of July and November

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