AGRICULTURE AND IRRIGATION
Kani or Dane-kani.
Spacelotheca Sorghi is a grain smut of jowar, locally known
as kani or danekani. It is a seed borne sporadic disease. When
the attack is mild, it causes damage to the extent of two to five
per cent. When it is severe, the extent of damage is of the
order of 20 to 25 per cent. This disease cannot be detected until
the ear-heads come out. Normal grains are not formed in the
diseased ear-heads. On the contrary, black masses known as
'sori' are formed in place of grains. Sori comprises black
powder which consists of millions of spores of the fungus.
Threshing together of diseased and healthy ear-heads provides
the source of infection. It attacks the kharif jowar between
September and November and rabi jowar between December and
February. At present, the disease is controlled by treating the
seed with 200-300 mesh fine sulphur at the rate of 0.028 kg. (one
ounce) of sulphur to 6.804 kg. (15 lbs.) of seed.
Spacelotheca cruenla is a loose smut of jowar, locally known
as kajali. It is a seed borne disease of jowar prevalent in Amravati. The symptoms of kajali are pretty nearly the same as those of kani or danekani, with the difference that the wall of
sorus gets ruptured and a black mass of powder is exposed
which gives a blackish appearance to the ear-heads. It is of
seasonal occurrence. It affects kharif jowar between September
and November and rabi jowar from December to February. Its mild attack causes damage varying from two per cent to five per cent and severe attack causes damage to the order of 20 to 25
per cent. The diseased and healthy ear-heads get mixed up on the threshing-yard which spreads the infection. Removal and destruction of affected ear-heads helps to check the disease to some extent. Another method of control is to treat the seed with 200-300 mesh tine sulphur at the rate of 0.028 kg. (one ounce) of sulphur to 6.804 kg. (15 lbs.) of seed.
Spacelia 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 drops of this oozing secretion which fall on the leaves are sticky. Hence the disease is named 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.
Ergot (Clavicep microcephala) is a disease of bajra. So far, this disease has been of rare occurrence and as such the extent
of damage caused has been negligible. It is a seed borne and a soil borne disease affecting the crop between September and November. Sclerotal bodies mixed with seed and soil act as source of infection. The disease is detected when sugary secretion from infected flowers in ear-heads is followed by dark black elongated sclerotal bodies in place of grains. The following steps are taken to control the disease: -
1. Procuring seed from disease-free areas.
2. Steeping the grain in 20 per cent salt solution and
removing sclerotal bodies and burning them. The steeped
grain is washed twice or thrice with water to remove the
trace of salt and finally dried.
3. Following the system of crop rotation which helps to
check the outbreak of the disease.
Tambera, Haldya or Gerwa.
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 stem, leaves, leafsheats and awns, etc., manifest in the early part of the season, reddish brown elongated linear eruptive spots known as pustules. When rubbed, brownish red powder smears the thumb. It contains spores called uredo spores. Later in the season, the endhophytic mycelium gives second type of black coloured sori or black pustules 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 black stem rust on account
of the black colour of the powder. The pest is active during
November and February. Infection spreads through spores
carried by wind and rain.
The chief measure for controlling this disease consists in
growing disease resistant varieties like Kenphad 25, MHD-345,
KCN and Hybrid 65 for irrigated crop and selection 59 and 125 for dry crop.
Kani or kajali.
Usfilago 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. The damage caused usually varies between four per cent and six per cent. The disease manifests itself when the ear-heads turn blackish. Every part of the ear-head except the rachis and awns gets affected and loose blackish powder is formed in place of grains. This blackish powder consists of the spores of the fungus. The infected seeds and the black mass of powder are blown by the wind to adjacent fields when the crop is in flowering stage. This spreads infection. Inasmuch as the disease is seed borne, dressing seed with fungicides is ineffective. Hence, a special method is evolved to sterilise the seed before sowing.
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 the disease is to grow wilt resistant varieties such as C-ll, C-28 and C-36.
Tikka (Cercospora arachidicola, Cercospora personala) is an air borne disease of groundnut. Usually it affects the crop
between July and September, though it affects late varieties even up to October. The disease appears when the crop is one or two months old. Conspicuous purple brown, round spots appear on leaves. Gradually, these increase in size and become blackish with a yellow halo around them. These give an appearance of tikka on leaves. Hence the name of the disease. In case of cercospora personata, spots are round and small in size whereas in case of cercospora arachidicota spots are larger in size and severe in intensity.
Infected plant debris provides the source of infection. Affected leaves shed and shedding becomes the striking feature of disease. The intensity of this disease can be reduced by spraying Bordeaux mixture (in the proportion of 5:5:50) thrice, during the growth of the crop. The first spraying is given five to six weeks after planting. The second and the third ones follow at an interval of three or four weeks. Care should be
taken to spray both sides of the foliage. The disease can also
be Controlled by dusting the crop with 200-300 mesh-fine sulphur.
Dusting should be done early in the morning or late in the
evening and towards the windward side. The cost of dusting or spraying the crop is estimated to be around Rs. 62 per hectare (Rs. 25 per acre).
Kawadi, the anthracnose is a seed borne disease of cotton caused by a fungus parasite. Infected seeds and plant debris provide the source of infection. The disease manifests itself as 'seedling-rot", 'collar-rot' and damping off in the seeding stage of the crop and as boll-rot when the crop starts bearing. In the latter case, it results in developing short, immature, weak and discoloured lint.
The control measures include destroying the affected debris, sowing healthy seeds and treating the seed with one per cent organo mercurial compound at the rate of 0.057 kg. (two ounces) for 6.804 kg. (15 lbs.) of seed.
Dahiya or Dahya.
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 grayish 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 appears in the last week of August and continues till November. The spores of the fungus are propagated by wind from diseased to healthy crops. Prophylactic dusting of 200-300 mesh fine sulphur at the rate of '16.783 kg.-22.68 kg. (15-20 lbs.) per hectare before the appearance of the disease in August helps to prevent the disease. If found necessary, another dusting could be done in the month of October.
Karpa (Xanthamonas malvacearum), the blackarm or angular
leaf spot is a minor disease of cotton which causes damage to the extent of two to live per cent. The disease first appears as small water-soaked areas on leaves which are angular in shape. These spots later coalesce involving greater " part of the leaf. The stem and bolls also get affected. The disease extends to the edges of mid and lateral 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 American cotton varieties are more susceptible to its attack than deshi varieties. This 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 he controlled by any direct method. Breeding for resistance is, therefore, the only practicable method.
Uncinula necator is a powdery mildew of grapes. It is an air
borne disease locally known as Bhuri. It affects grapes of all
varieties and when its attack is severe, it causes loss to the tune
of 10 per cent to 15 per cent. The disease appears in the form of whitish patches on both the sides of leaves. These patches gradually grow in size covering a maximum part of the lamina
which gives whitish green appearance. When the attack is severe, withering and shedding of leaves take place; patches also appear on shoots near the base which turns black. 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 giving three dustings of 200-300 mesh fine sulphur 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. The disease manifests itself in the form of yellow oily spots appearing oh the upper surface of leaves. There is simultaneous downy growth on the undersurface. These symptoms become conspicuous under humid conditions. Later on the oily spots turn brown, tissues dry up and become brittle and the leaves are shed. Water soaked spongy spots develop on shoots, petioles and tendrills, which later on turn yellow and finally become brown in colour. Owing to early attack the blossoms get blighted and berries drop down exhibiting dried up condition in case of an advance attack. The disease occurs between June and August.
Spraying Bordeaux mixture in the third week of May and October and in the last week of July and October helps to control the disease.