Everything you need to know about rapeseed mustard cultivation and harvest. Learn about:- 1. Description of Rapeseed Mustard 2. Cultivation of Rapeseed Mustard 3. Area and Production under Rapeseed Mustard Cultivation 4. Climate, Season and Soil Suitable for Cultivating Rapeseed Mustard 5. Sowing of Rapeseed Mustard 6. Manures and Fertilizers for Rapeseed Mustard Cultivation and Other Details.
Contents:
- Description of Rapeseed Mustard
- Cultivation of Rapeseed Mustard
- Area and Production under Rapeseed Mustard Cultivation
- Climate, Season and Soil Suitable for Cultivating Rapeseed Mustard
- Sowing of Rapeseed Mustard
- Manures and Fertilizers for Rapeseed Mustard Cultivation
- Harvesting of Rapeseed Mustard
- Yield of Rapeseed Mustard
- Diseases of Rapeseed Mustard
- Pests of Rapeseed Mustard
1. Description of Rapeseed Mustard:
A much-branched, very variable, annual or biennial herb, upto 1.5 m in height, cultivated in India as a cool season crop. Taproot fusiform or tuberous; basal leaves lyrate-pinnatifid, lobes decreasing in size towards petiole, glaucous, glabrous, with a few bristly hairs, especially along the veins; lower cauline leaves several lobed, upper cauline leaves sessile, amplexi-caul, oblong-lanceolate, sharply dentate; flowers yellow; siliqua, 50-100 mm x 2.5-4.0 mm, attenuating into a long slender beak 5-30 mm long; seeds mucilaginous or non-mucilaginous.
The present day B. campestris comprises a vast number of morphologically divergent forms. The various taxa in the complex can be divided into three well-defined groups purely on a morphological basis, viz. yellow sarson, brown sarson and toria. About 21 varieties of rapeseed mustard have either been released or recommended at the national or state level.
A large number of high yielding strains of mustard, toria, brown sarson and yellow sarson have been developed by different research centres following conventional methods of breeding such as selection, dwarfing, mutation breeding, collection and introduction of germplasm, hybridization and creation of synthetic varieties, etc.
At present, over 12,880 accessions of germplasm of Brassica species and their allies are being maintained, and 2,170 new lines have been selected from within the country. In a study made on 7,972 cultures, 14 lines were identified for earliness, four for drought situations, eleven for tolerance to Alternaria blight, thirty four to white rust, twelve to bacterial blight, nineteen to aphid, twenty three to sawfly, and seven to flea beetle.
Elaborate crossing work has now been initiated for evolving superior commercial cultivars by recombining desirable agronomic characteristics in toria and rai at Kanpur, Hissar, Ludhiana, Pantnagar, Durgapur and Dholi (Bihar). Some of the promising experimental toria composite cultivars have been developed at Pantnagar (‘Pant Toria 30’, ‘PT 303’, ‘PT 10′, TP 507B’); Ludhiana (‘Ludhiana Composite 1,2,3’); Gurdaspur (‘Gurdaspur Composite 3’) and these are now being tried in All-India trials. At Hissar ‘Syn 65’, developed as a result of synthetic cultivar breeding programme was released as a commercial cultivar ‘Sangam’. At Kanpur, brown sarson ‘Pusa Kalyani’ was also developed by utilizing this breeding approach.
The growing of rapeseed mustard as mixed crops with wheat still predominates throughout the country. In a crop like brown sarson which is ideally suited for such a situation, a plant type has been reconstructed from a cross between ‘BSH 1’ x ‘DS 17 M’ in such a way that the spreading and bushy growth habit of ‘BSH 1’ could be reduced and made compact and erect so as to accommodate more plants per unit of land.
In toria, a plant type with a strong stiff stem, compact branching habit and closer arrangement of siliqua is required. Incidentally, a new source of dwarfing gene showing monogenic inheritance with a lot of modifiers has been obtained at Pantnagar from the natural population of ‘Experimental Torial Composite I’. The plants showed compact and close arrangement of siliqua on the branches.
One of the major constraints limiting the production of rapeseed mustard is the absence of frost resistant varieties. During 1980-82 two strains of rapeseed mustard, ‘DPS 1’ of brown sarson and ‘RW 175’ of mustard were identified as resistant to frost. These two strains can be utilized in hybridization as donor parent. To provide greater stability to rapeseed mustard production, emphasis on breeding for aphid pest and Alternaria disease resistance was given.
As a result, the following genotypes in rapeseed mustard showing resistance/tolerance to aphid and leaf miner pests, Alternaria blight, white rust and downy mildew diseases have been identified:
(a) Mustard aphid-‘T 6342’, ‘RC 736’, ‘RC 574’, ‘RC 978’, ‘RLM 198′, TM 4’, ‘PR 2’.
(b) Leaf miner— ‘RC 1008’, Alternaria blight— ‘RC 781’, ‘RC 1401’ and ‘YRT 3’ (raya).
(c) White rust and downy mildew— ‘RC 781’ (B. jun-cea), ‘Pant Toria 77’, ‘Pant Toria 82’, ‘Pant Toria 811’ and ‘Bharbari’ (B. campestris).
These resistant strains are being used as donor parents in hybridization programmes. In an attempt to breed toria varieties for drought situations three drought resistant strains of toria, ‘Pant Toria 30’, ‘Pant Toria 40’, and ‘Pant Toria 42’ have been developed at Pantnagar.
Selection from local population for dwarfness, early maturity and erect and semi-erect habit, to withstand close planting have resulted in improved types Type 11′ and ‘L 16’ of rai; ‘Abohar’ of toria; T 42′ and T 16′ of yellow sarson; and some improved lines in Gurgaon Brown Sarson.
A dwarf B. juncea of about 30 cm in height, with upright habit owing to adhesion of secondary branches, was also isolated. Non-shattering cultivars with appressed branching were obtained in X-ray irradiated material; these cultivars also showed increase, though only slight, in yield and oil content.
In toria and sarson, it was possible to increase the oil yield upto 35 per cent by mass selection; disruptive selection of flowering time also resulted in increased yield of oil. Commercially, exploited crosses between various cultivars of brown sarson yielded seeds containing oil to the extent of 63 per cent.
It is possible to alter the fatty acid composition, pungency, and sulphur content of the oil. Selection for low erucic acid content, made in Sweden and Canada, has increased the possibility of using the extracted material for human consumption.
Male sterility sources in rapeseed mustard were discovered and under experimental conditions, stable sources of male sterility in B. juncea were obtained by substituting the genome of this species in the cytoplasm of B. nigra. Cytoplasmic male sterility has been transferred to twenty-nine improved cultivars at the Indian Agricultural Research Institute, New Delhi. The fertility restorer lines are in the process of being transferred to the pollen parents and it is likely that a complete fertility restorer line could be developed in the near future.
Rapeseed and Mustard:
The seeds of oleiferous brassicas contain 35-50 per cent fatty oil and about 20 per cent protein. The free essential oil content is usually very low, but the seeds contain small proportions of glucosides which on hydrolysis yield the volatile mustard oils. The fatty oils from the different cultivars of brassicas closely resemble each other and are characterized by a high proportion of erucic acid. Rapeseed is a general term applied to the seeds of oleiferous brassicas, cultivated in many parts of the world as an oil-seed crop.
Although several of these are distinct species or varieties, they all yield oils with similar contents and composition, known as rapeseed oil or colza oil. In India, the edible oil derived from the cultivated brassicas (Hindi—sarson ka tel. kadwa tel) is called mustard oil, a term which, in Europe and America, is applied to the volatile oil of mustard seeds. Indian mustard oil is generally obtained from the seeds of yellow and black sarson, toria and rai.
2. Cultivation of Rapeseed Mustard:
India is the third largest oilseed producing country in the world. Rapeseed mustard production accounts for nearly 15 to 20 per cent of the total oilseeds produced in India. The chief growing states are Uttar Pradesh, Punjab, Assam, Bihar, Madhya Pradesh, Rajasthan and West Bengal.
Rai, sarson and toria are all grown in U.P. Brown sarson, toria and taramira are popular in Punjab. Brown sarson is more popular than yellow sarson in Assam. Sarson and rai are preferred in Bihar.
The earliest forms of rapeseed mustard are found in Bengal while the latest maturing types are met with in Punjab. The boldest- seeded varieties of rai are found in Punjab, central and western districts of U.P. In brown sarson, the variety which is grown in the eastern districts of U.P. is bolder in seed size than lotni grown in the central and western districts of U.P.
The multi-valved forms of yellow sarson which are generally small-seeded and early or medium- maturing, are found mostly in the western districts of U.P. West Bihar and North Bengal.
Rapeseed mustard is commonly sown mixed with other crops like wheat, barley and gram. Mixed cropping is especially common in U.P. Toria, however, is chiefly sown as a pure crop, lotni brown sarson is also grown pure in rain-fed areas of U.P. and Punjab. The main reason for mixed cropping is as an insurance against total crop failure.
3. Area and Production under Rapeseed Mustard Cultivation:
India is the leading country in the world regarding the area under cultivation of rapeseed mustard. During 1983 to 1985, 3.8 to 4.4 million hectares were occupied by the crop which amounted to 28.5-30.3 per cent of the world area under the crop, and 46 to 48.7 per cent of the area in the developing countries. China is the leading producer of rapeseed mustard contributing 25.4 to 30.2 per cent to the world production, Canada—18 to 20 per cent and India ranks third with about 16 per cent of the world production. India’s share in the production of rapeseed mustard in the developing countries amounted to 32 to 36 per cent.
Rapeseed and mustard in different forms (rai, toria, brown sarson, yellow sarson, black mustard) have been grown in India and China for thousands of years. They were introduced to Europe in the 15th century. The cultivation has increased, particularly since World War II. Rapeseed was introduced to Canada in the 1950’s and there it has become an important crop. Today, rapeseed ranks fifth among the oilseeds of the world. Cultivation of the crop for oilseed production is almost entirely confined to the temperate and warm temperate zones.
Among the oilseed crops in India, rapeseed mustard occupies the second largest cultivated area (3.8 to 4.4 million hectares during 1983 to 1985) ranking next only to groundnut. Although rapeseed mustard varieties are grown in all states and union territories, about 90 per cent of the production and 89 per cent of the area in the country is concentrated in six major producing states— Uttar Pradesh, Rajasthan, Madhya Pradesh, Haryana, Punjab and Assam.
The ten-yearly average annual area and production of rapeseed mustard in India during 1950-51 to 1959-60, 1960-61 to 1969-70, and 1970-71 to 1979-80 is as follows: area— 2.41, 3.03, and 3.45 million hectares, respectively and production— 0.94, 1.34, and 1.76 million tonnes respectively.
Between 1954-55 and 1973-74, area, production and yield in the country increased by 40.5%, 63.2% and 16.2%, respectively. The increase in area, production and yield during the above period was different in each of the major producing states. The percentage increase in area was more than the all-India average in Assam, Rajasthan, Madhya Pradesh and Punjab.
Similarly, the percentage increase in yield was more than the all-India average in Assam, Uttar Pradesh, Madhya Pradesh and Punjab. The all-India average yield of rapeseed mustard has been one-fifth to one-sixth of the average yields in European countries.
During 1983, 1984, and 1985 an area 3.8, 3.8 and 4.4 million hectares was under the crop, producing 2.2, 2.6 and 3.6 million tonnes, respectively.
In Uttar Pradesh, rai, sarson and toria are grown both pure and mixed. In the sub-montane tracts of terai and bhabar, they are grown as pure crops. Yellow toria is grown pure also in the central districts of Etawah, Farrukhabad, Manipuri, and Kanpur. Rai and sarson are growth as mixed crops almost throughout U.P, yellow sarson taking a lead over brown sarson in the western districts.
Of the two varieties of brown sarson, Tora (self-fertile) and Lotni (self-sterile), the former is grown exclusively in the eastern districts of U.P. as a mixed crop, and the latter in the central and western districts. Lotni is cultivated also as a pure crop in the barani (rain-fed) areas in the drier districts of Agra and Mathura.
Rajasthan mostly grows brown sarson in Bharatpur and Alwar. In Punjab and Haryana, sarson and rai are grown as an admixture with wheat, barley and gram; but toria is generally grown as a pure crop. Sarson (brown sarson in particular) is cultivated in the districts of Amritsar, Ferozepur, and Karnal; toria is also grown mainly in these districts.
In north-eastern India, brown sarson is more popular than yellow sarson and the crop is extensively grown in the districts of Goalpara, Kamrup, Darrang, Nowgong, Sibsagar, Lakhimpur, Garo Hills and Cachar.
In West Bengal, all the three crops are grown in West Dinajpur, Murshidabad, Nadia and Malda. The districts cultivating rapeseed mustard in Bihar are Purnea, Palamau, Ranchi, Hazaribagh and Giridih, in Orissa, they are grown in Phulbani, Kalahandi, and Dhenkanal. In Gujarat, these crops are grown in Mehsana and Banaskantha districts, and in Jammu & Kashmir, Anantnag is the chief producing area. Toria is possibly the only oilseed crop grown in Ladakh.
4. Climate, Season and Soil Suitable for Cultivating Rapeseed Mustard:
Rapeseed mustard is grown in India as a rabi crop. Moisture is conserved as much as possible during rainy season for growing brown sarson during rabi. It requires somewhat cool climate for satisfactory growth and is grown mostly in the sub-tropical parts of India. Since frost arrests the development of seed, it is usually sown earlier than other winter oilseed crops.
The actual time of sowing depends on the place, the crop occupies in rotation. Toria is sown in Aug-Sept and treated as kharif crop. Sarson is sown usually in Oct-Nov. In Uttar Pradesh, sarson is sown from the middle of October to beginning of November. The sowing period for rai is from mid-October to mid-November in Assam and in the first week of October in U.P.
In India, toria takes 85-100 days to mature, sarson (yellow variety) 120-160 days and the brown varieties 105-145 days.
Soil:
Rapeseed mustard thrives best in the light to heavy loams. Rai may be grown on all types of soils, but toria does best in light to heavy loams. Sarson is suited to light loam soils. Water logging due to heavy winter-rains may cause considerable damage. In northern Gujarat, rai is better suited to salt affected soils than toria and sarson and its tolerance variation is also wide.
Preparation of Land:
A fine seed-bed is required to ensure good germination. In irrigated areas, the first ploughing is done with a medium-sized soil-turning plough, followed by two to four ploughings with a desi plough or a cultivator. Planking is given after every ploughing. In rain-fed areas, one or two ploughings with a desi plough or a cultivator, each followed by planking may be given. Toria, in particular, requires a fairly moist seed-bed for good germination, but excessive moisture should be avoided.
Under dryland conditions, establishment of optimum plant stand is a real hurdle in realising a good harvest. To overcome this problem, seed should be sown in furrows with ridge-seeder. This practice besides maintaining a perfect crop stand helps in better conservation of moisture.
5. Sowing of Rapeseed Mustard:
The seed-rate in the case of mixed cropping depends on the proportion of the rapeseed to the main crop. When sown pure, 5 kg of seed per hectare is used for all rapeseed mustard.
When sown mixed with other crops, the time of sowing rapeseed mustard is governed by that of the main crop. The first half of September is best for sowing toria. If wheat is to follow, it should be sown by the end of August. Similarly, sarson should be sown between September 25 and October 15 and rai between September 30 and October 15.
To ensure good germination and early seedling vigour, seeds must be soaked in water before sowing. This is best done by covering the seeds with a moist gunny bag or directly with damp earth overnight.
Optimum plant population should be maintained to attain higher yields. Five kg of seed is enough to plant one hectare. If the soil moisture is good, the seed rate can be reduced to 4 kg/ha. In mixed cropping, rapeseed mustard requires irrigation water. The first two irrigations should be light and the remaining with 75 mm water each. It is better to delay the first irrigation as much as possible.
This helps the plants to branch well, which in turn results in profuse flowering and fruiting. The best time for the first irrigation is when the flowering has sufficiently advanced. The second irrigation should be given at fruiting stage, i.e. 55 days after sowing in toria and 60 days in mustard.
Rapeseed mustard is grown as an irrigated crop in parts of Bihar, Gujarat, Jammu & Kashmir, Maharashtra, Madhya Pradesh, Punjab, Rajasthan, Uttar Pradesh and Delhi. In Jammu & Kashmir, more than half the area under this crop is reported to be irrigated. Gujarat and Maharashtra together have c 40 per cent area under irrigation. In Uttar Pradesh only c 20 per cent of the area under this crop is irrigated; in terai region, no irrigation is generally needed.
In Punjab, toria is generally grown on irrigated land while others are grown on un-irrigated lands. Brown sarson is grown entirely on un-irrigated land. The crop in other states is reported to be predominantly rain-fed.
6. Manures and Fertilizers for Rapeseed Mustard Cultivation:
Rapeseed mustard responds well to organic and inorganic manures. Nitrogenous fertilizer in the form of ammonium sulphate is beneficial for the crop. The effect of nitrogenous fertilizer can be optimised by combining soil application with foliar spray. Half of the recommended dose must be applied (preferably drilled) at the time of sowing. The remaining half must be applied in the form of foliar spray (1.5 to 2%). The first spray should be given at the time of flower initiation.
Application of 40-60 kg of nitrogen in toria and 50 kg in sarson and 80 kg of nitrogen per hectare in rai has given good results; 20-30 kg phosphorus in toria and sarson, and 50-60 kg phosphorus per hectare in rai, when drilled, gives good results. These crops give poor yield in sulphur deficient soils. Application of 25 kg of zinc sulphate in combination with 40 kg of ammonium sulphate per hectare leads to higher yields.
In terai areas in Uttar Pradesh, the crop is generally cultivated after green-manuring. For good yields 33 kg N/ha for toria, 45 kg for sarson and 55 kg for rai are recommended. In Punjab, ammonium sulphate at the rate of 60-81 kg/ha, half at the time of sowing and the other half during the first irrigation, is reported to give higher return. For lotni variety of brown sarson, when grown pure in the districts of Mathura and Agra, 10-15 cartloads of farmyard manure per hectare are added before sowing. In Uttar Pradesh, significant increase in the yield of sarson and rai was reported on addition of 55 kg of N/ha.
In Haryana, it was found that though brown sarson and rai responded well up to c 100 kg N/ha, the economic dose was 33 kg/ ha. The application of P2O5 either alone or in combination with N, was reported to be ineffective for sarson, but rai responded well to application of 27 kg P2O5/ha. In Assam, the optimum dose of ammonium sulphate for sarson ranges between 220 and 330 kg/ha.
It is reported that a mixture of cow-dung, oilcake, and compost and ammonium sulphate gives good returns. It is better if the fertilizer is applied before sowing and is properly drilled.
The effect of N, P, and K deficiency in B. juncea has been studied. When deficient in N, the plant is severely stunted and the leaves small and pale green. Intense purple tinge in mature leaves, and bright red in older ones is observed on account of deficiency of P; and K- deficiency causes brown scorching along the entire leaf margin in mature leaves.
Application of sulphur has shown direct effect upon the uptake and utilization of phosphorus. If there is iron deficiency, the plants become dwarfed, intervenal chlorosis appears, followed by loss of fruiting; a reduction in the total uptake of potassium and, to a certain extent, phosphorus is apparent.
Micronutrients:
The oilseed crops require sufficient quantities of different micronutrients for their growth and development. These elements are directly or indirectly involved in activating enzymes and oil synthesis. The application of zinc has resulted in raising the yield to the extent of 37-66 per cent in Punjab and 70 per cent in Uttar Pradesh.
The other elements like molybdenum (0.5 ppm), boron (22 ppm), copper (20 ppm) have also increased the yield significantly. 20 kg sulphur and 1 kg boron per hectare should be applied as basal dose wherever the deficiency of these nutrients is felt.
7. Harvesting of Rapeseed Mustard:
The crop is generally harvested when the pods turn yellow but are not fully ripe, as at the later stage, the fruits shatter and the seeds disperse. Also the moisture content of the seed should be around 40 per cent. The oil content is maximum at this stage. Harvesting too soon when the moisture content of the seed is more than 45 per cent, reduces not only the yield, but also the oil content and seed viability drastically.
When rapeseed and mustard are grown as mixed crop with food grains, the crops are harvested at different times, depending upon their time of maturity. When grown with linseed, the two crops, which mature almost simultaneously, have often to be harvested together, and it results in mixing up the produce of both the crops, thereby adversely affecting the quality of both. This mixture should therefore be discouraged.
The harvesting of rapeseed and mustard is done from the second half of December to June, depending upon the time of sowing, the cultivar, and the location. Toria which takes 75-90 days is the earliest to mature and the first to be harvested. The different cultivars of toria, grown in Uttar Pradesh, Punjab and Haryana, mature between mid-December and mid-January.
The cultivars of yellow sarson take 120-160 days, and those of brown sarson 105-160 days to mature. Their harvesting is done during Feb-April. Sarson is less liable to shattering and can be left in the field relatively longer without much loss to the crop.
However, it is safe to harvest the crop when the plants turn yellow. Rai cultivars mature between 110 and 160 days and are harvested from February to March. The plants should not be allowed to over-mature, as the over dried pods shatter.
Night moisture prevents the dehiscence of pods, and harvesting is, therefore, generally done in the early hours. The plants are either pulled out, or cut with a sickle a few centimetres above the ground. They are then tied into small sheaves and dried in the sun for 4-10 days.
The plants of toria are generally exposed to the sun without bundling, since at the time of harvest of this crop, the weather is not as hot as at the time when sarson and rai are harvested. Sometimes, insufficient drying, particularly in toria, results in moist seeds with less oil content, reaching the market. Since the moisture affects the quality and suitability for crushing, the seed should be allowed to dry completely. Some immature capsules also are harvested; the yield of oil from such capsules is less and of inferior quality.
When the cut crop is sufficiently dry, it is threshed with a wooden mallet, shattering the seeds; shattering may also be done by trampling by bullocks on cemented floors to avoid mixing up of earth, stones, etc. The seeds arc winnowed to remove the chaff, and arc allowed to dry in the sun for another two days. Moisture content of the seed must be less than 8 per cent at storage time.
8. Yield of Rapeseed Mustard:
The average yield of rapeseed mustard is about 500 kg/ha. Under good crop management, toria, which is a short duration crop, gives a yield of about 450 to 650 kg/ha, sarson 800 to 1,000 kg and rai 1,000 to 1,200 kg/ha. Ten yearly average yield of rapeseed mustard in India showed a rising trend from 390 kg/ha in the 1950’s to 441 kg/ha in the 1960’s and further to 511 kg/ha during 1970’s.
Yet, even the average yield of 680 kg/ha of Punjab is low as against world’s average of 917 kg/ha; Netherland, 2,428 kg; Sweden, 2,238 kg; West Germany, 2,500 kg and France 2,294 kg/ha. However, yields of 2,000 to 2,500 kg/ha have been obtained at the farms of progressive cultivators of Punjab, Haryana and Uttar Pradesh.
Though Uttar Pradesh and Rajasthan are premier producing states, the yields are low when compared to those of Jammu & Kashmir, Punjab and Haryana. The yields in southern states—Andhra Pradesh, Karnataka and Tamil Nadu— were lower, ranging between 240 kg and 375 kg/ha. The reduced yields in southern India are perhaps due to hotter climate, which is not very suitable for rapeseed and mustard.
Rapeseed mustard crop has all types of breeding systems from high cross-pollination to high self-pollination. Toria and lotni brown sarson are mainly cross pollinated, while brown sarson, yellow sarson and rai are predominantly self-pollinated.
9. Diseases of Rapeseed Mustard:
1. Downy Mildew:
It is caused by Peronospora brassicae Gaum., which attacks sarson, toria, rai and black mustard. It produces light purple lesions on leaves and causes malformation of stem and inflorescence. The secondary infection is through conidia which are abundantly produced on the under surface of the leaves. The pathogen probably survives from season to season in the form of oospores in the soil or in plant debris.
The disease first appears on the leaf as a small, light green lesion which enlarges and becomes greyish white on the under surface. The upper surface is marked by white spots corresponding to the patches underneath. When the attack is severe, the spots grow in number and size and become crowded, resulting in drying up of the leaves. Similar spots also appear on the other parts of the plants and cause swollen distortions or other malformations.
Removal of other Brassicaceae weeds and spraying of the crop with 0.2 per cent Zineb, Ziram or Maneb helps to control the disease. Burning the debris and rotation with non-cruciferous crops is also useful.
2. White Rust:
This is caused by Albugo Candida (Pers.) Kuntze which is common to all members of Brassicaceae. The disease is frequently associated with downy mildew.
White rust produces prominent white or creamy yellow pustules which often coalesce to form patches. Marked hypertrophy, swellings, distortions and discolouration take place. When the attack is severe, the leaves thicken and get distorted, reduced, and curled. Sometimes, whole plant may be dwarfed and may not bear flowers, or may bear only imperfect ones. The hypertrophy of the stem and floral stalk is also observed.
White rust may not cause much damage except when associated with downy mildew; the control measures recommended for the downy mildew are applicable to both.
3. Black Rot:
The disease is seed-borne and is caused by Xanthomonas campestris (Pammel) Dowson, which attacks several members of the family, such as cauliflower, radish, turnip, knol-khol, mustard and rai. The organism may attack the host at any stage of growth. The diseased leaves show prominent brown veins, causing withering in severe cases. Seedlings may die when attacked. Treatment of the seeds with 1% mercuric chloride solution for 30 min. before sowing, or with corrosive sublimate, or with hot water at 50° for 25-30 min is helpful.
Long crop rotations without any cruciferous plants for 3- 4 years is also beneficial. Citrinim controls the internally seed- borne disease; Streptocycline (200 ppm) inhibits the multiplication of the organism. Clean seed in a well-drained clean plot and thin sowing ensure a healthy crop. The diseased plants of cauliflower are also prone to stump-rot, presumably caused by Erwinia carotovora (Jones) Holland.
4. Phyllody:
The virus, which causes phyllody in sesamum is responsible for the disease in toria and yellow sarson as well. The incidence is low and the total loss to the crop is negligible. Species of Deltoce- phalus and Orosius albicinctus Distant are reported to be the vectors. The corolla becomes sepaloid, the stamens turn green and become indehiscent; and gynoecium exhibits a distinct gynophore and does not produce ovules. Sesamum and sunnhemp besides several others, serve as important alternate hosts for the virus. Advance sowing and closer spacing reduce the incidence of the disease.
5. Mosaic:
In India, a severe mosaic on Chinese sarson or pahadi rai [B. juncea var. rugosa (Roxb.) Tsen & Lee] was observed in the Shimla Hills. This virus is transmissible to B. juncea, B. nigra, and B. ccunpestris. The virus is non-persistent type. The mealy cabbage aphid (Brevicoryne brassicae Linn.), the melon aphid (Aphis gossypii Glov. and A. rumicis Linn.) and green peach aphid (Myzus persicae) have been reported to be the vectors.
The symptoms are vein-clearing, green vein-banding, mottling and severe puckering of the leaves. The affected plants are stunted, and flowering is either absent or scanty, producing a few poorly filled and shrivelled pods. In advanced stages, the stem and fruit also show distinct mottling.
10. Pests of Rapeseed Mustard:
A big pest complex takes a heavy toll of rapeseed and mustard crops in the field. The major pests are aphid, sawfly, painted bug, pea leaf-miner, flea beetles, Bihar hairy caterpillar and the cabbage caterpillar.
At the seedling stage, the crop is damaged by saw-fly, painted bug and flea beetles. The painted bug infests the crop at pod stage also. Although the aphids occur throughout the year, they cause damage to these crops mainly during Dec-Feb. The leaf-miner and cabbage butterfly are more serious towards the pod formation stage of the crop. The Bihar hairy caterpillar damages toria crop considerably but is not a serious problem to rai and sarson.
One or the other of the pests continues to damage rapeseed and mustard crops at every stage and inflicts heavy losses in yield. It is estimated that aphids cause 66 to 96 per cent losses in yield of Brassica campestris cultivars and 27 to 69 per cent in B. juncea. On an average, the loss comes to about 62 per cent.
1. Mustard Aphid— Lipaphis pseudobrassicae:
Davis is a tiny, 2 mm long, soft bodied pale green insect. It is present throughout the year, but is more active during Dec-Feb. Its colonies feed on almost all the cruciferous plants. They suck the sap from the plants and devitalize them. They usually feed on the growing point, inflorescence and the underside of the leaves.
When the attack is severe, the entire plant gets densely covered with aphids, resulting in stunted growth and poor pod formation. The excessive secretion of honey dew by the aphids interferes with the normal functioning of the leaves due to mould formation. The attacked flowers fail to produce any pods; if any pods are formed, seed setting is very poor and the seeds are shrivelled and of poor quality.
The mustard aphid can be controlled by removing twigs by the end of December. When the aphid number reaches 9-18 per plant, or when 30% of the plants are infested, insecticides such as Oxydemeton methyl (Metasystox 25 EC) at 625 ml or Dimethoate 0.03% (Rogor 30 EC) at 850 ml in 1000 1 of water should he sprayed thrice at 15 days’ interval starting from the end of December.
Depending upon the intensity of infestation, the number of sprays may be decided. Timely spray is very important and chemicals should be sprayed in the afternoon to avoid destruction of the pollinators.
The crop should not be used for saag/fodder purpose upto 15 days of spraying. Soil application of systemic insecticides in granular formulation at the time of sowing (Disulfoton Gr.) and seed treatment with Carbofuran followed by a foliar application of Dimethoate at critical stage of aphid development proved most effective in controlling the pest. Spraying with 0.1% BHC, 0.1% gamma BHC, 0.2% DDT, 0.025% Diazinon, 0.05%-0.0625% Malathion, 0.05% Menazon, or 0.05-0.075% nicotine sulphate have also been suggested.
There are many predators such as lady bird beetles, chrysopa, and syrphid flies which feed on the aphid colonies. But these usually appear late in the season when considerable damage to the crop has already been done and the aphid population starts declining due to rise in temperature, and hardening of host tissues (Bakhetia & Brar, loc. cit.).
Cultivars of mustard are more resistant to aphid damage than those of yellow and brown sarson. Brassica napus and B. tournefortii Gouan were more resistant to aphid damage than yellow sarson and hence, have been utilized in crosses for building up resistance in B. campestris, B. juncea or B. nigra. In rai, several mutants resistant to mustard aphid have been reported. ‘RLM 198′, T 6342’, ‘RLM 171’, ‘RLM 29’ and ‘RLM 82’ were found to be moderately resistant.
2. Sawfly:
Athalia lugens proxima (Klug.) is a serious pest of cruciferous crops in seedling stage and prefers rapeseed and mustard, cabbage, and turnip. It is orange yellow in colour having smoky wings with black veins. The grubs feed on the mustard plants and the adults find it suitable for egg-laying. A chemical factor sinigrin was identified as the phagostimulant. The grubs either riddle the entire leaves or cause numerous shot-holes by excessive feeding. Under heavy infestation, the entire lamina may be eaten up and re-sowing of the crop becomes necessary.
In Punjab, Uttar Pradesh, Bihar, Madhya Pradesh, Assam, Karnataka, Tamil Nadu and West Bengal, the pest makes its first appearance in October and is found in the fields and kitchen gardens upto the beginning of March, the highest number being found from October to December. In Maharashtra, the sawfly larvae are found as early as June, but most of the damage is caused in August and September.
In Madhya Pradesh, the insect aestivates in the larval stage in March, appears in the field on radish in the first week of July, and migrates to the mustard crop in the second week of August. In Punjab, the insect aestivates as a grub in silken cocoons in the soil from the end of February to the end of September, when it starts pupating, the period of activity being from September to January.
Treatment of mustard seeds with Lindane and Phorate at 2.5 kg and 1.0 kg per 100 kg of seed respectively, rendered the seedlings toxic to the larvae of sawfly up to 28 days after germination. Perilis- sus cingulator Morley and Cantheconidia furcellata Wolff, parasitize the grubs.