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Symptoms, perpetuation and control strategies

Assistant Professor (Plant Pathology)
Sindh Agriculture University, Tandojam

Nov 19 - 25, 2001

Human beings are cultivating different crops for food, fiber as well as fodder for their animals. The land and irrigation water resources available to them are limited and could not be increased. However, there is a need to grow more from each piece of land and from every drop of irrigation water available. Otherwise, it is very difficult, but even impossible to meet the requirements of ever increasing population. Hence, there is a need to preserve and save the basic resources along with the environment, to face the present as well as future challenges.

Edible oil is one of the basic food requirements. The shortage of edible oils had started developing from 1970 due to rapid increase in population, per capita consumption and local edible ol production remained almost stagnant. Despite the fast increasing demand of edible oil, the outflows for the last 5 years were 413.4 to 856 million US Dollar (Table 1). Cottonseed is the major domestic source of edible oil with rapeseed mustard and canola occupying the second place. Part production from sesame and entire production from groundnut is comsumed as raw with no oil extracted. On over all, the content vary from 10-50 per cent according to variety (Table 2). Sunflower, soyabean, groundnut, sesame and caster belong to Kharif, while canola, rapeseed and mustard, safflower and linseed are Rabi oil seed crops, which are being used to fulfil local requirements.

Table 1: 
The outflow (import) of edible oils (US Dollars in million) for the last 5 years

Year 1996





Dollar 856





Source: State Bank of Pakistan, Annual Report, 1999-2000.



Table 2:
Oil content percentage of various oil seed crops.

Name of crop

Oil content (%)


Kharif oil seed crops


Over 40

Good edible, free from toxic compounds



Used in ghee & industrial purposes

Groundnut (Peanut)


High edible quality



Good quality edible oil


Over 50

Used for number of industrial purposes

Rabi oil seed crops

Rapeseed and mustard


Several edible and non edible uses



Excellent quality edible oil


Over 40

Used for medicines, paints, printing ink etc.

Source: Bhatti and Soomro. 1996. Agriculture inputs and field crop priduction in Sindh. Directorate General, Agri. Res. Sindh, Hyderabad.

Amongst the Kharif oilseeds, sunflower has gained higher popularity and acreage among the new oilseed crops introduced for boosting edible oil production. The important features of this crop are short growing period, high yield potential and wide range of growing season viz. autumn, spring and winter. It fits well in different cropping patterns, low irrigation water requirements, wide adaptability to soil and moisture conditions. Its seed contain high oil (over 40%) of good edible quality and meal of good quality free from toxic compounds. Three irrigations are necessary. The 1st irrigation should be given 30-35 DAS. 2nd at start of flowering and 3rd just after petal fall. Soyabean requires 5-7 irrigations from sowing to maturity. Irrigation at pod filling stage is very necessary, drought at this stage will reduce yield drastically. Groundnut needs 30 acre inches during 5-7 irrigations. The first irrigation shold be given 25-30 DAS and subsequent at 15-20 days intervals. The critical stage is seed development. The sesame is cultivated throughout Pakistan as irrigated as well as un-irrigated crop. It requires 3-4 (21 acre inches) irrigation at 30 days interval. Caster is grown, under arid conditions, mostly as rainfed crop. Under irrigated conditions, it needs 5-7 (20 acre inches) irrigation at days interval.

Canola, Rapeseed and Mustard, Safflower and Linseed are Rabi crops. In case the cultivation of Canola, Rapeseed and Mustard, 3-4 irrigations may be given to Toria and Sarsoon, 1-2 irrigations to Jambho or Taramira at 25-30 days intervals. Seed development stage is critical for irrigation. No irrigation is required for Dobari Bosi crop. Safflower is sensitive to heavy irrigations, especially in later growth stage. However, 5-6 irrigations are required under irrigated conditions. Linseed needs 4-5 irrigations. First irrigation 30 DAS and subsequent doses at 20-25 days intervals should be given. No irrigation is required, when it is grown as Dobari crop.

It must be kept in mind that only irrigation water is not alone input for increasing per unit production, nor a land alone or in combination with irrigation water is enough for the purpose. Different diseases are aso responsible to damage the crops and result sometimes negligible and sometimes 100 per cent loss in out put. Oil seed crops are subject to various mechanical, physiologic and biological stresses in all stages of growth and in all natural enviroments, that interfere with their normal growth and development. Weather, toxicants, pollutants, insects, viruses, fungi, nematodes, bacteria and seeds are primary hazards to the production. Overall, all diseases are injurious in some areas, in some years and on some plant parts. All parts of plant are subject to diseases and one or more diseases can occur on virtually every plant and in every field. All draw attention because of symptoms or signs and generate great concern because of their effects on the quality and/or quantity of plants, straw or grain.

Crop wise brief account of the most important diseases of oil seed crops in Pakistan being discussed for readers (including agriculture research and extension workers, students and teachers) as well as for the benefit of farmers or growers. This will include the causes, symptoms, perpetuation, preventive and curative control measures of very destructive diseases. All information is based on personal experience and the recommendations by Hafiz (1986), Chaudhry et al. (1988), Mirza (1988), Bhatti and Jiskani (1996), Bhatti and Soomro (1996) and Khoso (1992).


Septoria leaf spots, Septoria helianthi

Symptoms: Small angular to more or less circular or sometimes diamond shaped, brown to dark brown spots develop on upper leaf surface and lighter gray brown on lower leaf surface. In these spots many small black bodies (Pyenidia) are develop on both surfaces of leaves under moist conditions. Spots coalesce and leaves wither and dry first on lower and gradually spread to upper leaves.

Charcoal rot, Macrophomina phaseolina, Rhizoctonia bataticola and Sclerotium bataticola

Symptoms: Brown to dark brown spots appear on stem. The plants become weak, dry and show light gray or ashy black discoloration of stem. Poorly filled heads can be seen and premature ripening and drying of stalks occur, which also become normally discolored. Pith distintegrates and vascular fibers apppear shredded, covered with small bodies (Sclerotia) of disease causing fungi.

Perpetuation: The fungi perpetuate on the infected host plant debris in dry soils for a long period., but in moist (wet) soil it can not survive for longer.

Alternaria blight, Alternaria helianthi

Symtomps: Dark brown to black, circular to oval spots appears on leaves. The spots are surrounded by necrotic zones with gray white necrotic center marked with concentric rings. Spots enlarge and coalesce resulting in leaf blight and sometimes cause rotting of stem and heads.

Perpetuation: Infected seeds, plant debris, weed host plants help the fungus to survive, while it is wind borne also.

Sclerotinia stalk and head rot, Sclerotinia sclertiorum

Symptoms: The disease is characterized by sudden wilting of leaves. Gray to brown colored portions encircling the stems. The spots are covered partially or completely with white cottony mold having large whitish gray to black bodies, irregular in shape. Stems shred in to vascular strands and become straw colored on drying. Heads disintegrate and stalk rot can occur at any part of plant.

Rhizopus head rot, Rhizopus arrhizus and R. stolonifer

Syptoms: Brown irregular water soaked spots at back of head. These spots enlarge, turn brown, become soft and pulpy.

Perpetuation: The fungus is air borne but injury by borers or birds are necessary for infection.

Rust, Puccinia helianthi

Symptoms: Small, chestnut brown or orange to black powdery scattered pustules appears on lower leaves, may also found on stem and floral bracts of capitulum. The leaves become dry prematurely affecting yield and seed quality.

Perpetuation: The fungus survives on volunteer seedlings in high altitude areas and carried through air currents.

Verticillium wilt, Verticillium dahliac

Symptoms: Prominent yellow, inter-veinal patches appear on leaves, which are gradually enlarged and coalesce, while leaf centers turn brown and necrotic having mottled appearence. Plants show stunting, small flower heads and destruction of root system.

Perpetuation: The fungus survives in the soils.

Minor diseases

Root rot caused by Rhizoctonia and Macrophomina species, Cercospora leaf spots caused by Cercospora helianthi are also sometimes less as well more important fungal diseases.


Anthracnose, Colletotricum truncatum

Symptoms: Dark brown lesions on cotyledon, become water soaked, quickly wither and fall off in seedling stage. Irregular brown lesions appear on stem and petiole and round to elongate on pods. Pin cushions like fruiting bodies with minute black spines can be seen with hand lens.

Perpetuation: Infected crop residues and seeds help the fungus to survive.

Charcoal Rot, Macrophomina phaseolina, Rhizoctonia bataticola and Sclerotium bataticola

Symptoms: The disease characterized by sudden wilting of plants. Brown to dark brown lesions appear on stem. Plants become weak, mature early and when dry, show light gray or ashy black discoloration of stem. Small minute black bodies are found in plant tissue as well as in pithy area of stem after removing of epidermis.

Perpetuation: The fungi perpetuate on the infected host plant debris in dry soils for a long period, but in moist (wet) soil it can not survive for longer.

Pod and stem blight, Diaporthe Phaseolorum

Symptoms: Many black flasks shaped pycnidia developed on the lower portion of the main stem, branches and pods as plants reach maturity. Pycnidia also found scattered on dry poorly developed pods. Seeds are badly cracked, shriveled and covered with mycelium.

Perpetuation: Carry over through infected seeds and host plants.

Purple seed stain, Cercospora kikuchii

Symptoms: Pink to pale or dark purple coloration of seed coat. Seed are often dull, cracked and rough. Round, reddish purple spots that later become purplish black also develop on pods.

Perpetuation: Carry over through infected seeds and host plants.

Minor diseases

Leaf spot caused by Alternaria tenussine, pod bligh cause by Alternaria species and yellow patches on leaves turn chlorotic to brownish, remain stunted and do not flower in early infection.

Groundnut (Peanuts)

Tikka disease, Cercospora personata

Mirza (1998) reported this disease as early leaf spot (caused by Cercospora arachidicola) and late leaf spot (caused by Cercosporidium personatum).

Symptoms: When the crop becomes two months old, conspicuous dark brown circular to subcircular spots appears on leaves. These spots spread to other plant parts also. Mature spots are surrounded by light yellowish haloes, leaves started shedding and development of nuts are badly affected.

Perpetuation: Carry over through diseased seeds and plant debris.

Minor Diseases

Root rot and wilt (caused by Rhizoctonia bataticola, Fusarium coeruleum and Botryodiplodia theobromac), stem rot (Diplodia sp.), kernel rot in storage (Aspergillus sp.), anthracnose (Colletotrichum arachis and C.demtium), leaf spots (Alternaria arachidis and A. alternatia) and crown rot (caused by Choancphora sp., Phyllosticta sp. and Aspergillus sp.).


Root and Stem Rot, Rhizoctonia phaseoli, Macrophomina phaseoli and Botryosphaeria ribis)

Symptoms: The disease attacks roots and stems, causing discoloration and rotting. As a result the leaves turn yellow and wither. Brown blackish patches on stems and dot like structures on diseased plant parts.

Perpetuation: The disease causing fungi may survive due to mixed with seed and plant debris, while are reported as soil borne in nature.


Symptoms: Floral parts are transformed in to green leafy structures with abundant vegetative growth. Sepals become leaf like and stunted . Veins are thickened and dark green in color. Anthers do not contain viable pollen. Carpels also are transformed in to leafy out growth . The leaves are formed small in heavy bunches at top portions of the plants. Grains shriveled and not viable.


Root rot (caused by Rhizoctonia bataticola) and powdery mildew is recorded but not distructive. The symptoms, perpetuation and control measures are similar to that of caused by same organisms on other oil seed crops.

Canola, Repeseed and Mustard

White Rust, Albugo candida

Symptoms: Initially white or cream colored pustules of varying size develop on under surface of the infected leaves. The pustules also appear on stem, pod and terminal parts of flower stalk. The pustules increase in number and size, coalesce to form big patches. These pustules raised up and ultimately rupture releasing chalk like powdery mass of disease causing fungus. Infected leaves and other plant parts looked thikened because of swelling.

Perpetuation: Carry over through plant debris and seed, spread by wind.

Downy Mildew, Peronospora parasitica

Symptoms: The disease also appears on several Brassica species as irregular spots. The spots are small light green or grayish white on the lower and yellowish brown on the upper surface of the leaves. The spots increase in size and number, covering large area of foliage followed by defoliation and infection of stem also.

Perpetuation: Perpetuate through diseased plant debris or seed.

Powdery Mildew, Erysiphe polygoni

Symptoms: Initially white talcum powdery spots appear on leaves, stem and pods. These spots increase in number and size, cover entire surface of the host plant like a talcum powder. Severely affected leaves start dropping., stems rot, pod and seed formation badly affected because chlorophyll of plant is checked.

Perpetuation: The diseased plant debris and volunteer host plants help the fungus for its survival.

Blight, Alternaria brassicae, A. raphani and A. brassicola

Symptoms: Initially light brown spots appear on leaves including cotyledon, which rapidly turn black or range from gray to black. The spots also develop on stem and pods and plants are heavily damaged.

Perpetuation: Infected seeds, plants debris and weed host plants help the fungi to survive and wind to spread.

Minor Diseases

Fusarium wilt, stem and root rot (caused by Selerotinia selerotiorum), and storage rots (caused by Rhizoctonia bataticola, Aspergillus, Penicillium and Fusarium species) are also some times cause damage to the crop and produce.


Alternaria Blight, Alternaria carthami

Symptoms: Small brown to dark spots with concetric rings appears first on lower leaves and later spread on upper ones. These spots increase in number and size, coalesce and form large irregular lesions. The center of mature spots usually becomes lighter in color. Infected seeds may show dark sunken lesions on the testa at the floret end.

Perpetuation: The disease causing fungus may perpetuate through seeds and plant debris, reported as wind borne also.

Remularia Leaf Spot, Remularia carthami

Symptoms: Light brown circular spots with silvery appearance due to fungus spores or conidia and conidiophores on leaves. These spots coalesce and form large irregular withered areas on leaves during rainy weather.

Perpetuation: Germinating conidia penetrate the stomata

Rust, Puccinia carthami

Symptoms: Orange yellow or chestnut brown colored pustules developed on leaves, flowers and capsules. When plants mature, pustules turn in to dark brown color.

Perpetuation: Wild safflower species help the fungus to survive.

Sclerotinia Wilt, Sclerotinia sclerotiorum

Symptoms: Infected plants become yellowish, light brown, wilted and killed. White mycelial growth and large whitish gray to black. Sclerotia are found on stem as well as inside stem. Shredding of the affected tissue may also take place.

Perpetuation: The disease causing fungus is soil and seed borne.


Wilt, Fusarium lim

Symptoms: End points of brances begin to droop and whole plants dry. Root bark becomes loose and shredded.

Perpetuation: The fungus is reported as soil borne.

Control strategies

1. Cultivation of disease resistant or tolerant varieties are alone safe, economical and most easy way against all diseases.

2. Healthy and un-damaged quality seeds should be used, otherwise seed treatment with any suitable seed dressing fungicide must be done.

3. Crop rotation with non host crops for 2-3 years is also reported as beneficial.

4. Proper tillage operations can minimize the diseases caused by seed borne pathogens.

5. Irrigation water and fertilizers must be applied as per requirement of the crop with normal methods and proper dose.

6. Collection and burning of diseased plant parts and debris may minimize disease intensity.


1. Bhatti, I. M. and A. T. Soomro. 1996. Agricultural inputs and field crop production in Sindh. Agri. Res. Sindh, Hyderabad.

2. Bhatti, I. M. and M. M. Jiskani. 1996. Modern Agricultural Guide. Agri. Res. Sindh, Hyderabad.

3. Chaudhry, A. H., B. R. Oad and K. Mehraj. 1988. Highlights of improvement research on oilsed crops in Sindh. A. R. I., Tandojam.

4. Hafiz, A. 1986. Plant diseases. PARC, Islamabad.

5. Khoso, A. W. 1992. Crops of Sindh. 5th revised edition.

6. Mirza. M. S. 1988, Major diseases of oilseed crops in Pakistan. In 'Field crop diseases', CDRI, NARC, PARC, Islamabad.

7. State Bank of Pakistan, Annual Report, 1999-2000.