IDM PRACTISES OF BRASSICA VEGETABLES

Subhrajyoti ChatterjeeDepartment of Vegetable ScienceRoll no-H-15-109-MDr.YSPUHF,Nauni,Solan

Brassicaceae is the name of a medium-sized and economically important family of angiosperm which was previously known as Cruciferae, or the cabbage family.

The name Brassicaceae is derived from the included genus Brassica. Cruciferae, an older name, meaning "cross-bearing", describes the four petals of flowers, which resemble a cross; it is one of eight plant family names without the suffix '-aceae' that are authorized alternative names (according to ICBN Act. 18.5 and 18.6 Vienna Code); thus both Cruciferae and Brassicaceae are used.

INTRODUCTION

The family contains 372 genera and 4060 accepted species.

These vegetables are widely cultivated, with many genera, species, and cultivars being raised for food production such as  Cauliflower , Cabbage , Knolkhol, Bokchoy, Kale, Pakchoi, Sprouting broccoli, Brussels sprouts etc..These are also known as “Cole crops” because they originated from same ancestor known as “Cliff cabbage” or “Colewort”(Brassica sylvestris).

Other vegetables under this family are Cress, Radish, Turnip, Rutabaga, etc.

,

CONTD....

Benefits of Brassica VegetablesChemicals contained in crucifer

vegetables induce the expression of the liver enzyme CYP1A2. Furthermore some drugs such as haloperidol and theophyllin are metabolized by CYP1A2. Consequently consumption of cruciferous vegetables may decrease bioavailability and half-life of these drugs.

Brassicaceae contain a number of compounds under preliminary research for potential hepato protective properties. Cruciferous vegetable consumption may induce  glutathione S transferases,  uridine diphosphate-glucuronosyl transferases and quinone reductases all of which are potentially involved in detoxification of carcinogens such as aflatoxin.

Commercial Brassica Vegetables Cultivated

Brassica vegetables

Alternaria Blight (A.brassicae/A.brassicicola)Black Leg (Phoma lingam)Cercospora leaf spot (Cercospora brassicicola)Clubroot of Crucifers (Plasmodiophora brassicae)Damping off(Pythium sp, Fusarium sp,Rhizoctonia

sp) Downy Mildew (Perenospora cubensis)Phytophthora Root Rot (Phytophthora

megasperma)Scletotinia Stalk Rot (Sclerotinia sclerotiorum)White Leaf Spot (Mycosphaerella capsellae)White Rust (Albugo candida)

Important Fungal Diseases of Brassica Vegetables:-

Causal Agent: Alternaria brassicae, A. brassicicola, A. raphaniSymptoms:These Alternaria species cause leaf spots that appear onolder tissue and often begin as small, circular lesions. Theselesions expand and develop concentric rings with chlorotichaloes. Lesion centers may break apart, giving a shotholeappearance to the leaf or, if conditions are favourable,become covered with a sooty black mass of spores. Thesefungi may also infect seedlings with symptoms appearingas black streaks on cotyledons and hypocotyls, which mayresult in damping-off. Alternaria spp. may also infect thebase of cabbage heads and cause browning of cauliflowerand broccoli heads, rendering the heads unmarketable.Flower clusters may also become infected during seed production

Alternaria Diseases

Cruciferous crop residues are commonly the primary

source of inoculum. Cruciferous weeds may also harbor these fungi. Alternaria species may be seed borne. Conidia of Alternaria spp. are disseminated by wind and water. Disease development is favoured by free moisture on plant surfaces and temperatures between 20-27°C.

Favourable Conditions for Disease Development

Disease can be managed through Integrated way, which are shown schematically underneath.

Disease Management

Integrated Disease

Management

Cultural method

Biological

Methods

Resistant varieties

Chemical applicatio

n

Incorporate cruciferous residues of previous season, as these may overwinter in the crop residues..

Use of disease free or treated seeds.Adequate N fertilizer application in the fieldCrop rotation with non Cruciferous cropsTimely sowing of crop, and maintaining the proper

spacing.Removal of alternate weed host in which the

pathogen may overwinter.Avoidance of irrigation in susceptible stage of the

crop by this pathogen attack.(45 and 75 days).Soil application of potash and other mineral

matters like S, B, K, Zn etc.

Cultural Methods:-

High degree of resistance against Alternaria blight has found in B. alba, Eruca sativa, and Sinapis alba.

The highest degree of resistance to A. brassicae was found in the wild relatives of Brassica outside the tribe Brassicaceae. These are False Flax(Camelina sativa),Neslia paniculata, Capsella bursa-pastoris.

Gene transformation in Brassica sp can be done using particle bombardment to resist the crop against Alternaria attack. The uid4 gene has been incorporated with CaMV35S or Actin promoters. The uid4 gene encodes the 1,Beta-glucuronidase(GUS) enzyme which is responsible to resist the attack of Alternaria in the crops.

RESISTANCE BREEDING

Spraying of Eucalyptus leaf extract reduces the number of spores/leaves.

Spray of Calotropis, Ocimum, Polyanthi extracts can also significantly reduce the minimum size of spots and minimum disease index.

Foliar spray of aqueous bulb extract of Allium sativum(garlic) effectively reduces the disease severity in the leaves.

Foliar application of soil inhabitant isolates of Trichoderma harzianum and Pseudomonas fluorescens were found effective in management of Alternaria blight.

BIOLOGICAL CONTROL

Multiple application of fungicides are required to achieve economic yield and acceptable quality in infected crops.

Three systemic fungicides Thiophanate methyl, Ridomil MZ(Mancozeb,64%+Metalaxyl,8%) and Carbendazim alone and in combination of four non systemic fungicides Captan, Mancozeb, Zineb, Thiram in the field @0.2% a.i/l can effectively control the disease.

Ridomil MZ was found most effective followed by a combination of Carbendazim+Captan.

Foliar spray of Mancozeb(2 g/l of water) have been found most effective in disease management.

CHEMICAL CONTROL

Causal Agent: Plasmodiophora brassicae(many races are identified)Symptoms: This soilborne fungus infects nearly all cultivated

crucifers. The disease is difficult to detect as affected plants wilt on hot days but may recover after sundown.

Plasmodiophora brassicae enters through root hairs, and root cells stimulated by the pathogen multiply rapidly in size and number, forming club-like galls on roots. Deformed roots no longer function normally and are

susceptible to rot by secondary soilborne organisms. Young plants affected by this disease often die. Older plants grow to maturity, but are unable to produce a marketable product.

Club Root Disease of Crucifers

Infected roots serve as the major source of inoculum and release zoospores, which infect root tissue.

Zoospore contaminated irrigation water, equipment and people may spread this disease. Propagation of the pathogen may occur if asymptomatic, infected seedlings are transplanted into clean fields.

Acidic soils and temperatures ranging from 12-27°C allow for rapid disease development.

Conditions for Disease Development

The main objective is to reduce resting spore population/inoculum load in soil or to create unfavorable condition in soil which inhibit resting spor germination and movement of primary zoospores

Clubroot can be effectively controlled by using trap crop cultivated before main crop to reduce inoculum load in main crop by stimulating resting spore germination. These require carefully formulated combinations of husbandry measures, manipulation of soil structure, water table and alkalinity control of calcium, boron, nitrogen and irrigation applications, use (where feasible) of resistant cultivars and pesticides.

CONTROL MEASURES:Cultural practices

C0ntd. Enhancing soil pH using lime Cao. According to

Webster & Dixon (1991), the disease is more severe at pH lower than 5.7. Between pH 5.7 and 6.2 disease severity decreases and above pH 7.8 the pathogen is completely inhibited.

Application of calcium, Cyanide fertilizer and boron.

Practice simple and practical hygiene guideline

Trap/Bait Cropping with resistant and non brassicas where applicable can be followed.

Field studies in France for sources of resistance to P. brassicae identified two resistant kale (B. oleracea var. acephala) that could be used in breeding cauliflower and broccoli hybrids (Manzanares-Dauleux et al., 2000b).

In Chinese cabbage (B. rapa ssp. pekinensis) the dominant gene for resistance CRb has been identified(Piao et al 2004)

Resistance in radish (Raphanus spp.) may be utilized to produce cultivars of Daikon (R. sativus var. longipinnatus) (Buniand Yoshikawa, 1991) and in the amphidiploid Raphanobrassica (McNaughton, 1973).

Scope of Utilizing Genetic Resistance

In Germany Clubroot resistant B. napus variety Mendel and Tosca derived from resynthesised form (stubble turnip x kale), resistance from stubble turnip (B. rapa, ECD-04) (Diederichsen etal2006).

Syngenta Cabbage cultivars B. oleracea var capitata (Kilaton, Kilafur, Clapton) carry monogenic resistance from Chinese cabbage Parkin ‚Parkin received resistance from stubble turnip (B. rapa) (Diederichsen et al 2006).

Contd......

Cabbage cultivars resistant to Club Root released by SYNGENTA

KILATON TOLERATOR

RAMCO

Calcium nitrate [Ca(NO3)2] is effective as a nitrogen source because of its alkalinizing properties (Dobson et al., 1983).

Another N source Calcium Cyanamide “Perlka” – a very popular fertilizer in Europe manufactured by Syngenta contain 50% calcium oxide, 19.8 % nitrogen, 1.5 % magnesium oxide.

Calcium cynamide have both herbicidal and fungicidal properties and has shown good potential for clubroot control (Klasse, 1996) provided that the application be made 1 week before planting.

Moderate to high-risk sites, additional protection in the form of and boron and/or a protectant fungicide such as fluazinam can prevent the disease .

Chemical control is difficult because it is a pathogen of soil.

Chemical control:-

Causal Agent:-Pythium spp.,Fusarium spp., Rhizoctonia solani

Symptoms: Pre-emergence damping-off is generally caused by the

invasion of the host by the fungus prior to plant emergence from soil.

This is due to conditions that inhibit or slow seed germination, while allowing the pathogen to grow

Post-emergence damping-off occurs on young seedlings at or near the soil line, although, Pythium spp. may infect at the roots or root hairs. The host tissue appears water-soaked and constricted, eventually leading to seedling collapse.

Damping-off becomes less of a problem as the host plants mature.

Nursery Disease(Damping off)

Conditions for Disease Development: These fungi may be present in the soil

for a long time, but will not generally affect plants until the right environmental conditions, such as wet soils and cool temperatures, are met. Disease damage is generally greater in soil with infected, non-decomposed plant debris.

Conditions for disease development:-

Cultural practisesManaging irrigation water. Soil solarization before seed sowing. Rotating to Non-host crops. Sowing fungicide-treated seedLittle fertilizer application during germination

of seeds in the nursery.Proper drainage so seeds should be planted in

the raised beds.When seeds are germinated indoors proper

ventilation is necessary.Sowing of the seeds maintaining proper spacing.

Disease Control:-

Contd......Biological control

Soil borne non pathogenic bacteria Pseudomonas flurescens can be applied in the soil to control Damping off.

Application of Bacillus subtilis(BS-2) as seed treatment @10g/kg and soil application (2.5kg mixed in 50kg FYM/ha) can effective in reducing Fusarium.

Chemical control Seed bed can be drenched

with Formalin(1:7)that is 1 part of Formalin in 7 part of water before sowing the seeds.Then it is covered with transparent polythene sheet for 21 days. In between soil turned upside down to remove the fumes of formalin.

Seed treatment with Captan @2-3 g/kg of seed.

Metalaxyl, Iprodione, Etridiozole @2-2.5 g/l of water can be sprayed after disease appearance.

It is the most devastating disease when the crop is grown for SEED PURPOSE.

Causal Agent: Sclerotinia sclerotiorrum

Symptoms:In moist weather, stem infections spread rapidly

downward to decay the roots and expand upward wilting leaves, resulting in plant collapse.

A white, cottony growth and black, seed-sized sclerotia may be visible on or embedded in the affected tissues.

Sclerotinia Stem(stalk) Rot:-

Sclerotia of this fungus are long-lived, allowing it to persist in

Soil for many years. Disease development is generally favoured by abundant soil moisture and temperatures ranging from 10-25°C

Sclerotia that come in contact with the stem or foliage may directly infect host tissue. However, the ascospores of Sclerotinia sclerotiorum require a supply of nutrients to infect.

Pollen and flower parts from the host crop or adjacent weeds, such as common ragweed (Ambrosia artemisiifolia), serve as a nutrient source and permit the fungus to develop specialized structures which then penetrate the crucifer host.

Conditions for Disease Development

Implement good sanitation practices and long rotations to non-host crops.

Cultivate to help promote good soil drainage. Flood fields for a long period of time during warm weather to destroy sclerotia.

Manage weeds.Soil sterilization with steam in greenhouseMaintain proper spacing for air drainage.This pathogen can survive very well in alkaline soil,

so soil pH should be maintained <5.2 for effective control.

Disease Management:-Cultural practises

Biological controlNumerous species of fungi, bacteria, insects,

and other organisms have been reported to parasitize or to interfere with the growth of Sclerotinia spp.

Encouraging results with biological control of Sclerotinia diseases in Brassica crops have been obtained by incorporating the mycoparasitic fungi which are enlisted below-

Coniothyrium minitans Gliocladium roseum Trichoderma viridae

Sporodesimum sclerotivorum

Contd......

These method of control till

not comercializ

ed in farmers level till

date..

The genotypes of cauliflower Janavon , EC 162587 and RSK 1301 were found to be resistant with less than 10% incidence of stalk rot.

Janavon S3, Pyramis and KN 81 cauliflower varieties with 11-20% disease incidence were moderately resistant.

Among commercial varieties varieties like Pusa Snowball K1, Pusa Subhra of cauliflower can be used.

Use of Resistant Varieties:-

Pusa Snowball K-1

The maximum reduction in disease incidence to 9.7 % was recorded with 1.5 g/l Bavistin( 50% ) by 15.3 % with 5.25 g/l Sailaxyl-MZ (72 %), 16.7 % with 8.3 g/l Mancozeb (75%), 20.8% with 1.1 g/l Topsin-M (70% ). The above fungicides also reduced disease index.

Bavistin 50% also gave highest seed yield.

Chemical control:-

Infected plants by some other Diseases:-

Black Leg of Crucifers

Black Root of Crucifers

Downy Mildew

To control Black Leg disease hot water treatment of seeds in 50°c for half an hour is done.

Use of resistant varieties (like Pusa Drumhead variety of Cabbage).

To control Black Root Use high-quality seed free from crop residues. Implement good field sanitation practices, manage irrigation water, practice three-to-four year crop

rotations to non-host and apply chemical soil treatments.

Management practises:-

Black Rot (Xanthomonas campestris pv. campestris)

Bacterial Leaf Spot (Pseudomonas syringae pv. maculicola)

Bacterial Soft Rot (Erwinia spp)Scab (Streptomyces scabies)Xanthomonas Leaf Spot (Xanthomonas

campestris pv. armoraciae)

Important Bacterial Diseases of Brassica Vegetables:-

Black Rot Diseases:- Causal Agent: Xanthomonas campestris

pv.campestris Symptoms Symptoms first appear as yellow V-shaped areas with the

open part of the “V” along the edge of the leaf . The diseased areas then become brown and brittle, and

the affected leaf veins turn dark brown to black. The V-shaped areas enlarge and the entire leaf eventually turns yellow or wilts and falls from the plant.

When a young seedling is affected, the infection usually spreads throughout the plant causing it to remain stunted and unproductive.

A cut made through the stem of infected plants usually reveals a ring of black discolored tissue within the stem.

Stages of Disease Development:-

The black rot bacterium is seed borne and can survive the winter on plant parts left in the field. Cruciferous weeds, such as wild mustards, are hosts of this and can serve as reservoirs of inoculum. The bacterium can be carried to the field on infected transplants and it can be spread within the field by splashing rain, insects and windblown plant debris. Warm(27-30°C), rainy weather favours the spread of the black rot bacterium.

Disease Development & Spread:-

Cultural control:Use high-quality seed free of X. campestris

pv. campestris. Implement a three-year rotation to non

cruciferous crops. Seed beds should be geographically

isolated from commercial crucifer crops. Do not mow or clip transplants.

Plant crops in well-drained soils and use irrigation practices that minimize leaf wetness.

Keep fields free of cruciferous weeds.

Management Practises:-

Manage and weeds (especially weeds in the cruciferae family). The following cruciferous weeds are susceptible to black rot: Birdsrape mustard (Brassica rapa), Indian mustard (B. juncea), black mustard (B. nigra), Shortpod mustard (Hirshfeldia incana),Virginia pepper weed and other Pepper grasses (Lepidium spp.), Shepherds purse (Capsella bursa-pastoris), Radish (Raphanus sativus), Wild radish (R.raphanistrum), Hedge mustard (Sisymbrium

officinale), Swinecress (Coronopus didymus)and Hairy Whitetop (Cardaria pubescens).

Weed management

Contd.....Resistant Varieties

Plant varieties of cabbage and broccoli with partial resistance (tolerance) to black rot are reported. Cabbage varieties reported to be tolerant include Alantis”, ‘BlueDynasty’, ‘Bronco’, ‘Cecile’, and Ramada’.

The Broccoli varieties Arcadia’, ‘Eureka’, and Greenbelt’ have shown tolerance to black rot.

Chemical control Chemical against this disease

are not so much effective. Seed treatment with

Streptocycline @ 100 ppm before sowing.

The spread of black rot in fields may be slowed in some instances through applications of fixed coppers.

Actigard, a chemical that induces resistance to certain diseases in some plants, is labeled for suppression of black rot on commercially grown crucifers; however, results have been disappointing with this material in general.

Application Streptocycline @100 ppm(100mg/l of water) can be effective.

Causal Agent: Pseudomonas syringae. pv. maculicola

Symptoms:The disease occurs mainly on cauliflower, though

Broccoli, cabbage, Brussels sprouts and turnips can also be affected.

Symptoms consist of leaf spots that begin as small, water soaked pinpoint lesions. Later, these lesions become dark brown or purple with translucent haloes.

Individual spots are slightly sunken and up to 3 mm (1/8 in.) in size. Often spots will coalesce to form an irregular angular lesion, giving a puckered, ragged appearance to the leaf.

Bacterial Leaf Spot:-

Affected cabbage Head Affected leaf

Affected cauliflower Curd

Disease affecting Different Crops

Use seed free of Pseudomonas syringae pv. maculicola

Sow into seed beds free from the organism.

If the disease occurred previously in the seed bed, the soil should be sterilized before planting.

Rotate to a non-host seed bed for at least one year following a cruciferous crop.

Use of streptocycline @100ppm (100mg/l of water) after the disease infection has taken place.

Clean cultivation and sanitation.

Management Practises:-

Cauliflower Mosaic Disease caused by Cauliflower Mosaic Virus(CaMV)

Radish Mosaic Disease caused by Radish Mosaic Virus (RaMV)

Turnip Mosaic Disease caused by Turnip Mosaic Virus (TuMV)

Turnip Yellow Mosaic Disease caused by Turnip Yellow Mosaic Virus(TYMV)

Important Viral Diseases of Brassica Vegetables:-

Causal Agent: Turnip Yellow Mosaic Virus (TYMV).It is the most devastating disease in Turnip.

Symptoms:This virus only infects crucifers. In Turnip,

symptoms begin as vein clearing, but subsequently develop into permanent yellow patches on older leaves.

Symptoms on Chinese cabbage develop into bright yellow and dark green mosaic patterns.

During cool weather, infected plants remain stunted. Symptoms are mild in other Brassicas.

Turnip Yellow Mosaic Disease:-

It is transmitted by sap as well as a host of insect vectors. The most prominent of these are in the Phylotreta and Psylliodes  genera of flea beetles although  Phaedon cochleariae and its larva have also been known to help spread this virus. The larva lose their ability to transmit the disease once they converted to pupal stage, suggesting a mechanical infection process.

This virus overwinters in cruciferous weeds. Temperatures near 25° are optimal for symptom development.

Conditions for Disease Development:-

Implement an insecticide spray program to help control vectors.

Eradicate cruciferous weeds and volunteers.Incorporate plant residues immediately after

harvest. Isolate transplant beds from crucifer crop fields.Picking out of the infected plants from the field,

burying them deep in the field or burning them.Planting the resistant varieties.Planting the trap crops to reduce the attack of

insect vectors.

Management:

Plants affected by TYMV

Infected Turnip Leaves

Infected Chinese Cabbage Leaves

Some other Virus affected plants:-

Radish Mosaic

Turnip Mosaic

Cauliflower Mosaic

Cabbage Cyst caused by Cabbage Cyst Nematode (Heterodera cruciferae)

Crucifer Root Knot Disease caused by Root Knot Nematode (Meloidogyne spp)

Important Diseases of Brassica Vegetables caused by Nematodes:-

Causal Agent: Meloidogyne spp.Symptoms:Symptoms of this disease are similar to those of

clubroot, but clubroot affected plants produce larger more continuous swellings on the older portion of their roots. Root-knot nematodes on crucifers induce prolific root branching and galling above the point of infection.

Invasion of infected roots by fungi may occur. Above ground symptoms include stunting, chlorosis and wilting. Though infected plants may survive a growing season, the resulting crop is generally small and may be unmarketable.

Root Knot Diseases:-

These nematodes survive in infected root debris. Juveniles are attracted to root exudates of host plants and feed on root tissue. The most severe damage can occur in sandy soil with moderate moisture, but these nematodes are not limited these conditions. Infection can occur at temp. range 10-35°C

Freezing temperature can kill all the life cycle stages of this nematode

Conditions for Disease Development

Soil fumigation is very effective to reduce the population of nematodes.

Flooding or fallow farming help control populations of root knot nematodes.

Avoid cultivation in light sandy soils.No effective chemical control is so far

recorded.Clean cultivation, proper field sanitation.Using Marigold as trap crop in between

the main crop.

Management:

Brassicaceae family comprises vegetables with both regional and national importance in India. These are the major vegetables (eg-cabbage, cauliflower ,radish) which are grown almost through out the India during cool season. These are very much nutritious and remunerative crop now a days especially after the release of heat tolerant variety which makes possible its cultivation year round. The demand of exotic crop like Sprouting Broccoli, Brussels Sprout are also increasing day by day. But these crops are very much sensitive to different devastating diseases, which significantly reduces the yield and cut off the net profit..so we have to think of a integrated management practise which makes the crop cultivation profitable by efficiently managing the infection in such a way that will be ecofriendly, and non harmful to other beneficial creatures.

Conclusion:-

“Crucifer Disease Guide” by SEMINIS Research papers entitled- “ Inheritance of Resistance to Stalk Rot in Cauliflower (Brassica

oleracea var. botrytis L.)” by Bhupinder Singh Thakur “Integrated management of major diseases of cauliflower (Brassica

oleracea var botrytis subvar cauliflora)” by Sharma Pratibha et al. “Controlling Damping off Disease” By Master Gardener “Alternaria Blight Of Oilseed Brassicas: A Comparative Review” by

Kumar Dharmendra et al. “Black Rot of Crucifers” by Kenny Seebold et al from Plant

Pathology Fact Sheet Different pictures of crop Varieties are taken from IARI , Seminis,

Syngenta official website. Management of Clubroot Disease (Plasmodiophora brassicae) of

Brassicas Using Trap Cropping Techniques by Bhattacharjee I et al. Class notes

References:-

Thank you…..Submitted to-Dr. Sandeep

Kansal&

Dr. Shalini Verma