SUBMITTED TO:

Dr. B. PUSHPAVATHI,

ASSOCIATE PROFESSOR.

SUBMITTED BY:

Mr. K. SAI SANTHOSH

RAM/13-50

SEED SCIENCE AND TECHNOLOGY.

1. Crop production practices

2. Seed treatment

3. Seed certification

4. Plant quarantine

For production of quality seed the grower has to follow some practices like:

Crop should be maintained & inspected carefully to

produce clean seed.

Additional care should be ensured for genetic purity,

freedom from diseased & weed seeds, etc.

Seed crop should be grown in regions with minimum

disease pressure.

Disease resistant varieties has be preferred.

Management practices to be considered at different

crop stages are :

1) Before planting the seed

2) During crop establishment

3) During flowering & seed development

4) During seed maturation

5) During harvesting, threshing & processing

6) During storage

a) Selection of site:

Factors critical for successful seed production are

climatic conditions, previous crop history, weed

population, disease history, isolation, position of field

in relation to other key areas, the nature of the soil,

water & other physical features of that site.

The disease pressure is often regionally based.

Risk of disease infection varies widely by crop,

disease & location.

In India, incidence of Karnal bunt of wheat is

promising in Northern states.

Destruction of crop residues is done based on the

type of crop, type of pathogen & size of the crop.

Burying the residues – S. oryzae, X. campestris pv.

malvacearum.

Burning of the debris – sclerotia which is the

primary source of inoculum in perennial grasses in

seed production fields.

Sanitation of pruning implements, inter cultivators,

etc. which may carry viral infections. Eg: TMV

In addition to detrimental effect on yield some

weeds also serve as reservoir of many seed borne

pathogens.

Rice tungro virus, paddy blast, certain rusts cannot

complete their life cycle without alternate host-

where sexual recombination occurs.

Perennial weeds around the fields act as over-

wintering hosts for harmful viruses

Insects like aphids, leaf hoppers, trips & beetles

not only feed on plants but also spread many viral

diseases.

Soil type, texture, aeration, acidity or alkalinity,

suppressive-ness, soil temperature are certain

factors responsible for seed & soil borne diseases.

Covered smut of wheat is more severe in low soil

temperature & high soil moisture.

Soil temperatures <29.5C inhibits soybean growth,

promotes seed rot & damping off, particularly if

soils are wet.

Fluorescent Pseudomonas were isolated from

tobacco roots grown in suppressive soils to black

root rot (Thielaviopsis basicola), it was detected to

a depth of 1m; below 1m there was no Fluorescent

Pseudomonas & was found conducive to disease.

A highly suppressive strain CHAo was identified

as Pseudomonas fluorescens. Black root rot of

tobacco was suppressed in 36 of 39 conducive soil

samples by adding strain CHAo at 10 c. f. u/cm of

soil.

It can reduce weeds, number of fungal propagules,

insects & nematodes in the soil.

Flooding reduces Hill bunt (T. laevis) incidence in

wheat.

Flooding causes destruction of crop debris & it

also carries the propagules of some pathogens

growing in the flood water.

Excess use of N increases the incidence of rice blast, bacterial blight in rice, Kernal bunt in wheat & rhizoctonia seedling blight of pea, beans & vegetables.

Late application of N in wheat increases leaf blotch.

Deficiency of N or P results in take-all disease in wheat.

Excess Ca in soil- reduces bean root rot but favourshead smut of sorghum.

Ferric chloride- reduces rice brown spot

Sillica- reduces rice blast.

Molybdenum- reduces Ascochyta blight on beans &

peas.

Nutrients released from decomposing residues

stimulate the activity of some pathogens but they

don’t have host to attack & they die.

Soil incorporation of green manure as cover crops

can be used effectively to reduce root rot

pathogens.

Alfalfa is effective in suppressing disease

organisms in soil.

Successive planting of different crops in the same area, sometimes with fallow or resting period between crops.

It helps to reduce the buildup of root-rotting organisms.

Pepper may not be followed with Solanaceae crops as these crops share many soil-borne diseases.

Crop sequencing of cotton, sunflower and maize increase the infection of Macrophominaphaseolina.

Once in 4 year rotation in lentil helps to reduce Ascochyta blight incidence.

It is the best & cheapest method of disease control.

The term resistance describes the plant host’s

ability to suppress or retard the activity & progress

of a pathogenic agent which results in absence or

reduced of symptoms.

Tolerant plants can endure severe disease without

suffering significant loss in yield.

Horizontal resistance will be more useful in

subsistence agriculture.

Resistant to black rot in crucifers was first identified in

Japanese cabbage cultivar Early Fuji, from which many

resistant crucifer hybrids were developed.

Black seeded varieties in gram are more resistant to

Ascochyta blight than white seeded varieties- presence

of phenolic substances inhibitary to the pathogen.

Coloured testa in ripened bean seeds inhibit

C. lindemuthianum.

Anti-microbial substances in seed coat of bean, pea &

sweet pea inhibit seed infection by

C. flacumfacience pv. flacumfacience.

a) Clean planting material /Disease free seeds & transplants:

Use of healthy seeds can help growers to avoid

many costly & environment damaging fungicides

in later season.

ABSTRACT

On farm research using manual seed cleaning and seed treatingby a 15% brine solution are the simple and easy practicethat did not harm to the environment. Experiments wereconducted in the two continuous seasons, 2001 wet season anddry 2002 dry season. Ten farmers were selected toparticipate the experiment. Results showed that farmer’sfields used clean seeds decreased transmission of rice seed-borne diseases such as brown spot, red stripe, leaf scald,bacterial leaf blight, sheath rot and grain discoloration. Yieldincreased from 12 to 15 % and quality of seeds were observedin which 7.4-10.65% clean seeds in the dry season and 9.27-9.6% in the wet season. Moreover, use of clean seedsalso decreased 5.83-8.73% unfilled grains in the dry seasonand 8.32-8.65% discolored seeds in the wet season.

Results showed that farmer’s fields used clean

seeds decreased transmission of rice seed-borne

diseases such as brown spot, red stripe, leaf scald,

bacterial leaf blight, sheath rot and grain

discoloration.

Yield increased from 12 to 15 % and quality of

seeds were observed in which 7.4-10.65% in the

dry season and 9.27-9.6% in the wet season.

Moreover, use of clean seeds also decreased 5.83-

8.73% unfilled grains in the dry season and 8.32-

8.65% discolored seeds in the wet season.

Change in time of sowing may exploit weather

conditions that are unfavourable to the pathogen &

reduce yield losses.

Early sowing – reduces the ergot disease in bajra

& avoids black rot disease in crucifers.

Deep sowing favours covered smut, flag smut &

Kernal bunt in wheat, & loose smut in sorghum.

Narrow spacing & dense seedling reduces aeration

& provide humid canopy that encourages the

introduction & spread of disease.

It has indirect effect on spread of disease.

Some forms of inoculum spread extensively during

tillage.

Tillage buries pathogens present on the top soil

deeper where they are less likely to cause the

disease.

Also helps in release of nutrients in soil & benefits

the crop.

Practice of growing more than one crop in

alternate rows.

Reduces disease by increasing the distance &

creating physical barrier between the plants of

same species.

Successful intercropping partly depends upon

combination of crop plants chosen.

Organic amendments increases the activity of

competing or predatory microorganisms in the soil.

They also help in rectifying the problems related to

soil pH & make nutrients available to plant.

Overhead watering can prolong the leaf wetness-

increases likelihood of germination & infection by

fungal spores.

Excess irrigation – favours Karnal bunt

Frequent irrigation- reduces flag smut of wheat

Alternate wetting & drying destroys sclerotia.

Drip irrigation delivers water directly to root zone

& at rate insufficient to disperse pathogen.

Trap crop are susceptible plants grown on land

containing pathogens, they become infected &

destroys before pathogen completes its life cycle-

reducing the amount of inoculum in the area.

Decoy crops stimulate germination of pathogen

propagules, but the pathogens are unable to

establish & infect the decoy host & die- reduces

the inoculum.

Removal & destruction of diseased plants as soon

as disease symptoms are observed.

In sorghum & pearl millet ergot ear heads are

rogued & burnt.

In viral diseases effective roguing reduces the

spread of the pathogen.

Loose smut spore have already been spread &

infection of the seed crop has taken place by the

time symptoms are visible- certification schemes

do not allow removal of smut-infected plants.

The distance between the seed production &

commercial plots is maintained to reduce disease

incidence in seed crop.

This distance varies from region to region based

on weather conditions.

For loose smut of wheat & barley isolation

followed in different countries is:

Germany, UK - 50m

Holland - 100m

India - 150m

a) chemical protection in the field:

Several seed borne fungi, such as Colletotricum sp., Cercospora kikuchii, Alternaria, Tilletia sp. etc. and viruses such as lettuce mosaic virus, bean common mosaic virus, cucumber mosaic virus etc. become established in seed during flowering, seed setting and maturation.

Prophylactic measures using timely application of appropriate fungicides/chemicals/insecticides or bio agents, from early blossom to maturity of the crop at an appropriate stage of the plant growth is one of the effective management practice.

Fungal infection of seed is often more pronounced

during the later stages of maturation, especially in

areas where seed maturation coincides with the

season of high atmospheric humidity.

The rainfall from maturity to the harvest of the

crop appears to effect the incidence, prevalence

and severity of seed borne fungal pathogens.

If excessive rainfall occurs during harvest, the

colonization and infection of the pods and seeds by

pathogens and saprophytic fungi cause seed

discolouration.

Harvesting equipments are adjusted for minimum

kernel or seed damage and maximum cleaning.

Timely harvesting and processing avoids the

anthracnose infection which usually occurs on

mature fruits.

After proper processing, subsequently stored under

low temperature and low moisture content to avoid

contamination in storage.

Most storage fungi belong to the genera

Aspergillus, Pencillium, Rhizopus, & Chetomium.

Storage fungi are frequent where seed moisture

level is above safer level (>10%).

A. niger attacks seed at moisture content of 12% at

RH 75%.

Physical methods:

Seed dip in water: soaking seed in plain water at

20°c for 41 hrs- loose smut of wheat.

Hot water treatment:

The seeds are dipped for specific period of time in

hot water to a particular temperature safe to the

seed embryo and deleterious to the associated

pathogen

Useful for low volume high value seed

Effective for internally associated fungi and

bacterial pathogens.

High temperature damage the embryo

Temperature and duration of treatment differs from

crop to crop

HOT WATER THERMAL TREATMENT FOR

CONTROLLING SEED-BORNE MYCOFLORA OF

MAIZE

The seed material is exposed to hot air stream for a

specific period, which is safe for viability of seed.

More effective for the pathogens associated on to

the seed surface.

Eg: Tomato mosaic virus of tomato -3 days at 70 °c

Safe and convenient method than hot water

treatment.

J. C. Luthra suggested this method for control of

loose smut of wheat.

Wheat seed is presoaked in water for 4-5 hrs in the

shade or in a room and then dried on ground

/concrete floor in a thin layer in sun for 1 hr

usually at noon time to eradicate the pathogen

established inside the embryo.

It is the reduction of inoculum density or disease

producing activities of a pathogen or parasite in its

active form or dormant state by one or more

organisms accomplished by naturally or through

the manipulation of the environment of host /

antagonist or by mass introduction of 1 or more

antagonists.

It aims at eradication and control of the pathogen

through antagonistic activity of micro organisms

which is achieved by parasitism, predation and

commensalism etc.

An experiment was carried out at the Oil seed Research Unit,Marathwada Krishi Vidyapeeth Parbhani, Maharashtra, Indiato evaluate the efficacy of different chemicals and bioagentsagainst seed/soil borne diseases of safflower on disease incidence(PI or DI). Significantly low disease severity (DS) and lowdisease incidence (DI) were recorded in treatment withT7, thatis, Trichoderma harzianum Th4d sc at 2ml/kg to the tune of41.66% in Fusarium sp, 08.33% in Rhizoctonia sp, 06.66%in Phytophthora sp, 04.33% in Alternaria leaf spot and03.33% in Cercospora leaf spot respectively, in comparisonwith the untreated control. The seed yield data indicatedthat T. harzianum produced highest seed yield (2778 kg/ha)followed by Captan at 0.2% (2115 kg/ha) andCarbendazim+Mancozeb (SAFF) at 0.2% (2114 kg/ha). Highinfestation of safflower seeds by causal agents of seed/soilborne foot and root rots, reduction of seed germination andconsiderable infection transmission from seed to seedlingwere determined. Fungicide seed treatments, T1 to T8, markedlydecreased incidence of diseases. Though the treatment with T7,that is, T. harzianum recorded the disease incidence, it producedthe highest yield

Harmless to human beings and animals

Cheaper than pesticides (50%).

High Cost Benefit ratio

Highly effective throughout the crop growth period with high rhizospherecompetency.

Easy to deliver.

Improve plant growth.

Increases yield

Abstract

Seeds contaminated with pathogens are the primary inoculum for plantdiseases in many food crops. Conventional treatments for seedborne diseasesuse hot water, chlorine or fungicide applications. A novel seed treatmentmethod based on non-thermal plasma generated by an air dielectric barrierdischarge (DBD) device was evaluated in this study as an alternative to theseconventional treatments. The non-thermal plasma at atmospheric pressure androom temperature consisted of partially-ionized gases that are chemicallyreactive. The antimicrobial activity of non-thermal plasma was evaluatedagainst an important seedborne pathogen, Gibberella fujikuroi,that causesbakanae disease in rice. Non-thermal plasma treatments effectively inhibitedthe growth of G. fujikuroion nutrient growth medium and reduced the numberof fungal colony forming units (CFU) on the rice seed surface by > 92% after120 s exposure. Effective exposure times to 50% (ET50) and 90% (ET90)control of G. fujikuroiCFU on the seed surface were 9 and 76 s, respectively.Ten minutes of non-thermal plasma treatment on seeds infested with G.fujikuroisignificantly reduced disease development. No adverse effects weredetected on the seedling emergence and height when non-infested seeds weretreated with nonthermal plasma for up to 20 min. The treated seedsgerminated and grew similarly compared with non-treated non-infested seeds.This study indicates that non-thermal plasma had antifungal activity andshowed potential as an effective disinfection technique to reduce thecontamination of seedborne fungal pathogens from seed surfaces withoutcompromising seed health

Abstract Thirty six rice seed samples of varieties BR6, Pajamand Joya were collected from Parshuram upazila, Feni district ofBangladesh and nine seed-borne fungi were detected from theseseed samples. The identified fungi were Fusarium oxysporum,F. moniliforme, Bipolaris oryzae, Alternaria padwickii,Curvularia lunata, Aspergillus flavus, Aspergillus niger,Penicillium sp. and Nigrospora oryzae. Five different plantsextracts viz. garlic, allamanda, neem, chirata and bishkatali withtwo dilutions (1:1 & 1:2) were tested for seed treatment. Garlicextract (1:1) dilution found best for three varieties whichsuccessfully reduced seed-borne infection and also increasedseed germination up to 68.39% over control. Neem (1:1) andchirata (1:1) extracts also increased seed germination up to66.09% and 67.81%, respectively. Based on the present study, itmay be concluded that among the five plant extracts with twodilutions (1:1 & 1:2), garlic (1:1) is most effective in controllingseed-borne fungal flora of rice followed by neem (1:1) andchirata (1:1) extract.

Application of chemical to seed is cheapest method & most effective method for controlling seed borne pathogens.

Fungicidal seed treatment may kill or inhibit seed born pathogens by forming protective covering.

FORMULATIONS:

Seed treatment chemicals are available in different formulations.

Dusts

Slurry

Liquid

Fungicidal-insecticidal formulation

Simple and economical

Add the required quantity of fungicide and shake

them in a closed vessel or a rotary drum for 5-

15minutes.

1. Seed Dip Method:Involves dipping of the seed in fungicide solution.

Recommended for seeds with tough seed coats.

The seed should be treated just prior to planting

This method is mainly used for treating vegetativelypropagated materials like tubers, bulbs and cuttings

Water dispensable fungicide formulations aremixed in water to form slurry.

Seeds are sprayed with high conc. Fungicidesolution and dried.

The chemical is deposited on the surface of seed inthe form of thin paste.

ABSTRACT

In organic seed production more than a half of seed lots are often discarded due to heavy infection with seed bornepathogens. To prevent this, various techniques are used:

seed heat treatment, ultrasound treatment, brush cleaningand seed dressing with plant extracts or natural chemicals. In 2008, the efficiency of wheat seed treatment with the stone meal was tested and the results of preliminary investigation are presented. Two tests were performed using the official procedure for seed health testing.

Test 1:

Heavily infected wheat seedwas treated with the stone

meal EKORAST (particle size <0.08 mm). Dry and

wet treatment procedures were applied: both with 1, 2,

10 and 20%. Heavy application (10 and 20 kg per 100

kg of seed) significantly increased germination and

energy of wheat seed, and it was effective against

bacterial pathogensand some fungi, but only partially

effective against heavy infection of Fusariumspp.

However, the amounts of stone meal (10 and 20%) are

practically not applicable, and adhesion of stone meal

to the seed should be improved.

Test 2:

Wheat cleaned seed of seven genotypes was wet

treated with Ekorast (1 %) and chemical fungicide

Vitavax 200FF (250 ml/100 kg). The untreated seed

was used as control. There were no significant

differences between the three variants in germination

and energy. The stone meal Eko-rast was equal or

better than Vitavax 200FF in seed protection against

seed borne pathogens, and could be recommended

for seed treatment in organic seed production. Search

for an additive with better adhesion to seed is under

way.

Mineral Percentage

SiO2 56.9%

CaO 8.8%

MgO 5.9%

K2O 3.0%

P2O5 0.8%

Fe2O3 1.3%

Al2O3 8.7%

Na 0.8%

Mn 54.2mg/kg

Zn 21.2mg/kg

Cu 35.3mg/kg

Pb 2.2mg/kg

Cd 0.3mg/kg

Protects germinating seeds and seedlings from soiland seed borne pathogens / insects

Seed germination enhancement

Uniform crop stand, even in adverse conditions(less/high moisture)

Treated Untreated

It was potato seed certification, began in Germany

(1990s) & soon after in US, with the aim of

stooping the spread of viruses responsible for leaf

roll & other viral disease.

Certification goes hand in hand with seed quality

control in which the most important seed qualities

are viability, purity & health.

Certification involves strict procedure for labeling

& sealing seed packs.

Certification is limited generation system based on

4 seed classes.

Certification shall be completed in 6 phases.

Compulsory requirements to be followed for

certified seed production: application, field

eligibility, isolation, field inspection, offtypes,

weeds, diseases.

Quarantine is a legislative (regulatory) attempt to

exclude pathogens from invading into the areas

where they do not exist by monitoring the import

and export of plant, seed or planting material to

prevent spread of diseases and pests.

It aims to prevent the entry of dangerous

pathogens but not the movement of biological

material.

Agrawal, V. K. and Sinclair , J. B. (1987) Principles of seed pathology, CRC press, BOCA Raton, Florida.

Vishunavat, K. (2009) Fundamentals of seed pathology, Kalyanipublishers, New Delhi.

Anam, M. K., Fakir, G. A., Khalequzzaman, K. M., Hoque, M. M., Abdur Rahim. (2002) Effect of seed treatment on incedence of seed-borne diseases of okra. Pakistan Journal of Plant Pathology. 1(1): 1-3.

Lindsey du Toit, WSU Mount Vernon. Infection of Seed & Transmission of Seed Borne Pathogens. NWREC

Pham Van Du, Huynh Van Nghiep and Nguyen Duc Cuong. (2003) Application of seed cleaning in management of seed-borne diseases of rice. OMONRICE: 11. pp 103-109.

Rahman, M. M. E., Ali, M. E., Ali,M. S.,. Rahman,M. M., and Islam, M. N. (2008) Hot water thermal treatment for controlling seed-borne mycoflora of maize. Bangladesh Agricultural Research Institute, International Journal Sustainable Crop Production. 3(5): 5-9.