Brief detail of Antibiotics.

1. ANTIBIOTICS
General Introduction:
 Alexander Fleming observed the killing of staphylococci by a fungus (Penicillium notatum).
 Penicillin- the first antibiotic used in 1928.
 The first time antibiotics used against the fire blight of pear (Erwinia amylovora) in 1953.
 Antibiotics have been used since the 1950s to control certain bacterial diseases of high-value
fruit, vegetable, and ornamental plants. Today, the antibiotics most commonly used on plants
are oxytetracycline and streptomycin. In the USA, antibiotics applied to plants account for
less than 0.5% of total antibiotic use. Resistance of plant pathogens to oxytetracycline is rare,
but the emergence of streptomycin-resistant strains of Erwinia amylovora,Pseudomonas spp.,
and Xanthomonas campestris has impeded the control of several important diseases.
Definition: the antibiotics defined as metabolites of microorganisms which in very dilute in
concentration, have the capacity to inhibit the growth of,or even kill other microorganisms.
Important antibiotics: Antibacterial antibiotics
1. Streptomycin: Synthesized by the soil organism Streptomyces griseus. Streptomycin was
discovered by American biochemists Selman Waksman, Albert Schatz, and Elizabeth Bugie
in 1943. Streptomycin, an aminoglycoside antibiotic, is formulated as either streptomycin
sulfate or streptomycin nitrate and marketed under the trade names Agrept, Agri-mycin,
Agri-strep, Fructocin, and Plantomycin. This is used for control of bacterial blight of
pomegranate (Xanthomonas axonopdis pv. punicae).
Dose: @ 100ppm method of application as spray
2. Oxytetracycline: Oxytetracycline, a tetracycline antibiotic produced by Streptomyces
rimosus, structure identified by Robert Woodward in 1953, is formulated either as an
oxytetracycline calcium complex or oxytetracycline hydrochloride and marketed under the
trade names Biostat, Glomycin, Mycoshield, Terrafungine, and Terramycin. In the USA, it is
registered for control of fire blight of pear (E. amylovora).
Dose: @50-100 mg OTC/tree in case of palm 100ppm method of application as spray.
3. Gentamicin: It is isolated from fermentation of Micromonospora spp., structure is identified
by Schaffner and Machr.

2. Gentamicin, an aminoglycoside antibiotic, is formulated as gentamicin sulfate. It is marketed
under the trade name Agry-gent. Gentamicin is sometimes mixed with oxytetracycline and
marketed as Agry-gent Plus or Bactrol. Gentamicin is used in Mexico to control fire blight of
apple and pear (Erwinia amylovora).
DOSE: @100-500 ppm method of application as spray.
ANTI-FUNGAL ANTIBIOTICS:
1. Aureofungin: It is produced by Streptoverticillium cinnamonium var.terricola.
It is used for control of citrus gummosis (Xanthomonas campestris pv. citri), apple scab
(Venturia inaequalis), tikka leaf spot of groundnut (Cercospora personata), powdry mildew of
grapes (Uncinula necator). This is sold as Aureofungin – A.
DOSE: It is normally used @ 50-100ppm method of application as spray.
2. Grisiofulvin: It is produced by Penniciiium griseofulvom and commercially sold in the trade
name Griseofulvin and Graseovin.
This is used against the diseases like- powdery mildew of bean (Erysiphe polygoni) and
downey mildew of cucumber (Erysiphe cichoracearum).It is also used for control of early blight
of tomato (Alternaria solani).
DOSE: @ 50-150ppm method of application as spray.
3. Blasticidin: It is product of Streptomyces griseocromogens and specially used for the control
of blast of rice (Pyricularia oryzae). Commercially sold as BLA-S.
DOSE: @100-200ppm method of application as spray.
4. Antimycin: It is produced by several species of streptomyces. It is used against early blight
of tomato (Alternaria solani), blast of rice (Pyricularia oryzae). Commercially sold as
Fintrol.
DOSE: @100-200ppm method of application as spray.
5. Bulbiformin: It is produced by Bacillus subtilis.It is very effective against wilt of red gram
(Fusarium oxysporum f. sp. udum). Commercially sold as Serenade.
DOSE: @ 50-100 ppm method of application as spray.
6. Cycloheximide: It is produced by different species of Streptomyces, including S.griseus and
S. nouresi. It is commercially sold as Actidione, Actidione PM, Actidione RZ and Actispray.
It is effective against powdery mildew of beans (Erysiphe polygoni), Bunt of wheat (Tilletia
spp.) brown rot of peach (Sclerotinia fructicola)
DOSE: @ 50-100 ppm method of application as spray.

3. NEW MOLICULES OF ANTIBIOTIC:
1. Validamycin: Validamycin is an antibiotic and fungicide produced by Streptomyces
hygroscopicus. It is used as an inhibitor of trehalase. It is mainly use to control sheath blight
of rice (Rhizoctonia solani) and wheat stem rot (Sclerotinia sclerotiorum).This is sold as
Sheathmar.
Dose:@ 1000ppm /acre method of application as spray.
2. Eurocidin: This antibiotics is produced by Streptomyces anandii and sold as G-8. It is
effectively used against anthracnose caused by several species of Colletotrichum and againt
brown spot of rice caused by Helminthosporium oryzae
DOSE: @50-100 ppm method of application as spray
3. Thiolutin: It is produced by Streptomyces albus and effectively used for the control of late
blight of potato (Phytophthora infestans) and downy mildew of cruciferous (Peronospora
parasitica).This is sold as Thiride.
DOSE: The dosage of foliar spray varies from @ 100-1000 ppm
4. Kasugamycin: It is obtained from Streptomyces kasugaensis. It is also very specific
antibiotic against blast of rice (Pyricularia oryzae). It is commercially available as
Kasumin.
DOSE: @ 50-100 ppm method of application as spray.
MODE OF ACTION OF ANTIBIOTICS:
1. Inhibitors of cell wall synthesis. While the cells of humans and animals do not have cell
walls, this structure is critical for the life and survival of bacterial species. A drug that targets
cell walls can therefore selectively kill or inhibit bacterial organisms. Examples: penicllins,
cephalosporins, bacitracin and vancomycin.
2. Inhibitors of cell membrane function. Cell membranes are important barriers that segregate
and regulate the intra- and extracellular flow of substances. A disruption or damage to this
structure could result in leakage of important solutes essential for the cell’s
survival. Because this structure is found in both eukaryotic and prokaryotic cells, the action
of this class of antibiotic are often poorly selective and can often be toxic for systemic use in
the mammalian host. Most clinical usage is therefore limited to topical applications.
Examples: polymixin B and colistin.

4. 3. Inhibitors of protein synthesis. Enzymes and cellular structures are primarily made of
proteins. Protein synthesis is an essential process necessary for the multiplication and
survival of all bacterial cells. Several types of antibacterial agents target bacterial protein
synthesis by binding to either the 30S or 50S subunits of the intracellular ribosomes. This
activity then results in the disruption of the normal cellular metabolism of the bacteria, and
consequently leads to the death of the organism or the inhibition of its growth and
multiplication. Examples: Aminoglycosides, macrolides, lincosamides, streptogramins,
chloramphenicol, tetracyclines.
4. Inhibitors of nucleic acid synthesis. DNA and RNA are keys to the replication of all living
forms, including bacteria. Some antibiotics work by binding to components involved in the
process of DNA or RNA synthesis, which causes interference of the normal cellular
processes which will ultimately compromise bacterial multiplication and
survival. Examples: quinolones, metronidazole, and rifampin.
5. Inhibitors of other metabolic processes. Other antibiotics act on selected cellular processes
essential for the survival of the bacterial pathogens. For example, both sulfonamides and
trimethoprim disrupt the folic acid pathway, which is a necessary step for bacteria to produce
precursors important for DNA synthesis. Sulfonamides target and bind to dihydropteroate
synthase, trimethophrim inhibit dihydrofolate reductase; both of these enzymes are essential
for the production of folic acid, a vitamin synthesized by bacteria, but not humans.

5. NEMATICIDES
HISTORY OF NEMATICIDES:
Kuhn (1881) first tested CS2 to control sugarbeet nematode in Germany and he could not get
encouraging results.
In South Carolina State, U.S.A. Bessey (1911) treated CS2 or the control of root – knot
nematodes but the method proved impractical.
Latter on the chemicals like formaldehyde, cyanide and quick line were observed to have
nematicidal properties, but all these chemical were found to be highly expensive.
Mathews (1919) observed the effect of chloropicrin (tear gas) against plant parasitic nematodes
in England.
Carter (1943) an entomologist of Hawai, Pineapple Research Institute, reported the efficacy of
1,3 dichoropropene 1,2 dichloropropane (DD) mixture@ 250 1b/acre, against the plant parasitic
nematodes. In 1944, scientists from USA reported the efficacy of ethylene dibromide (EDB).
In the same year the Dow Chemical company, USA introduced the chemical as a soil fumigant
for the management of nematodes. The introduction of these two nematicides viz., DD and EDB
paved way for the chemical control of nematodes.
Important nematicides:
1. Ethylene dibromide (EDB): 1.2 Dibromonehane. It is a colourless liquid and the gas in
noninflammable. It is available ad 83% liquid formulation containing 1.2 kg active ingredient
per litre and as 35% granules. It is injected or dibbled into the soil for the control of
nematodes at 60 to 120 1 or 200 kg ai/ha but it is not very effective against cyst nematodes.
Heterodera sp. and soil fungi, Crops like onion, garlic and other bulbs should not be planted
after soil treatment with EDB. It is available as Bromofume and Dowfume.
2. Dibromochloropropane : (DBCP) 1,2 – dipromo – 3 – chloropropane. It is a straw coloured
liquid, a litre of it weighing 1.7 kg. It can be used s soil treatment before planting, at the time
of planting or as post when the soil temperature is above 20˚C. It is applied as a sprinkle
depending upon the crop and stage. Certain crops like tobacco and potato are sensitive due to
high bromine content in the chemical. It functions more efficiently than other fumigant at
high soil temperature due to its high boiling point (195.6˚C). Trade names are Nemagon and
fumazone.

6. 3. DD mixture: It is the trade name of the mixture of compounds, chief of them contain thecis
and the trans isomers in equal quantities of 1,3 – dichloropropene 30.35%, and a few other
chlorinated compounds up to about 5%. Of these, dichloropropene is the most toxic
compounent and among its two isomers, the transisomer is twice as toxic as the cis-isomer. It
is a black liquid of 100% formulation and a litre of it contains approximately 1kg of technical
compounds. It is used in the control of soil insects and nematodes and injected into the soil at
a depth of 15 -20 cm at 25 x 30 cm spacing. It is a fungicide a very high diseases. Since it is
highly phytotoxic, it is used for preplant soil application at least 2 -3 weeks before planting.
It is used for preplant soil application at least 2 -3 weeks before planting. It is used as such at
225 – 280 1/ha, but in clay and peaty soils a higher dosage is required. It taints potato tubers
and carrots grown in treated soil. Dichloropropence is available under the trade name Telone
andin mixture with dibromoetane under the name Dorlane.
4. Methylbromide or Bromomethane: Its insecticidal properties were described by Le Goupil
in 1932. Its power of penetration into packed foodstuffs such as flour is remarkable. As it
kills insects slowly a longer period of exposure to gas may be required. For control of stored
grain pests it is used at 24 – 32 g. m3, exposure period being 48 h. For fumigating live plants,
the dosage is 16-32 kg.
In soil application for the control of nematodes.
5. Phorate: 0,0 – diethyl S – (ethylthiomethyl) phosphorodithioate. Trade name is Thimet. It is
systemic insecticide cum nematicide, available as 10% granule. It has got both contact and
fumigant action. It does not persist for a longer period and gets metabolically oxidized
yielding for rat: oral 16 – 3.7; dermal 2.5 to 6.2.
6. Aldicarb: 2 – methyl – 2 (methilthio) propinaldehyde 0(methylcarbomy) oxime. Trade name
is Temik. The sulphur atom in the molecule is oxidized to sulfoxide and then to sulfone. It is
a systemic 10% granule. The residues remain in plants for 30 -35 days as a lethal dose. It also
acts as repellent, contact nematicide and interferes with reproduction of the nematodes by
way of sex reversal.
7. Carbofuran: C12 H15 No3. It is 2,3 – dihydro – 2, 2, dimethyl 7 benzofuranyl methyl
carbamate.Trade name Furadon. It is a systemic insecticide cum nematicide. It is formulated
as 3% granule.The residual effect last for 30 – 60 days. It has also got phytotonic effect. This
systemic chemical has got acropetal action and applied @ 1 - 2 kg ai.ha.

7. NUTRIENTS
Element/status Visual symptoms
Nitrogen (N)
Deficiency Light green leaf and plant color with the older leaves turning yellow, leaves that will
eventually turn brown and die. Plant growth is slow plants will be stunted, and will mature
early.
Disease/ Disorder: Butnning in cauliflower.
Dose: 130-140 kg n/ha.
Excess Plants will be dark green in color and new growth will be succulent; susceptible if
subjected to disease and insect infestation; and subjected to drought stress, plants will
easily lodge. Blossom abortion and lack of fruit set will occur.
Ammonium
toxicity
Plants fertilized with ammonium-nitrogen (NH4- N) may exhibit ammonium-toxicity
symptoms, with carbohydrate depletion and reduced plant growth. Lesions may occur on
plant stems, there may be a downward cupping of the leaves, and a decay of the conductive
tissue at the base of the stem with wilting of the plants under moisture stress. Blossom-end
rot of fruit will occur and Mg deficiency symptoms may also occur.
Phosphorus (P)
Deficiency Plant growth will be slow and stunted, and the older leaves will have a purple coloration,
particularly on the underside.
Disease/disorder: Necrosis & Scorching in sunflower.
Dose: 70-100 P/ha.
Excess Phosphorus excess will not have a direct effect on the plant but may show visual
deficiencies of Zn, Fe, and Mn. High P may also interfere with the normal Ca nutrition,
with typical Ca deficiency symptoms occurring.
Potassium (K)
Deficiency On the older leaves, the edges will look burned, a symptom known as scorch. Plants will
easily lodge and be sensitive to disease infestation. Fruit and seed production will be
impaired and of poor quality.
Disease/Disorder: Marginal drying in banana.
Dose: Foliar spray ofK2So4 (1%)
Excess Plants will exhibit typical Mg, and possibly Ca deficiency symptoms due to a cation
imbalance.
Calcium (Ca)
Deficiency The growing tips of roots and leaves will turn brown and die. The edges of the leaves will
look ragged as the edges of emerging leaves stick together. Fruit quality will be affected
with the occurrence of blossom-end rot on fruits.
Disease/Disorder: Blossom end rot oftomato.
Dose: Foliar spray ofcalcium chloride (3 g/litre ofwater) also controls this disorder.
Excess Plants may exhibit typical Mg deficiency symptoms, and when in high excess, K
deficiency may also occur.
Excess Results in a cation imbalance showing signs of either a Ca or K deficiency.

8. Sulfur (S)
Deficiency A general overall light green color of the entire plant with the older leaves being light
green to yellow in color as the deficiency intensifies.
Disease/Disorder: Younger leavesshowyellowing, rolls upward.
Dose: Apply elemental sulphur
Excess A premature senescence of leaves may occur.
Boron (B)
Deficiency Abnormal development of the growing points (meristematic tissue) with the apical growing
points eventually becoming stunted and dying. Rowers and fruits will abort. For some
grain and fruit crops, yield and quality is significantly reduced.
Disease/Disorder: Internal necrosis ofmango
Dose: Borex@0.6%
Excess Leaf tips and margins will turn brown and die.
Copper (Cu)
Deficiency Plant growth will be slow and plants stunted with distortion of the young leaves and death
of the growing point.
Disease/Disorder: Exanthema disease in citrus.
Dose: Apply Cupprite
Excess Fe deficiency may be induced with very slow growth. Roots may be stunted.
Iron (Fe)
Deficiency Interveinal chlorosis will occur on the emerging and young leaves with eventual bleaching
of the new growth. When severe, the entire plant may be light green in color.
Disease/Disorder: Chlorosis in sugarcane, groundnut.
Dose: Apply Ferrous sulphate
Excess A bronzing of leaves with tiny brown spots on the leaves, a typical symptom frequently
occurring with rice.
Manganese (Mn)
Deficiency Interveinal chlorosis of young leaves while the leaves and plants remain generally green in
color. When severe,the plants will be stunted.
Disease/Disorder: Pahala blight of sugarcane.
Dose: Apply MnCl2(17 %)
Excess Older leaves will show brown spots surrounded by a chlorotic zone and circle.
Molybdenum
(Mo)
Deficiency Symptoms will frequently appear similar to N deficiency. Older and middle leaves become
chlorotic first, and In some instances, leaf margins are rolled and growth and flower
formation are restricted.
Disease/Disorder: Whiptail in cauliflower.
Dose: Apply 1-2 kg Sodium or Aluminium molybdate.

9. Excess Not of common occurrence.
Zinc (Zn)
Deficiency Upper leaves will show interveinal chlorosis with an eventual whiting of the affected
leaves. Leaves may be small and distorted with a rosette form.
Disease/Disorder: Khaira disease in rice
Dose: Spray @5kg ZnSO4.
Excess Fe deficiency will develop.