PEST AND WEED CONTROL & DISEASE MANAGEMENT OF MEDICINAL AND AROMATIC PLANTS
BY INDER MAKHIJA
WHAT IS MEANT BY PEST?
Pest is an undesirable animal or plant species
TYPES OF PEST
The different types of pests infesting the medicinal plants are
Fungi and virus
Insects
Weeds
Non insect pests
FUNGI Ø Ascochyta atropae Ø Cercospora atropae Ø Phytophthora nicotianae Ø Ø Ø
Ø
VIRUSES
Tobacco mosaic virus
Cucumber mosaic virus
Tobacco ring spot virus
Yellow vein mosaic,
Graft transmissible virus
Distortion mosaic virus
INSECTS
“Total number of insect species>Total number of all other forms of life put together”
Biting and chewing
Piercing and sucking
Examples:
Agrotis species
Heliothis armigera
WEEDS
A weed is undesirable plant.
Weed leads to loss of nutrients, water, light and space.
Increase in cost of labour and equipment
Low product quality
Enhanced chances for attacks of bacteria,fungi and insects
A weed is undesirable plant.
Rag weed
Medican tea
Yellow dock
Parthenium
METHODS OF PEST CONTROL
MECHANICAL METHOD
AGRICULTURAL METHOD
BIOLOGICAL CONTROL
ENVIRONMENTAL METHOD
CHEMICAL METHOD
MECHANICAL METHOD
The simple techniques used are:
Hand picking
Pruning or cutting
Burning
Trapping
A proper approach is made for collection and destruction of eggs , larvae, pupae and adults of insects
AGRICULTURAL METHOD
The techniques are:
Hybridization
Tissue culture
Transgenic plants
Other aspects of Agricultural control are:
Ploughing
Crop rotation
Changes in environment
BIOLOGICAL CONTROL
This method is practiced by combating the pests, mostly the insects with other organism, the parasitic form.
If the method is properly designed it may emerge as an effective, safe, economical method of pest control.
The chemical substances produced and released by some female insects, are capable of eliciting a sexual response from the opposite sex, which could be properly exploited for the biological control of pests. Such substances are called as SEX PHEROMONES
ENVIRONMENTAL METHOD
Environmental condition surrounding the pest is changed either by removing its food supply or by interfering the completion of its life cycle.
e.g., mosquito larvae in water are killed by spreading a layer of oil.
CHEMICAL METHOD The chemical control is done by with the help of PESTICIDES. Pesticides are chemicals derived from synthetic and natural sources effective in small concentration against pest
Various forms of preparation of pesticides used: Spray or wettable powders Powders Granulates Selfemulsifying concentrates Solution in mineral oil fractions Fumigants
PESTICIDE
These are the chemicals derived from synthetic and natural sources effective in small concentrations against the pest
Ideal requirements for pesticides It should be nontoxic and noninjurious to medicinal plants and human being. It should be highly toxic to insect It should be effective in small concentrations Stable under ordinary conditions of storage,non inflammable, noncorrosive and free from obnoxious odours It should be noncumulative in the soil and possess stability on treated surface. Cheap and easily available.
MODE OF ACTION OF PESTICIDES ON ANIMALS CHEMICAL COMPOUND
BIOLOGICAL EFFECT
EFFECT ON ANIMALS
Organophosphorous compounds and carbamates
Inhibition of Ach esterases
Chlorinated hydrocarbons and Neurotoxication pyrethroids Nicotinoids
Inhibition of neuromuscular junction
MODE OF ACTION OF PESTICIDES ON PLANTS CHEMICAL COMPOUND EFFECT ON PLANTS Carbamates, substituted ureas, triazines Carbamates 2,4D; 2,4,5T Metals, sulphur 3amino1,2,4 triazole Chlorinated aliphatic hydrocarbons
BIOLOGICAL EFFECT Inhibition of photosynthesis Inhibition of oxidative phosphorylation Harmone analogue Unknown cause Inhibition of chlorophyll synthesis Inhibition of pentothenate synthesis
DIFFERENT CLASSES OF PESTICIDES BASED ON THE CHEMICAL COMPOSITION:
CHLORINATED HYDROCARBONS AND RELATED PESTICIDES
CHLORINATED PHENOXYALKANOIC ACID HERBICIDES
ORGANOPHOSPHOROUS PESTICIDES
CARBONATE INSECTICIDES
INORGANIC PESTICIDES
DITHIOCARBAMATE FUNGICIDES
CLASSIFICATION OF PESTICIDES
FUNGICIDES
HERBICIDES
INSECTICIDES
ACARICIDES
RODENTICIDES
NEMATOCIDES
FUNGICIDES
TYPES:
§ DISINFECTANTS FOR SEEDS Eg., Dithiocarbamates,organophosphorous compounds,pyridine compounds
§ DISINFECTANTS FOR SOIL § LEAF FUNGICIDES Eg., Copper oxychlorides,Bordeaux mixture,Barium sulphate
§ §
HERBICIDES
They are the weed killers, which are used for destroying the unwanted plants or to prevent their growth
Types:
§ Selective herbicides2,4D § Nonselective herbicidespotassium cyanide § herbicidessulphuric acid § Translocated herbicidespicloram § §
INSECTICIDES § OVICIDES § LARVICIDES § STOMACH POISONS § POISONS Classified by the mode of action: General cell toxins Enzyme toxins Nerve toxins
ACARICIDES
They are substances that are used to control the infestation caused by the mites, especially spider mites.
These insects acquire resistance to the chemicals because of their rapid multiplication and therefore new acaricides have to be developed
Examples:
§ Phosphoric and thiophosphoric acid esters § Carbamidic esters § Chlorinated aromatics
NEMATOCIDES
For the control of the phytopathogenic thread worms i.e.,nematodes living free in the soil and also occuring in the plants the agents required are Nematocides.
Halogenated hydrocarbons
Carbamidic and thiocarbamidic acid derivatives
Thiophosphoric acid esters
RODENTICIDES
The pesticides acting against rodents are called rodenticides
Examples:
q Warfarin q Arsenic trioxide q Thallium sulfate. q Natural origin examples: Red Squill, Strychnine
DISEASE MANAGEMENT OF MEDICINAL AND AROMATIC PLANTS PLANT DISEASE:
According to” STAKMAN and HORRAR” “Any disturbance of a plant that interferes with its normal growth and development , economic values or aesthetic quality, a continuously often progressively affected condition in contrast to injury which result from momentary damage” The deviation is sufficiently pronounced and permanent to produce visible symptom. The deviations are produced by pathogenic organisms or environmental condition and hence their failure to reach the full genetic potential.
CLASSIFICATION OF PLANT DISEASES
BIOTIC (PATHOGENIC) FUNGI BACTERIA VIRUS AND VIROIDS PHYTOPLASMA PARASITIC PLANT NEMATODES
ABIOTIC (NONPARASITIC DISEASES)
COMMON DISEASES IN PLANTS
PHYTOPHTHORA ROT
ROOT ROT
PHYTOPHTHORA ROOT ROT
LEAF NECROSIS
LEAF SPOT
DAMPING OFF
PREVENTION OF DISEASES
EXCLUSION
AVOIDANCE
SANITATION
CULTURAL CONTROL
PHYSICAL CONTROL
BIOLOGICAL CONTROL
CHEMICAL CONTROL
MECHANICAL METHOD
MODE OF ACTION OF EACH CHEMICAL CLASS
CHEMICAL CLASS
TARGET
Benzimidazole
Cell mitosis
Benzonitrile
multi site
Carbamates
Cell membrane
Carbozamide
Fungal respiration
Cinnamic acid
Cell wall synthesis
Thiadiazole
Lipid peroxidation
REFERENCES
TEXT BOOK OF PHARMACOGNOSY BY KOKATE,C.K PUROHIT,22nd EDITION
TREASE AND EVANS PHARMACOGNOSY,15th EDITION
MOHAMMAD ALI, TEXT BOOK OF PHARMACOGNOSY,CULTIVATION AND UTILISATION OF MEDICINAL PLANTS
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