Crop protection in organic agriculture aims at preventing pest, disease and weed problems through the optimization of the cropping system as a whole. Growing resistant varieties, crop rotation are some of critical steps to be taken for the success of the system. Urgent research is needed to determine and control the key pests and diseases of the organic systems . Organic Plant protection mainly aims at Removing reasons or Encouraging conditions for occurrence of harmful organisms. Organic Crop Protection Includes:
1. Management of Pest and Disease
2. Weed Management
These Management Practices are described as Follows
1. Management of Pest and Disease
Pests and Diseases are generally not a significant problem in case of organic systems. Healthy plants with balanced and proper nutrition are resistant against pest and disease attack. Major Pest damage sometimes, seen in organic crops. Vegetable crops such as carrots, brassicas are highly susceptible to damage from root flies. Pest control Strategies are mainly preventative in case of organic farming. Crop Species, Management of cropped and Uncropped area, choice of variety , crop rotations are some of practices use to maintain diverse plant population of beneficial organisms which includes parasites, competitors of pests. Since use of synthetic chemicals is avoided so focus is given on prevention of pests before they occur in the field. Pests only produce economic losses when infestation levels reaches to a certain point. In organic systems, levels of soil borne pathogens and root Diseases are realtively lower. Powdery Mildews in Vegetable/Fruit Crops, Potato late blight are some of airborne pathogens which cause serious problems in organic systems.Proper balanced rotations should be followed to reduce risk of diseases in organic systems. In case of highly Mobile airborne pathogens, resistant varieties and species should be grown. Natural Plant Extract-based fungicides should be applied from time to time to control various diseases . Fungal diseases can be controlled through biological control. Effective pest and disease management can be achieved through following methods
AVOIDANCE OF INSECT-PEST AND DISEASES
(i) Seed Quality& Sowing: High quality of seed should be used for planting purpose. Seed should be free from smut and other seed-air borne diseases. Seed should be tested in the laboratory. Seed planted should be physically sound. Sowing time Is also an important factor which helps to Avoid certain pests and diseases. Seed should be timely sown so that it forms proper seedlings before the infestation by insect-pests and diseases. Late sowing should be avoided.
(ii) Crop Residue Management: Crop residue contain infected weed seeds which attract various type of insect-pest and diseases so Crop residue should not be left over in the field it should be properly managed. Useful Crop residue should be incorporated into the field.
(iii) Crop Rotations: Crop rotation is the most effective way to minimize the problems of weeds and diseases. Crop rotation is very helpful in maintaining and enhancing the levels of soil fertility. Successful crop rotation can be performed by maintaining proper diversity among various crops. Diverse rotations helps to control cabbage butterfly, flea beetles , wheat stem maggot and other pests. Rotation of various crops such as annuals, perennials, garsses and broadleaf crops helps in the management of pests and diseases as each of these crops types, have specific rooting habits, nutrient and moisture requirement etc. Green manure crops should also be used in the crop rotation systems which is highly effective to suppress pests, disrupt their life cycles etc. Green manures and Leguminous crops also provides additional benefits like Nitrogen Fixation and Improvement of soil properties.
(iv) Weed Management: Weeds are important in some of the cases as it act as a host for some of the insect pest which otherwise affect main crop. Field which is completely free from any kind of weeds is not necessary. With the increased diversity of weeds(which are host of pest-insects), the attack of aphids and leafhoppers decreases on the main crop. A few insects such as grasshoppers, caterpillars prefer to feed on weeds than some crops.
(v) Forecast: Proper attention should be paid towards the outbreak of various insect-pest and diseases for each crop year. Maps are also available each year for many of major destructive insect-pests as well as some diseases.
GROWTH ENVIRONMENT MANAGEMENT
(i) Intercropping: The process of growing two or more crops in the same field at the same time is known as intercropping. Intercropping helps to reduce pest population as insect-pests are unable to find a host crop for their diet. It is also helpful for some beneficial organisms. Relay cropping is also an important practice which involves growing one crop, then planting another crop in the same field before harvesting. It also helps in better use of growing area.
(ii) Seeding Rate & Seeding Time: Seeding rate affect the insect-pest and disease in different ways. Seeding rate should be proper . Higher seed rate tends to attract insect-pests which occurs in dense canopy while lower seeding rate may allow weeds to invade. Seeding should be done when the soil have enough moisture conditions for rapid germination.
(iii) Seeding Depth: Depth of sowing seeds is an important factor. Seed should be sown at proper depth. Deep sowing of seeds may result in Damping-off, seedling blight in case of pulses and small-seeded crops. Seed depth should be adjusted according to Seed size, Soil type and Moisture conditions.
(iv) Roguing: Roguing is a time consuming and labor intensive process to destroy diseased or pest-infected crop plants. It may not be practical for large area of field. It can be highly effective for seed plots ,in small areas having destructive and infectious diseases.
(v) Tillage Practices: Summer tillage is very important to destroy large no. of insect-pest and diseases. Timely tillage before seeding and after harvesting helps to reduce insect-pest population to a great extent. Tillage cause starvation of insects in the spring or during fallow land, it also prevents adults from laying eggs in soil surface and also expose insects to harmful predators and sunshine.
(vi) Crop Variety Selection: Choice of Crop and Crop variety is a important step in organic weed management process. Crop should be carefully selected according to prevailing environmental conditions. Mainly regional and native varieties are grown which thrives well in prevailing environmental conditions. Choice of crop should also fit well in the crop rotation system that has been developed.Selection of variety is also an important process. Disease-resistant varieties can be Useful tool in prevention of weed infestation. For e.g. Solid stems Wheat varieties are highly resistant against wheat stem sawfly. Various plant species are highly resistant against various diseases but agronomic practices, time of seeding have more influence on disease incidence.
(vii) Soil Health: Optimum soil health is a key step in defense towards insect-pest and diseases. Soil having good drainage and biologically active supports vigorous crop growth and also helps the crop plants to compete with the weeds. Soil should be properly provided with FarmYard Manure, various Nutrients, Mulches to improve soil health. Soil testing should be properly done in the laboratory and deficiency of certain micronutrients should be completed to protect crop from infestation from certain diseases and insect-pests.
Direct management includes the removal of pests and diseases from the crop system through suitable methods. For direct mangament of insect-pest and diseases proper knowledge of pest biology, behavior and crop interaction should be required.
(i) Natural Insecticides: Some of the microbial insecticides Bacillus thuringiensis which contains bacteria are used as a natural insecticides. There are mainly Three strain of this kind of bacteria. One is marketed as Dipel (Thuricide) which is effective against larvae of moths and butterflies. Second Strain, Marketed as Novodor, which is effective against Beetle larvae and it can be used to control Potato beetles. Third strain, Which is effective against mosquito and Fly Larvae. Rotenone can also be used as a botanical insecticide but they are too expensive to use on large area of land.
(ii) Biological Control: Biological control includes when a living organism feeds upon another living organism which is harmful to the main crop plant. With the more diverse cropping system, the spectrum of insect-pest species and micro-organisms within it also becomes wider. In this way, Natural predators of insect-pests within ecosystem increases. Aphids, bertha, armyworm larvae, sunflower beetles, grasshoppers are attacked by its natural enemies such as spiders, birds, frogs and toads. Insects are attacked by various types of fungi, either they are killed or their ability to reproduction is greatly reduced. Plant diseases are less likely to control by biological control method.
(iii) Naturally Occuring Products For Insect-Pest Control: Neem, Trichoderma, Pongamia are some of the natural products which can be used to control insect-pest population in the field.
(iv) Other Control Methods: Commercial Insect vaccums, Synthetic insect pheromones, plant-derived pesticides, dormant oil etc. can also be used to control insect-pest and diseases in the field.
2. WEED MANAGEMENT
Weeds have been considered as significant problem as they tends to decrease crop yields by competing with the main crop for sunlight, water and nutrients. Herbicides play a major role in weed management. But many of weeds have developed resistance against herbicides. Moreover, many herbicides are harmful to crops. So farmers are now shifting towards organic weed management. Weed management in case of organic farming can be done through cultural as well as direct and thermal methods. Weeds must be controlled within its critical period of growth. Various Weed management method in case of organic farming is described as follows:
CULTURAL CONTROL METHODS
Cultural control methods includes various cultural practices which helps to prevent the incidence of weeds in the fields. Various cultural practices for weed management in organic farming are discussed as follows:
(i) Crop Rotation: Crop rotation is a system of growing different crops sequentially on the same piece of land one after another. It is most efficient method developed to control long term weed control program. Weeds thrive mainly when same crop is grown again and again, followed cultural practices are same. Monoculture is the main reason for the major infestation occurs through weeds. When different and diverse crops are grown each year in a rotation, weed life cycles are disturbed by the variation in cultural practices of each crop. Crop rotation also helps to maintain good soil health and fertility levels.
(ii) Mulching: Mulching is the process of providing a protective layer of any beneficial material which helps to protect top layer of soil. Mulches helps to improve soil health and fertility status of soil. Mulches also helps to suppress the weed population in the field.
(iii) Variety Selection: Selection of proper crop variety is an important factor which helps to manage the weed population in the field. Those varieties should be preferred whose maturation period is very small and can grow more rapidly in prevailing environment to suppress the weeds in the fields.
(iv) Tillage System: Tillage is the physical manipulation of the soil. Tillage alters the soil and weed seeds are buried on depths. Tillage practices should be proper to reduce the weed population in the field. Summer ploughing is very useful and helps to reduce weed population in the field. Weed seeds on the soil surface are more likely to be eaten by insects, birds and other predators.
(v) Plantating Pattern: Cropping pattern is the pattern of crops on a piece of land. Planting density, plant population, spatial arrangement are some of the major factors which affect weed population. Crops grown with high density will reduce the weed population by reducing the available light amount for weeds located below crop canopy. Crop varieties with high growing cultivars are also very suitable as it helps to compete with the weed species and suppresses their growth.
(vi) Water Management: Proper Irrigation and water management is very effective against proper weed management in case of organic farming. Irrigation schedule should be proper for efficient weed management.
(vii) Intercropping: Intercropping is the process of growing a smother crop between the rows of main crop plants. Intercropping is also an effective process which helps to suppress the weed population.
(viii) Cover Cropping: Cover crops are also an important phenomenon for management of weed population. Rapid development & highly dense growth covering the ground by crop will help to suppress the weed population. Cover crops such as red, rye, clover, oilseed in the cropping system can helps to suppress the weed population. Residues of the cover crops decomposed in the soil helps to release allele chemicals which inhibit the development and germination of seeds of weed.
(ix) Buried Drip Irrigation: During dry period drip irrigation taped below the soil surface provide water and moisture to crop and helps to minimize the water availability to weed species. In the absence of water weed species are unable to grow and reproduce.
(x) Sanitation: Sanitation is an important process which helps to prevent introduction of new weeds into the field. From Planting High quality clean seed upto harvesting of clean grain, sanitation play a major role and helps in reduction of large no. of weeds in the fields. Clean seeds, mowing weeds after harvesting to prevent weeds from going to seed can greatly reduce the introduction of weeds seeds. Hand- Eradication is also effective to stop weed outbreaks.
THERMAL CONTROL METHODS
(i) Flames: Flaming is an useful process in weed control. Flaming is done either before the crop emergence or after the crop plants has emerged to give the crop plant a good advantage over suppression of weeds. Flaming during standing crop should be done very carefully to avoid any damage to crop plants. Initial equipment cost for flaming is very high, However Flaming may prove cheaper than hand weeding after that. Flaming process doesn’t burn weeds into ashes, instead they raises the temperature of weeds upto 140 F. This sudden rise in temperature results the cell sap of plant to expand and rupture. For higher efficiency, weeds should have fewer than three true leaves. Weeds changes to Duller appearance after they have been killed. Band Flaming is very successful in case of Transplanted cabbage. Onion have tolerance against flaming, So it can be easily used in case of pre and post emergence conditions. Best results of Flaming are Obtained under Windless, Early Mornings and Early conditions.
(ii) Soil Solarization: Sterilization of soil through solarization is an important phenomenon of weed management in case of organic farming. After Performing Tillage, A Plastic sheet or Film is Placed over entire area and is tightly sealed at the edges properly. Due to this, heat gets stored under this plastic sheet, and this heat is intense enough to kill the weeds & weed seeds prevailing in the field.
(iii) Freezing: Freezing is used as an weed management practice, to freeze the weeds with the use of Liquid nitrogen and solid carbon dioxide. Freezing is mostly used in case where there is high fire risk from Flaming the weeds.
(iv) Infrared Weeders: Infrared weeders are used to cover specific and closely defined area. Mostly they can be used in combination with the flaming to kill the targeted weeds.
BIOLOGICAL CONTROL METHODS
(i) Beneficial Organisms: Using Predatory, Parasitic microorganisms may prove to be a useful management practice in management of weed populations of organic farming. Weeds are also subjected to diseases and pest attacks as just crops are. Geese can feed upon weed populations so they are used to graze upon weeds. Geese mainly feed upon grass species and doesn’t affect crop species. Johnson Grass and Bermuda Grass is their preferred food. Proper care should be taken While growing certain crops like corn, sorghum, tomatoes and certain small grain crops. Clean drinking water , shade during hot weather, protection from predators should be provided to the geese.
(ii) Allelopathy: Allelopathy is the useful or harmful effect of one plant over the other on their growth, germination or development. There are number of crops which shows allelopathic effect over the weed species and suppresses their growth. Crops such as Barley, oats, Rye, Wheat, Sunflower, Carrot etc. are powerfull allelopathic releaser crops. Buckwheat is strongly allelopathic, fields infested with high weed problem can be cleanup by growing buckwheat. Along with this, it also provides phosphorus and improves soil conditions.
(iii) Use Of Biocontrol Agents: Various Biocontrol agents can be used to Control weed population in the field. These bioagents feeds upon the specific weed species and destroy them completely. For E.g. Nut Grass (Cyperus rotundus) can be easily controlled with the help of Javelin moth (Bactra verutana).
MECHANICAL CONTROL METHODS
Mechanical weed control includes removal of weeds manually with the help of some tools. It is most effective method of weed control but it is very time and labor-intensive method. Frequency, timing of operation will depend upon the type of crop and weed infestation. Cutting of weeds at soil surface is the most effective method of weed management. Mechanical weed control include various tools such as harrows, hoes, brush weeders etc. Choice of tools depend upon type of crop and morphology of weeds. For e.g. Brush weeder is used effectively against carrots, garlic, leeks etc. Hand-weeding is performed after mechanical weeding to pickup weeds left in the field.