Organic Horticulture

Organic Horticulture

Muhammad Muzammil Jahangir and Ahmad Sattar Khan♦

Abstract

Organic farming is a holistic style farming which is aimed at high quality production of agricultural crops beneficial for human consumption, by promising food safety through focusing on conservation of biodiversity, environment, natural habitats and wildlife etc. Organic farming is ensured by assuring improved soil physical characteristics, reduced soil erosion, nitrate pollution, emissions of methane, carbon dioxide and ammonia, by guaranteeing restricted pesticide use, enhanced water and energy efficiency, animal welfare, improved water quality and reduction in controlled waste levels. This chapter discusses salient characteristics of organic farming, organic farming standards and certification procedures, organic soil management practices based on manures, cover crops and composts, various types of organic sources present in global market, pest and disease management practices, organic weed management practices, postharvest handling and marketing of organic crops.

Keywords: Environment, organic crop certification, organic fertilizers, organic weed management, soil health and quality.

9.1. Introduction

Organic agriculture is defined as “an ecological production management system that promotes and enhances biodiversity, biological cycles, and soil biological activity”. It is based on minimal use of off-farm inputs and on farm management practices that

♦Muhammad Muzammil Jahangir* and Ahmad Sattar Khan

Institute of Horticultural Sciences, University of Agriculture, Faisalabad, Pakistan.

*Corresponding author’s e-mail: muzammil_jahangir@hotmail.com

Managing editors: Iqrar Ahmad Khan and Muhammad Farooq

Editors: Ahmad Sattar Khan and Khurram Ziaf

University of Agriculture, Faisalabad, Pakistan.

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restore, maintain or enhance ecological harmony. The primary goal of organic agriculture is to optimize the health and productivity of interdependent communities of soil life, plants, animals and people (USDANOSB 1995). Organic farming ensures conservation of natural habitats, wildlife, environment and biodiversity. Organic farming is known to improve soil physical characteristics, reduce soil erosion, nitrate pollution, and emissions of methane, carbon dioxide and ammonia. Organic farming also ensures restricted pesticide use, enhanced water and energy efficiency, animal welfare, improved water quality and reduction in controlled waste levels.

As compared to conventional foods, organic foods are becoming popular day by day due to general perception that organic foods are more nutritious (based on phyto- chemical constituents, minerals, vitamins, dry matter contents of fruits and vegetables) and hygienic (based on sanitary properties of organic fruits and vegetables such as free from contaminants or mycotoxins, pathogenic microorganisms and nitrate levels) than conventional foods (Brand and Molgaard

2001). For example, in case of dry matter contents of fruits and vegetables, relatively higher dry matter contents are reported in case of organically grown vegetables such as tubers, root and leafy vegetables, while, less difference has been reported in case of fruit vegetables and fruits (Bourn and Prescott 2002).

Zinc, magnesium, copper, iron, manganese, calcium, selenium and iodine are the key mineral elements present in fruits and vegetables. Limited alterations in mineral composition are reported in case of organically grown fruits as compared to conventional production system. However, in case of different vegetables such as turnip, onion, tomato, potato, carrot, lettuce, beetroot, kale and celeriac etc. generally higher levels of magnesium and iron contents are reported (Woëse et al. 1997).

Similarly, in case of organically grown potatoes, celeriac and tomatoes higher contents of vitamin C have been reported as compared to conventionally grown crops. Higher levels of phenols and polyphenols are also reported in case of organically grown fruits and vegetables such as pears, apple, orange, peach, onion, potato, tomato and pepper etc. (Carbonaro et al. 2002).

Permaculture can be defined as a scheme of agricultural and social design principles which are mainly focused on simulation or utilization of the features and patterns perceived in natural ecosystem. Bill Mollison and David Holmgren were pioneers for the introduction of term permaculture in 1978. Several important branches of permaculture include environmental design, ecological engineering, ecological design, construction and integrated management of water resources that is helpful in development of regenerative and self-maintained habitat, sustainable architecture and agricultural systems modeled from natural ecosystems. Several disciplines such as integrated farming, agro-forestry, sustainable development, applied ecology and organic farming, etc. provide foundation for Permaculture. Basic fundamental principles of Permaculture include care for the earth, care for the people and return of surplus (Mollison and Holmgren 1978).

Sustainable environment is the management of features and practices in a sustainable manner on long-term basis that plays a vital role to improve quality of environment. Environmental degradation, global warming and extreme weather changes occur due to industrialization, over population and pollution etc., which ultimately effect

sustainability of environment. Population of the world is increasing day by day, due to which demand of resources is also increasing gradually. Industrialization is increasing to meet the demand for resources. Due to these anthropogenic activities our natural resources are being depleted and ultimately our society is being affected. Some ecosystems are adversely affected so that they can’t be recovered. So, there is need to overcome these problems to maintain our environment for our present and future generation. Many countries have gathered and planned about the solutions of these problems, which are causing environmental degradation (Attah 2010).

At present, organic agriculture is being practiced in more than 172 countries of the world. As for as distribution of organic agricultural land is concerned, Oceania contributes about 40% of the total organic agricultural land followed by Europe (27%), Latin America (15%), Asia (8%), North Africa (7%) and Africa (3%) respectively. Major countries having largest area of organic agricultural land round the globe include, Australia (17.2 Mha), Argentina (3.1Mha), USA (2.2 Mha), China (1.9 Mha), Spain (1.7 Mha), Italy (1.4 Mha), Uruguay (1.3 Mha), France (1.1 Mha), Germany (1 Mha) and Canada (0.9 Mha). At present, 2.3 million organic crop producers have been reported on the glonbe. Most of these organic crops producers are from developing countries like India, Uganda, Philippines, Tanzania, Ethiopia, Turkey, Peru, Paraguay and Mexico etc.

Area under organic temperate fruit production is 1.5 % (188000 ha) of total temperate fruits growing area in the world, while area under organically produced tropical and subtropical fruits produced organically is 1 % (233000 ha) of total tropical and subtropical fruits growing area. Major organic temperate fruit growing countries include China, Turkey, Serbia, India, Iran, Russia and USA. While, major countries growing organic tropical and subtropical fruits are Mexico, Dominican Republic, China and Turkey. Major temperate fruits, which are produced organically include, apple, apricot, peach, nectarines, cherries, quinces and plums etc. Major tropical and subtropical fruits organically produced include banana, date, fig, avocados, cashew apple, mango, papaya, litchi, pomegranate, passion fruit, kiwi and guava etc. Organically produced vegetables cover about 0.5 % (290137 ha) area is of total vegetable growing area on the globe. Major countries growing organic vegetables include USA, Poland, Italy, China and Turkey etc. Among organically produced vegetables, peas and fresh beans are the major vegetables followed by leafy, salad and fruit vegetables (Lemound and Miller 2016).

9.2. Salient Characteristics of Organic Farming

Various principles framed by International Federation of Organic Agricultural Movements (IFOAM), like rules of care, fairness, health and ecology etc., provide basis for concept of organic farming. Implementation of these rules into practicable form is the main aim of various organic farming systems. Organic farming systems are mainly dependent on renewable resources, normally generated on farm and less dependent on external sources, and take into account different biological and ecological procedures for provision of basic nutrients and protection against different diseases and pests.

9.3. Organic Farming Standard and Certification

Organic farming certification programmes are vital component of existing organic farming systems. Certification programme generally consists of some specific standards/rules, followed by inspection (making sure whether these standards or rules are being implemented or not), and later certification. These specific rules or standards ensure what can be labeled as “organic” and can be sold in the international market. Organic farming certification is generally ensured by independent third party. It means that certification procedure is not carried out by the producer or the buyer. The certification system normally consists of farm inspector and audit inspector. Organic farming certificate is considered valid only if certification is carried out by accredited certifying agency.

Organic certification programme differ from country to country and region to region due to varying climatic, environmental, cultural and social factors. From a commercial perspective, it is not enough that product is produced organically, what is equally important is that it should be certified as such.

At present, approximately there are more than 60 standards including CODEX Alimentations Commission guidelines, National Organic Program (NOP) of USA, IFOAM basic standards, and EU Regulation 2029/91, which are being practiced for organic farming certification in the international market. Various certification agencies like Organic Crop Improvement Association (OCIA) of USA, BCS of Germany, Ecocert of France, Organic Growers and Buyers Association (OGBA) of USA, Institute for Marketecology (IMO) of Switzerland, The National Association for Sustainable Agriculture, Australia (NASAA) of Australia, SkalBiocontrole (SKAL) of the Netherlands, Naturland of Germany, Krav of Sweden and Organic Agriculture Certification Thailand (ACT) of Thailand, etc., are certifying different organic commodities in different countries. Moreover, in some countries locally instituted certifying agencies like Japan Organic and Natural Foods Association JONA of Japan, Organic Food Development and Certification Center of China (OFDC), and China Green Food Development Center (CGFDC) of China, Agrior of Israel, Indocert of India, and Organic Certification Centre of the Philippines (OCCP) of Philippines, are also working (Bhattacharyya and Chakraborty 2005).

9.4. Management Practices

9.4.1. Soil Management

Soil may be considered as primal basal component of any organic horticultural crop production system. Soil not only serves as principal growth medium, but also helps in sustainable horticultural crop production, environment quality sustainment and ensures human, animal and plant health. Soil health or soil quality depicts capability of soil to execute these vital processes. Success of any organic horticultural crop production system is normally based on soil health/soil quality. Soil quality improvement and sustainability for longer period of time are important and major management objectives of organic horticultural crop production (Doran and Safley

1997).

9.4.2. Soil Quality and Soil Health Indicators

Major quantitative soil health indicators include soil physical properties (bulk density, rooting depth, water holding capacity of soil, soil water infiltration rate and aggregate stability of soil), chemical properties of soil (exchangeable calcium, cation exchange capacity, pH, exchangeable potassium, mineralizable nitrogen, soil organic matter and electrical conductivity), soil biological properties (earthworms, microbial biomass carbon, enzymes, microbial biomass nitrogen and disease suppressiveness) (Reganold 1988; Carter et al. 1997). Different types of macro- and micro-organisms are present in soil and are key indicators of soil health and quality (Table 9.1).

Table 9.1 Various kinds of soil inhabiting soil organisms.

Macro soil organisms Micro soil organisms

Slaters Fungus

Mites Actinomycetes Beetles Protozoa Spiders Algae

Slugs and snails Bacteria

Millipedes Earthworms Spring tails

Quantity of organic matter in a soil is commonly used as indicator for evaluating soil quality or soil health. Numerous soil properties such as bulk density, aggregate stability, infiltration rate, biological activity and cation exchange capacity etc. are normally linked with various key soil functions and are usually influenced by soil organic matter. Moreover, soil organic matter is responsible for soil tilth maintenance, enhancement of water retention by soil and facilitation of air and water infiltration into the soil. Gradual increase in soil organic matter over time can ensure augmentation and diversification in population of soil organisms and can lead to enhanced biological control of plant diseases and pests. However, addition of fresh organic matter to the soil can accelerate the growth of pathogenic organisms of plants, and pests of seedlings and seeds such as, wireworms and cabbage maggots (Liebig and Doran 1999: Loes and Ogaard 1997; Doran and Parkin 1994).

Strategies to manage soil quality and health

Soil fertility can be enhanced by utilizing crop rotations, manures, cover crops or composts etc.

Crop rotations for horticultural crops

For short term increase of soil organic matter, carefully planned crop rotations could be a practicable scheme for establishment of productive, healthy and fertile soils for production of horticultural crops. Inclusion of small grain crops like rye, wheat, oats, barley in rotations should be encouraged for organic vegetable production systems, as these crops after harvest may ensure addition of dry matter of 8000-10000 pounds on per acre basis to the soil. Inclusion of these crops in vegetable rotation can be helpful in reducing the incidence of different vegetable crop soil diseases and

nematode problems. Similarly, after broccoli harvest, field residues may ensure addition of almost 7,000 pounds of dry matter per acre, and remains of garlic, onion, lettuce and tomato can add 500, 700, 1200 and 2500 pounds dry matter per acre on average basis (Ferris et al. 1996).

In case of organic citrus production leguminous crops, such as Neonotonia wightii, Arachis pintoi and Teranamus labialis, are successfully used for ensuring organic soil management. Similarly, for organic pineapple production systems, pineapples are incorporated with rice, vegetables, beans and peanuts in rotation. While, prior to pineapple production, green manuring plants like Mucuna capitata, Vigna unguiculata and Crotolaria juncea are normally sown in the field. For organic carrot production system, spinach, onions, small grains, alfalfa and leguminous crops can be rotated successfully with carrot. In case of organic sweet corn production system, beans and pumpkins can be rotated successfully with sweet corn. For four and five- year organic winter vegetable crop production, garlic can be rotated successfully with winter squash, spinach, soybeans, oats, fababeans, brassicas, vetch and tomatoes. Similarly, in case of summer vegetables e.g., tomatoes and pepper, can be successfully rotated with red clover, winter brassicas, lettuce, okra, vetch, cucurbits and crimson clover, etc.

Composts and manures

For any soil fertility management programme in organic horticultural crop production system, composts and manures are believed as vital components (Fig. 9.1). Manures and composts based amendments have variable nutritive composition and are popularly used as basic carbon source for enhancement of soil tilth. On a dry weight basis, carbon content of these manures and composts based amendments usually range from 20 to 40 percent. For organic vegetable crop production, normally composts/ manures application (3-5 tons per acre per year) is recommended. Use of these manures and composts based organic materials contribute substantially to soil carbon quantity and can increase water infiltration, improve tilth and lower the bulk density. In case of organic citrus orchard nursery production system, compost @ 10 tons/ha should be applied. Similarly, 5 tons/ha compost is recommended in case of organic pineapple crop production system (Stamatiadis et al. 1999; Leifeld et al. 2002).

Animal manure based composts can serve as cost effective organic source of macro- and micro-nutrients. Immature or poor quality compost may decrease nitrogen availability to the organically growing vegetable crops by tying up nitrogen in the soil. An important indicator for nitrogen availability from compost

Fig. 9.1 Different pictorial views of a modern commercial compost manufacturing unit: (A) water application tank, (B) compost mixer, (c) compost mixer in action, (D) loading of compost material into grinding unit, (E) grinding of compost material, and (F) finally prepared compost.

is C:N ratio. Generally, composts with C:N ratio ≤ 20:1 releases nitrogen for the next crop. Similarly, when applying composts, other compost related quality considerations such as compost age, salt concentration, pH, particle size, and compost purity (the volume of nonorganic materials mixed with the compost, soil and sand) should also be considered. Manure of aged animal is a good source of nitrogen and other major as well as minor nutrients. It can be applied in organic production system only if it is used on non-food crop land. If the edible portion of organically grown crop is in contact with the soil, then manure application should be ensured at least 120 days before crop harvesting. If the eatable portion of organically grown crop is not directly in contact with the soil, then manure addition at least 90 days prior to harvesting should be ensured. Easy accessibility and consistent supply

of uniform manure material that can be used for organically grown crops and public sensing of health problems associated to fertilization of manure possibly restrict manure utilization for organically grown crops. Food safety related risks may be minimized by composting of manure before use in organic crop production system (Gaskell et al. 2006).

Cover crops/green manuring

In organic horticultural cropping system, soil quality maintenance by using cover cropping system or green manuring system are vital components. Cover crops/ green manuring serve as economical and practical means for trapping and fixation of nutrients, organic matter incorporation, enhancement of fertility of soil, weed suppression, attraction of beneficial insects to crops, attraction of spiders and predatory mite’s, and reduced leaching losses of nitrate, reduction in soil erosion and nutrient run off. Both, leguminous and non-leguminous crops including, grasses and Brassica species, and their different mixtures are commonly used in organic crop production system e.g. mustards. It is normal practice to till them into the soil cover crops (e.g. mustards, legumes and cereals etc. at younger stages) when C:N ratio is below 20:1. Several crops are available which are successfully used as cover crops in organic horticultural crop production system (Table 9.2).

Table 9.2 Examples of various cover crops being used in organic horticulture. Horticultural Crops Cover Crops

Citrus Centrosema pubescens, Desmodium, Cassina obtusifolia and Alysicarpus vaginalis

Tomatoes Crottolaria, Hairy vetch or Vicia fava

Asparagus Vicia faba

Apple Annual ryegrass, field pea, hairy vetch, crimson clover Grapes Sudan grass, ryegrass, barley, sweet clover, buckwheat Spinach Oats, field peas, buckwheat

Cole crops Bell, faba bean

Tillage

Main objective of any organic soil management programme is increase in soil organic matter. Conventional intensive soil tillage may lead to significant soil carbon loss and is therefore discouraged. However, moderate tillage can ensure conducive conditions of soil for short term weed control and better organic crop growth and development (Berner et al. 2008). Conservation tillage (crop production systems in which at least 30 percent of the soil surface is covered by residues from previous crops) could be a better option for organic crop production. For example, rye and vetch are commonly used as mulches and cover crops in various conservation tillage systems. Both, rye and vetch as cover crops are responsible for nutrients recycling, reduction of soil erosion, organic matter addition to the soil, and nitrogen fixation (e.g. vetch). Moreover, when these crops are mowed and converted to mulch, they may reduce soil temperature, water loss from soil, weed emergence, and behave like slow release fertilizers (Bausenwein et al. 2008; Gadermaier et al. 2012).

Commercial organic fertilizers

For organic soil management programme of horticultural crops, different commercial organic fertilizers are also available in market. These fertilizers are normally by products of food processing industries, livestock and fishries with variable nutrient composition and commercial formulations. These organic fertilizers are normally expensive and are recommended in situations where compost application or cover cropping is not practicable. Some common organic sources present in market include kelp powder, fish meal, bat guano high P, soft rock phosphate, cotton seed meal, rock powder, fish powder, processed liquid fish residues, corn gluten meal, feather meal, seabird, seaweed, bat guano, alfalfa meal,bat guano high N, meat and bone meal, soybean meal, pelleted chicken manure, fish emulsion, bone meal, Chilean nitrate, potassium-magnesium sulfate, colloidal phosphate, kelp meal, enzymatically digested hydrolyzed liquid fish and liquid kelp, etc. Nutrient composition of these commercial organic fertilizers varies from source to source. Chilean nitrate contains

16% nitrogen, blood meal and feather meal contain 12% nitrogen, Fish meal or powder contains 10-11% nitrogen, 6% phosphorus and 2% potassium, Seabird and bat guano contain 9-12% nitrogen, 3-8% phosphorus and 1-2% potassium, Meat and bone meal contain 8% nitrogen, 5% phosphorus and 1% potassium, Soybean meal contains 7% nitrogen, 2% phosphorus and 1% potassium, Processed liquid fish residues contains 4% nitrogen, 2% phosphorus and 2% potassium, Alfalfa meal

contains 4% nitrogen, 1% phosphorus and 1% potassium, Pelleted chicken manure

contains 2-4% nitrogen, 1.5% phosphorus and 1.5% potassium, Bone meal contains

2% nitrogen and 15% phosphorus, Kelp contains less than 1% nitrogen and 4% potassium, Soft rock phosphate contains 15-30% phosphorus, Potassium- magnesium-sulfate contains 22% potassium (Gaskell et al. 2006).

According to another report, alfalfa meal or pellets contains 2% nitrogen, 1% phosphorus and 2% potassium; corn gluten meal contains 9% nitrogen; cottonseed meal contains 6% nitrogen, 0.4% phosphorus and 1.5% potassium; soybean meal contains 7% nitrogen, 2% phosphorus and 1% potassium; bat guano ( high N) contains 1% potassium, 3% phosphorus and 10% nitrogen; bat guano (high P) contains 3% nitrogen, 10% phosphorus and 1% potassium; blood meal contains 12% nitrogen; bone meal, contains 3% nitrogen and 15% phosphorus; feather meal contains 7-12% nitrogen; fish emulsion contains 5% nitrogen, 2% phosphorus and

2% potassium; enzymatically digested hydrolyzed liquid fish contains 4% nitrogen,

2% phosphorus and 2% potassium; fish meal contains 10% nitrogen, 6% phosphorus and 2% potassium; fish powder contains 12% nitrogen, 0.25% phosphorus and 1% potassium; kelp meal and liquid kelp contain negligible amount of nitrogen, phosphorus and potassium; kelp powder contains 1% nitrogen and 4% potassium. Seaweed is an important source of micronutrients, while kelp meal is regarded as an important source of trace minerals (Card et al. 2015).

These commercial organic fertilizers can be used before crop planting or later on as side-dressings. Drip irrigation systems can be used for application of liquid soybean meal, processed liquid fish, or sodium nitrate. Sometimes, diluted liquid “teas” based on these commercial organic fertilizers are also directly sprayed on plants or on soil for improved nutrient availability. Use of bone meal and blood meal is limited in

some organic vegetable production systems due to market associated reasons. Similarly, use of mined Chilean nitrate is also limited due to environment related issues.

Nitrogen deficiency can be overcome by using fish meal, dried blood or guano. Phosphorus deficiency can be fulfilled by using reactive rock phosphate or fish meal or fish meal. Potassium deficiency can be reduced by using kelp extract. Calcium deficiency can be reduced by using lime, bone meal, dolomite or gypsum. Magnesium deficiency can be minimized by using serpentine or dolomite. Sulfur deficiency can be overcome by using poultry manure and gypsum. Manganese, boron and iron deficiencies can be overcome by using kelp extract (Mitchell et al. 2000).

9.4.3. Pest and Disease Management

In any organic horticultural crop production system, it is important to know pests, diseases and beneficial microorganisms related to particular crop grown organically. It is always wise to control these pests at initial stages when they are low in number, before they reach at damaging level. In any organic horticultural crop production system, biological and cultural control methods should be preferred for management of insects and pests. Population buildup of various pests can be prevented by incorporation of crop residues and proper crop rotations (Koike et al. 2000).

Season after season, continuous growing of same crop on same piece of land may lead to various diseases, pests and insects. Proper knowledge of local growing conditions, specific crops grown and their proper planting time will be an appropriate solution for control of different pests. Economic loss of organic horticultural crop may be prevented by correct identification and monitoring of insects and pests at their immature life stages like larvae, nymphs and eggs etc. Various approaches for insect, pest and disease management of organic horticultural crops include biological approaches; mechanical, chemical and cultural control techniques etc. Different strategies for organic management of citrus pests and diseases are discussed in Table

9.3 and 9.4, respectively.

It is necessary for organic crop growers to render optimal growing conditions for their crops as many organic crops have capability to resist insect feeding if these crops are growing actively and can compensate foliage loss and root tissues to some extent. Organic crop vigour is affected by nutrient content and soil type. Poor water management can make organic crops susceptible to specific pests like spider mites. Cover crops should be planted before main organic cash crop, which can ameliorate soil fertility and furnish organic matter. Pest population can be kept at minimal level by judicious rotation of important organic crops, which are highly pest sensitive with relatively non-susceptible varieties or non-susceptible cover crops (Wyland et al.

1996).

Table 9.3 Pest management strategies for organically grown citrus.

Pests Management Strategies

Phyllocoptruta oleivora Use predatory mites or an entomophagous fungi Hirsutella thompsonii

Heliothrips haemorrhoidalis Application of pyrethrum or rotenone

Use minute pirate bugs or predatory mites such as Anystis agilis and Euseius hibisci

Dialeurodes citrifoli Use parasite wasps

Coccus hesperidum Use parasitic flies or ladybird beetle larvae

Unaspis cirti Use parasites and ladybird beetle

Pachneus citri Use Beauveria bassiana

Table 9.4 Disease management strategies for organically grown citrus.

Disease Management Strategies

Citrus canker Use appropriate hedges or trees as windbreaks

Sooty mould Use appropriate copper based fungicides

Use appropriate techniques to reduce population of honeydew producing insects such as Coccus hesperidum and Dialeurodes citrifoli

Greasy spot Use appropriate copper based fungicides

Remove leaf litter

Gummosis Ensure appropriate pruning strategies

Ensure treatment with copper based fungicides on wounds

Use appropriate disease resistant rootstocks like rough lemon, trifoliata, sour orange and cleopatra

Ensure appropriate irrigation and better soil drainage strategies

Citrus tristeza virus Ensure removal of infected trees

Do not use sour orange as rootstock

Use Citrus tristeza virus free bud wood and minimize vectors such as Toxoptera citrisidus

Citrus blight Ensure appropriate pruning

Remove infested trees

Use citrus blight tolerant rootstocks

In organic crop production system, use of various grass species in a rotation is normally encouraged as grasses are usually tolerant to diseases, insects and pests of different important organic crops. Introduction of field strips/borders of varieties and species inside the organic crop field, different from major organic crop, can render habitat for useful arthropods and maybe helpful to reduce the spread of pest species in organic crop fields. Use of flowering plants along edges and borders of organic crop fields can serve as a habitat and can serve as a food source for beneficial insects. Use of alfalfa crop, attracting pests away from organically grown strawberries, has enormous potential. Trap crops/ alternate crops serve as extra reservoir for beneficial

parasites and predators related to the organic crop field. Trap crops/ alternate crops should be kept in a robust state so that pests do not leave the trap crop.

As for as mechanical control is concerned, soil tillage may be helpful in destroying insects as well as exposing these harmful insects to different kinds of birds and also to different predators. Soil tillage is capable of speeding up the breakdown process of crop residues, harboring plant pathogens and various insects as well. Population of bulb mites, cutworms and root maggots can be controlled by allowing complete decomposition of organic matter in the organic crop field before succeeding crop plantation or by keeping land unploughed and unseeded for specific time period between two successive organic crop growing cycles. For high value organic vegetable crop production pest barriers can be used. Access of various pest species can be reduced by using plastic tunnels and floating row covers. Aphid infestations in case of squashes, tomatoes and eggplants can be effectively prevented by using reflective mulches.

Biological control

Conservation of useful organisms, which occur naturally, is a wise approach. If it is essential to control some specific pest to prevent economic loss, pesticides with short residual effects should be used, as these pesticides will help predator mites and beneficial insects to comeback to organically grown crops. While introducing these biocontrol organisms to the organic production system, it is necessary to make sure that correct biocontrol organisms, which are well adapted to specific site or climate, are used. For control of aphids, normally syrphid flies, ladybird beetles, wasp parasites, lacewings are used. Several organic vegetable crops are infested by caterpillar pests. In order to control caterpillar damage Trichogramma wasps are commonly used. Eggs of various species of pests are parasitized by Trichogramma wasps, which normally kill the pests before they can cause any feeding injury to organic vegetable crops. The viability of biological control (beneficial) agents can be affected by cold, heat, diseases and time.

Chemical control

Several insecticides are available for chemical control of pests, which are acceptable for organic crop production system. While selecting such pesticides, it should be kept in mind that these organic pesticides should ensure low mammalian toxicity, should have minimal effect on beneficial organisms and should provide adequate essential plant coverage. Combinations of soaps, oils, rotenone/ pyrethrum etc. can be used to control aphids. Ants can be destroyed physically or can be controlled by using boric acid baits. Similarly, suppression of whitefly nymphs is achievable by using oils and soaps. Populations of leaf miner can be controlled by using pyrethrins, azadirachtin and rotenone based sprays. Population of Leafhoppers can be minimized by applying rotenone or pyrethrins. Population of flea beetles can be minimized by using different combinations of rotenone/ pyrethrin and soaps. Sulfur dust or sprays can control russet mites. Soap based sprays are useful in controlling initial stages of stinkbugs. Pest mites can be controlled by using neem seed oil or different vegetable based oils. Control of worms can be ensured by using different formulations of Bacillus thuringiensis. Management of diseases occurring in organically grown crops is a difficult process as these crops are prone to various nematodes, viruses, bacteria and

fungi. Development of disease control approaches, having ecological basis, are necessary for organic crop production systems. Diversification of epiphytic and soil inhabiting microorganisms, having potentially beneficial pathogen antagonistic influences, should be encouraged. Pathogen resistant cultivar selection and their planting should be encouraged because they can ensure reduced use of chemicals or even their elimination (Griffiths et al. 1994).

In any organic crop production system, growers should select those sites for crop production which are free from soil borne pathogens. Plant pathogenic fungi like, Fusarium, Armillaria, Plasmodiophora, Verticillium and Sclerotium, can remain in soil for several years. So, it is better for organic crop growers to choose crop production site away from such fields.

Grasslands, pastures, riverbanks and foothills normally encourage natural vegetation and weeds, which serve as reservoirs for pathogens that can induce viral diseases. Incidence of downy mildew is increased near coastal areas due to persistent high humidity. Risk for occurance of damping-off and root rot of spinach crop can be reduced by selecting sandy soils because these are well drained soils.

Certified seeds must be used because several diseases are caused by seed borne pathogens. Similarly, crop transplants should be disease free and should be free from contamination of pathogens. Water and soil can harbour different pathogens. Infested water or soil should not be taken to uninfected crop production land. Contamination of runoff water, flood water and river water with tomato bushy stunt virus is reported at many places, and farmers who use such soil or water, their fields become contaminated with it and subsequent crops become diseased. Soil solarization can be useful in regions with high summer temperatures (Stapleton et al. 2002; Rieger et al.

2001).

Rouging can be useful for removal of sclerotia-forming fungi, e.g., Sclerotinia minor in lettuce crop fields. Field sanitation, “removal or destruction of diseased plant residues,” is also a suitable approach for disease control in organic crop production system (Fouche et al. 2000).

9.4.4. Weed Management

Protocols for weed control in any organic horticultural crop growing system should be based on such techniques which can ensure economically satisfactory weed control and organic crop yields. In ideal situation farmers would prefer to have no weeds on the organic crop production farm. However, in actual practice, this goal is difficult to achieve but reduction in weed population and weed seeds can make succeeding approach of weed control somewhat less expensive. In modern organic orchards, mechanical weed control is very popular and is an economic method of weed management as well (Fig. 9.2 and 9.3).

Fig. 9.2 Machinery used for weed and insect management in organic fruit orchards: (A) mechanical mover, (B and C) mechanical weed harrow, and (D) boom sprayer for mineral oil application.

Fig. 9.3 Pictorial view of mechanical weed management in an organic cherry orchard; (A, B and C) weed harrow in action, (D and E) clean tree drip line after removing weeds using weed harrow; (F) a close view of weed harrow.

9.4.5. Water Management

Efficient management of water use is vital for weed control in organic horticultural crop production system. Early weed germination due to application of irrigation or due to occurrence of rainfall just before plantation of organic crops can be killed by flaming or light cultivation. It is better that pre germination of weeds occurs close to planting date of main organic horticultural crop in order to avoid change in weed spectrum due to variation in weather. Burial of drip irrigation system or drip tapes below planting bed surface will ensure provision of moisture to organic crop only and will reduce available moisture to the weeds near surface (Katherine et al. 2013).

9.4.6. Crop Competition

It is normally anticipated that vigorously growing crops can contend weeds easily. Weeds preferably develop fast at places where contest from main cash crops is low, i.e., main crop is sparse e.g. between rows. Organic crops properly adapted to specific growing areas better compete with weeds because normally these crops rapidly occupy a growing site. Tomatoes having an early competitive advantage will compete with weeds effectively. However, garlic and onion are unable to build a competitive canopy. Introduction of transplants in organic crop production system provide an advantage to organic crops over different weeds as these transplants are planted at highly developed stages as compared to weeds in freshly prepared field. Reduction in the seed banks of weeds can also reduce weeds populations (Boydston et al. 2011).

9.4.7. Cultivation

In organic horticultural crop production system, cultivation is the most commonly used weed control method. Almost all weeds, except some parasitic forms (dodder), can be controlled by cultivation. Commonly used cultivation implements include sweeps, different knives, crescent shaped and L-shaped beet hoes, rolling cultivators, brush hoes, spring -tine cultivators, budding in-row weeders and torsion bezzerides cultivators etc. (Barberi 2002).

9.4.8. Flammers

Use of flammers for weed control is also getting popularity. Propane-fueled based models are commonly used. Flaming is normally employed before crop emergence in case of parsley, peppers, onions, carrots and other slow germinating vegetables (Ulloa et al. 2012). While, in case of garlic and onion post emergence flaming can be practiced at younger stages. Windless conditions ensure better results for flaming (Knezevic and Ulloa 2007; Cisneros and Zandstra 2008). Presence of moisture on plants due to rain or dew can reduce flaming efficiency.

9.4.9. Soil sterilization

Soil sterilization, by using naturally generated biocides (ozone) or heat, is helpful in killing weeds. Soil solarization or steam is used for providing heat for soil

sterilization. Steam sterilization is expensive and is recommended in case of horticultural commodities with high market value. Soil solarization can be achieved by using clear plastic mulch (Campiglia et al. 2000).

9.4.10. Mulches

Use of mulches as weed control method is also getting popularity. Mulches normally can block light and can suppress weed seed germination and weed growth. Different materials like sawdust, hay, municipal yard waste, wood chips, newspapers and straw etc. can be used as mulches.

9.4.11. Chemical control/ Herbicides

Organically acceptable herbicides based on solutions of acetic acid, sodium nitrate and citric acid, and corn gluten are also available for weed control in organic crop production system (Smith et al. 2000).

9.5. Postharvest Handling

Amelioration of the integral quality of organic horticultural crops is not possible after harvest. However, quality of organic horticultural crops can only be sustained for some specific time after harvest. As a general practice it is always wise that organic horticultural crops should be harvested at coolest time to ensure lower respiration rate of the crops. Damage to organic horticultural crops from bruising, wounding, crushing, harvesting equipment’s, harvest containers and humans, should be avoided. Harvested organic crops should be kept in shade to keep these commodities cool. Use of reflective pads for covering of harvest totes or bins which may effectively reduce premature senescence, loss of water and heat gain of organic crops. Harvested organic horticultural crops should be immediately moved into cold storage facility or cooling treatment units. Decayed or damaged organic horticultural crops should not be mixed with high quality organic horticultural crops. Use of sanitized or cleaned transport and packing containers should be ensured. Based on specific organically grown commodity, appropriate cooling method, like hydro cooling technique, forced air cooling technique, room cooling technique, top/ liquid icing technique and vacuum cooling, should be used to remove field heat. Disadvantage of room cooling is that it takes longer time to cool organic horticultural crops. Forced air cooling is relatively 75 to 90% quicker than room cooling system. Leafy vegetable crops like, celery, spinach and lettuce, respond well to vacuum cooling; however, this is an expensive method of cooling.

During all stages of postharvest handling of organic horticultural crops, disinfection of water, sanitation of food contact surfaces of organic horticultural crops, cleanliness of equipments and other preventive food related safety measures must be ensured. Quality of cooling/washing water is of utmost importance for washing of organic horticultural crops (Fig. 9.4). Water used during postharvest operations should be free from dissolved banned contents. Organic horticultural crop producers and handlers should keep proper records of after harvest rinse or washing treatments applied to organic horticultural commodities. Prevention of food borne illnesses and

commodity related postharvest diseases can be ensured by using appropriate disinfectant usage during postharvest cooling and washing.

Generally, during prewashing of organic horticultural crops it is better to ensure that minimum field soil should be present on organic horticultural crops, pallets and bins, which will ultimately reduce requirement of disinfectant use in water. Liquid sodium hypochlorite is commonly used water disinfectant. Water pH should be between 6.5 and 7.5 for favourable antimicrobial activity. Materials, like sodium bicarbonate and citric acid, utilized for pH modification should be of natural origin. Calcium hypochlorite is also reported beneficial in extending shelf life of bell peppers and tomatoes, and reducing sodium injury in some specific varieties of apples. Use of ozone for disinfection of water for various postharvest operations is an appealing choice because ozonation can ensure efficient control of food borne pathogens and decay of microbes resistant to chlorination.

Fig. 9.4 Various steps in organic apple pack house: (A) washing, (B and C) sorting and grading, and (D) packaging of fresh cut slices.

Ozone reacts quickly than chlorine and can ensure short contact time of produce and creates less disinfection byproducts, like trihalomethanes, than chlorine. Disadvantage of ozonation is that it is expensive method than chlorination. Food grade peroxyacetic acid and hydrogen peroxide are other options. Peroxyacetic acid is better option than ozone and chlorine for controlling and removing microbial biofilms in flumes and dump tanks, however its use is limited due to high cost.

Different disinfectants, sanitizers and cleaners allowed in postharvest operations for horticultural crops include: acetic acid (organic source based permitted as sanitizer or cleanser), ethyl alcohol (organic source based are permitted as disinfectant),

isopropyl alcohol (under limited conditions, permitted as disinfectant), ammonium sanitizers e.g. quaternary ammonium salts (normally allowed on non-food contact surfaces), bleach (chlorine dioxide, sodium hypochlorite and calcium hypochlorite etc. permitted as water sanitizers and for food contact surfaces), detergents (permitted as cleaners for equipments), hydrogen peroxide (permitted as surface and water disinfectant), ozone (permitted for disinfection of equipments and crops) and peroxyacetic (permitted for disinfection of water and surfaces of vegetables and fruits), etc. Moreover, postharvest use of carbon dioxide (under controlled atmosphere storage and modified atmosphere storage conditions), fumigants (permitted in case of natural origin based materials like heat vapourized acetic acid etc.), and waxes (from permitted sources like carnuba), is also gaining popularity. During organic postharvest operations, transport and storage bins/containers and packaging materials containing synthetic fungicides, fumigants and preservatives are not permitted.

Normally use of irradiation technologies is discouraged by organic crop producers. However, use of X-ray irradiation for detection of metals in packing is permitted in different minimally processed organic salad mixes and vegetables. Moreover, particular necessities for transportation of organic crops by air carrier, highway truck or containerized marine shipping, should be ensured by shipper (Suslow 2000).

9.6. Marketing

Organic horticultural crop production is a prominent and developing segment of global organic industry and expansion of this industry is related to both domestic and international demand of organic produce. In order to ensure better economic returns, organically produced horticultural crops are separately marketed from horticultural crops which are grown conventionally. As compared to conventionally grown horticultural crops, organic horticultural crops should ensure better prices. Usually, specialty markets or niche can offer better prices for organic horticultural crops. Restaurants, farmer markets and roadside stands are also viable options for better crop returns for small scale organic horticultural growers. Thorough investigation of potential markets and development of marketing scheme is essential for marketing of organic horticultural crops. Productive organic horticultural farmers should normally spend much time in activities related to marketing of organic horticultural crops, as requirements for organic horticultural crops change greatly throughout different parts of the world and also between different retailers of different region. For making production decisions related to organic horticultural crops, market is a worth full guide, but neither production of organic horticultural crops nor marketing of organic horticultural crops will be productive if production and marketing are separated from each other. Organic horticultural crop farmers should work closely with experienced and knowledgeable brokers or sales agents. Improper handling of organic horticultural crops by inexperienced individuals can be economically fatal for organic horticultural farmers (Tourte et al. 2000).

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