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Agronomic concepts andAgronomic concepts and

Agronomic concepts and

approaches for sustainable cottonapproaches for sustainable cotton

approaches for sustainable cotton

productionproduction

production

Stella Galanopoulou-Sendouca

and Derrick Oosterhuis

University of Thessaly, Dept. of Agriculture, Crop Production and Rural Environment,

Fytokou Str, Nea Ionia, Volos GREECE

University of Arkansas, Department of Crop, Soil and Environmental Sciences, Fayetteville

Arkansas USA

Correspondence author [email protected]

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Agronomic concepts and approaches for sustainable cotton production

ABSTRACTABSTRACT

ABSTRACT

Stagnating yields, lower cotton prices, higher in-

put costs and concerns about environmental pro-

tection, coupled with the World Trade Organiza-

tion agreement, have imposed the need to pro-

duce more sustainable and competitive cotton

crops. Additionally, the cotton crop has emerged

as one of the major consumers of agrochemicals

for yield maximization and because the crop re-

quires a comparatively longer growing season com-

pared to other row crops. Furthermore, cotton is

a perennial plant grown as an annual and is re-

puted to have the most complex growth habit of

all major row crops. This greatly complicates the

production of cotton for efficient management and

profitability, sustainability and protection of the

environment. This paper presents an overview of

agronomic concepts for consideration in current

or alternative systems for lowering inputs, sustain-

ing production, protecting the environment, and

maintaining or improving profitability. The major

concepts covered include:

Crop rotation:Crop rotation:

Crop rotation: Monoc-

ulture of “competitive” crops has commonly re-

placed crop rotation, because of the false view

that crop productivity is calculated on an annual

basis instead of over an extended period. Appro-

priate crop rotation systems are of high priority

for integrated management of soil fertility, plant

pests, diseases and weeds, and for increases in

yield and quality.

Soil compaction:Soil compaction:

Soil compaction: Intensive and

incorrect use of machinery has led to rooting prob-

lems, poor growth and lowered yields. Conserva-

tion tillage, including minimum and no-till prac-

tices, should reduce wind and water erosion, as

well as lower the costs of fuel, labor and other

inputs.

Judicious fertilization:Judicious fertilization:

Judicious fertilization: Research has shown

that systems with reduced fertilization are feasible

for high yields. Emphasis should be on the correct

timing and availability of nutrients. Foliar fertiliza-

tion, for main nutrients, should only be used to

correct a deficiency on a timely basis.

Irrigation: Irrigation:

Irrigation:

The availability of water is one of the most critical

factors for optimum cotton yields. Attention should

be paid to water conservation, through correct land

preparation, optimum planting times, and efficient

use of irrigation water in order to decrease water

consumption and conserve this precious resource.

Early sowing:Early sowing:

Early sowing: The earliest possible sowing is of

major importance, especially in marginal cotton

countries, because it maximizes season length,

helps plants better exploit the earliest favorable

period for plant growth, and leads to avoidance

of late-season insect and weather problems. Sow-

ing on beds or covering the row with plastic film

during emergence can enhance the effectiveness

of early sowing.

Narrow row spacing:Narrow row spacing:

Narrow row spacing: Conven-

tional row spacing of 1 m between rows was im-

posed by machinery requirements, mainly mechani-

cal pickers. However, numerous studies show that

narrow row systems are superior to conventional

systems because they provide more desirable plant

distribution for improved exploitation of resources,

and early canopy closure for efficient radiation use.

Low input growing systems are expected to reduce

plant growth and consequently increase the effec-

tiveness of closer rows. The advent of genetically

engineered herbicide resistant cottons has facili-

tated weed control in closer rows.

Plant growthPlant growth

Plant growth

regulators (PGRs):regulators (PGRs):

regulators (PGRs): PGRs and nutritional additives

should only be used when needed. Research has

demonstrated that most PGRs are not effective in

significant yield enhancement. In most cases, ap-

propriate good farming practices should success-

fully control and balance growth and yield devel-

opment.

Crop monitoring:Crop monitoring:

Crop monitoring: Recent improvements

and simplification of crop monitoring techniques

have greatly aided in the achievement of optimum

crop management, particularly in the detection of

crop stress for timely amelioration, and also for

late season decisions.

Organic cotton:Organic cotton:

Organic cotton: Produc-

tion of organic cotton constitutes a novel produc-

tion system requiring premium prices, abundant

hand labor, and locations free of harmful pests.

In regard to sustainable production, production

costs may increase and competitiveness decrease.

Varieties resistant to stress:Varieties resistant to stress:

Varieties resistant to stress: Traditionally, plant

breeders have strived to create high yielding vari-

eties, which are generally responsive to high in-

puts. However, research is now aimed at the evalu-

ation of a wider range of germplasm for the cre-

ation of low inputs demanding varieties with more

tolerance to biotic and abiotic stresses.

T T

ransgenicransgenic

ransgenic

varieties:varieties:

varieties: The very rapid expansion of transgenic

cotton varieties verifies their successful contribu-

tion to the control of weeds and some key insects.

However, there are cases where yields and agro-

nomic performance of transgenic varieties have not

been as consistent as hoped. Transgenic varieties

have great potential, but should only be adopted

when economic returns warrant their use.

Inte-Inte-

Inte-

grated pest control:grated pest control:

grated pest control: The principles of integrating

pest control within the whole production manage-

ment system should be evoked in both low input

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and intensive cotton systems for efficient, profit-

able and sustainable cotton production.

IntroductionIntroduction

Introduction

Since 1930, there has been a profound increase

in crop yields and animal production due to support-

ing research and agricultural policies. However, the

intensification of agriculture aimed at yield maximiza-

tion has resulted in the overuse of chemical fertiliza-

tion, irrigation water, agrochemicals and soil mechani-

cal tillage, as well as the abandonment of rotation,

and genetic erosion. The intensive agriculture with high

inputs, and with the substantial subsidies, in developed

countries, given to the production, and not for improved

quality has led to: production surpluses, high cost of

production, pollution of the environment, deterioration

of the quality and over competition against third world

countries (Galanopoulou-Sendouca et al., 2001).

The 1992 World Summit in Rio de Janeiro as-

sembled to deliberate on how to heal the ailing envi-

ronment. Ten years later, last September, world leaders

convened at the World Summit on Sustainable Devel-

opment in Johannesburg (in the same country which

hosts the 3

World Cotton Conference) to reassess the

planet’s condition and decide about future policies.

Sustainable agriculture is among the most im-

portant components of sustainable development. Since

the early 1990s, the World Trade Organization (WTO)

agreement, coupled with environmental initiatives, has

imposed the need for reform in crop farming aimed at

producing internationally competitive crops, while deal-

ing with ecological disturbances caused by agricultural

activities. However, the path to sustainable agriculture

is a matter that needs careful consideration for it is

possible, under the mask of environmental protection,

to deteriorate the farming system and crop productivity

in a way which may exaggerate farm problems and

human starvation (Galanopoulou-Sendouca, 1998). As

it was pointed out in Johannesburg, the issue is not

environment versus development or ecology versus

economy. Sustainability and development must be in-

tegrated, as both bioengineering and organic farming

can play their own unique and important roles (Kluger

and Dorfman, 2002).

In cotton, economic components for crop profit-

ability restrain optimism. Cotton yield appears to be on

a plateau or short decline since 1987 (Meredith, 1998).

Since 1997/98, the indicator of international prices has

been lower than the long-term average. The Cotlook A

index for 2001/02 is the lowest in the last 29 years.

Low prices will affect cotton yields in many countries,

lowering the average world cotton yield (ICAC Recorder,

2002a). Furthermore, recent world consumption fore-

casts have been lowered due to economic weakness of

developing countries.

Stagnating yields, lower cotton prices, higher in-

put costs and concerns about environmental protec-

tion, coupled with the World Trade Organization agree-

ment, have imposed the need to produce more sus-

tainable and competitive cotton crops. For example,

the cost of controlling insects is one of the major pro-

duction costs. It thus makes economic and environmen-

tal sense, to reduce the crop’s dependence on farm

chemicals. Additionally, the cotton crop has emerged

as one of the major consumers of agrochemicals for

yield maximization. The crop also requires a compara-

tively longer growing season compared to other row

crops. Furthermore, cotton is a perennial plant grown

as an annual and is reputed to have the most complex

growth habit of all major row crops (Oosterhuis and

Jernstedt, 1999). This greatly complicates the produc-

tion of cotton for efficient management and profitabil-

ity, sustainability, and protection of the environment.

However, there is space for increased production in-

puts in some developing countries. Many developing

countries use less inputs than are optimum because

farmers face financial difficulties to buy inputs, e.g.

Nigeria and Benin (ICAC Recorder, 2001). Singh et al.

(2000) estimate that in India (Punjab region) there is

still space to increase energy input in order to raise

cotton crop, mainly for soil cultivation, irrigation and

weed control (0,3% increase may lead to 2,5% increase

of production).

Developing countries should take stock of what

technology is already available (i.e. use of herbicides,

acid delinted seed, and precision sowing, and the use

of high plant populations), validate the appropriate tech-

nologies for their conditions and thereby raise the overall

standard of their cotton growers.

More efficient production practices are a key to

lowering production costs and improving cotton profit-

ability. This paper presents an overview of agronomic

concepts for consideration in current or alternative sys-

tems for lowering inputs, sustaining production, pro-

tecting the environment, and maintaining or improv-

ing profitability.

Crop rotationCrop rotation

Crop rotation

Continuous cultivation of the same crop, leads

to deterioration of the soil and makes it poor due to

depletion of crop specific needs of natural resources,

especially soil nutrients. However, within the framework

of intensive agriculture, crop rotation has been replaced

in most cases by monoculture of ‘competitive’ subsi-

dized crops. There is also the false view that crop prof-

itability is calculated on an annual basis instead of over

a period of years.

The yield decrease in monoculture systems is at-

tributed to “soil sickness”. Crop growth and develop-

ment is prohibited as plant resistance to diseases and

insects is decreased. “Soil sickness” is also connected

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with the fact that different crops have different nutrient

demands. Another dimension of “soil sickness” is the

root excretions of toxic substances from certain plants

with allelopathic adverse effect on the growth of other

plants. Allelopathy has greater effects on weeds con-

trol (Lampkin, 1992). The most important advantages

of crop rotation are:

a) Conservation or even improvement of soil fertility.

b) Control of plant pests, diseases and weeds due to

great differences among crops. Many pests and

diseases infest only certain crops, so that crop rota-

tion is a main factor of Integrated Pest Manage-

ment (IPM) (e.g. most cotton pests and weeds would

be killed by rice flooding). Crop rotation is more

effective in disease control than for insect control.

For example, severe soil infestation by the fungus

Verticillium dahliae Kleb, often causes severe cot-

ton yield losses, and obligates farmers to grow an

alternative crop for a few years.

c) Yield and quality increase of crops. Adding legumes,

e.g. as green manure or forage in different crop-

ping systems, can fully open up the limited land

resources, increase the potential of soil and improve

soil fertility. In China, legumes used as green ma-

nure incorporated into the soil 22,5 t/ha biomass,

and decreased N fertilization for following cotton

crop by 50%. Also, broad bean (Vicia faba L.) or

peas (Pisum sativum L.) are inter-planted with wheat

in the autumn or early winter and picked as fresh

pods for vegetables. The residues are incorporated

as basal manure for the succeeding cotton crop the

next spring. Experiments showed that inter-plant-

ing broad bean gained 5.4 t fresh pods/ha, a bo-

nus yield, and 16.8 t fresh matter/ha, which pro-

vided additional organic matter and nutrients (Chen,

1992).

In Greece, cotton cultivation has become, due to

highly subsidized prices, a monoculture in some re-

gions, e.g. Thessaly, and this situation has led to “soil

sickness”. Today, legumes and cover crops must be in-

cluded in rotation systems to minimize inputs in cotton

cultivation. Traditionally, cotton is rotated in Greece with

winter wheat. Such a rotation permits the use of cover

crops for green manure (Galanopoulou-Sendouca,

1998). On the contrary, the effect of sugar beet in cot-

ton cultivation in Greece is considered negative based

on various field observations and the personal experi-

ence of farmers. According to research data, increased

soil compaction observed in plots planted to sugar beet

combined with delayed cotton growth, support the hy-

pothesis that the swollen sugar beet roots increase soil

compaction, prohibiting root penetration of the follow-

ing cotton crop (Galanopoulou et al., 1998).

Long-term research is needed to identify the ap-

propriate rotation systems for each region. In Pakistan,

a cotton–wheat rotation gave the highest five-year av-

erage returns compared to systems such as cotton-sun-

flower, and cotton-maize (Ahmad et al., 1998). Double

cropped wheat-cotton rotations in irrigated cotton sys-

tems in Australia provide high ground cover levels and

significantly reduce soil erosion with a similar decrease

in the off-farm movement of pesticides (Rohde et al.,

1998). Deep-rooted crops as safflower (Carthamus

tinctorious L.) used in cotton rotation systems can im-

prove the overall water and N use efficiencies of crop-

ping systems and help minimize nitrate leaching to

ground water (Bassil et al., 2002).

In conclusion, appropriate rotation is the most

effective factor for lowering production inputs and for

successful sustainable cotton crop. The adoption or even

the mandatory inclusion of crop rotation, in countries,

such as Greece with high subsidies for cotton produc-

tion, will restrict the expansion of cotton cultivation and

consequently will limit the decline in prices. Crop rota-

tion is included in the “Codes of good farming” im-

posed by the EU for subsidized “friendly to the environ-

ment” agricultural enterprises (Reg. 1259/99).

Conservation tillageConservation tillage

Conservation tillage

The intensive use of heavy machinery in connec-

tion with cotton monoculture initiated problems of soil

compaction, which led to adverse effects on plant root-

ing and consequently crop yield. Additionally, the im-

portance of conserving soil moisture and reducing en-

ergy and labor-related costs, as well as equipment re-

quirements, have been a key concern in economic sur-

vival for farmers and that has led many of them to

adopt conservation tillage practices (Barnet and Stevens,

1996; Larson et al., 2001). “Conservation tillage” was

initially used for tillage practices that conserved soil by

reducing the potential for wind/water erosion. How-

ever there has been an increasing realization that con-

servation tillage also greatly reduces the cost of fuel,

labor and other inputs. Consequently there are a wide

variety of approaches and terms under conservation

tillage including reduced tillage, optimum tillage, mini-

mum tillage, and no-till.

Soil erosion, especially in slopping areas with

heavy rainfall and/or sandy land with strong blowing

winds, is a severe problem for depletion of natural re-

sources. According to Brown and Wolf (1984) 7% of

the world surface cultivated soil is lost in a decade due

to soil erosion, which appears, as a quiet crisis in the

world economy. On a world scale, soil erosion is the

main factor for soil fertility deterioration. Improved sur-

face cover (or protection) from cover crops or minimal

tillage facilitate water infiltration and prevent surface

soil crusting, and thereby decrease soil erosion (James

and Russel, 1996; Moseley et al., 1996). The efficiency

of different cover crops (vetch, rye, broad bean, etc.)

as an independent practice or in combination with mini-

mum tillage is well established provided there is no

delayed destruction of the cover crop and the cost of

the cover crop seed is not too high (Moseley et al.,

1996; Chen, 1992).

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Concerning yields, it was found in Texas that in a

burley-cotton rotation, cotton yield was always higher

under no-till than under conventional system due to

increased water conservation (Herman et al., 1989;

Weise et al., 1994). Similarly, under irrigation in Greece

it was found that cotton yield was higher under no-till

compared to conventional systems due to better water

and nutrients availability, apart from the benefits of re-

duced energy costs and less environmental pollution

(Billalis et al., 2000). Conservation tillage also proved

profitable for cotton production in the high plains of

Central Texas (Herman et al., 1989). Also a method of

establishing wheat after cotton by broadcasting the seed

without any previous stalk chopping and/or tillage and

seed incorporation by a light cultivator was studied

under Greek conditions in comparison with conven-

tional (ploughed) tillage. The results showed that wheat

plant emergence and development were not signifi-

cantly affected by the tillage treatment and yields from

plots with unchopped stalks did not differ significantly

from ploughed plots (Gemtos et al., 1998).

In Sudan cotton yields from reduced tillage sys-

tems and conventional ones were not statistically dif-

ferent (Skeikl and Gadir, 2000). Reduced yields under

no-tillage system were reported in Arkansas (Keisling

et al., 1993). Similarly in Alabama, yields from no-till

treatments have not been competitive with conventional

tillage on the silt-loam and silty-clay loam soils of the

Tennessee valley (Reeves et al., 1996). The success of

minimum tillage appears to depend on the use of ap-

propriate machinery for soil preparation and seed sow-

ing, as well as weed control and crop rotation. Effec-

tive weed control is a critical factor for the success of

reduced tillage systems. Genetically engineered cotton

resistant to certain herbicides greatly facilitates the prob-

lem of weed control in narrow rows and no-till growing

systems.

Judicious fertilization andJudicious fertilization and

Judicious fertilization and

irrigationirrigation

irrigation

FertilizationFertilization

Fertilization

The effectiveness of chemical fertilization in com-

bination with irrigation has led to the overuse of fertil-

izers, especially nitrogen, even though cotton is gener-

ally considered as a low fertilizer demanding plant. In

Thessaly, the main cotton belt of Greece, there is sur-

face and underground water nitrate pollution, due to

excessive nitrogen fertilization (up to 240 N/ha) in cot-

ton cultivation. The problem of water pollution with ni-

trates is intensified by excessive irrigation, which not

only has adverse effects on crop productivity, but also

leads to dangerous shortages of precious water re-

serves. Agricultural policymakers in many developed

countries are close to imposing fees on farmers who

exceed the economic and environmental optimum irri-

gation and fertilization level (Galanopoulou-Sendouca,

1998). Judicious timing of fertilizer application, and ap-

propriate irrigation practices are included in the “Codes

of Good Farming” which is compulsory for subsidized

environmental projects in the EU. Research has shown

that systems with reduced fertilization are feasible for

optimum yields. Results from Greece provide strong evi-

dence that conventional high levels of major produc-

tion inputs, such as nitrogen fertilizer or irrigation wa-

ter, did not result in yield increases compared to lower

levels. Furthermore, low input treatments, generally led

to an increased yield in the first pick, which represents

the most important part of the total cotton yield and the

highest fiber quality (Galanopoulou-Sendouca, 1998).

Optimum yield response to N application varies among

regions, varieties, irrigation levels and other cultural

techniques and consequently is an ongoing concern of

cotton producers. In Thessaly, Greece, yield seems to

maximize near 120 N/ha, instead of 240N/ha used a

few years ago (Galanopoulou-Sendouca, 1998). In

Arkansas, yield response of all tested cultivars maxi-

mized near 112 N/ha (McConnell et al., 2001a). A

sound basic soil fertility program combined with plant

tissue analyses should provide a means to limit excess

fertilizer inputs while obtaining maximum economic

yield.

The timing of nitrogen fertilizer application has

changed in the last few decades. Instead of pre-plant

fertilization nitrogen is applied now closer to the time

the crop needs the nutrient (Gerik et al., 1998; Plunkett

et al., 2001). The correct timing and availability of nu-

trients may greatly enhance the effectiveness of fertili-

zation and reduce environmental pollution. In coun-

tries, such as Israel and Greece, where drip irrigation

is a common practice for cotton, fertigation is a prom-

ising technique according to research findings. Experi-

mental results in Greece provide evidence that irriga-

tion and fertilization in cotton in the form of fertigation

may be reduced in accordance to the imposed low in-

put agriculture without a serious variation in the cost/

benefit ratio (Polychronides et al., 1998). Correct tim-

ing may be also on cotton monitoring (see below).

Foliar fertilization for main nutrients (e.g. KNO

)

may be considered as an extravagant luxury for cost

production efficiency. Cost increase is higher when sev-

eral foliar sprayings are suggested to meet for nutri-

tional requirements especially in cases there is no need

for pesticides application. Foliar fertilization, for main

nutrients, should only be used to correct an urgent de-

ficiency on a timely basis.

Precision agriculture is a new approach to inte-

grated crop management, which encompasses fertili-

zation of cotton. Producers that have adopted preci-

sion agriculture maintain that it holds great potential

for benefits to the environment and for economic gains.

However, farmers need to realize how to use the com-

plicated new technology to improve profit. Furthermore,

the use of precision agriculture is not appropriate for

small-size farms and/or in developing countries where

the necessary technology does not exist (Robinson,

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Agronomic concepts and approaches for sustainable cotton production

2002).

IrrigationIrrigation

Irrigation

Only 2.5% of world’s water is fresh water of which

only a fraction is accessible, and agriculture accounts

for about two-thirds of the fresh water consumed. There-

fore, protection of this precious natural resource, which

becomes increasingly limited in supply, must be con-

served through careful agricultural management. Within

the concept of “more crop per drop”, this calls for more

efficient irrigation techniques, planting of drought - and

salt - tolerant crop varieties that require less water, must

be implemented for sustainable use of water.

The cotton plant originates from arid areas and

exhibits more drought tolerance than other row crops,

such as maize and soybean (Oosterhuis and

Wullschleger, 1988). However, this characteristic is lim-

ited in most current commercial varieties (Meek et al.,

2002) and cotton does not grow well without adequate

water (Oosterhuis and Bourland, 2001). Consequently,

the availability of water is one of the most critical fac-

tors for optimum cotton yields. As water availability is

becoming a limiting factor for successful cotton grow-

ing, attention should be paid to water conservation,

through correct land preparation, optimum planting

times, and efficient use of irrigation water in order to

decrease water consumption and conserve this precious

resource.

One effective irrigation system is drip irrigation.

Drip irrigation has expanding rapidly in Greece, espe-

cially in Thessaly where it covers approximately 50% of

the cotton acreage. It is mainly used in regions with

intense water shortage problems and lack of irrigation

delivery networks but with high crop yielding capacity,

so that covering the expenses of buying the system can

be achieved during its relatively short life span. Usu-

ally, a single dripper line supplies water to two adja-

cent rows. Drip irrigation is broadly used in Israel, where

the shortage of water is very serious and where the

drip irrigation system had its origin. Compared with

sprinkler irrigation, yields of crops irrigated by drip irri-

gation are generally 15-20% higher, according to re-

search work carried out for at least 15 years (Goren,

1994). The main advantages of drip irrigation are: ef-

fective use of water (approximately 40% less water in

comparison to surface systems as there is not much

waste due to evaporation or its movement below the

root system), and the more efficient and cheaper fer-

tilization and weed control applied through the system

(Goren, 1994). In South Africa cotton yield under drip

irrigation was 24-65% higher than sprinkler irrigated

cotton (Dippenaar et al., 1994). However, fertigation

of cotton was slightly inferior to the conventional fertili-

zation program but proved to be easy, accurate and

labour saving.

Early sowingEarly sowing

Early sowing

The earliest possible sowing is of major impor-

tance, especially in marginal cotton areas, because it

maximizes season length, helps plants better exploit the

earliest favorable period for plant growth, makes maxi-

mum use of seasonal solar radiation, and leads to

avoidance of late-season insect and weather problems.

Early sowing is usually related to higher yields, espe-

cially in years with a reduced growing season (i.e. pe-

riod with minimum temperature >15

C), and/or de-

creased sunshine duration. The above holds true even

in cases with reduced emergence and plant popula-

tion (up to 50% of the optimum population, provided

the gaps are uniform), as it is well known that the cot-

ton plant with its indeterminate growth habit is capable

of compensating for great losses in population densi-

ties (Chlichlias et al., 1977; Galanopoulou-Sendouca

et al., 1980). The optimum date of sowing in Greece is

usually 10-20 of April and the latest date is the end of

April. Delayed sowing after that period, leads to dras-

tic yield reduction, such that sowing in June has only a

limited probability of producing any yield (Christidis,

1965). Nowadays, early sowing has generally been

adopted by cotton farmers. In Greece for example, the

optimum date of sowing has been moved approximately

10 days earlier than previous.

Generally, an earliness management program

helps the cotton crop better utilize the specific growing

season, escape late-season pests and allows a better

chance of escaping adverse late-season weather

(McCarthy, 1996). Furthermore, early harvest permits

the incorporation of the cotton crop into successful ro-

tation systems. However, there is an optimum earliness

for each case and cotton crop should exploit the whole

growing season for yield optimization (Galanopoulou-

Sendouca et al., 1980). As cotton plant is very sensitive

to low temperatures, the success of early sowing is pur-

sued through cold resistant varieties and cultural tech-

niques, such as sowing on beds or covering the row

with plastic film during emergence.

Cotton emergence under plasticCotton emergence under plastic

Cotton emergence under plastic

filmfilm

film

The method of early cotton sowing under plastic

film is broadly used in Spain to guarantee seed germi-

nation under early sowing (Portero, 1994). For Greece,

especially in northern regions, which are characterized

by short growing seasons, this system contributes to

early and uniform plant emergence, an important com-

ponent for the crop’s success. The use of plastic film in

the early stages of cotton cultivation is supported by

research data from the 1970’s (Galanopoulou-

Sendouca et al., 1978) as well as evidence from farm-

ers who have adopted the recently mechanized method.

However, there are some contradictory results, and fur-

ther investigation is needed. Row covering with poly-

ethylene strips increased soil temperature by approxi-

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mately 2

C, which improved plant emergence by 9%

and shortened the emergence duration from 18 to 11

days, with a 20% yield increase. The covering was more

effective under adverse conditions of low temperature

during early sowing and low soil moisture

(Galanopoulou et al., 1978). Recent research in Greece

showed that higher yield overcompensates for the cost

of plastic, and that earlier cotton maturation guaran-

tees successful cotton harvesting (Stathakos and

Galanopoulou-Sendouca, 1996). Colomer and his

colleagues (1998) found that the productive potential

of cotton sown under plastic mulch is greater than tra-

ditional sowing; however success ultimately depends

on the growing practices used. Frequent irrigation with

appropriate, timely fertilization is needed due to a shal-

low root system (Stathakos and Galanopoulou-

Sendouca, 1996).

The continuous use of plastic films will create

environmental problems which may be faced by the

production and use of either biodegradable plastic or

films from starch, e.g. cornstarch (Anonymous, 1991).

Cotton sowing on bedsCotton sowing on beds

Cotton sowing on beds

The necessity of successful early sowing, espe-

cially in wet regions with heavy soil, where drainage is

prohibited, led to the use of beds in the USA and later

in other countries. Soil drainage is improved and con-

sequently temperature increases resulting usually in

accelerated and improved emergence as well as lower

Verticillium wilt infestation. Furrows between beds fa-

cilitates mechanical picking and furrow irrigation

(Galanopoulou-Sendouca et al., 1978). The effective-

ness of the method relies on appropriate machinery

and effective herbicides applied during bed formation.

Absence of weeds at sowing is a prerequisite for suc-

cess, as weed control before sowing is problematic.

Where genetically engineered herbicide resistant cot-

ton varieties are used, the control of these weeds may

be easily accomplished.

Narrow-row spacingNarrow-row spacing

Narrow-row spacing

Conventional row spacing of 1 m between rows

was imposed by machinery requirements, mainly me-

chanical pickers. However, numerous studies have

shown that narrow-row systems can be superior to con-

ventional systems because they provide more suitable

plant distribution for improved exploitation of resources,

and early canopy closure for efficient radiation use

(Galanopoulou-Sendouca et al., 1980).

Cotton producers in the United States and in other

cotton producing countries have made continued at-

tempts to grow the crop on various row spacing and

row configurations, including double rows, on beds or

on the flat soil, ranging from six to 14 inches and single

rows ranging from 19 inches to 40 inches. Most nar-

row-row cotton currently consists of 30 inch. Increased

yields is the most common rationale for using narrow-

row cotton, but convenience of growing it with other

crops which lend themselves to 30 or 32 inch rows (e.g.

corn and soybean) is also important. Other benefits

reported include water conservation, early maturity,

better response to the growth regulator pix, improved

lint quality, fewer pesticide applications, and better use

of solar radiation (Galanopoulou et al., 1980; Weir,

1996; Bartzialis et al., 1998; Spencer, 1998). Increased

plant population densities with narrow rows decrease

also Verticilium wilt infestation and can compensate

emergence losses (Lefkopoulou et al., 1980;

Galanopoulos and Galanopoulou-Sendouca, 1992).

The superiority of narrow-rows is more evident

when the prevailing conditions prohibit full canopy clo-

sure in 1m rows. Such cases are expected to become

more frequent with the use of low nutrients - demand-

ing, short-season cotton varieties and the use of low

input growing systems, which will reduce plant growth.

Since the 1980s in California, there has been an

increasing trend in the use of transformed cotton pick-

ers, which can successfully harvest cotton sown in 76

cm rows (Weir, 1996). Research data showed a yield

increase in rows 76 cm apart compared to rows 102

cm apart. This superiority was associated with better

plant exploitation of soil and solar energy is due to the

spatial by uniform distribution of plants (Heitholt et al.,

1993). Early maturity was also documented and attrib-

uted to reduced plant growth and a lower first fruiting

branch (Heitholt et al., 1993; Robinson, 1991; Williford,

1992). This system is also currently being evaluated in

Greece, with promising results (Bartzialis et al., 1998).

Ultra narrow-row cotton (UNR) systems (i.e. with

row spacing of seven to 30 inches apart) seem also

advantageous in some regions, such as the High Plains

in Texas, and in the Mississippi Delta but they can only

be harvested with stripper harvesting machines, which

are considered to deteriorate cotton fiber quality. The

development of new cotton strippers with addition and

improvement of field cleaners should increase farmer

and research interest in UNR cotton. Also GE cotton

(Roundup Ready cotton) can further contribute to suc-

cessful weed control programs in a system that removes

the possibility of cultivation and/or band application of

herbicides. Potential benefits of UNR cotton production

include reduced production costs, utilization of poorer

soils, decreased soil erosion, utilization of the same

equipment for cotton, soybeans and maize, and lower

N requirements for maximum yield compared to con-

ventionally spaced cotton (McConnel et al., 2001). The

advent of genetically engineered herbicide resistant

cottons has facilitated weed control in closer rows, which

was until recently severe limitation in UNR systems.

Plant growth regulatorsPlant growth regulators

Plant growth regulators

Plant growth regulators are organic compounds,

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Agronomic concepts and approaches for sustainable cotton production

other than nutrients that affect physiological processes

of plants when applied in small concentrations and

provide numerous possibilities for altering crop growth

and development. The possible benefits and uses of

PGRs in cotton production include control of vegetative

growth, increased boll retention, earlier crop maturity,

preparation of the crop for harvest, and increased yields.

These responses are a reflection of the interaction of

genotype, cultural inputs and environment. Because of

this complex interaction, crop response to PGRs is not

always predictable and results, especially with yield

enhancement, have often been disappointing, variable

and inconsistent (Cothren et al., 1996; Oosterhuis and

Egilla, 1996; Oosterhuis et al., 1998). Intensive cotton

cultivation aimed at maximizing yield, often without cost

considerations, led also to the foliar application of vari-

ous nutritional additives such as amino acids or su-

crose with questionable benefits and often with detri-

mental effect on cotton plant.

Previous review of literature concluded that plant

growth regulator use in cotton is a viable option for

effectively modifying plant growth and development.

Success with growth retardants, yield enhancers and

crop terminating compounds makes managing the crop

an easier task. Suppressing excessive vegetative growth

also allows for better control of insects and assists with

harvest (Cothren, 1994).

PGRs are widely used in cotton. Among them,

the most widely used is the growth retardant PIX

(mepiquat chloride), which has been used as an im-

portant management tool for upland cotton, especially

in the USA, for the past 30 years since it was registered

in 1971. Results showed that when internode length

increased (prior to applications of mepiquat chloride-

Pix) at less than 5.5 cm/node, no response or even

negative yield responses to Pix were obtained (Con-

stable, 1994). When internode length was increasing

at more than 6.5 cm/node, significant yield increases

were obtained.

In a recent review, Oosterhuis and his colleagues

(1998) stated that numerous field tests have been con-

ducted across the U.S Cotton Belt comparing select PGRs

for affect on yield, but most of the PGRs tested have

failed to significantly or consistently increase yields. Even

mepiquat chloride, the most broadly used PGR in the

world, does not increase yield consistently.

Although Arkansas research has shown incon-

sistent yield responses of cotton to mepiquat chloride

(PIX) applications, its use continues to be of interest to

the state’s producers. However, accumulated results

from research with PGRs treatments did not indicate

any significant yield, maturity, or growth advantages.

Mepiquat chloride-based PGRs did not substantially alter

cotton growth and development and the costs associ-

ated with PGRs negatively affected crop revenue (Benson

et al., 2001).

In conclusion, in low input growing systems PGRs

should only be used when needed, until a better un-

derstanding of PGRs is fulfilled for more predictable

crop responses and greater economic results. Until then,

rational use is suggested with great attention on the

appropriate dose and time of application in correla-

tion to the developmental plant stage. Research has

demonstrated that most PGRs are not effective in sig-

nificant yield enhancement. In most cases, appropri-

ate good farming practices should successfully control

and balance growth and yield development.

Crop monitoringCrop monitoring

Crop monitoring

As cotton plant is very responsive to changes in

the environment and to management, it is essential that

producers understand the development pattern of the

crop and the stage-dependent requirements in order

to avoid possible problems and protect yield (Oosterhuis

and Jernstedt, 1999). Crop monitoring provides a pre-

cise means to follow crop growth and pinpoint prob-

lems for timely action (Danforth and O’Leary, 2001).

Recent improvements and simplification of crop moni-

toring techniques have greatly aided in the achieve-

ment of optimum crop management, particularly in the

detection of crop stress (e.g. poor or excessive plant

growth) for timely amelioration, and also for late-sea-

son management decisions. Early detection of stress

and timely crop management also improve economic

inputs.

A model for cotton monitoring is COTMAN

(COTton MANagement). The simulation model

COTMAN derived from concepts of stress physiology

research in Arkansas. COTMAN relies on recording the

number of squaring nodes of the main stem and square

retention before flowering initiation and after that on

the number of sympodia above upper white flower

(Nodes Above White Flower-NAWF). Plant monitoring

provides opportunities for changing management to

aid in fruit retention or modifying plant height (Plunkett

et al., 2001). It makes also use of the “good stress”

manifested by slowing down of the terminal part when

cotton plants approach physiological maturity so that

resources are preferentially diverted to the developing

bolls. Although the growth habit of the cotton plant is

indeterminate, development eventually slows, with a

substantially reduced rate of flowering and square re-

tention. This stage is called “cutout” and signals the

end of the useful flowering period. Too early cutout leads

to earliness of maturation but also to reduced produc-

tivity, while late cutout results to the riskful lateness of

yield maturation. Knowing when cotton crop is ap-

proaching cutout helps optimum crop management

regarding end of insect control, end of irrigation and

right time of defoliation. A reliable indication for cutout

is NAWF. It was found that as NAWF decreases crop

photosynthesis is also reduced (Bourland et al., 1992,

1997). When NAWF=5, the crop has reached cutout

and later flowers contribute little to the total yield or

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even act as parasites to the plant.

Research data support the concept of COTMAN

but further validation is needed (Brown et al., 2001;

Kharboutli and Allen, 2001), for different regions with

these unique prevailing environmental conditions and

cultural techniques. Definition of the “Target Develop-

ment Curve” should take into consideration the differ-

ent conditions so that cotton development should ex-

ploit the whole growing season as it is defined by pre-

vailing ecological conditions (temperatures, rainfall,

solar radiation, soil properties).

Organic cottonOrganic cotton

Organic cotton

Organic cotton production, by totally excluding

agrochemicals, has the least impact on the environ-

ment, i.e. it is the most “environmentally friendly” pro-

duction system available. Organic products are pro-

duced for three years from the same fields and accord-

ing to specific control before being appropriately certi-

fied and labeled, and finally sold for premium prices,

as they satisfy the requirements of consumers who care

about their health as well environmental protection. In

Europe, organic production must obey all certification

requirements set out in the EEC regulation 2092/91 on

organic agriculture and food processing. This regula-

tion is based on the International Federation of Or-

ganic Agriculture Movements (IFOAM) regulation

(1995). Organized efforts to grow cotton without agro-

chemicals began in USA in 1989 (ICAC Recorder, 1993).

Organic cotton is knitted into T-shirts, sweaters, infant

wear, towels etc.

According to research data and practical evi-

dence, maintaining yields in organic cotton production

is not easy. The average yield decrease is estimated at

25%, especially during the first few years. Also, in most

cases the cost of production is higher, mainly due to

higher labor requirements, especially for weed control

and expensive non-conventional means of insect con-

trol (Oosterhuis and Galanopoulou-Sendouca, 2001).

In California (northern San Joaquin valley) a 15% de-

crease in yield coupled with an 11% higher cost per

hectare resulted in 51% higher costs per kg of lint cot-

ton, which can not be compensated by the estimated

44% higher lint price of organic cotton compared to

conventional cotton (Swezey and Goldman, 1996).

These results explain why in the USA, there was an ini-

tial expansion of organic cotton cultivation (~10,000

hectares) followed by a steady and sharp decline since

1995. This pattern also occurred in other countries such

as Greece, probably due to the enthusiastic adoption

of this new production system (i.e. organic cotton culti-

vation) before the solution of many problems concern-

ing mainly pest and weed control (Marquardt, 2001).

In 1999 the area in the USA partially recovered (about

6,700 ha, representing only about 0.1% of the total

cotton area in the USA) but this is insufficient to meet

their high industrial demands. Furthermore, the broad

expansion of GE cottons in USA does not leave room

for organic production. According to 1999 data, Tur-

key overtook the USA with 41% of the world organic

cotton production, compared to USA 34%, Africa 13%,

India 8% and Latin America 4%. However, as organic

cotton is expected to eventually comprise more than

5% of total world cotton production, countries with low

labor costs, abundance of hand labor and traditional,

low input cotton cultivation (e.g. Turkmenistan), may

benefit from organic cotton production. In Tropical West

Africa research has provided evidence that, if market

prices for organic produce could guarantee 20% price

premium in the long term, organic cotton production

might generate the same revenues as conventional

cotton while reducing environmental pollution (Ton,

1998). It must be noticed that research on organic cot-

ton in tropical regions as everywhere is still too limited

to justify any judgment on its potential to be a viable

alternative to conventional cotton.

Generally, the conversion of conventional cotton

production to organically grown cotton is not as easy

as other less intensive crops with fewer input require-

ments. Organic production demands higher levels of

skill (especially for plant protection) than conventional

production, but insufficient research has been conducted

to provide guidelines for shifting from conventional to

organic production. Rotation systems (obligatory in or-

ganic farming) must be evaluated to improve produc-

tivity, competitiveness and marketing of all organic prod-

ucts from the same enterprise. Priority in such rotation

systems should be given to legumes which are easily

incorporated into organic system, contribute to plant

nutrition of the successive organic crops, produce ex-

cellent animal food, for biological animal production,

which is in high demand. Mixed enterprises, of crop

and animal production, may contribute to the success

of organic farms. The success of organic production

relies, mainly, on the use of fertile soils and of suitable

varieties, and on the absence of pests, diseases and

weeds. Similarly, other components of integrated pest

management could contribute to the success of organic

production. A comparative cost analysis of organic and

conventional cotton production in Greece (Fotopoulos

and Pantzios, 1998) concluded that unless specific so-

lutions are developed that address the problems of bio-

logical control and make efficient combinations of pro-

duction costs and yields possible, organic cotton grow-

ing will lag behind conventional system in economic

performance. Alternatively, achievement of much higher

price premiums than subsidies given through EU Reg.

2078/92 could also improve the economic performance

of organic cotton.

Varieties resistant to stressVarieties resistant to stress

Varieties resistant to stress

Within the framework of cotton growing intensi-

fication, cotton breeders (like all plant breeders) have

strived to create high yielding varieties, which are gen-

erally responsive to high inputs. According to Constable

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Agronomic concepts and approaches for sustainable cotton production

(2000), the high cotton yields in Australia, which are

second only to those in Israel, is 45% attributable to

breeding high yielding varieties, 25% from soil-nutri-

tion-irrigation management, 20% from insect control,

and 10% from disease management. Due to high yields,

and despite relatively high costs for insect control, weed

control, planting seed and ginning, Australia has one

of the lowest costs of production per unit of lint. How-

ever, it seems that breeding work for yield increase has

reached a plateau. In a study to determine if lack of

progress in genetic improvement was partially respon-

sible for stagnating cotton yields in the USA (Meredith,

1998) a comparison of obsolete versus modern culti-

vars indicated that breeding progress for yield peaked

in 1987. According to these results Meredith suggested

broadening the genetic base being used by breeders

(Meredith, 1998).

The need to lower inputs, the confrontation of

environmental problems, and the need of adoption of

integrated crop management systems, has re-orientated

breeding objectives. Use of appropriate varieties ac-

cording to persisting insects, and biotic and abiotic

stresses is of most importance. Research is now aimed

at the evaluation of a wider range of germplasm for

the creation of low inputs demanding varieties with more

tolerance to biotic and abiotic stresses (El-Zik and

Thaxton, 1998). For example, the creation of determi-

nate varieties with fewer buds developed after 5 NAWF

and naturally defoliating will improve sustainable grow-

ing systems.

More urgent is the increasing limitation of pre-

cious water sources, which greatly elevates importance

of improved drought resistance. Although Oosterhuis

(1989) showed that cotton was more drought tolerant

than most other major row crops, there is a lack of

significant drought tolerance in current commercial

cultivars (Nepomuceno et al., 1998; Meek et al., 2002).

Crosses between relatively diverse germplasm provided

evidence that it is possible to select lines with improved

physiological water use efficiency (Stiller and Constable,

1998). Moreover, promising information comes from

Israel for cotton varieties tolerant to drought (Musaev,

1993). Resistance genes to dry conditions have been

discovered in wild cotton species as G. anomalum and

G. thurberi (Musaev, 1993; Nepomuceno et al., 1998).

Development of early-maturing cotton cultivars

has become even more important than in the past to

allow production in regions with short or dry seasons.

Intensive concentration on this goal is of urgent impor-

tance for sustainable cotton. Future cotton germplasm

should be screened for increased seedling vigor and

rapid root system establishment to improve drought

tolerance with the concept of the Multi-Adversity Resis-

tance system used successfully in Texas (El-Zik and

Thaxton, 1998). Heat tolerance should also be taken

into consideration (Oosterhuis, 1997; Oosterhuis et al.,

2003). Biotechnology is expected to play a major role

to achieve these perspectives.

ransgenic varietiesransgenic varieties

ransgenic varieties

Commercial production of transgenic cotton

started in 1996/7, and in six years the area planted to

GE cotton has increased to 6.8 million hectares, or 20%

of the total area planted to cotton in 2001. However,

the GE cotton area was only 13% of the total world

area planted to GE crops during 2001. The major

transgenic crop is soybean, accounting for 63% of to-

tal average. Corn is second with 19% of the total area

(ICAC Recorder, 2002).

Cotton is grown in over 60 countries out of which

only eight have approved the use of transgenic cotton.

The countries that have allowed commercial produc-

tion of transgenic cotton resistant to insects are Argen-

tina, Australia, China, India, Indonesia, Mexico, South

Africa and the USA. The herbicide resistant transgenic

cotton, alone and in the stacked gene form, is allowed

for commercial production only in Argentina, Australia

and in the USA. Outside the USA, insect resistant Bt

cotton is more popular than herbicide resistant variet-

ies. In the USA in 2001/02, varieties having the herbi-

cide resistant gene, alone and in conjunction with the

Bt gene, were planted on over 97% of the transgenic

cotton area, compared with less than 3% of area un-

der Bt gene varieties (ICAC Recorder, 2002). GE crop

varieties are not allowed to be cultivated in the EU ter-

ritory, although it seems that EU legislation may change

soon.

The transgenic cotton area is increasing. Accord-

ing to the USDA, GE cotton was planted on 78% of the

total cotton area in the USA during 2001/02. Australia

has put a limit on its transgenic cotton area in order to

avoid the development for resistance; otherwise, the

area planted to GE cotton would be much higher than

30% of the total. In South Africa, Bt varieties were

planted on 40% of the total area in 2001/02. In China

most of the cotton planted in 2001/02 was Bt cotton.

India was seriously considering allowing commercial

production of Bt cotton, and many other countries are

evaluating the performance of transgenic Bt cotton

(ICAC Recorder, 2001).

Large-scale application of modern biotechnol-

ogy to cotton in seven countries by 2002 is an indicator

of the technology success. Economic analysis of Bt cot-

ton varieties versus conventional practices in Argentina

indicates a two-thirds reduction in pesticide sprays (ICAC

Recorder, 2001). The total cost of production per hect-

are was found to be high in Bt cotton over conven-

tional practices, but net income per hectare and per kg

was higher in Bt varieties. Transgenic Bt cotton in China

also looks promising and has increased recently (ICAC

Recorder, 2001).

Several reports from Australia, China, South Af-

rica and other countries that have grown Bt cotton over

significant areas indicate that the cost of production is

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lower with Bt cotton due to reduced spending on pest

control (ICAC Recorder, 2002). Thus, pest pressure/

number of sprays per season to control target bollworms

and the cost of pesticides versus the cost of the tech-

nology fee will determine the extent of savings in the

cost of production. However, if the target bollworms do

not become a major threat in a particular year, and a

farmer has already paid the technology fee, savings in

the cost of production could be negative (ICAC Recorder,

2002).

Transgenic cottons expressing insecticidal proteins

with activity against one or more key pests offer great

scope to allow the integression of a wide range of IPM

compatible tactics and consequently to enhance IPM

success (Fitt, 1998). The development and use of

transgenic tolerance to herbicides is influencing posi-

tively some cropping systems, allowing changes in weed

control strategies, row spacing and mechanical har-

vesting methods.

However, the initial euphoria for transgenic cot-

ton is slowing down according to very recent results.

Main concerns and criticism are as following:

• The Committee of the Australian Cotton Growers

Research Association (2001-2002) makes it clear

that Bt is in some circumstances failing to control

the principal target pest it was introduced for, i.e.

Helicoverpa armigera, which is the predominant

race of bollworm in many countries, such as Greece.

So, farmers in Australia are now being advised to

spray additional insecticide on Monsanto’s GM Bt

cotton known as INGARD “under conditions of re-

duced INGARD plant efficacy”. The same Commit-

tee also expressed concerns about the sustainability

of the Bt technology due either to potential build up

of resistant insects, or inadequate expression of the

Bt gene in the plants, or both. Previous results in

Australia clearly showed that the efficacy of Bt cot-

ton plants in killing H. armigera larvae declines

during the growing season (Daly and Fitt, 1998).

Recently, Oosterhuis et al. (2003) have reported the

use of a protein translocation enhances foliar spray

to increase endotoxin levels and subsequent boll-

worm mortality.

• Chinese researchers also found that the use of Bt

cotton, which is designed to target bollworms, was

leading to larger populations of other cotton-eat-

ing pests, which could cause unpredictable disrup-

tions to the environment (Associated Press, 2002).

• In India, the initial euphoria for the Bt cotton ap-

pears to be strangely missing, according to recent

data. Bt cotton was found prone to leaf curl virus in

North India (Revathy, 2002). Also yield of the Bt

cotton crop was much more adversely affected by

the drought than other cotton varieties, and eco-

nomics were proved against Bt cotton, mainly due

to the quadruple higher price of Bt cotton seeds in

comparison to existing conventional cotton seeds

(Shah and Banerji, 2002).

• Although greater benefits from Bt cotton was re-

corded in South Africa (ICAC Recorder, 2001),

doubts are now being expressed in Africa concern-

ing the gain from genetically modified crops (The

Nation, Nairobi, June 3, 1999).

• Bt cotton is effective for control of tobacco budworm

(Heliothis virensis F.) but the control of bollworm

(Helicoverpa zea Boddie) and other lepidopterous

pests has been less dependable (Lorenz et al.,

2001). Effectiveness also varies with the species of

bollworms (ICAC Recorder, 2002). If a particular

species of bollworms is vigorously controlled for a

number of years, which the Bt cotton is meant to do

effectively, some minor insects may become major

insects. It is also feared that some insect species

may emerge, which could be even more difficult to

control with current insecticides. Similar apprehen-

sions are also true of weeds (ICAC Recorder, 2002).

Requirements for a refuge crop, to delay develop-

ment of resistance, are also a negative aspect of

GE/Bt cotton production.

• Recent research indicated that the Roundup Ready

system (i.e. cultivar and glyphosate herbicide treat-

ment) exhibited a reduction in yield or net returns

(Ribera et al., 2001).

• According to a study compiled on behalf of the

World Wildlife Found, WWF, (WWF® International,

2002) the extensive cultivation of genetically engi-

neered cotton over a period of four years in the

USA has brought no appreciable reduction in the

use of insecticides and herbicides.

• A number of reports indicate a decline in average

quality in the USA, which is partially attributed to

GE cotton as it slowed down the rate of creation

and adoption of new varieties with improved fiber

qualities and probably yield (ICAC Recorder, 2002).

• Concerns are addressed to cotton breeders about

stagnant yields and declining quality (Lewis, 2000).

Since the mid 1980’s, the effort for backcrosses to

obtain GE cotton has weakened conventional breed-

ing programs, aimed at thorough gene recombi-

nation, while cotton breeding was passed to pri-

vate companies thereby weakening the Public Sec-

tor. The lack of genetic diversity in commercial vari-

eties is now considered a problem that, in part,

compounds the criticism that genetic engineering

limits diversity because of backcross breeding rather

than forward breeding (ICAC Recorder, 2000a).

Concern is expressed also about the threat of ge-

netic shrinkage related to the wide spread use of

relatively few GE cotton varieties.

However, farmers are still confident with

transgenic cotton, as it is widely acknowledged that

conventional technology alone cannot meet the future

needs of food, feed and fiber. Therefore, biotechnol-

ogy in conjunction with conventional technology may

secure the increase of crop productivity and

sustainability.

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Integrated pest controlIntegrated pest control

Integrated pest control

Following years of intensive pesticide applications,

there are many cases where the efficacy of insecticides

has declined gradually, resulting in increasing num-

bers of applications and high risk to the economic vi-

ability of the crop. Also changes in the susceptibility to

some conventional and novel insecticides have been

observed (Horowitz et al., 1998). As a result of ineffec-

tive pest control, Integrated Pest Management (IPM) aims

to control insects, diseases and weeds by alternative

means in conjunction with decreased use of chemicals

to avoid pollution of the environment, decrease the build

up of resistance, and restore sustainability in cotton

growing.

The ICAC Recorder (2000b) issued a compre-

hensive paper on Integrated Pest Management in Cot-

ton. The term integrated pest management is over 40

years old. Now, IPM is more commonly associated with

cotton than any other crop, as the cost of complications

from excessive use of pesticides pushed researchers and

farmers to think of alternative approaches to pest con-

trol. According to the Food and Agriculture Organiza-

tion of the United Nations, IPM is “a broad based eco-

logical approach to pest control utilizing a variety of

control technologies compatible in a pest management

system”. IPM is a durable, environmentally and eco-

nomically justified pest control system whereby dam-

age caused by pests is prevented through the use of

natural factors and, if needed, supplemented with ap-

propriate chemical control measures. Even though

IPM is still not fully implemented in many countries, the

significance of a multi-dimensional approach to pest

control in cotton has increased tremendously in the last

few years and is now accepted as the best approach to

pest control in terms of long-term sustainability of cot-

ton production, environmental protection, human safety

and sound profitability (ICAC Recorder, 2000b).

The current trend shows that the role of IPM in

the sustainable cotton production system will increase.

The main components of IPM in broad terms are: cul-

tural control, biological control, host plant resistance,

and chemical control.

IPM does not exclude rational use of insecticides

and relies on the use of damage thresholds to decide

when to apply pesticide products. The category of host-

plant resistance includes genetically engineered Bt cot-

ton and varieties resistant to certain herbicides. Bt-cot-

ton could supply a very successful element of an inte-

grated control strategy in countries where these variet-

ies are allowed to be grown (organic farming excludes

GM varieties). However, it must be emphasized that

the continual use of Bt cotton most probably will change

the biological balance of the pest complex. If a par-

ticular minor pest is suppressed for years, it may be-

come a major pest with the changed pest control

scheme, and new pests may also subsequently appear

on cotton. Bt cotton has been utilized so far rather as

an additional component of IPM rather than a founda-

tion of the whole IPM system, as many would like it to

be (ICAC Recorder, 2002b).

Fundamental principles of the IPM program are

assumed to be the same in different countries and re-

gions. However, generic recommendations have to be

adjusted in a particular country, or even according to

different areas within countries, according to the pest

complex, agroclimatic conditions, varieties, growing

conditions, and even target yields and farmers’ capa-

bilities (ICAC Recorder, 2000b).

In the framework of a combination of operations

undertaken by the farmer to produce conditions unfa-

vorable for pests to survive or multiply, the following

practices are of importance:

• Crop rotation that interrupts the normal life cycle of

a pest by changing the environment to one in which

the pest cannot flourish or even survive.

• “Mating disruption”, involving the use of sex phero-

mones and the release of sterile moths. These tech-

niques have proved very successful in the control of

the pink bollworm (Pectinophora gossypiella).

• Optimum plant nourishment.

• Weed-free and clean fields (cutting and incorpora-

tion of cotton stems immediately after harvest re-

duces bollworm and pink worm populations).

• Allelopathy for weed control.

• Crop monitoring.

• Cover crops for weed control.

• High plant populations for Verticillium wilt integrated

control.

• Appropriate time of sowing, early sowing, and uni-

form planting to avoid late generations.

• Maximum possible period between crops in order

to provide the longest host-free periods.

• Use of acid delinted seed.

• Use of biological control.

• Application of insecticides according to existing

populations of harmful and beneficial insects es-

pecially for the start of sprayings (Conway and Kring,

2001). Preservation and augmentation of natural

enemies is a key component of pest management

programs (Kharboutli, 2001).

• Use of selective insecticides for the protection of

useful insects.

• Safe and effective use of pesticides. Definition of

economical thresholds. Use of insects’ traps for

counting insect catches. The ability to have daily

state wide information on adult moth activity (e.g.

for Lepidoptera) leads to improved decision-mak-

ing capabilities for producers, especially on an

Internet information delivery system for reporting

Heliothis moth trap catches (Bridges et al., 2001).

• Careful selection of the appropriate pesticide, dose

and sprayer.

• Host plant resistance.

• Early maturing varieties (fewer applications).

• Use of specific morphological and physiological

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Cape Town - South Africa

characters e.g. nectariless and high gossypol.

• Use of insect traps for counting insect catches.

ConclusionsConclusions

Conclusions

Sustainable cotton production demands higher

level of skill than conventional production. More re-

search is needed to provide reliable guidelines for an

efficient and competitive sustainable production. The

World Summit’s issue in Johannesburg was that

sustainability and development must be integrated and

that both bioengineering and organic farming can play

their own role. We believe that this issue is correct.

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