Modeling Ghanaian cocoa farmers’ decision to use pesticide and frequency of application: the case of Brong Ahafo Region

TL;DR: It is recommended that policies by government and non-governmental organisations should be aimed at mobilizing resources towards the expansion of extension education and extension service should target younger farmers as well as provide information on alternative pest control methods in order to reduce pesticide use among cocoa farmers.

Abstract: Pesticides are a significant component of the modern agricultural technology that has been widely adopted across the globe to control pests, diseases, weeds and other plant pathogens, in an effort to reduce or eliminate yield losses and maintain high product quality. Although pesticides are said to be toxic and exposes farmers to risk due to the hazardous effects of these chemicals, pesticide use among cocoa farmers in Ghana is still high. Furthermore, cocoa farmers do not apply pesticide on their cocoa farms at the recommended frequency of application. In view of this, the study assessed the factors influencing cocoa farmers’ decision to use pesticide and frequency of pesticide application. A total of 240 cocoa farmers from six cocoa growing communities in the Brong Ahafo Region of Ghana were selected for the study using the multi-stage sampling technique. The Probit and Tobit regression models were used to estimate factors influencing farmers’ decision to use pesticide and frequency of pesticide application, respectively. Results of the study revealed that the use of pesticide is still high among farmers in the Region and that cocoa farmers do not follow the Ghana Cocoa Board recommended frequency of pesticide application. In addition, cocoa farmers in the study area were found to be using both Ghana Cocoa Board approved/recommended and unapproved pesticides for cocoa production. Gender, age, educational level, years of farming experience, access to extension service, availability of agrochemical shop and access to credit significantly influenced farmers’ decision to use pesticides. Also, educational level, years of farming experience, membership of farmer based organisation, access to extension service, access to credit and cocoa income significantly influenced frequency of pesticide application. Since access to extension service is one key factor that reduces pesticide use and frequency of application among cocoa farmers, it is recommended that policies by government and non-governmental organisations should be aimed at mobilizing resources towards the expansion of extension education. In addition, extension service should target younger farmers as well as provide information on alternative pest control methods in order to reduce pesticide use among cocoa farmers. Furthermore, extension service/agents should target cocoa farmers with less years of farming experience and encourage cocoa farmers to join farmer based organisations in order to decrease frequency of pesticide application.

Full text

Modeling Ghanaian cocoa farmers’
decision touse pesticide andfrequency
ofapplication: the case ofBrong Ahafo Region
Elisha Kwaku Denkyirah
1
, Elvis Dartey Okoffo
2*
, Derick Taylor Adu
1
, Ahmed Abdul Aziz
4
, Amoako Ofori
2
and Elijah Kofi Denkyirah
3
Abstract
Pesticides are a significant component of the modern agricultural technology that
has been widely adopted across the globe to control pests, diseases, weeds and other
plant pathogens, in an effort to reduce or eliminate yield losses and maintain high
product quality. Although pesticides are said to be toxic and exposes farmers to risk
due to the hazardous effects of these chemicals, pesticide use among cocoa farm-
ers in Ghana is still high. Furthermore, cocoa farmers do not apply pesticide on their
cocoa farms at the recommended frequency of application. In view of this, the study
assessed the factors influencing cocoa farmers’ decision to use pesticide and fre-
quency of pesticide application. A total of 240 cocoa farmers from six cocoa growing
communities in the Brong Ahafo Region of Ghana were selected for the study using
the multi-stage sampling technique. The Probit and Tobit regression models were
used to estimate factors influencing farmers’ decision to use pesticide and frequency
of pesticide application, respectively. Results of the study revealed that the use of
pesticide is still high among farmers in the Region and that cocoa farmers do not
follow the Ghana Cocoa Board recommended frequency of pesticide application. In
addition, cocoa farmers in the study area were found to be using both Ghana Cocoa
Board approved/recommended and unapproved pesticides for cocoa production.
Gender, age, educational level, years of farming experience, access to extension
service, availability of agrochemical shop and access to credit significantly influenced
farmers’ decision to use pesticides. Also, educational level, years of farming experi-
ence, membership of farmer based organisation, access to extension service, access
to credit and cocoa income significantly influenced frequency of pesticide applica-
tion. Since access to extension service is one key factor that reduces pesticide use
and frequency of application among cocoa farmers, it is recommended that policies
by government and non-governmental organisations should be aimed at mobiliz-
ing resources towards the expansion of extension education. In addition, extension
service should target younger farmers as well as provide information on alternative
pest control methods in order to reduce pesticide use among cocoa farmers. Further-
more, extension service/agents should target cocoa farmers with less years of farming
experience and encourage cocoa farmers to join farmer based organisations in order
to decrease frequency of pesticide application.
Keywords: Pesticide, Cocoa farmers, Decision to use pesticide, Frequency of pesticide
application, Probit and Tobit regression models, Berekum Municipality, Ghana
Open Access
© 2016 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 International License
(http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium,
provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and
indicate if changes were made.
RESEARCH
Denkyirah
et al. SpringerPlus (2016) 5:1113
DOI 10.1186/s40064-016-2779-z
*Correspondence:
edokoffo@st.ug.edu.gh;
elvispogas@yahoo.com
2
Institute for Environment
and Sanitation Studies (IESS),
University of Ghana, P. O.
Box 209, Legon, Accra, Ghana
Full list of author information
is available at the end of the
article

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Denkyirah
et al. SpringerPlus (2016) 5:1113
Background
Agriculture plays a significant economic role for many countries in West Africa. Indeed,
the importance of agriculture to the growth of the Ghanaian economy cannot be over
-
emphasized in relation to the labour force it attracts. Agriculture is the largest sector of
the Ghanaian economy and the highest contributor to Ghana’s GDP, employing about
60% of the country’s labour force (ISSER 2010). e agricultural sector in Ghana is
dominated by tree crops such as cocoa, coffee, oil palm and rubber. Among these tree
crops, cocoa is of particular interest for Ghana and for the global chocolate industry
(Danso-Abbeam etal. 2014). e cocoa sector represents more than half (70–100%)
of the income for roughly 800,000 smallholder farm families in Ghana, providing food,
employment, tax revenue and foreign exchange earnings for the country (Appiah 2004;
Anim-Kwapong and Frimpong 2004; Ayenor etal. 2007; Anang 2011; Danso-Abbeam
etal. 2014).
Despite the economic importance of cocoa, its production in Ghana is threatened by
insect pests and diseases, a situation which has resulted in the decline in cocoa produc
-
tion, with adverse impact on the Ghanaian economy. A significant component of the
modern agricultural technology which has been widely adopted by cocoa farmers in
Ghana to prevent or control insect pests and diseases in order to reduce or eliminate
yield losses in cocoa and to maintain high product quality is pesticide.
However, the use of pesticide in agriculture, and for that matter the cocoa industry in
Ghana has raised a lot of concerns about the safety of residues in cocoa beans, soils and
water, as well as other potential harm to humans and the environment (e.g. destruction
of natural enemies of pest and the development of pest resistance) (Antle and Pingali
1994; Pimentel 2005; Adeogun and Agbongiarhuoyi 2009; Hou and Wu 2010; Adejumo
etal. 2014). In most developing countries like Ghana, these consequences have often
been severe because farmers do not use approved pesticides, and do not follow recom
-
mended frequencies of pesticide application by government agencies for crops. ey
however misuse, overuse and apply pesticides indiscriminately (Konradsen 2007; Sam
etal. 2008), with disregard to safety measures and regulations on chemical use.
is has expose farmers to risk due to hazardous effects of these chemicals. According
to Atu (1990), pesticides are toxic and can have serious health hazards on human beings.
WHO/UNEP (1990) reported that the use of pesticides is responsible for 3million acute
poisoning and results in about 20,000 deaths of farm workers annually mostly in devel
-
oping countries. It is also reported that exposure to pesticides have long term effects on
thyroid function, cause low sperm count in males, birth defects, increase testicular can
-
cer, reproductive and immune malfunction/problems, endocrine disruptions, dermati-
tis, behavioural changes, cancers, immunotoxicity, neurobehavioral and developmental
disorders (PAN International 2007; Mesnage etal. 2010; Tanner etal. 2011; Cocco etal.
2013; Gill and Garg 2014). Furthermore, Ntow etal. (2006), Pan-Germany (2012) and
Gill and Garg (2014) reported on the short term effects such as headaches, body aches,
skin or eye irritation, respiratory problems, weakness, dizziness, impaired vision and
nausea as a result of pesticide exposure.
Although studies have revealed that pesticide use poses threats to the environment
and farmers themselves, and that farmers can improve yields as well as increase prof
-
its following adoption of integrated pest management (IPM), integrated plant nutrition

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et al. SpringerPlus (2016) 5:1113
systems (IPNS) and other technologies (Pretty 1995), pesticide use is still high among
farmers in Ghana, particularly, cocoa farmers. e question that arises is “what are the
factors that influence the decision of a farmer to use pesticide”? Another major concern
aside the use of pesticide is the frequency of pesticide application. e Ghana Cocoa
Board (COCOBOD) recommends that for effective and sustainable control of pests and
diseases, cocoa farmers need to apply pesticides on their cocoa farms four times per sea
-
son (Adu-Acheampong etal. 2007). is notwithstanding, farmers do not apply pesti-
cide on their cocoa farms at the recommended frequency. e question that arises is
“what are the factors that influence frequency of application”? Knowing the factors that
influence pesticide use and frequency of application would enable stakeholders such as
Ghana COCOBOD and the Ministry of Food and Agriculture (MoFA), to identify the
specific issues (socio-economic characteristics) that influences cocoa farmer’s pesti
-
cide use and frequency of application in order to put up policies (such as Cocoa Disease
and Pest Control (CODAPEC) programme and IPM Farmer Field Schools) that would
reduce or increase pesticide use and frequency of application if necessary. In view of
this, it is imperative to assess the factors that influence cocoa farmers’ decision to use
pesticide and frequency of pesticide application.
Although studies have assessed factors influencing farmers’ choice of pesticide or
use of pesticide (Adejumo etal. 2014; Anang and Amikuzuno 2015), little information
is known in the case of Ghana, particularly, on cocoa farmers. Also, studies which sort
to assess frequency of pesticide application (Avicor etal. 2011; Oesterlund etal. 2014;
Antwi-Agyakwa etal. 2015), only described the frequency of pesticide application and
did not estimate the factors which influence frequency of pesticide application.
One of the major cocoa producing regions in Ghana is the Brong Ahafo Region. In
order to control insect pests and diseases and increase cocoa yield, farmers in the region
use pesticides extensively. ese chemicals are however used improperly or in danger
-
ous combinations with disregard for approved pesticides and recommended frequency
of application by Ghana COCOBOD for cocoa production. In view of this, the question
that arises is “why do cocoa farmers use approved pesticides in combination with unap
-
proved pesticides and with disregard for the recommended frequency of application”?
Unfortunately, there is little documentation on pesticides management by cocoa farmers
in the region. is study therefore seeks to analyse the pesticides used by cocoa farmers,
frequency of pesticide application, the factors influencing cocoa farmers’ decision to use
pesticide and the factors influencing frequency of pesticide application by cocoa farmers
in the Berekum Municipality of the Brong Ahafo Region of Ghana.
Methods
The study area
e study was carried out in the Berekum Municipality. It lies between latitude 7′15°
South and 8′00° North and longitude 2′25° East and 2′50° West. Berekum Municipality
lies in the North-western corner of the Brong Ahafo Region of Ghana. e Municipality
covers total land area of about 863.3q.km. e Municipality lies within the wet semi-
equatorial climate zone which occurs widely in the tropics and it experiences a maxima
pattern of rainfall with a mean annual rainfall ranging between 1275 and 1544mm in
May to June (Berekum Municipal Assembly report 2013). Basically the Municipality has

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the most semi-deciduous forest type of vegetation which covers 80% of the entire stretch
of the land. e population of Berekum Municipality, according to the 2010 Population
and Housing Census, is 129,628 representing 5.6 percent of the region’s total population.
More than half (57.0%) of households in the municipality are engaged in agriculture.
Most householdsengaged in agriculture in the municipality (97.6%) are involved in crop
farming (Ghana Statistical Service 2014). Soils in the municipality fall into the ochrosols
group which is generally fertile and therefore support the cultivation of cocoyam, maize,
cassava, cocoa and plantain.
Sampling technique andsample size
A total of 240 cocoa farmers were selected for the study using the multi-stage sam-
pling technique. At the first stage, the Brong Ahafo Region of Ghana was purposively
selected due to the predominance of cocoa production in the region. At the second
stage, the Berekum Municipality was randomly selected out of the several cocoa pro
-
ducing districts in the region. At the third stage, six (6) cocoa growing communities,
namely, Koraso, Kutre no. 1 and 2, Senase, Kato, Biadan and Ayimom in the district were
randomly sampled. At the fourth stage, a minimum of forty (40) cocoa farmers were
selected from each of the six cocoa growing communities. All participants agreed to par
-
ticipate in the research study by signing informed consent forms.
Instrumentation fordata collection
A pre-tested semi-structured questionnaire was developed as an instrument for data
collection. e structure of questions in the data collection instrument was a combi
-
nation of close-ended, open-ended and partially close-ended questions. e survey was
conducted from March 2015 to July, 2015.
Analytical framework
A farmer is assumed to make choices or adopt a particular technology which maximizes
his or her utility. e choice a farmer makes to either use or not to use a particular tech
-
nology is estimated using the discrete choice models. e two models used to estimate
farmers’ choice to use a particular technology or not are the logistic regression or logit
and probabilistic regression or probit models. e dependent variable of these models
takes the form of a dummy variable equal to 1 if a farmer chooses to use a particular
technology and 0 if otherwise. e major difference between these two models is the
distribution of the error term, ε. For the logit model, the error term is assumed to have
the standard logistic distribution while the error term for the probit model is assumed to
have the standard normal distribution (Bryan etal. 2009). e probit model was adopted
for this study because it has the ability to resolve the problem of heteroscedasticity
and also has the ability to constrain the estimated probabilities to lie between 0 and 1
(Asante etal. 2011). Again, economists tend to prefer the normality assumption of the
probit model, given that several specification problems are more easily analyzed because
of the properties of the normal distribution (Wooldridge 2006). If we assume a depend
-
ent variable Y having only two possible outcomes as 1 and 0 and which is influenced by
independent variables X, the probit model takes the form:
(1)
Pr(Y = 1|X ) = ϕ(X
′
β)

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where Pr denotes probability and φ denotes the cumulative distribution function of the
standard normal distribution. e maximum likelihood analysis is used to estimate the
parameters (β). e probit model can further be written as:
where Y denotes the discrete choice variable; F denotes the cumulative probability distri
-
bution function; β denotes the vector of parameters; x denotes the vector of explanatory
variables; z denotes the Z-score of βx for the area under the normal curve.
e probit model can be specified as a linear function of the variables that determine
the probability:
Marginal effect is estimated for Xi. e marginal effect of X
i
is ∂p/∂X
i
and is computed
as:
f (Y) is the derivative of the cumulative standardized normal distribution and is just
the standardized normal distribution itself:
e cumulative standard normal distribution is given as F (Y) and it gives the probabil
-
ity of the event occurring for any value of Y:
Furthermore, the Tobit regression model was used to estimate the frequency of pes
-
ticide application. is is because there is a possibility that not all the farmers may use
pesticides. Frequency of pesticide application for such group of farmers who do not use
pesticide was captured as zero. e Tobit model is a better choice than the ordinary least
square estimates because the ordinary least square presents censoring bias. Also, the
Tobit model interprets all the zero observations in the data set as corner solution. is
model has been used in many studies (Nkamleu 2004; Holloway etal. 2004; Oladede
2005; Nkamleu etal. 2007; Nkamleu and Tsafack 2007) to estimate farmers’ adoption of
technology packages.
where
FPA
∗
i
is the observed response on the frequency of pesticide application. x is the
vector of independent variables, β is a vector of parameters and ui is the error term
which is randomly distributed.
(2)
Y = F (α + βx
i
) = F (z
i
)
(3)
Y = β
0
+ β
i
X
i
+···+β
n
X
n
(4)
∂
p/∂X
i
=
∂p
∂Y
∂Y
∂X
i
=
f (Y )β
i
(5)
f (Y )
=
1
√
2π
e
−
1
2
Z
2
(6)
P
i
= F (Y )
FPA
i
=
FPA
∗
i
if FPA
∗
i
>
0
FPA
∗
i
= 0 if otherwise
(7)
FPA
∗
i
=
xi
′
β
+ ui