The Economic Impact of Weeds and Their Control in Turkey
Yakup Erdal ERTÜRK1
İlhan ÜREMİŞ2
Ahmet ULUDAĞ3
Abstract
Weeds are among limiting factors in maize production, which is an important crop in Turkey. There
are common problematic weeds in all maize producing regions of Turkey although there are some
different problems in some regions due to varying climate and soil factors, and cropping practices.
When weeds are left for interfering with maize during entire cropping season, 31-65 % of crop lost
depending on locations and years. The cost of weed control in maize in Turkey in 2011 was assessed
as roughly 154 million TL (1 €= 2.322 TL as average in 2011) which might caused saving 50 % of
current maize production of Turkey which was 4 200 000 tons in 2011. The return was calculated as
over one billion TL due to weed control in maize.
INTRODUCTION
Maize is an important crop with its various uses from animal husbandry to industry. It is mainly a
fodder crop with its 64% use worldwide. However, it is produced 45% for human consumption in
Turkey, which is 19% only worldwide (Turgut, 2002). The Black Sea, the Marmara, the Aegean, the
Southeast Anatolia and the Mediterranean Regions of Turkey are main maize producing regions
although it is sown all over Turkey for farmers’ own consumption (Table 1).
Table 1. Maize producing regions of Turkey their share in area and production in 2007 (Source:
Ozcan, 2009)
Regions
Mediterranean
Area Sown (ha)
197,867
Production (ton)
1,681,714
Yield (ton/ha)
8.50
Aegean
65,582
511,900
7.81
East Marmara
64,547
456,423
7.07
Southeast Anatolia
53,079
439,702
8.28
West Black Sea
64,726
179,028
2.77
East Black Sea
43,529
84,773
1.95
West Anatolia
11,671
76,665
6.57
West Marmara
10,150
68,190
6.72
Central East Anatolia
3,188
19,545
6.13
Central Anatolia
2,119
15,592
7.36
498
1,478
2.97
Northeast Anatolia
The world maize areas reached to 163 million hectares with 8.7% increase and production 824 million
metric tons with 15.4% in the last 5 years. Bioethanol production, increase in fodder demand, climatic
factors such as drought and raise in crop prices are among main drivers of increases in maize areas and
productions (Daşdan et al. 2011).
1
Assist. Prof. Dr., Department of Agricultural Economics, Igdir University
Prof. Dr., Department of Plant Protection, Mustafa Kemal University
3
Assoc. Prof. Dr., Department of Plant Protection, Igdir University
2
Maize producing area in Turkey has been about 600 000 hectares since 1960s in spite of year by year
fluctuations (FAO, 2012). The area decreased in late 1980s but mainly it as ascended for last decade
(Table 1). Maize yield have had a steady increase since 1960s. The yield was 1400 kg/ha in 1961 and
over 7 tons in 2010 (FAO, 2012). It was almost doubled after mid 2000s (Table 2) due to some
financial and technical support systems.
Table 2. Maize production in Turkey (1990-2011) (Source: Ministry of Agriculture)
Year
1990
1995
2000
2005
2006
2007
2008
2009
2010
2011
Area Harvested
(1000 ha)
515
515
555
600
536
517
595
592
594
589
Increase in Area
(%)
0,01
0,06
0,07
0,10
-0,11
-0,03
0,15
-0,01
0,00
-0,01
Production
(Ton)
Increase in Production
(%)
2.100.000
1.900.000
2.300.000
4.200.000
3.811.000
3.535.000
4.274.000
4.250.000
4.310.000
4.200.000
0,05
0,03
0,00
0,40
-0,09
-0,07
0,21
-0,01
0,01
-0,03
Yield
(kg / ha)
4080
3690
4140
7000
7110
6830
7180
7180
7260
7130
Pests are among factors causing crop losses in quantity and quality and requiring extra costs to control
them. It has been known that there are over 400 pests, 60 diseases and some weed species interfere
with maize production worldwide. Pests in Turkey in maize show similarity with common pests
worldwide. Ostrinia nubilalis, Sesamia nonagrioides, Agrotis spp., Helicoverpa armigera,
Rhopalosiphum spp., Spodoptera spp., Tetranychus spp., Mythimna spp. and Nezara viridula are
important pests in maize in Turkey. Helminthosporium spp. and Fusarium spp. are main disease
agents in Turkey’s maize production.
Weeds also cause crop losses in maize if they are not controlled. Weeds could cause potentially 37%
crop loss in the world production. There has been 10% (5 to 17% depending on regions) actual crop
loss worldwide in spite of application of weed control measures (Oerke and Dehne, 2004)
The aim of current paper is to review weed problem in maize production and assess economic impact
of weeds and weed control in Turkey.
WEED PROBLEM IN MAIZE IN TURKEY
Due to climatic, geographic, and edaphic differences in maize producing areas of Turkey and varying
cropping techniques, field sizes, and economical levels, foremost weed species change region to
region. However, there are many common species.
In the Samsun province in the Black Sea Region, weed species reduced from 43 species in 1973 to 30
species in early 2000s (Mennan and Isik, 2003; Ozduman, 2005). Sorghum halepense (L.) Pers. and
Cynodon dactylon (L.) Pers. were among important species in 1973. No narrow leaf species except
Alopecurus myosuroides Hudson was among important species in 2000s where Artemisia vulgaris L.
and Convolvulus arvensis L. were only important perennials. Inner part of the Black Sea Region
(Kazova area), C. arvensis was only perennial species in top 10 common species (Kacan et al. 1997).
Echinochloa crus- galli (L.) P. Beauv. , Setaria spp. and Digitaria sanguinalis (L.) Scop. were narrow
leaf species.
In the Cukurova plain in the Mediterranean Region of Turkey, 18 species were mentioned most
common and dense species (in the alphabetical order): Amaranthus albus L., A. retroflexus,
Amaranthus viridis L., Chrozophora tinctoria (L.) Rafin., Convolvulus arvensis L., Cyperus rotundus
L., Echinochloa colonum (L.) Link, E. crus-galli, Euphorbia chamaesyce L., Hibiscus trionum L.,
Paspalum paspalodes (Michx.) Schrib., Physalis alkekengi L., Portulaca oleracea L., Prosopis farcta
(Banks and Sol.) Macbride, Setaria viridis L., Solanum nigrum L., S. halepense, Xanthium
strumarium L. (Orel, 1996). Other studies in the region give the same species with different
importance orders (Gonen, 1999; Oksar, 2000).
Actualy maize in the Cukurova plain as well as the Aegean and the South Anatolian Regions was
produced as main crop or the second crop following small grain harvest in general. The second crop
maize consists 26% of the total maize production of Turkey (Dagdelen and Gurbuz, 2008). Farmers’
view for the most problematic species for the both cropping type was similar for two types of
productions in the Cukurova Region. Echinochloa spp., Amaranthus spp., Sorghum halepense,
Setaria spp. and Portulaca oleracea were the top five problematic species in the main crop maize
while Setaria spp., Xanthium strumarium, Echinochloa spp., Amaranthus spp., and Sorghum
halepense in the second crop maize in the order of magnitude by farmers (Gungor, 2005). In the field
surveys in the second crop maize those species were detected over 50% of fields except Setaria
viridis. However, S. viridis was the densest species in the region. Cyperus rotundus was among the
most common and dense species, which was in the sixth rank as farmers’ preference.
There has been no study about weed problem in maize in the other maize producing regions. However,
similarities problematic weeds in other summer crops such as cotton in those regions, problematic
weeds in the Southeast Anatolia, the Aegean and the Marmara Regions are similar to Mediterranean
Region where also later two are located in the same phyto-geographic region with Mediterranean and
the former is next to Mediterranean Region.
If weeds were left during entire season, studies with natural weed stands, which were mainly common
weeds of the regions of Turkey, showed that maize yield can be reduced 34-65% depending on year in
the main crop corn in the Aegean Region and 49% in the second crop maize (Dogan et al. 2004). In
the Cukurova plain crop loss changed from 38 to 61% in the second crop maize due to season-long
weed competition (Uremis et al. 2009).
WEED CONTROL IN MAIZE IN TURKEY
Critical period for weed control (CPWC) was found 3 to 10 leaf stage in the Aegean Region (Dogan et
al. 2004). CPWC in the second crop maize was calculated in the Mediterranean Region as 131 to 927
growing degree days (GDD) after sowing in 1996, 337 to 731 GDD in 1997 and 266 to 551 GDD in
1998 for 10% yield loss; for 2.5 - 5% yield loss, the critical period starts with germination and lasts
longer (Uremis et al. 2009). They suggested that preemergence (PRE) or presowing (PPI) herbicides
would be preferred to avoid higher yield losses. However, a postemergence (POST) herbicide can be
applied in the second week after crop sowing, and the field should be kept weed free for 4 or 5 weeks
if a farmer can tolerate 10% yield loss.
Hand hoeing, interrow tillage and herbicide applications are the common weed control methods in
maize production. The effect of methods on maize yield differs. In fact, weedy treatments yielded less
than sole hand hoeing, interrow tillage with hand hoeing, and herbicide application at 17.6, 19.9, and
37.9%, respectively, in the Southeast Anatolian Region (Oktem et al. 2004). Some farmers apply
interrow tillage twice, hand hoeing is common practice of small farmers. In addition earthen can be
considered a weed control method although weeding is not the main aim (Uremis, 1993)
Farmers chose different methods and their combinations. Sole hand hoeing was chosen by only 2% of
farmers while interrow tillage by 27%, interrow tillage with hand hoeing by 47%, PRE herbicides by
8% and POST herbicides by 16% in the Hatay Province of the Mediterranean Region (Gozubenli et al.
2000).
The number of herbicides applied was changed depending on crop type and year in the Çukurova
Region (Gungor, 2005). One herbicide applied by 28, 44, 34% of main crop maize producers and 20,
32, 40% by the farmers producing second crop in 2002, 2003, and 2004, respectively. The percentage
of farmers who applied herbicides more than once was less: 8, 14, and 2% in main crop and 2, 5, 9%
in the second crop depending on growing years above mentioned. Herbicide application time choice of
farmers showed fluctuations year by year (Gungor, 2005). PRE was chosen 46.88, 44.93, and 68.42%
by main crop maize producing farmers and 28.00, 16.28, and 29.82% by the second crop producers in
2002, 2003, and 2004, respectively. Remaining of farmers who applied herbicides chose POST
application. Herbicide choice of farmers not only affected by cost and weed species; but also
regulations, companies’ marketing techniques and farmers’ habits. The main crop maize producers’
main choice was acetochlor followed by nicosulfuron and foramsulfuron. In the second crop maize
2,4-D and rimsulfuron also applied beside above three herbicides (Gungor, 2005). It is surprising that
farmers mainly used few herbicides among many registered choices in those years. Due to prohibition
by Turkish Ministry of Agriculture, few choices, especially PRE, remained. Currently Isoxaflutole,
Linuron, Acetochlor, and Pendimethalin for PRE, 2.4-D, Florosulam, Bromoxynil, Pyridate,
Rimsulfuron, Nicosulfuron, Foramsulfuron, Iodosulfuron, Isoxadifen, Mesotrione, Tritosulfuron,
Dicamba for POST are available registered herbicides as solo and/or mixtures.
COST OF WEED CONTROL
Main production and cost components of maize production are presented in Table 3. Among activities
showed in the table, weed control under plant protection and interrow tillage/rotatilling directly aim
weed control. However, Plowing, tillage in spring, disking, harrowing for seedbed preparation,
earthing up and preparation of irrigation ditches requires special attention if weed pressure is high in
the given field. Under such a condition, all those activities can be considered as weed control
technique. But we added only half of the cost as weed control cost for those processes. The compiled
list of weed control techniques in maize and their costs are given in Table 4. Consumption of diesel
was taken from a report of Cukurova Irrigation Association (CSB, 2009) and price of rural diesel,
which was average 3.64 TL per litre for 2011, obtained from Energy Market Regulatory Authority
(EPDK, 2012). We assumed a flat rate 5 TL per ha for labor. Indeed, Labor cost was 3.6% of overall
maize production costs (Aktas and Yurdakul, 2005). Total cost of weed production for maize was
calculated as 373.1 TL for 2011 /Table 4).
Table 3. Main cost components of maize production (Anonymous, 2011)
Components for Maize Production
Field Lease
Plowing in Autumn
Tillage in Spring
Disking-harrowing (up to 3 times)
Seed purchasing
Seeding with pneumatic machine
Smooth roller (up to 2 times)
Fertilizer and Fertilizing
Interrow tillage - Rotatilling - Earthing up - Preparing irrigation ditches
Water and irrigation
Plant protection (Weeds, Pests)
Harvest
Transportation of produce
Guard
Table 4. Calculation of weed control costs in maize
Cost Components
Diesel consumption
(l/ha)
Plowing
Tillage
Interrow tillage ( 3 times)
Preparing irrigation ditches
Earthing up
Herbicide
Smooth roller
30
30
10
10
10
10
10
Cost
(TL/ha)*
109.2
109.2
109.2
36.4
36.4
36.4
36.4
Total
Part of Cost for
weed control
(TL/ha)
54.6
54.6
109.2
18.2
18.2
36.4
18.2
0,0
Labor and
herbicide
(TL/ha)
Total Cost
(TL/ha)
58.7
5.0
TOTAL
54.6
54.6
109.2
18.2
18.2
95.1
18.2
5.0
373.1
*1€=2.322 TL average of entire year for 2011
No all farmers apply the same processes. Some farmers practice less than 3 times interrow tillage.
Farmers used herbicide in the Cukurova Region where is the most pesticide consuming for a given
area part of Turkey were about 36% mostly (Gungor, 2005). Regarding to those data and observations,
we might say one third of maize farmers spent 373.1 TL for weed control. It can be assumed the
remaining might spend 205.2 TL per hectare for weed control excluding herbicide costs and reducing
interrow tillage costs. The area sown in 2011 was 589 000 ha. Using these assumptions, the cost of
weed control in maize in Turkey in 2011 was roughly 154 million TL.
Regarding to crop loss data from Dogan et al (2004) and Uremis et al (2009), weeds without any
control measure can reduce maize yield from 34 to 65% depending on year. We might assume 50%
maize crop loss as average. It means 2 100 000 ton maize was gained applying weed control
techniques, which the maize production of Turkey was 4 200 000 tons in Turkey in 2011. The
monetary value of saved crop for 2011 was assessed 1,323,000,000 TL(average price of maize was
0.63 TL/kg), which means over 1 billion TL return was obtained by farmers. However, average 10%
loss is still occurs under weed control measures worldwide (Oreke and Dehne, 2004). It means,
probably under ideal weed control measurements, it would have saved another 500 000 tons maize,
roughly.
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