The difficulty of manual hoe weeding presents a major challenge to the adoption of conservation agriculture (CA) by smallholder farmers in Zimbabwe. Herbicide use is known to reduce manual hoe weeding requirements during the season while increasing economic returns. Studies to determine the efficacy of herbicides in maize under CA were carried out in Zimbabwe. The treatments evaluated were:(i) manual hoe weeding (ii) paraquat (0.2 kg a.i. ha-1) (iii) glyphosate (1.025 kg a.i ha-1) (iv) atrazine (1.8 kg a.i. ha-1) (v) glyphosate (1.025 kg a.i ha-1) + atrazine (1.8 kg a.i. ha-1) (vi) glyphosate (1.025 kg a.i ha-1) + atrazine (1.8 kg a.i. ha-1) + metolachlor (1.152kg a.i. ha-1). Greater efficacy of weed control was higher in herbicide treated plots compared to hoe weeding alone. Atrazine combined with other herbicides or alone significantly (P<0.05) suppressed Garlinsoga parviflora, Bidens pilosa and other broadleaf weeds that dominated the weed spectrum at study sites. A tank mix of glyphosate + atrazine + metolachlor had significantly higher (P<0.05) maize grain yield than hoe weeding alone. Results showed that herbicides lowered weeding time requirement and were more effective in controlling weeds than manual hoe weeding alone. Farmers are thus likely to enjoy more net economic benefits if they adopt herbicide use as a weed control strategy in CA systems.

1. Evaluation of the Efficacy of Herbicides during Transition to Conservation Agriculture in Zimbabwe
Evaluation of the Efficacy of Herbicides during Transition
to Conservation Agriculture in Zimbabwe
Muchineripi H. George
Faculty of Agriculture and Natural Resources, Africa University, Box 1320, Mutare, Zimbabwe
E-mail: gmuchineripi@yahoo.co.uk
The difficulty of manual hoe weeding presents a major challenge to the adoption of conservation
agriculture (CA) by smallholder farmers in Zimbabwe. Herbicide use is known to reduce manual
hoe weeding requirements during the season while increasing economic returns. Studies to
determine the efficacy of herbicides in maize under CA were carried out in Zimbabwe. The
treatments evaluated were:(i) manual hoe weeding (ii) paraquat (0.2 kg a.i. ha-1
) (iii) glyphosate
(1.025 kg a.i ha-1
) (iv) atrazine (1.8 kg a.i. ha-1
) (v) glyphosate (1.025 kg a.i ha-1
) + atrazine (1.8 kg
a.i. ha-1
) (vi) glyphosate (1.025 kg a.i ha-1
) + atrazine (1.8 kg a.i. ha-1
) + metolachlor (1.152kg a.i. ha-
1
). Greater efficacy of weed control was higher in herbicide treated plots compared to hoe weeding
alone. Atrazine combined with other herbicides or alone significantly (P<0.05) suppressed
Garlinsoga parviflora, Bidens pilosa and other broadleaf weeds that dominated the weed
spectrum at study sites. A tank mix of glyphosate + atrazine + metolachlor had significantly higher
(P<0.05) maize grain yield than hoe weeding alone. Results showed that herbicides lowered
weeding time requirement and were more effective in controlling weeds than manual hoe weeding
alone. Farmers are thus likely to enjoy more net economic benefits if they adopt herbicide use as
a weed control strategy in CA systems.
Key words: weed control, conservation agriculture, economic benefits, herbicides, weeds
INTRODUCTION
Maize (Zea mays L.) is the world’s third most important
cereal grain (Naveed et. al., 2008) and in Zimbabwe it is a
staple crop where smallholder farmers produce more than
70% of the crop annually. Manual hoe weeding remains
the predominant weed control method used by most
smallholder farmers to control weeds (Vissoh et. al., 2004),
but this method is slow, labour-intensive and inefficient
(Chivinge, 1990). Weed competition early in the
development of maize is one of the most serious and
widespread production problems faced by smallholder
maize farmers in Southern Africa (Waddington and
Karigwindi, 1996). In conservation agriculture (CA), weed
pressure usually increases in the initial stages of adoption
due to concentration of weed seeds on the soil surface
layers. Management of the increased weed densities
during the transition phase from conventional ploughing
(CP) to CA requires a weed management system that
reduces drudgery on farmers. The reduction of weeding
and the associated drudgery involved is a key issue that
needs addressing to enhance the performance of African
farmers (Sibuga, 1999), especially in CA systems were
absence of tillage poses new challenges for farmers
(Shrestha et. al., 2006).
In CA systems shallow manual or hand weeding in the top
layer of the soil, use of herbicides or a combination of both
methods can be employed to deal with weeds (Vogel,
1994). Use of hand weeding requires several weeding
operations in a single maize cropping season (Baudron et.
al, 2005). However, the frequency of hoe weeding to avoid
yield loss can be reduced when weeding is combined with
other weed management options such as the use of
herbicides (Vogel, 1994). Limiting factors that deter
smallholder farmers from using herbicides include poor
Research Article
Vol. 7(2), pp. 248-253, October, 2020. © www.premierpublishers.org. ISSN: 2326-3997
World Research Journal of Agricultural Sciences

2. Evaluation of the Efficacy of Herbicides during Transition to Conservation Agriculture in Zimbabwe
Muchineripi G.H 249
access to herbicides, sprayers, high costs of herbicides
and lack of knowledge for proper herbicide application
(Steiner and Twomlow, 2003).
The downside of herbicide use by farmers is the potential
for adverse impacts to human health, non-target
organisms and the environment. Risks are always present
with any herbicide use, but improper use or improper
application can increase these risks. Applying herbicides
according to label instructions and established safety and
health procedures minimizes herbicide exposure to
humans and the environment. Different herbicides have
different persistence periods in the environment. One way
of reducing environmental pollution by herbicides is to
reduce the amount of these chemicals applied to crop
lands. Studies by Mashingaidze (2004) showed that using
half the recommended dosages of atrazine and
nicosulfuron resulted in the lowest weed biomass. Using
herbicides that are rapidly broken down in the environment
may also lower environmental pollution. Glyphosate is
known to be rapidly broken down after application making
it less persistent in the environment thereby making its use
less harmful to the environment (Mamy et. al., 2010).
The ever-increasing costs of labour makes chemical weed
control an attractive alternative for smallholder farmers.
The objectives of this study were to: (i) evaluate the
efficacy in controlling weeds of different herbicides or their
combinations in maize grown under CA and (ii) evaluate
the economic benefits of different herbicides or their
combinations on maize grown under CA in comparison to
manual hand weeding alone.
MATERIALS AND METHODS
The study was undertaken at two locations, International
Maize and Wheat Improvement Centre (CIMMYT) mid
altitude research station located at the University of
Zimbabwe farm outside Harare (17o80’S; 31o5’E) and
Hatcliffe Institute of Agriculture Engineering (17°42’S;
31°08’E). The soils at both sites were red clay loams.
Treatments
T1: Manual hoe weeding alone (No herbicide applied
but plots were hand weeded with hoes)
T2: Paraquat at a rate of 0.2 kg active ingredient (a.i.)
ha-1 applied at planting of maize seed.
T3: Glyphosate at a rate of 1.025 kg a.i ha-1 applied at
planting of maize seed
T4: Atrazine at a rate of 1.8 kg a.i. ha-1 applied at
planting of maize seed
T5: Glyphosate (1.025 kg a.i. ha-1) + Atrazine (1.8 kg a.i.
ha-1) applied at planting of maize seed
T6: Glyphosate (1.025 kg a.i. ha-1) + Atrazine (1.8 kg a.i.
ha-1) + Metolachlor (1.152kg a.i. ha-1) at planting of
maize seed
NB: After crop emergence all plots were hand weeded
with hoes each time when weeds were 10 cm tall or
10 cm diameter for prostrate type weeds.
Experimental procedure
The trial layout was a randomized complete block design
(RCBD) with six treatments and three replicates per each
site. The gross plot size was 6.3m x 6m. Plant spacing was
0.9m x 0.25m, 2 seeds were placed per each planting
station and later thinned to one plant. Land was not tilled
and 2.5-3 t / ha maize residues were spread uniformly in
the plots to achieve 50 % ground cover. Compound D (8%
N: 14 % P2O5: 7% K2O) at 150 kg/ha was applied at
planting and 150 kg/ha ammonium nitrate (34.5% N) was
applied as top dressing, split equally in two dressings: one
at 4 weeks after emergence and the other at 7 weeks after
emergence. Weeding was done each time there were 10
cm tall or 10 cm long (diameter)for prostrate type weeds.
Field measurements
Before each weeding operation weed counts were taken
using a 0.5m x 0.5m quadrant which was randomly placed
at four places in each plot. Weed samples of each species
were cut at ground level. The samples were dried to a
constant mass in an oven at 66C. Comparison of weed
densities was done on the total weed density and for
Bidens pilosa and Garlinsoga parviflora the dominant
weed species at both sites.
At each site, one person weeded each replicate and the
time taken to weed each plot measured. Grain yield was
estimated from a net plot (harvest area) of 4 rows by 5m
after attainment of physiological maturity. The maize grain
was dried to 12.5% moisture content and yield per hectare
calculated from the net plot yield.
Data Analysis
Total weed density was converted to unit area (1m2). Weed
densities were transformed using common logarithm log10
(x+1) to achieve normal distribution and homogeneity of
variances (Gomez and Gomez, 1984.). Analysis of
variance (ANOVA) was carried out on the total weed
density and densities of dominant weed species using
STATISTIX version 9. Comparison between significantly
different means was done using the least significant
difference (LSD) test at 5% level.
Economic analysis was done according to
recommendations from the CIMMYT economic training
manual (CIMMYT, 1988).
Yield was adjusted downwards by 10 percent. The
adjusted yield for a treatment was the average yield
adjusted downward by 10% to reflect the difference
between the experimental yield and the yield farmers could
expect from the same treatment (CIMMYT, 1988).

3. Evaluation of the Efficacy of Herbicides during Transition to Conservation Agriculture in Zimbabwe
World Res. J. Agric. Sci. 250
The formula used to adjust yield downwards by 10 % was:
Adjusted yield = Actual average yield x 0.9
Gross field benefits for each treatment were calculated
using the average prevailing price of maize of US$265 per
tonne that was offered by most buyers. The gross field
benefits were calculated using the formula below:
Gross field benefits = Adjusted yield X Field price
(US$265).
The total costs that varied for each weed control strategy
were calculated. In this case, the costs that varied were
those associated with weed control (i.e. cost of herbicide,
cost of labour to apply herbicide and cost of labour for hand
weeding). The herbicide or herbicide combinations used
under each treatment was measured and the costs per
hectare calculated. Net economic benefits were calculated
using the formula below:
Net economic benefits = Gross field benefits ($/ha) – Costs
that vary ($/ha)
The next step in the analysis was dominance and marginal
analysis. Dominance analysis was carried out by listing the
weed control strategies in order of increasing variable
costs. Any weed control strategy that had net benefits that
were less than or equal to those of a weed control strategy
with lower costs that vary was deemed to be dominated
and was thus eliminated from further consideration. Net
benefits of each weed control strategy were compared to
the total costs that varied. A minimum rate of return of
100% was used in the economic analysis. The next steps
involved the calculation of the marginal rate of return
(expressed as a percentage) using the formula below.
Marginal rate of return = Marginal benefit ($/ha) X 100
Marginal cost ($/ha)
RESULTS
Effect of weed control strategy on weed density and
biomass
Treatments had no effects on total weed density at
Hatcliffe in the first weeding (Table 1) but significant
differences (P=0.011) were recorded in the density of
Garlinsoga parviflora at CIMMYT. During the second
weeding, treatments had significant effects on the density
of G. Parviflora (P = 0.011) at CIMMYT and B. pilosa (P =
0.017) at Hatcliffe while no significant differences were
observed on the total weed density at both sites. At
CIMMYT (Table 1), weed pressure was higher at second
weeding (45DAP) than at first weeding (22 DAP) while at
Hatcliffe (Table 1) weed pressure decreased with each
successive weeding.
Weed biomass generally increased until third weeding
before decreasing late in the season at 76 DAP (Table 2).
Application of paraquat at planting resulted in significantly
higher weed biomass (P=0.0128) than all the other
treatments at 76 days after planting (DAP). An application
of glyphosate at planting and manual weeding had
biomass that were not significantly different (P>0.05)
between each other.
Table 2: Mean dry biomass in kilograms of broadleaf and
annual grass weeds at Hatcliffe
Weed control
strategy
Weed biomass
0 DAP 25 DAP 45 DAP 76 DAP
Manual weeding 21.33 40.00 70.67 35.33abc
Paraquat 34.00 61.00 117.67 61.00a
Glyphosate 23.67 44.33 88.00 51.67ab
Atrazine 24.33 31.00 61.33 26.67bc
Glyphosate +
Atrazine
19.33 41.67 73.33 23.67c
Glyphosate +
Atrazine +
Metolachlor
27.67 42.33 84.33 22.67c
P value NS NS NS 0.0395
LSD0.05 NS NS NS 26.53
TABLE 1: Mean of weed density (m-2) at first and second weeding at CIMMYT and Hatcliffe sites
First weeding (22 DAP) Second weeding (45 DAP)
CIMMYT Hatcliffe CIMMYT Hatcliffe
Weed
control
strategy
Garlinsoga
parviflora
Bidens
pilosa
Total
weeds
Garlinsoga
parviflora
Bidens
Pilosa
Total
weeds
Garlinsoga
parviflora
Bidens
pilosa
Total
weeds
Bidens
pilosa
Total
weeds
T1 1.78b 0.99 2.14 1.67 3.2 3.35 2.77b 1.93 3.14 2.67a 2.99
T2 2.10a 0.5 2.33 2.07 3.29 3.54 3.09a 1.28 3.33 2.63ab 2.83
T3 2.14a 0.9 2.32 2.36 3.36 3.58 3.14a 1.42 3.32 2.48abc 2.85
T4 1.85b 0.93 2.20 1.84 3.13 3.37 2.84b 1.69 3.2 2.00d 2.67
T5 1.94ab 0.79 2.21 1.72 3.04 3.25 2.94ab 1.59 3.2 2.29bcd 2.67
T6 2.16a 1.19 2.28 1.94 2.89 3.22 3.16a 2.15 3.28 2.17cd 2.81
SED 0.10 0.29 0.08 0.36 0.196 0.14 0.10 0.38 0.08 0.17 0.11
P value 0.0108 NS NS NS NS NS 0.0108 NS NS 0.0169 NS
LSD 0.05 0.1 NS NS NS NS NS 0.22 NS NS 0.25 NS

4. Evaluation of the Efficacy of Herbicides during Transition to Conservation Agriculture in Zimbabwe
Muchineripi G.H 251
Effect of weed control strategy on grain yield and
above ground biomass of maize
Table 3 shows that weed control strategy had a significant
effect (P<0.05) on maize biomass yield at Hatcliffe, but not
at CIMMYT. At Hatcliffe applying paraquat or glyphosate
alone at planting resulted in significantly lower (P=0.0112)
maize above ground biomass yield at harvest. There were
significant differences (P<0.05) in maize yields among
treatments at both sites (Table 3). At both sites an
application of glyphosate + atrazine + metolachlor had
significantly higher (P<0.05) maize yield than manual
weeding alone with no herbicide application.
Table 3: Mean maize yields and above ground biomass in
kilograms per hectare at harvest
Maize biomass
kg/ha
Maize grain yield
kg/ha
Weed control
strategy
CIMMYT Hatcliffe CIMMYT Hatcliffe
Manual
weeding 2113 2402.9b 4419.2b 3986.7ab
Paraquat 3130 1390.4a 4817.6ab 2869.5b
Glyphosate 2375 1295.2a 4990.4a 2664.2b
Atrazine 2530 2286.6b 4892.7ab 4119.2ab
Glyphosate +
Atrazine 2111 2627.0b 5981.4a 4092.7ab
Glyphosate +
Atrazine +
Metolachlor 2364 2357.9b 6082.6a 4351.3a
Significance NS * * *
LSD0.05 NS 817.55 589.49 660.10
Figures followed by a different letter in a column are significantly
different at 0.05 (*), 0.01 (**) and 0.001 (***) level of significance
respectively. LSD(0.05) are only shown for figures that showed
significant differences
Use of herbicides resulted in a decrease in weeding time
at both sites, with the highest labour requirement being
recorded for manual hoe weeding alone (Table 4). The
combination of glyphosate + atrazine had least mean
labour requirements at both sites.
Table 4: Mean labour hours for different treatments in plots
at Hatcliffe and CIMMYT
Labour requirements
(hrs/ha)
Weed control strategy Hatcliffe CIMMYT
Manual weeding 586.4 313.1
Paraquat 470.3 307.2
Glyphosate 426.2 308.6
Atrazine 427.7 299.8
Glyphosate + Atrazine 368.9 285.1
Glyphosate + Atrazine +
Metolachlor 395.4 286.6
Mean 445.82 300.07
Effect of weed control strategy on net economic
benefits (NEB)
Application of glyphosate + atrazine + metolachlor had
highest net economic benefits (NEB) of $868.98/ha (Table
5) at Hatcliffe and $1336.99/ha (Table 6) at CIMMYT. At
both sites, soil applied herbicides with longer soil
persistence had more NEB than manual weeding alone.
Net economic benefits increased when herbicides were
combined at both sites.
At Hatcliffe, T6 (glyphosate + atrazine + metolachlor) was
the only treatment that was not dominated by any other
treatment (Table 7). At CIMMYT of all the herbicide
treatments that were not dominated, glyphosate + atrazine
+ metolachlor proved to be the best strategy.
Table 5: Mean net economic benefits (NEB) of weed control strategies at Hatcliffe
Manual
Weeding
Paraquat Glyphosate Atrazine Glyphosate
+ Atrazine
Glyphosate
+Atrazine+
Metolachlor
Average yield (kg/ha) 3986.70 2869.50 2664.20 4092.70 4119.20 4351.30
Adjusted yield (kg/ha) 3588.03 2582.55 2397.78 3683.43 3707.28 3916.17
Gross field benefits ($/ha) 1022.59 736.03 683.37 1049.78 1056.57 1116.11
Cost of herbicide ($/ha) 0.00 5.11 11.93 18.14 30.07 39.07
Labour cost to apply Herbicide ($/ha) 0.00 5.00 5.00 5.00 5.00 5.00
Cost of labour to hand weed ($/ha) 439.80 293.94 266.38 267.31 230.56 247.13
Total costs that vary ($/ha) 439.80 304.05 283.31 290.45 265.63 291.20
Net Economic Benefits ($/ha) 582.79 442.09 416.99 782.47 826.01 868.98
Table 6: Mean net economic benefits (NEB) of weed control strategies at CIMMYT
Manual
Weeding
Paraquat Glyphosate Atrazine Glyphosate +
Atrazine
Glyphosate
+Atrazine+
Metolachlor
Average yield (kg/ha) 4419.20 4817.60 4990.40 4892.70 5981.40 6082.60
Adjusted yield (kg/ha) 3977.28 4335.84 4491.36 4403.43 5383.26 5474.34
Gross field benefits ($/ha) 1133.52 1235.71 1280.04 1254.98 1534.23 1560.19
Cost of herbicide ($/ha) 0.00 5.11 11.93 18.14 30.07 39.07
Labour cost to apply Herbicide ($/ha) 0.00 5.00 5.00 5.00 5.00 5.00
Cost of labour to hand weed ($/ha) 439.80 192.00 192.88 187.38 178.19 179.13
Total costs that vary ($/ha) 439.80 202.11 209.81 210.52 213.26 223.20
Net Economic Benefits ($/ha) 693.72 1033.60 1070.23 1044.46 1320.97 1336.99

5. Evaluation of the Efficacy of Herbicides during Transition to Conservation Agriculture in Zimbabwe
World Res. J. Agric. Sci. 252
Table 7: Dominance and marginal analysis for Hatcliffe
and CIMMYT
Weed
control
strategy
Costs that
vary ($/ha)
Net
Benefits
($/ha)
Marginal rate
of return (%)
Hatcliffe
T5 265.63 826.01 ---
T3 283.31 416.99 Da/
T4 290.45 782.47 Da/
T6 291.20 868.98 168%
T2 304.05 442.09 Da/
T1 439.80 582.79 Da/
CIMMYT
T2 202.11 1033.60
T3 209.81 1070.23 476%
T4 210.52 1044.46 Da/
T5 213.26 1320.97 7263%
T6 223.20 1336.99 161%
T1 439.80 693.72 Da/
T1 - Manual weeding only
T2 - Paraquat
T3 - Glyphosate
T4 - Atrazine
T5 - Glyphosate +Atrazine
T6 - Glyphosate + Atrazine + Metolachlor
DISCUSSION
Effect of weed control strategy on weed density and
biomass
The study showed that herbicides were more effective in
controlling weeds than the farmer practice of manual hoe
weeding alone. Application of atrazine alone or as a tank
mix with other herbicides had lower weed densities (Table
1) because atrazine controlled most small seeded annual
broadleaf weeds and some annual grasses (Korieocha et.
al., 2011). Second weeding at CIMMYT showed high total
weed density and density of Garlinsoga parviflora in
treatments containing paraquat and glyphosate alone
(Table 1). These results are consistent with Johnson et. al.
(1980) who observed higher germination and re-growth in
plots treated with glyphosate and paraquat. High weed
densities continually observed in treatment where manual
weeding alone was done at Hatcliffe (Table 1) were
attributed to the shallow cultivation that was thought to
bring weed seeds buried in the soil to the surface where
conditions favourable for germination were present
(Mohler et. al., 2001) hence higher weed numbers in
manually weeded plots.
At Hatcliffe weed biomass gradually increased at second
and third weeding and later decreased later in the season
at 76 DAP (Table 2) which can be attributed to the
increased weed numbers that emerged after each
successive weeding. The increase in weed density could
have been due to breakage of seed dormancy as season
progressed (Mishra and Singh, 2012) and vertical
movement of weed seeds to the soil surface where
conditions for germination are favourable (Mohler et. al.,
2001).
Effect of treatments on grain yield and maize above
ground biomass
Significantly higher (P<0.05) grain yield (Table 3) in
glyphosate + atrazine + metolachlor treatment than
manual weeding alone observed at both sites was
attributed to the ability of herbicides to control existing
weeds at planting. This was also credited to the ability of
herbicides to sufficiently suppress weeds during the critical
period of weed control for maize (4 -6 weeks after crop
emergence) (Uremis et. al.,2009), the period during which
yield losses in maize occur when there is high weed
pressure.
The higher weed pressure (Table 1) and weed biomass
(Table 2) at Hatcliffe was thought to have contributed to the
lower maize biomass yields observed in treatments where
paraquat and glyphosate alone were respectively applied.
Weeds competed with maize for growth resources such as
nutrients and space hence resulting in lower above ground
biomass of maize in treatments that had higher weed
biomass and density at this site.
Effect of weed control strategy on weeding time and
net economic benefits (NEB)
A consequence of lower weeding times observed in
herbicide treated plots was decreased costs that vary
which resultantly led to higher NEB compared to manual
weeding alone (Table 7). At both sites a tank mix of
atrazine + glyphosate + metolachlor was the best strategy
which resulted in highest NEB. This strategy resulted in
$1.61 and $1.68 for every dollar invested at CIMMYT and
Hatcliffe respectively compared to the next best strategy.
Such a return is likely to persuade farmers to adopt
chemical weed control because it was considered an
attractive enough incentive for farmers. This return was
above the minimum marginal rate of return of 100% set for
this study because experience and empirical evidence by
CIMMYT (1988) has previously shown that new
technologies exhibiting marginal rate of return (MRR) of
100% over existing practices can be safely recommended.
Efficacy of weed control and consequently NEB was
greater when herbicides were combined. This was
ascribed to the fact that combining herbicides that have
different modes of action and target species increases the
spectrum of weeds controlled.
CONCLUSION
Herbicides were shown to be effective in controlling weeds
than manual weeding alone. Use of herbicides led to
higher NEB because they reduced weeding time and
labour required compared to manual weeding. If farmers
use herbicides they will reap increased NEB than with the
current practice of manual weeding alone. Combining

6. Evaluation of the Efficacy of Herbicides during Transition to Conservation Agriculture in Zimbabwe
Muchineripi G.H 253
herbicides that have different target species increased the
spectrum of controlled weeds resulting in even higher
efficacy of weed control. Grain yield in herbicide treated
plots were higher than where only hoe weeding was done
which implied that farmers need to manually weed their
fields more frequently for them to obtain the same yields
as when herbicides are used. However, this will involve
investing more time and labour towards weeding.
Incorporating herbicides in a weed control strategy
requires less time and labour for weeding which may free
up time and allow farmers to carry out other chores that
are normally ignored or postponed during peak weeding
times.
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Accepted 29 June 2018
Citation: Muchineripi G.H. (2020). Evaluation of the
Efficacy of Herbicides during Transition to Conservation
Agriculture in Zimbabwe. World Research Journal of
Agricultural Sciences, 7(2): 248-253.
Copyright: © 2020 Muchineripi G.H. This is an open-
access article distributed under the terms of the Creative
Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium,
provided the original author and source are cited.