ORIGINAL RESEARCH
published: 16 April 2021
doi: 10.3389/fagro.2021.655824
Farmer Friendly Options for
Sterilizing Farm Tools for the Control
of Xanthomonas Wilt Disease of
Banana
Walter Ocimati 1*, Anthony Fredrick Tazuba 2 and Guy Blomme 3
1 Bioversity International, Kampala, Uganda, 2 Independent Consultant, Kampala, Uganda, 3 Bioversity International, Addis
Ababa, Ethiopia
The adoption of tool sterilization using either 3.5% sodium hypochlorite (household
bleach) or fire, a core element of the cultural control packages for Xanthomonas wilt (XW)
of banana has been poorly adopted hampering XW control in East and Central Africa.
Household bleach is costly and not accessible to the rural poor while repeated heating
weakens metal blades of garden tools (machetes, knives, and hoes). Identification of
economically viable tool sterilization options is thus crucial for XW management. We
explored a range of practices including tool insertion for varying time periods into cold and
Edited by:
hot ash, fire and boiling water; tool exposure over varying time periods to the sun while
Francesco Spinelli,
University of Bologna, Italy under black or transparent plastic sheets; and washing tools with cold water and laundry
Reviewed by: soap or detergent. Cleaning with household bleach served as a negative control while
Jaindra Nath Tripathi, uncleaned tools as positive control. Like for household bleach, no Xanthomonas vasicola
International Institute of Tropical
Agriculture (IITA), Kenya pv. musacearum (Xvm) the causal agent of XW was recovered from tools washed with
Sophie Trouvelot, cold water and different laundry soaps or detergents. Culturing Xvm in varying detergent
Université de Bourgogne, France
and soap concentrations (0.00125–0.035 g/mL), only resulted in growth at lower
*Correspondence:
concentrations of 0.00125 and 0.0025 g/mL. The cleaning effect of soap could thus
Walter Ocimati
w.ocimati@cgiar.org be due to both an anti-bacterial effect and dislodgment of bacteria from tools. Laundry
soaps/detergents are cheaper than household bleach and used for various purposes
Specialty section:
within and across households, including the resource poor and rural households, hence
This article was submitted to
Disease Management, a cheaper and convenient tool sterilization alternative. Tool insertion into boiling water was
a section of the journal effective from the 40th second and thus a viable alternative. Heating tools in fire required
Frontiers in Agronomy
up to a minute to clear all bacteria. The currently recommended 20–40 s heating could
Received: 19 January 2021
Accepted: 15 March 2021 thus be inadequate. Repeated heating for 1min may also damage tools. Other practices
Published: 16 April 2021 (washing with cold water only, use of solar radiation, repeatedly and forcefully inserting
Citation: tools into the soil, tool insertion into hot and cold ash for up to 5min) only reduced Xvm
Ocimati W, Tazuba AF and Blomme G
populations on tools, thus not independently recommended. We recommend expanding
(2021) Farmer Friendly Options for
Sterilizing Farm Tools for the Control of the tool sterilization options to include washing with soap/ detergents and tool insertion
Xanthomonas Wilt Disease of Banana. into boiling water for at least 1 min.
Front. Agron. 3:655824.
doi: 10.3389/fagro.2021.655824 Keywords: bacteria, detergent, hot water, soap, sodium hypochlorite, tool sterilization
Frontiers in Agronomy | www.frontiersin.org 1 April 2021 | Volume 3 | Article 655824
Ocimati et al. Tool Sterilization for XW Management
INTRODUCTION 55% have been, respectively, reported in eastern DR Congo
(Blomme et al., 2014) and Uganda (Kikulwe et al., 2019). The
Xanthomonas wilt (XW) of banana is an important disease of reach/availability of household bleach in the rural areas is poor
banana in the east and central African region (Kalyebara et al., in addition to being costly. In a more recent study, farmers
2006; Biruma et al., 2007; Tripathi et al., 2009; Blomme et al., reported that repeated heating of metal garden tools with fire
2014, 2017a; Ocimati et al., 2019). Yield losses due to XW can between plants or after cutting all diseased plants, a practice
reach 100% in case of poor or delayed management. A 35% drop previously thought to be more feasible among the resource
in sales and doubling of bunch prices due to XW have been poor households, to weaken the metal blades of their tools
reported in Tanzania and Rwanda (Nkuba et al., 2015). It might (Blomme et al., 2019). The reported damage to metal tools
also not be a coincidence that the period 2001–2014 has also seen could be attributed to heating the tools for a much longer
a 50% and a 39% decline in banana production and area with time than the recommended 20–30 s. Although the cost of a
banana, respectively, in Uganda (FAO, 2020). machete is only about 3 USD, this cost is often perceived as
The disease is caused by the Gram-negative bacteria too high to subsistence small-scale rural farmers. More still,
Xanthomonas vasicola pv.musacearum (previouslyXanthomonas lighting a small fire in the field during the rainy season is also
campestris pv. musacearum). Cultural practices have been not feasible as dry mulch, twigs or leaves collected from within
predominantly used for XW management mainly through the fields are normally used by farmers. Fostering the adoption
interventions that prevent pathogen introduction and or of the entire XW control package is crucial for maintaining or
eliminate/ reduce disease inoculum. The core cultural control improving banana production levels. Adoption of technologies
practices promoted include the rouging of entire diseased mats in agriculture has remained a challenge and is directly related to
and/ or singly cutting at soil level of diseased plants, sterilization the efficiency of any agricultural technology (Bozeman, 2000).
of farm tools by flaming/heating with fire or cleaning with 3.5% The adoption of new technologies has also been reported to
sodium hypochlorite (NaOCl/ household bleach), timely removal vary among farm households due to differences in their socio-
of the floral male buds with a forked stick and the use of clean economic characteristics (Asfaw and Admassie, 2004; Somda
planting materials (Karamura et al., 2008; Blomme et al., 2014, and Kamuanga, 2005). There is a need to investigate additional
2019; PROMUSA, 2020). With respect to tool sterilization with or alternative options for tool sterilization other than the use
fire, the recommendation advised to heat the metal tool until of fire or chemical disinfectants that are out of reach of most
when too hot to touch, and 20–40 s over a strong flame was farm households.
perceived as sufficient to achieve this (PROMUSA, 2020). The Farmers who dis-adopted heating of farm tools on fire
control practices are promoted as complete packages comprising reported that tool sterilization should preferably be carried out
of at least three individual technologies. The main packages by pushing the metal blade in hot ash, and not directly in a flame,
include the (i) complete diseased mat uprooting (CDMU) which to protect the metal tool against heat damage (Blomme et al.,
comprises uprooting entire mats, farm tool sterilization and 2019). However, hot ash most likely has a lower temperature
male bud removal; and (ii) single-diseased stem removal (SDSR) compared to flames and this could potentially fail to eliminate all
which consists of the removal of single diseased stems, farm tool bacteria on the blade and have a negative effect on disease control.
sterilization and early male bud removal. This practice needs to be evaluated under controlled situations,
Full adoption of these practices has been reported to have e.g., in the laboratory and screenhouse. Another potential option
positive results. For example, the SDSR control package has could be the use of boiling water to sterilize the metal tools,
been reported to rapidly recover fields even when the initial after all diseased plants have been cut. Washing a machete with
incidence on farm was as high as 80% (Blomme et al., 2017b, water and soap, and subsequently drying the machete in the
2019). Full adoption of the SDSR technology package in Uganda sun, could potentially eliminate the bacteria on metal blades
was reported to improve annual banana production per acre or reduce the number of bacteria to levels that do not cause
by US$187 compared to no adoption and by US$ 139 when infection when subsequently used on a healthy plant. Sterilizing
two practices out of the full SDSR XW control package were garden tools through solar radiation could have potential as
adopted (Kikulwe et al., 2019). The adoption of one, two the central African region lies on the equator with regular
control practices and the full package translated to a 36, 193, sunshine and would need to be investigated. The effect of solar
and 216% improvement in revenue obtained (USD/acre/annum) radiation especially during days of intense sunshine could also be
from banana on farm. Despite the success of control packages hastened by wrapping the tools in black or transparent polythene
e.g., the SDSR package in controlled experiments, adoption level, sheets. Other potential options to evaluate include cleaning
application intensity and correctness, and success on farms has the farm tool blade by repeatedly pushing it in loosened soil,
been variable. Several factors including the timing of application, scrubbing with organic materials/plant debris and biorationals.
wrong application and dis-adoption of some elements of the These options nevertheless require thorough investigation. The
control packages have been observed (Blomme et al., 2019; exploration of less burdensome tool sterilization options and
Ntamwira et al., 2019). increase in tool sterilization options could potentially lead to the
Tool sterilization (using either household bleach or fire), full adoption of XW control packages and ultimately improve
which is a core part of the XW control packages, has been XWmanagement. This study therefore explored different options
poorly adopted, reducing the effectiveness the packages. For for tool sterilization with the hope of identifying more farmer-
example, tool sterilization adoption rates of <30% and about friendly options for scaling.
Frontiers in Agronomy | www.frontiersin.org 2 April 2021 | Volume 3 | Article 655824
Ocimati et al. Tool Sterilization for XW Management
MATERIALS AND METHODS postulated that the ash could dehydrate the bacteria, thus
reducing its population on farm tools.
This study was conducted between January 2019 and November iv) Heating farm tools with fire: Blades of the knives covered
2020 through four rounds of experiments at the National with Xvm ooze were completely inserted into a red hot
Agricultural Research Laboratories (NARL) in Kawanda, central fire made out of charcoal (in a charcoal stove) for various
Uganda. The study aimed at identifying cost-effective alternative time durations of 10, 20, 40, 60, 180, and 300 s. Heating or
methods to household bleach and heating tools with fire for flaming farm tools is a common practice currently being
sterilizing metal surfaces of tools (e.g., machetes, knives and hoes promoted for sterilizing farm tools used on XW infected
used by banana farmers for field operations, and during XW plants or fields.
control operations). v) Inserting farm tools into boiling water: Tools with Xvm
were fully immersed into boiling water for time durations
Exploration of Alternative Tool Sterilization of 10, 20, 40, 60, 180, and 300 s. Hot water was postulated
Options to denature the structural and physiological properties of
the bacteria.
Xanthomonas vasicola pv. musacearum (Xvm) inoculum
: For each round of experimentation, a pseudostem vi) Washing farm tools with common laundry soap andpreparation
cut from a single banana plant showing recent (i.e., less than cold water. The common practice of washing household
a week old) XW characteristic symptoms was sourced from utensils/dishes within the East African region was used for
the same banana field (located at NARL) for obtaining this treatment. To attain this, the tools were submerged intoXvm
inoculum. The transversally cut banana pseudostems were placed 0.005 g/mL of laundry soap-water solution (prepared by
on a work bench in the laboratory and allowed to ooze. The fresh dissolving 5 g of laundry soap in 1 L of sterile water) for 20 s
ooze containing was then scooped from the cut pseudostem followed by a thorough scrubbing with cotton wool soakedXvm
surface into a petri dish for the subsequent procedures. The in the same solution for about 10 s. This amount of soap was
bacterial ooze used in this study were all confirmed, with the able to form adequate amount of foam as observed while
help of a polymerase chain reaction (PCR), to contain using cleaning dishes within households. Thereafter the toolsXvm
Xvm-specific AvP1 primers that amplify genes encoding the were rinsed twice with autoclaved sterile water and allowed
Avirulence protein KFA14425.1 of the bacteria as described in to drain dry for about 5–10min before the subsequent step
Nakato et al. (2018). of recovering bacteria from the surface of the knives. The
laundry soap used in the study contained no antibiotics and
was obtained from a local market in Kampala, Uganda.
Application of Xvm on Farm Tools
vii) Solarisation of farm tools while wrapped into a black
Bacterial ooze was scooped and applied gently using a paint
polythene sheet: The tools were wrapped into a black
brush on the surface of knives previously sterilized with 70%
polythene sheet and thereafter subjected to solar radiation
(v/v) ethanol and a flame. Caution was taken to pick and
for time durations of 1, 2, 3, and 6 h.
apply a uniform amount of the bacterial ooze on the surfaces
viii) Solarisation of farm tools while wrapped into a transparent
of the knives. The amount of Xvm bacteria applied on each
6 polythene sheet: The tools with bacterial ooze were wrappedblade of the knife was approximately 3.5 × 10 CFU (colony
into a transparent polythene sheet and thereafter subjected
forming units)/mL.
to solar radiation for time durations of 1, 2, 3, and 6 h.
ix) Leave Xvm-laden farm tools in a dry place for varying
Assessment of Tool Sterilization Options
time durations: Tools with Xvm ooze were placed in a dry
After allowing the bacterial ooze to set on the knives for
place for 24 h, 3 days, and 7 days before the recovery and
about 30min, three knives, each acting as a replicate were then
enumeration of the bacteria.
subjected to nine different tool sterilization options, including a
x) Positive control: Xvm ooze laden tools assessed for
positive and negative control as described below.
Xvm presence and population without application of
i) Inserting tools with shear force into loosened soil or any treatment.
ground: knives with Xvm ooze were repeatedly inserted xi) Negative control: Farm tools were cleaned with 3.5%
forcefully into the ground/ soil with shear force. It was sodium hypochlorite (NaOCl) solution that has been
presumed that the shear force of insertion would result in proven to eliminate the bacteria from farm tools.
a cleaning effect on the knives.
ii) Inserting tools into hot ash: Xvm ooze laden knives were
Recovery and Enumeration of Xvm
completely inserted in hot ash freshly obtained from a
To recover bacteria from the knives subjected to the above
charcoal stove for time periods of 10, 20, 40, 60, 120, treatments, the surface of each knife was washed with 10mL
180, and 300 s. This was to mimic a common practice of of double distilled water under a laminar flow hood. A clean
inserting knives into hot ash by farmers. It was presumed sterile paint brush was used to repeatedly swab the surface of
that that the hot ash would desiccate and kill the bacteria on the knives followed by repeated rinsing to increase the chance
the blades of the knives. of dislodging all bacteria from the surface of the knives. Each
iii) Inserting tools in cold dry ash: Blades of knives covered with suspension was thoroughly mixed through repeated pipetting
Xvm ooze were inserted, fully covering all blades in to cold and serially diluted to 10−2. From two dilutions (100, and 10−2),
dry ash for 10, 20, 40, 60, 120, 180, 300 s; 1, 2, and 6 h. It was 10 µL of the suspension was plated in two replicates (resulting
Frontiers in Agronomy | www.frontiersin.org 3 April 2021 | Volume 3 | Article 655824
Ocimati et al. Tool Sterilization for XW Management
in a total of four replicates) on Petri plates containing a non- 50mL of sterile cold water. To fasten the dissolution, the
selective media of yeast peptone glucose agar (YPGA, containing soap/detergents were regularly vortexed until full dissolution.
per liter of distilled water: 5 g of yeast, 5 g of peptone, 10 g of
glucose, and 15 g of agar; Schaad et al., 2001). The plates were Experimental Setup and Renumeration of Xvm
then incubated for a period of 72 h at 28◦C, the presence/absence 5mL each of the different concentrations of laundry soap-water
of Xvm noted, and where present the number of Xvm colonies or detergent-water solutions were then mixed with an equal
counted. Xvm CFU per mL of the original suspension was then volume (i.e., 5mL) of the Xvm-water suspension in separate
computed for each replicate Petri plate as below. 15mL falcon tubes. This resulted in halving the soap or detergent
concentrations (g/mL) to 0.00125, 0.0025, 0.005, 0.01, 0.025, 0.03,
Number of CFU∗Dilution factor and 0.035, respectively, each soap/detergent concentration acting
CFU/mL of original suspension =
Volume plated (mL) as a treatment. Each treatment mixture was thereafter vortexed
for about 3min to break up any clogged Xvm colonies and to
increase the chance for the soap/detergent molecules to interact
Assessment of a Range of Laundry Soaps with individual bacterium. Each treatment was then incubatedat 28◦C for 1 h. For the control treatment, 5mL of the above Xvm
and Detergents suspensionwas diluted to 10mL by addition ofmore sterile water,
Due to the observed effectiveness of the laundry soap in the vortexed for 3min and incubated for an hour as above. 1mL
above trial, eight brands of laundry/washing soaps (without of each treatment (soap or detergent—Xvm—water mixture) was
antibiotics) and six brands of powder detergents were assessed pipetted after an hour, serially diluted to 10−2. 10 µL of the 100
for their effectiveness in eliminating Xvm from farm tools. All and 10−2 dilutions were then plated on Petri plates containing
the laundry soaps and detergents were procured from the local YPGA and incubated at 28◦C as described in the sections above.
market in Kampala, Uganda and are all readily available brands. The experiment was repeated three times, with each repeat acting
The laundry soaps included a locally made crude soap [a mixture as a replicate.
of different soap salts, water, liberated glycerol (glycerine) and
surplus fat or alkali (Chukwulozie et al., 2014)]. All the laundry Data Analysis
soaps and detergents were coded, and a 0.005 g/mL laundry soap- All data on Xvm colony counts were log10 transformed to reduce
water or detergent-water solution prepared from each laundry the variability within the data set. Linear mixed model analysis
soap or detergent as described above. The other steps of the of the relationship between Xvm incidence (i.e., percentage of
experiment i.e., inoculum preparation, application of Xvm ooze tools with Xvm) or the natural log of mean Xvm colony counts
on tools and tool sterilization by washing with soap and cold on tools and different tool sterilization options was performed
water were undertaken as for the laundry soap in the section using the lmer function of the lme4 package (Winter, 2013;
above. The laundry soap used in the section above and household Bates et al., 2015) and R statistical software (R Core Team,
bleach served as negative controls while washing tools with 2018). A linear mixed model was used to overcome potential
cold water only acted as the positive control. The recovery and errors due to presence of random effects arising from four
enumeration of Xvm on tools were conducted as described in repeat experiments performed using different pseudostem tissues
the above section. This experiment was repeated four times and separate days. A preliminary analysis of variance using
with three knives used per soap and detergent type in each the GenStat v. 12 statistical software (VSN International Ltd.,
repeat experiment. 2009) showed significant (p < 0.05) differences between the four
repeat experiments. The random effect (i.e., repeat experiments
Survival of Xvm in a Soap or a Detergent or replications) was entered as a nested random effect with
Solution intercepts. TheXvm incidence (%) or natural log of colony counts
This experiment sought to determine if the effect of using laundry served as the fixed effects. The above model(s) [here after full
soap was either through its washing effect only or in combination model(s)] and their null models (were fitted to the same data
with killing of the pathogen. using a maximum likelihood criterion and compared using the
Akaike’s Information Criterion (AIC) (Sakamoto et al., 1986), the
Inoculum Preparation deviance of the parameter estimates and p-values. The models
Yellow Xvm characteristic ooze from a single banana plant were considered suitable when the model fit criterions for the
showing recent (i.e., less than a week old) XW characteristic full models were smaller than those of the null models and
symptoms from the same field described above was harvested the P values less than 0.05. The models were then fit with the
into sterile falcon tubes, and thoroughly vortexed for about 3min restricted maximum likelihood criterion (REML) that is default
to weaken the gum structure of Xanthan (a polysaccharide that for lmer (Bates, 2010) to obtain the random and fixed effects.
protects Xvm) and to separate bacterial cells. Subsequently, the The lmerTest package gave the lmer4 package an extended output
Xvm suspension was diluted to an OD600 of 0.5 with sterile water using the Satterthwaite’s (Kenward-Roger’s) approximations for
for the subsequent steps. the t test and corresponding p-values (Kuznetsova et al., 2017).
P-values and treatment effects were then used for comparison of
Preparation of Soap and Detergent Solutions fixed effects. The R statistical software and statistical packages
Laundry soap and detergent solutions of varying concentrations ggplot2 (Wickham, 2016), ggpubr (Kassambara, 2018) and
(i.e., 0.0025 g/mL, 0.005, 0.01, 0.02, 0.05, 0.06, and 0.07 g/mL) patchwork (Pedersen, 2017) were used for data visualization (i.e.,
were prepared by dissolving their appropriate weights into drawing box plots).
Frontiers in Agronomy | www.frontiersin.org 4 April 2021 | Volume 3 | Article 655824
Ocimati et al. Tool Sterilization for XW Management
RESULTS on the tools and were thus as effective as household bleach and
the control laundry soap used in the study above in eliminating
All the models not only performed better than corresponding Xvm (Table 4). In contrast, a significantly higher number of Xvm
null models (i.e., lower AIC scores for models compared to the CFU (i.e., 1,239 CFU/mL; p < 0.01) and treatment effect (0.75;
nulls) but were also significantly different (p < 0.001) from their p< 0.001;Table 4) was observed in the positive control treatment
null models (Table 1). These models were thus subsequently used in which tools were washed with cold water only. This suggests
to determine the fixed effects, Xvm incidence and Xvm colony that the available laundry soaps and detergents in the [Ugandan]
counts of the different tool sterilization options. market can potentially eliminate the bacteria from farm tools.
Xanthomonas vasicola pv. musacearum The Survival of Xvm in Soap and Detergent
Incidence and Colony Forming Units (CFU) Solutions
on Farm Tools Cleaned Using Different Both the detergent and soap solution were observed to kill Xvm
Options and Stored Over Different Time compared to the positive control (water-Xvm suspension, PC)
Durations that had a significantly higher (p < 0.05) Xvm colony count
Significant differences (p 0.001) in the fixed effects i.e. after an hour’s incubation (Figure 2). For the same concentration<
incidence of tools with Xvm (Table 2) and mean Xvm CFU on (g/mL), the detergent solution was observed to have a higher
tools (Table 3) were visible between the tool sterilization options impact on the bacteria compared to the soap solution (Figure 2).
explored in this study. Similar estimates for the fixed effects (i.e., For the detergent, Xvm characteristic colonies were recovered
Xvm incidence on tools and CFU recovered from tools) were from the 0.00125 g/mL detergent solution while no colonies
attained for washing tools with cold water and laundry soap; were recovered from the detergent solution with a concentration
cleaning with 3.5% sodium hypochlorite (household bleach); varying between 0.0025 and 0.035 g/mL. In contrast, Xvm like
tool insertion into boiling water for at least 40 s, 60 s, 3min colonies grew in the 0.00125 and 0.0025 g/mL of laundry
and 5min; and tool insertion into fire for about 60 s, 3min soap-water-Xvm mixture, with no growth observed in the soap
and 5min (Tables 2, 3; Figures 1A,B). For these treatments, concentrations varying between 0.05 and 0.035 g/mL (Figure 2).
no Xvm colonies were recovered from the blade of the knives
(Figures 1A,B), suggesting they are effective for tool sterilization. DISCUSSION
Heating the farm tools on fire, one of the currently recommended
practices for tool sterilization however only eliminated all the Sanitation through removing diseased and asymptomatic
bacteria on farm tools after at least 60 s of heating (Figures 1A,B). infected plant tissue, as well as decontaminating tools, equipment
Other sterilization options explored did not eliminate all the and washing hands is one of many tactics for an effective disease
bacteria (Table 2, Figures 1A,B), with no significant (p > 0.05) management strategy (Salamanca, 2015). Decontamination of
differences in the incidence of tools with Xvm visible between the farm tools with fire and 3.5% sodium hypochlorite (household
negative control (household bleach) and tool insertion into hot bleach) that are critical components of the field sanitation
ash for at least 3–5min, and repeated tool insertion into soil with measures for the management of the XW disease in banana
shear force (Figure 1A, Table 2). In hot ash, Xvm incidence on have been poorly adopted. This study explored a range of
tools declined with increasing time, suggesting a longer time of simple, cost effective and less cumbersome potential practices
tool exposure to hot ash can potentially eliminate all the bacteria. that could be promoted for the sterilization of farm tools as
Xvm was recovered from all the farm tools stored in a dry place a measure for XW control on farm. Household bleach served
for up to 7 days. Immersion of tools into boiling water for 10–20 s, as a control in this study and consistently no bacteria were
using transparent polythene sheets, using shear force to insert recovered from tools cleaned with it. Household bleach rapidly
tools repeatedly into the soil and only washing with clean water dissociates in water to form the highly reactive hypochlorous
resulted in moderate estimates in the mean number of Xvm CFU acid which can alter the three-dimensional structure of a
per mL (between 1.3 and 4.9) (Table 3, Figure 1B). In contrast, protein, thus killing bacteria (Ledford, 2008; Winter et al.,
most of the hot and cold ash treatments, storing the tools for 2008). In contrast, fire only eliminated all Xvm from the tools
1–7 days had large estimates of mean Xvm CFU per mL and after at least 1 minute of exposure to fire. Dry heat from
did not differ from the untreated control (Table 3, Figure 1B). fire kills microbes through dehydration, altering membranes,
These results suggest that, though not effective practices such denaturing proteins, and incineration (Jay et al., 2005; Talaro,
as solarization, hot and cold ash treatment, forceful repeated 2008). However, the temperature and duration of exposure are
insertion into the soil and washing with plain cold water were important determinants of success (Talaro, 2008; Vu Thanh
still able to reduce the bacterial load on the tools. et al., 2012). For example, Xanthomonas translucens pv. pistaciae
was observed to survive in wood exposed to 40–55◦C for at least
Soap and Detergent Options 60min but killed when exposed to 60◦C for at least 15min (Vu
Different laundry soaps and detergents were examined for their Thanh et al., 2012). The results of this study suggest that the
efficacy in eliminatingXvm from farm tools. All the seven laundry current advise to heat farm tools above fire for about 20–40 s
soaps (including one crude soap) and the six detergents used with (PROMUSA, 2020) may be leading to partial survival of Xvm
cold water to wash contaminated tools eliminated all the bacteria and a continued disease spread through tools. The time of
Frontiers in Agronomy | www.frontiersin.org 5 April 2021 | Volume 3 | Article 655824
Ocimati et al. Tool Sterilization for XW Management
TABLE 1 | Model fit criterions comparing the null and full models for different fixed effects assessing the efficacy of different tool sterilization options on elimination of
Xanthomonas vasicola pv. musacearum (Xvm) from farm tools.
Experiment Dependent variable Models AIC Deviance Pr (>Chisq)
Tool sterilization options Xvm incidence Null 235.2 229.2
Model 137.7 51.7 <2.2e-16***
Xvm colony counts Null 4976.7 4970.7
Model 4732.6 4646.6 < 2.2e-16 ***
Laundry soaps and detergents Xvm incidence Null −11.3 −17.3
Model −67.0 −103.0 <6.4e-12***
Xvm colony counts Null 4976.7 4970.7
Model 4732.6 4646.6 <2.2e-16 ***
AIC denotes the Akaike’s information criterion. ***denotes significantly different at p ≤ 0.001.
Null model: y∼1 + (1|repeat experiment); and full model: y∼x + (1|repeat experiment). ‘y’ is the dependent variable (i.e. Xvm incidence or Xvm colony counts), ‘x’ the tool sterilization
treatment options. The ‘repeat experiment’ is the random effect of the model.
exposure to heat and effectiveness of sterilizing with fire could polymers bind and remove certain types of dirt, builders provide
also potentially be influenced by the strength of the heat or flame. the formulations (e.g., liquids, gels and tablets) while enzymes
More still, the advice to heat the metal blade till too hot to touch remove biological stains such as blood, coffee and wine (Learning
or between 20 and 40 s, may be ambiguous for farmers potentially Teaching Scotland, 2011).
resulting in under or over-exposure to heat, explaining farmer Incubating Xvm in laundry soap and detergent solutions
reports of tool damage and linked dis-adoption of the practice. for an hour resulted in a significant decline in Xvm colony
Repeated 1-min exposures of farm tools to fire can potentially counts whereas at higher concentrations between 0.005 and
damage farm tools as reported by farmers. 0.035 mg/mL no Xvm growth on YPGA occurred. This
In this study, thorough washing of farm tools with cold suggests that the cleaning effect of the soaps and detergents
water and different locally available laundry soaps that had no could be due to both Xvm being dislodged off tools and
antibiotics and detergents, just like household bleach eliminated killed or demobilized. Xvm are Gram-negative bacteria and
all the bacteria on farm tools. Soaps are the alkali salts of fatty the outer membranes of Gram-negative bacteria are made
acids and are obtained through alkaline hydrolysis of fats and of Lipopolysaccharides (LPSs) comprising of three important
oils by strong alkali/bases of sodium or potassium hydroxide structural components, the O-specific polysaccharide (or O-
(Learning Teaching Scotland, 2011). Soaps are thus composed antigen), the core region and the lipid A (the endotoxic active
of a hydrophobic (water hating), oil soluble (non-polar) tail and moiety) (Zähringer et al., 1999; Silipo et al., 2004). The lipid
a charged carboxylate group head that is hydrophilic (attracted A layer of Xvm could have got attracted and attached to the
to water) (Talaro, 2008; Learning Teaching Scotland, 2011). To non-polar, hydrophobic end of the soap or detergent molecules
remove stains/grease off objects, the hydrophobic, non-polar, in water. With the non-polar ends of the soap molecules
tails burrow into the greasy, non-polar molecule while the polar buried into the lipid, non-polar layers of the bacteria and the
hydrophilic ends get attached to the polar water molecules. The polar ends attached to the water molecules, the soap possibly
polar-to-polar interactions are stronger and cause mechanical lift perforates and corrodes the protective covering of the bacteria.
of the greasemolecule (Learning Teaching Scotland, 2011; Talaro, This can potentially lead to loss of virulence, leaking of the
2008). In combination with water, soaps are therefore surfactants, internal viscera of the bacteria, desiccation and ultimately death.
reducing the surface tension of water and the interfacial tension Baker et al. (1941) reported a range of cationic detergents to
between oil/grease/dirt and water. This surfactant action coupled inhibit the metabolism of Gram-negative and Gram-positive
with agitation help to pull off grease/ dirt off surfaces. This soap microorganisms to the same degree (i.e. 74–100% inhibition),
mechanism also potentially applied to the elimination of Xvm with some detergents being extremely potent and irreversibly
from the farm tools by dislodging the sticky sap of banana and inhibiting the metabolism of some bacterial species. In contrast,
bacterial ooze off farm tools. Using soap to wash hands has been Kim and Rhee (2016) observed Gram-negative bacteria to be
reported to be more effective than using water only because the more susceptible to soaps than Gram-positive bacteria. Xvm are
surfactants in soap lift microbes and soil off the skin, a process thus potentially highly susceptible to common laundry soaps
that further improves with thorough scrubbing of hands with and detergents.
soap (Luby et al., 2005, 2011; Burton et al., 2011). Burton et al. The action of the synthetic detergents on bacterial metabolism
(2011) reported a 92–100% reduction in the number of different has been reported to be influenced by several factors including
types of bacteria on hands following hand washing with plain the charge on ions containing the hydrophobic group; molecule’s
soap and water. Similar action is anticipated from the detergents hydrophilic-hydrophobic balance; pH; chemical structure of the
explored in the study. Detergents in addition to a surfactant detergent and the characteristics of the microorganisms (Baker
(accounting for about 35% of detergents’ cleaning performance) et al., 1941). For example, cationic detergents were more effective
contain bleach (∼27.5%), polymer (15%), builder (15%), and than the anionic ones while maximum efficiency in detergents
enzyme. Bleach enhances the appearance and effect of whiteness, with straight chain alkyl compounds occurred when the chains
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Ocimati et al. Tool Sterilization for XW Management
TABLE 2 | Fixed effects of different methods of tool sterilization on the percentage (%) of tool blades with Xanthomonas vasicola pv. musacearum.
Effect Estimate Std. Error t value Pr(>|t|)
Laundry soaps and cold water (Intercept) −1.55E-15 1.67E-01 0 1
Negative control (household bleach) 1.53E-15 2.29E-01 0 1
Boiling water −10s 5.00E-01 2.29E-01 2.186 0.03079
Boiling water −20s 2.50E-01 2.29E-01 1.093 0.27662
Boiling water −40s 1.35E-15 2.29E-01 0 1
Boiling water −60s 1.38E-15 2.29E-01 0 1
Boiling water −3min 1.39E-15 2.29E-01 0 1
Boiling water −5min 1.35E-15 2.29E-01 0 1
Fire −10s 7.50E-01 2.29E-01 3.279 0.00137
Fire −20s 1.00E+00 2.29E-01 4.372 2.67E-05
Fire −40s 7.50E-01 2.29E-01 3.279 0.00137
Fire −60s 1.46E-15 2.29E-01 0 1
Fire −3min 1.46E-15 2.29E-01 0 1
Fire −5min 1.38E-15 2.29E-01 0 1
Hot ash −40 s 7.50E-01 2.29E-01 3.279 0.00137
Hot ash −60s 1.00E+00 2.29E-01 4.372 2.67E-05
Hot ash −2min 5.00E-01 2.29E-01 2.186 0.03079
Hot ash −3min 3.59E-01 2.47E-01 1.45 0.1497
Hot ash −5min 2.54E-02 2.47E-01 0.103 0.91852
Cold ash −40s 1.00E+00 2.29E-01 4.372 2.67E-05
Cold ash −60s 1.00E+00 2.29E-01 4.372 2.67E-05
Cold ash −1 h 1.00E+00 2.29E-01 4.372 2.67E-05
Cold ash −3min 1.00E+00 2.29E-01 4.372 2.67E-05
Cold ash −5min 1.00E+00 2.29E-01 4.372 2.67E-05
Cold ash −2 h 1.00E+00 2.29E-01 4.372 2.67E-05
Cold ash −3 h 7.50E-01 2.29E-01 3.279 0.00137
Cold ash −6 h 5.00E-01 2.29E-01 2.186 0.03079
Transparent polythene + sun −1 h 5.00E-01 2.29E-01 2.186 0.03079
Transparent polythene + sun −2 h 5.00E-01 2.29E-01 2.186 0.03079
Transparent polythene + sun −3 h 1.00E+00 2.29E-01 4.372 2.67E-05
Transparent polythene + sun −6 h 5.00E-01 2.29E-01 2.186 0.03079
Black polythene + sun −1 h 1.00E+00 2.29E-01 4.372 2.67E-05
Black polythene + sun −2 h 1.00E+00 2.29E-01 4.372 2.67E-05
Black polythene + sun −3 h 7.50E-01 2.29E-01 3.279 0.00137
Black polythene + sun −6 h 7.50E-01 2.29E-01 3.279 0.00137
Shear force into soil 2.50E-01 2.29E-01 1.093 0.27662
Tool blade after 24 h of storage in an open dry place 1.00E+00 2.29E-01 4.372 2.67E-05
Tool blade after 3 days of storage in an open dry place 1.00E+00 2.29E-01 4.372 2.67E-05
Tool blade after 7 days of storage in an open dry place 1.00E+00 2.29E-01 4.372 2.67E-05
Washing with cold water only 7.50E-01 2.29E-01 3.279 0.00137
Positive control 9.72E-01 2.29E-01 4.238 4.49E-05
3.5% sodium hyphochlorite and uncleaned tools served as positive and negative controls, respectively.
contained 12–16 carbon atoms (Baker et al., 1941). The cationic communities. Secondly, laundry soaps serve multiple purposes
detergents were more active in the alkaline pH range while including cleaning utensils, clothing and the human body in the
the anionic ones in the acid range (Eggerth, 1926; Baker et al., study region, thus making it easily accessible by even the resource
1941). In the current study, all the laundry soaps and detergents poor households. Apart from being accessible it is cheap and thus
evaluated were found to eliminate bacteria. Thus, soaps and cost effective. However, at the time of promoting the practice,
detergents could be promoted across XW affected landscapes caution must be taken to understand the pH of the water sources
for the management of the disease. Soap has a wide reach and in different communities and its effect on potential efficacy of the
is very accessible even in the most rural and hard to reach soaps in the elimination of the bacteria from farm tools.
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Ocimati et al. Tool Sterilization for XW Management
TABLE 3 | Fixed effects of different methods of tool sterilization on the colony forming units of Xanthomonas vasicola pv. musacearum (Xvm) per mL of a suspension
obtained from the surface of Xvm-contaminated farm tools.
Effect Estimate Std. Error t value Pr(>|t|)
Laundry soaps and cold water (Intercept) −1.31E-14 1.84E+00 0 1
Negative control −3.5% sodium hypochlorite 1.27E-14 2.52E+00 0 1
Boiling water −10 s 4.97E+00 2.52E+00 1.972 0.050868
Boiling water −20 s 1.96E+00 2.52E+00 0.778 0.437897
Boiling water −40 s 1.26E-14 2.52E+00 0 1
Boiling water −60 s 1.17E-14 2.52E+00 0 1
Boiling water −3min 1.21E-14 2.52E+00 0 1
Boiling water −5min 1.17E-14 2.52E+00 0 1
Fire −10 s 9.06E+00 2.52E+00 3.597 0.000468
Fire −20 s 7.86E+00 2.52E+00 3.123 0.002247
Fire −40 s 6.40E+00 2.52E+00 2.541 0.01232
Fire −60 s 1.45E-14 2.52E+00 0 1
Fire — min 1.22E-14 2.52E+00 0 1
Fire −5min 1.31E-14 2.52E+00 0 1
Hot ash −40 s 9.01E+00 2.52E+00 3.579 0.000499
Hot ash −60 s 1.06E+01 2.52E+00 4.207 5.02E-05
Hot ash −2min 5.84E+00 2.52E+00 2.318 0.022136
Hot ash −3min 2.85E+00 2.52E+00 1.133 0.25953
Hot ash −5min 1.25E-14 2.52E+00 0 1
Cold ash −40 s 1.09E+01 2.52E+00 4.339 3.00E-05
Cold ash −60 s 1.10E+01 2.52E+00 4.379 2.57E-05
Cold ash −1 h 1.16E+01 2.52E+00 4.605 1.03E-05
Cold ash −3min 1.13E+01 2.52E+00 4.486 1.68E-05
Cold ash −5min 1.23E+01 2.52E+00 4.881 3.28E-06
Cold ash −2 h 9.22E+00 2.52E+00 3.663 0.000372
Cold ash −3 h 8.58E+00 2.52E+00 3.407 0.000893
Cold ash −6 h 4.33E+00 2.52E+00 1.719 0.088129
Transparent polythene + sun −1 h 4.92E+00 2.52E+00 1.954 0.053048
Transparent polythene + sun −2 h 3.64E+00 2.52E+00 1.445 0.151088
Transparent polythene + sun −3 h 7.09E+00 2.52E+00 2.816 0.00569
Transparent polythene + sun −6 h 4.51E+00 2.52E+00 1.793 0.075494
Black polythene + sun −1 h 1.07E+01 2.52E+00 4.262 4.05E-05
Black polythene + sun −2 h 1.11E+01 2.52E+00 4.422 2.16E-05
Black polythene + sun −3 h 8.71E+00 2.52E+00 3.461 0.000746
Black polythene + sun −6 h 9.34E+00 2.52E+00 3.712 0.000313
Shear force into soil 2.67E+00 2.52E+00 1.06 0.291145
Tool blade after 24 h of storage in an open dry place 1.51E+01 2.52E+00 5.988 2.27E-08
Tool blade after 3 days of storage in an open dry place 1.51E+01 2.52E+00 5.988 2.27E-08
Tool blade after 7 days of storage in an open dry place 1.51E+01 2.52E+00 5.988 2.27E-08
Washing with cold water only 4.04E+00 2.52E+00 1.605 0.111031
Positive control 1.48E+01 2.52E+00 5.859 4.14E-08
3.5% sodium hyphochlorite and uncleaned tools served as negative and positive controls, respectively.
Inserting farm tools in boiling water for at least 40 s also Department of Health, 2018). Wet heat has been reported to
effectively removed all the bacteria off farm tools and could be more effective in killing micro-organisms than dry heat (Jay
thus be promoted. Wet heat from boiling water has been et al., 2005; Talaro, 2008). Wet heat is reported to be effective
reported to kill or inactivate bacteria, viruses, protozoa, and at lower temperatures and over shorter exposure time, whereas
other pathogens through damaging structural components and dry heat requires moderate to high temperatures (Talaro, 2008).
denaturing proteins (Talaro, 2008; Center for Disease Control, Jay et al. (2005) also reports heat resistance to decrease with
2009; World Health Organization, 2015; New York State increasing humidity, moisture, or water activity. The use of
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Ocimati et al. Tool Sterilization for XW Management
FIGURE 1 | The (A) percentage of tools with Xanthomonas vasicola pv. musacearum (Xvm) and (B) log10 of the mean number of Xvm colonies per mL recovered from
contaminated farm tools following cleaning with different methods or storage. 3.5% sodium hypochlorite (Household bleach) served as the negative control or best
cleaning method whereas uncleaned freshly contaminated tool blades served as the positive control (PC). BP, BW, CA, HA, LS-CW, SF, and WP, respectively denote
black polythene sheet, boiling water, cold ash, hot ash, laundry soap, and cold water, repeatedly inserting tool with shear force into the soil, and white polythene
sheet. The horizontal “black lines” and “red points” within the boxes are, respectively, the median and mean values of the percentage of tools with Xvm or Xvm colony
counts. The lower and upper boundaries of the boxes are, respectively, the 25th and 75th percentile; the bars/whiskers below, above the box are the 10th and 90th
percentile and points beyond the 25th and 75th percentiles are outliers.
boiling water could especially be suitable for women farmers Reduction in Xvm population on farm tools after insertion
who often couple bananamanagement work with household food into ash could be due the high pH of ash and a possible
preparation tasks. dehydrating effect from the ash. Structural changes, more
Practices such as tool solarization or exposure to the sun vacuolated cytoplasm and discontinuities in the membrane cells
(uncovered/in open sun or while covered with black polythene that is a sign of cell lysis has been reported in the bacterium
sheets), forceful and repeated insertion of tools into the soil, tool cells after alkali stress (Luvielmo et al., 2016). Alkali stress
insertion in to hot or cold ash, and washing contaminated tools has also been observed to lower the viscosity and weaken
with plain water significantly reduced the bacterial population on the gum structure of Xanthan, a polysaccharide that protects
farm tools compared to the un treated control. Solarization more Xanthomonas campestris (Luvielmo et al., 2016). In soils, wood
often with a transparent polythene cover has been widely used ash has been reported to increase pH and pore water electrical
as an environmentally friendly method to control pathogens and conductivity, strongly impacting soil bacterial population and
pests such as bacteria, fungi, insects, nematodes, mites, weeds, community composition (Augusto et al., 2008; Kim et al., 2016;
and weed seeds in the soil (DeVay et al., 1991; Stapleton et al., Merghache et al., 2018). Bang-Andreasen et al. (2017) observed
2000). The effect of the sun on Xvm populations can be attributed a strong decline in bacterial richness and diversity in soil with
to the effect of the high temperature due to the accumulated increasing application of wood ash. Antibacterial activity of
radiant sun energy captured by the polythene sheets (DeVay et al., ash has also been reported, though with a higher sensitivity
1991; Stapleton, 2000). Tool exposure to the sun was however reported in Gram-positive bacteria than the Gram-negative
profoundly affected by the changes in weather conditions e.g., bacteria (Merghache et al., 2018). Though not explored in this
cloud cover, rainy weather. The reduction in bacteria due to the study, like soap, lye (mixture of ash with clean water allowed
repeated and forceful insertion into the soil can be attributed to to rest for at least 15 days) is also reported to be used as a
the corrosive and cleaning effect of the practice. cleansing and disinfecting agent (Howard et al., 2002) and has
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Ocimati et al. Tool Sterilization for XW Management
TABLE 4 | Fixed effects of different laundry soaps and detergents obtained from within Kampala, Uganda on the incidence of farm tools with Xanthomonas vasicola
pv. musacearum.
Treatments Estimate Std. Error Df t value Pr(>|t|)
Laundry soap control (Intercept) 2.00E-16 6.25E-02 4.80E+01 0 1
Detergent 1 −2.02E-16 8.84E-02 4.60E+01 0 1
Detergent 2 −2.00E-16 8.84E-02 4.60E+01 0 1
Detergent 3 −2.10E-16 8.84E-02 4.60E+01 0 1
Detergent 4 −1.97E-16 8.84E-02 4.60E+01 0 1
Detergent 5 −2.10E-16 8.84E-02 4.60E+01 0 1
Detergent 6 −2.05E-16 8.84E-02 4.60E+01 0 1
Laundry soap 1 −2.21E-16 8.84E-02 4.60E+01 0 1
Laundry soap 2 −2.23E-16 8.84E-02 4.60E+01 0 1
Laundry soap 3 −1.95E-16 8.84E-02 4.60E+01 0 1
Laundry soap 4 −2.13E−16 8.84E−02 4.60E+01 0 1
Laundry soap 5 −2.17E−16 8.84E−02 4.60E+01 0 1
Laundry soap 6 −1.92E−16 8.84E−02 4.60E+01 0 1
Crude laundry soap 7 −2.03E−16 8.84E−02 4.60E+01 0 1
Negative control (Household bleach) −2.04E−16 8.84E−02 4.60E+01 0 1
Washing with cold water only 7.50E−01 8.84E−02 4.60E+01 8.485 5.79e−11
3.5% sodium hypochlorite (Household bleach) and the laundry soap used in the sections above served as the negative controls while washing with water only as a positive control.
FIGURE 2 | Log10 of the mean Xanthomonas vasicola pv. musacearum (Xvm) colony counts per mL recovered according to detergent and laundry soap
concentration. One to seven (on the horizontal axis), respectively, stand for detergent and soap concentrations of 0.00125, 0.0025, 0.005, 0.01, 0.025, 0.03, and
0.035 g/mL. PC denotes the positive control treatment in which Xvm was only suspended in sterile water. The horizontal black lines within the boxes are the median
values while the “red circle” is the mean value of the Xvm colony counts. The lower and upper boundaries of the boxes are respectively, the 25th and 75th percentile;
the bars/whiskers below and above the box are the 10th and 90th percentile.
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Ocimati et al. Tool Sterilization for XW Management
been reported to be as effective as soap in removing bacteria tool sterilization. This study revealed that heating tools, a
(Anuradha et al., 1999; Laskar et al., 2005; Baker et al., 2014). currently widely promoted practice, eliminated all the bacteria
In the case of hot ash, death of the bacteria could have after 1min of exposure. Thus, the promotion of fire as a tool
been hastened by heat. The number of bacteria significantly sterilization measure must incorporate this time dimension,
decline in the 5-min hot ash treatment suggesting a prolonged though lengthening time will, as reported by farmers, continue to
exposure could eliminate all bacteria. However, it is not clear result in damaging of the metal tool blades. Despite the negative
how a prolonged and repeated exposure of the tools to hot ash impact of fire, resource-endowed farmers could continue to use
would impact the blades of the tools. Washing with plain water the practice on their farms. Tool immersion into boiling water
also dislodged as significant number of bacteria. Nevertheless, was also found to be an effective alternative measure, as it
the ability of tools to still transmit the bacteria after cleaning eliminated all bacteria after 40 s of exposure. We recommend
with these less-effective practices (cold and hot ash, water only, the inclusion of thorough washing of tools with soap and cold
insertion into soil) remains high though not investigated in water and the immersion of tools into boiling water for at least
this study. These practices could however be potentially used in 1min into the current pool (i.e., use of sodium hypochlorite and
combination with some of the effective measures such as tool heating tools on fire) of tool sterilization measures. The new
insertion into hot water, heating of the tool with fire and washing expanded list of sterilization options will offer farmers a wider
with soap. set of options to select from for managing the disease. These
Storing the tools in an open dry place over a period of up practices are potentially also useful for management of XW in
to 7 days did not affect the population of Xvm bacteria on the the enset (Ensete ventricosum) systems. Other practices such as
tools. Maina and Muthoni (2008) had a similar observation but tool insertion into cold and hot ash for up to 5min, washing with
over a shorter period of 72 h. Weekly monitoring and cutting of plain water, forceful and repeated insertion into the soil did not
diseased banana stems/plants has been recommended for a more eliminate all bacteria, and are thus not recommended. Studies to
effective control of XW (Blomme et al., 2017b). The finding on explore the effect of long storage time in cold and hot ash on
storing tools in open air suggests that transmission will still be bacterial survival and tool damage are recommended.
feasible if the farm tools are not sterilized over this week-long
period, though the transmission efficiency was not determined DATA AVAILABILITY STATEMENT
in this study. Maina and Muthoni (2008), reported that the
pathogenicity of the bacteria was not affected after the tools were The raw data supporting the conclusions of this article will be
stored for 72 h in a dry place. The survival of Xvm on farm tools made available by the authors, without undue reservation.
for a long period of time can be attributed to the presence of the
protective bacterial exopolysaccharide (EPS), Xanthan. Xanthan AUTHOR CONTRIBUTIONS
is produced by the bacterium species Xanthomonas campestris
(Sutherland, 1993). It is a slimy and gummy in texture, and yellow WO and GB conceived and developed the research concept,
bacterial exudate consisting of ring-shaped sugar molecules put contributed to data and result interpretation, writing, and
together into a very stable configuration (Sutherland, 1993; editing the manuscript. WO conducted laboratory experiments
Yoquinto, 2013). Xanthan offers several biological functions to and analyzed the data. AFT contributed to laboratory
the bacterium including protection from heat or temperature experimentation andmanuscript editing. All authors contributed
changes, ultraviolet rays, dryness, chemical products, destructive to the article and approved the submitted version.
enzymes and adhesion on to inert surfaces (Jenkins and Starr,
1982; Sutherland, 1993; López et al., 1999; Yoquinto, 2013). FUNDING
Brominated arylpolyene (xanthomonadin) pigments produced
by Xanthomonas campestris have been shown to protect bacteria This study was supported by funds from the Belgium
from photo-biological destruction (Jenkins and Starr, 1982). Development Cooperation to CIALCA and the CGIAR Fund
Donors (http://www.cgiar.org/about-us/our-funders/) through
CONCLUSION the CGIAR Research Program on Roots, Tubers and Bananas.
Washing metallic farm tools (machetes, knives, and hoes) ACKNOWLEDGMENTS
contaminated with Xvm with cold water and laundry soaps
or detergents was as effective as 3.5% sodium hypochlorite We are grateful for the support of CIALCA and the CGIAR
in the elimination of the bacteria. We thus recommend Research Program on Roots, Tubers and Bananas. We also
thorough scrubbing of farm tools with soap or detergents acknowledge Ms. Florence Nakamanya, Ms. Dorcus Nassazi, and
followed by rinsing with water as an additional measure for Ms. Leniru Salome for their assistance with laboratory work.
Frontiers in Agronomy | www.frontiersin.org 11 April 2021 | Volume 3 | Article 655824
Ocimati et al. Tool Sterilization for XW Management
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