27 July 2021
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Effect of different organic amendments on lettuce fusarium wilt and on selected soil-borne microorganisms.
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DOI:10.1111/ppa.12460
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Effect of different organic amendments on Fusarium wilt of lettuce and on
selected soil-borne microorganisms
Giovanna Gilardi, Massimo Pugliese, Maria Lodovica Gullino, Angelo Garibaldi
Abstract
The effect of different organic amendments against Fusarium wilt caused by Fusarium oxysporum f. sp. lactucae on lettuce was evaluate in four trials carried out in pot under controlled conditions. Moreover, the effect of incorporating different organic amendments on the density of F. oxysporum f. sp. lactucae, of total fungi and of fluorescent Pseudomonas spp. after two subsequent crops of lettuce was also evaluated. Brassica amendments provided a reduction of Fusarium wilt up to 50%, compared with the untreated control. In general, in the substrate used, an increase in Pseudomonas and a decrease in fungal population after two consecutive cropping cycles was observed. A significant reduction in the severity of F. oxysporum f. sp. lactucae by using pellets of Brassica carinata (reduction between 52% and 79%) and compost (reduction between 49% and 67%) was observed, while the Brassica green manure and the cattle and chicken manure provided only a partial control of Fusarium wilt. Generally, B. carinata pellet and compost had a positive effect in disease suppression after two cycles of cultivation of lettuce. An extended duration of Brassica and compost treatments from 30 to 60 days did not significantly affect disease severity as well as plant growth, and microbial population. The highest biomass of lettuce was observed in the non – inoculated substrate amended with Brassica flour, chicken manure, and compost, compared with the untreated control at the end of the first cycle. This positive effect was also evident in the second cycle with chicken manure and compost amendments. There is a potential for the practical use of soil amendments for managing Fusarium wilt of lettuce.
Keywords: Fusarium oxysporum f. sp. lactucae; Lactuca sativa; Brassica flour and pellet;
compost; chicken manure
Introduction
The management of Fusarium wilt agents, responsible of severe losses on a number of economically important crops, are currently investigated, with special attention to the use of measures with a low environmental impact (Reuveni et al., 2002; Klein et al., 2011; Katan et al., 2012; Gullino et al., 2012; Borrego-Benjumea 2014 a,b; Garibaldi et al., 2014a; Gilardi et al., 2014b).
The effect of organic amendments (compost, animal manure, vegetable residues, organic waste) against several soil-borne pathogens has been intensively exploited since many years and gained new attention after the phase-out of methyl bromide (Bonanomi et al., 2007). Studies carried out under controlled conditions showed the capability of Brassica crops used as fresh plant material (green manure), seed meals and, dried plant material to control several soil-borne pathogens (Matthiessen and Kirkegaard, 2006; Bonanomi et al., 2007; Motisi et al., 2009; Neubauer et al., 2014) either alone or when combined with other disinfestation methods (Gamliel 2000; Klein et al., 2011). Among organic amendments, composts are intensively exploited for their efficacy in the management of soil-borne pathogens and many examples of disease suppression due to composts are well-known (Noble, 2011; Pugliese et al., 2011). Gamliel and Stapleton (1993) indicated the positive effect of chicken compost alone or combined with soil solarization on lettuce against Meloidogyne incognita and Pythium ultimum as well as on yield.
By monitoring the population densities of soil microorganism and pathogens in soil it is possible to better understand the complex effect of organic amendments or crop residues on soil microorganisms including pathogens (Njoroge et al., 2008; Lu et al., 2010; Ferrocino et al., 2014).
Despite the many approaches developed to evaluate the effect of organic amendments on soil-borne pathogens and to study their effect on soil microorganisms, more research is still needed in order to foster their practical implementation.
This work was carried out in order to evaluate, in pot trials, the effect of different organic amendments against Fusarium wilt caused by Fusarium oxysporum f. sp. lactucae on lettuce. This pathogen, is seed-transmitted and occurs in most countries where lettuce is grown, causing serious economic losses (Garibaldi and Gullino, 2010, Matheron and Gullino, 2012; Scott et al., 2014). Moreover, the effect of incorporating different organic amendments on the density of F. oxysporum f. sp. lactucae, of total fungi and of fluorescent Pseudomonas spp. after two subsequent crops of lettuce was evaluated.
Material and methods
Layout of trials and plant material
Four trials were carried out in 20 L pots (56.5 x 42 x 20 cm) filled with a substrate obtained by mixing a blonde peat with a sandy loam soil showing the following characteristics: sand, 68.8% ± 5; silt, 6.8% ± 5; clay, 26% ± 5; pH, 7.1; organic matter content, 2.4%; cation exchange capacity, 5.7 meq100 g-1 soil. The substrate was not steamed.
Plants of lettuce 20-25 days after sowing (20 plants/pot), cv. Crispilla, highly susceptible to Fusarium wilt (Gilardi et al., 2014 b) were transplanted into the treated and untreated soil. Two subsequent crop cycles were carried out in the same substrate. In all the trials, soil treatment with organic amendments was carried out for 30 days before transplant. In trials 3 and 4, treatment duration for Brassica (flour, pellet and green manure) and compost has been extended also to 60 days (Table 1). The pots were maintained in a glasshouse at temperatures ranging from 23 to 28°C and watered daily.
Artificial inoculation with the pathogen and organic amendments application
The strain FUSLAT10RB (strain resistant to 10 mg L-1 of benomyl) of Fusarium oxysporum f. sp. lactucae was used. Resistance to benzimidazoles permits an easier reisolation of the pathogen from infested substrate on a semi-selective medium added with a benzimidazole fungicide. A talc formulation of the strain of F. lactucae was mixed into the soil at 1-6x104 Colony Forming Unit (CFU) ml-1 24 h before starting treatments.
Immediately before starting the trial, the substrate was irrigated with 3.5 L/pot corresponding to 75% of soil moisture capacity. Treated soil was covered with polyethylene (PE) sheets (50 m thick) immediately after the application of soil amendments. Soil mulching was removed 30-60 days after starting soil treatments.
Brassica carinata, as defatted seed meal (Biofence, N organic 6%, P 2.2%, K 2%, organic C 52%, Triumph, Italy), and formulated as flour ( Biofence 10, N organic 6%, P 2.2%, K 2%, organic C 45%, Triumph, Italy) were mixed into the soil at 2.5 g L-1.
Brassica juncea (ISCI99) was sown at 1-1.2 gm-1 in plastic pots filled with sterile blonde peat (Turco, Albenga) maintained in greenhouse at 24-26°C for 40-50 days until the use, corresponding to the 80% of flowering. Plants were weighted, harvested, cut into 1 to 3 cm pieces and incorporated into the soil, simulating a biofumigation treatment.
A compost (Ant.’s Compost, AgriNewTech, Torino, Italy)prepared from biodegradable municipal solid waste, was used at 10 kg m-2.
The chicken manure was formulated in pellets (Organic N 3% P2O5 3%, FA.CO ) while the cattle manure was obtained by local organic farms and used after 9 mouth of storage.
Quantification of the pathogen and of selected microbial population in soil
The soil dilutions plated method was used (Bridge and Spooner, 2001). Soil samples of 100 g were taken from each plastic pot at the end of the second cycle of cultivation in trials 1 and 2 (Table 1). Soil sub-samples (5g) were mixed for 30 min with 45ml of Ringer’s solution amended with 5 µl of
Tween 20 (Sigma, Milan, Italy). Within 24 h after the sampling, decimal dilutions in Ringer’s solution (Merck Millipore, Germany) were prepared, and aliquots of 1 ml of the selected dilutions were spread in triplicate in selected agar media. To detect the pathogen density after soil treatment the strain FusLAt10RB of Fusarium oxysporum f. sp. lactucae was used and maintained on a semi selective medium (Komada, 1975) plus 10 mgL-1of benomyl, incubated at 20°C for 4 days. The total fungal populations were evaluated by using Potato Dextrose Agar (PDA, Merck) plus 25 mg l -1
of streptomycin sulfate. The total Pseudomonas spp. bacteria were also evaluated by using the Pseudomonas agar with cetrimide-fucidin-cephalosporin (CFC) supplement (Oxoid, Milan, Italy). The number of units forming colonies were calculated as the of Log counts 48h to 120 h after incubation at 23°C. The mean value for three independent plates was reported (Tables 2 and 3).
Fusarium wilt evaluation and analysis
The effectiveness of different treatments on the severity of F. oxysporum f. sp. lactucae on lettuce was evaluated weekly during the trials. Throughout the experiments, wilted plants were counted and removed. In the final evaluation, 4 weeks after transplanting, the severity of symptoms was assessed by using a disease severity (DS) scale ranging from 0 to 100: 0 = healthy plant, 25 = initial leaf chlorosis, 50 = severe leaf chlorosis and initial symptoms of wilting during the hottest hours of the day, 75 = severe wilting and severe symptoms of leaf chlorosis; 100 = plant totally wilted, leaves completely necrotic. In order to evaluate the effect of each treatment on plant growth, the total fresh plant biomass was weighed at the end of each crop cycle.
The experimental scheme adopted was a completely randomized block design with three-four replicates for each treatment.
The data were subjected to the analysis of variance (ANOVA) and statistically analysed according to Tukey’s test (P=0.05). Before analysis, population density (CFU/g of soil) were logarithmically transformed, while disease severity data were arcsine transformed in order to normalize the distribution of the variance.
Results
Effect on disease severity
During the trials 1 and 2, Fusarium wilt severity in the untreated control pots ranged from 62.1 to 63.3 in the first cycle of lettuce and from 50 to 83.3 in the second cycle (Table 2). DS under the experimental protocol 2 was lowest in trial 3, ranging from 32 to 39.7 compared with values ranging from 40.9 to 60.9 in trial 4.
In trial 1, both formulations of Brassica (flour and pellet) significantly reduced Fusarium wilt of lettuce from 63.3 to 24.6 and 22.9, respectively. In pots amended with Brassica applied as green manure, disease severity was more severe than in the untreated control (Table 2). Chicken manure and compost reduced significantly disease severity at values of 36.5 and 32.5, respectively, while cattle manure was not reducing Fusarium wilt symptoms. The positive effect of Brassica formulated amendments and chicken manure on disease reduction was still observed in the second cycle of lettuce cultivation, while compost was no more effective (Table 2).
In trial 2, all the organic amendments tested significantly reduced Fusarium wilt severity compared with the inoculated and untreated control at the end of the first lettuce cycle, with the exception of chicken manure. In general, this significant efficacy was not maintained in the second cycle (Table 3).
In trial 3, in the presence of a lower disease severity in the inoculated untreated control of 32.2-39.7, all the organic amendments tested significantly reduced Fusarium wilt severity on lettuce, with values ranging from 8.4 to 23.1 at the end of the first cycle. This positive effect was still relevant at the second crop cycle (Table 5). No significant effect was found by extending from 30 to 60 days the period of soil treatment with Brassicas and compost (Table 5).
In trial 4, in the presence of an higer Fusarium wilt severity (59.6-60.9), the highest efficacy was provided by B. carinata pellet with value of DS of 12.2 and 15.0. Also Brassica, formulated as flour or used as green manure, and compost significantly reduced respectively to 33.8, 38.3 and
36.9 Fusarium wilt severity compared with the untreated control. Lettuce plants grown in soil treated with chicken manure were more affected by F. oxysporum f. sp. lactucae than those grown in untreated control soil (Table 6).
Effect on lettuce biomass
In trial 1, Brassica flour, chicken manure and compost provide the best effect on fresh weight of lettuce grown in non inoculated substrate. Generally this effect was more evident in the second crop cycle, compared with the non treated and non inoculated control. At the end of the first cycle in inoculated plots, the highest biomass was observed in the treatments providing the best disease control. At the end of the second cycle, any difference in fresh weight was observed compared to the inoculated and untreated control, with the only exception of the plants grown in pots amended with Brassica flour (Table 4).
In trial 2, chicken manure and compost significantly influenced lettuce biomass in the plots not inoculated compared with the untreated control. This effect was still maintained in the second cycle. Similar results, in terms of lettuce yield, were observed in the first and second cycles in the presence of the infested soil in pots treated with compost, chicken manure and B. carinata pellet (Table 4).
In trial 3, lettuce yield was slightly more variable among treatments in the first cycle. The best results in fresh weight were provided again by chicken manure and Compost in both cycles. This positive effect was maintained even in the presence of the pathogen also using Brassica carinata as pellet and flour (Table 5).
In trial 4 in general, no significant differences in plant fresh weight between treatments and inoculated and non treated control plants were observed, with the exception of the results obtained with Brassica flour and pellet (Table 6).
Effect on microbial population
In trial 1 the number of CFU/g of benomyl-resistant mutants of F. oxysporum f. sp. lactucae was significantly lower in the substrate treated with Brassica flour compared with the untreated control, with no differences among the other treatments. Also the total fungal population was significantly reduced by Brassica flour compared with the untreated control. The Pseudomonas population at the end of the second crop cycle was significantly higher in all the amended substrates, compared to the non-amended control. The highest values in Pseudomonas was recorded by using Brassica (flour and pellet) and compost amendments (Table 2). In trial 2, all amendments tested significantly reduced the pathogen population; the lower value was observed in the substrate amended with the B. carinata pellet that at the same time significantly reduced the total fungal population and improved the number of Pseudomonas spp. at the end of the second crop cycle (Table 3).
Discussion
Managing Fusarium wilts with non chemical measures (varietal resistance, organic amendments, biological control agents, cultural practices) has drawn increasing attention also by considering the present strong limitations in the use of chemical fumigants. Those tactics are exploited also in order to reduce the inoculum density of the pathogen in the soil, factor directly involved in the efficacy of disease suppression. The role of organic amendments in the suppression of soil-borne diseases, by inducing specific microbial, biological and chemical changes, has been reviewed in several pathosystem (Gamliel and Stapleton, 1993; Bailey and Lazarovits, 2003; Bonamomi et al., 2007; Borrego-Benjumea et al., 2014 a, b; Termorshuizen 2012; Ascencion et al., 2015). In our study, the impact of amendments based on Brassica as plants or dry matter (defeated pellet and flour), cattle and chicken and compost manure has been evaluated on Fusarium wilt of lettuce, by considering the impact on yield, as well as by evaluating the soil bacterial and fungal population dynamics. Our
results show that Brassica amendments provide a reduction of Fusarium wilt up to 50%, compared with the untreated control. In general, in the substrate used, an increase in Pseudomonas, a decrease in fungal population and a significant reductions of the pathogen density after two consecutive cropping cycles was observed. However, the effect on soil microorganisms is influenced by several factors such as the type of soil, the type and dosage of Brassica used (Mazzola et al., 2001; Borrego-Benjumea et al., 2014a). An increase of Pseudomonas populations has been observed by amending a sandy soil with seed meal of Brassica napus at rate below 1% v/v (Mazzola et al., 2001). In our pot trials, carried out under controlled conditions and with artificial inoculation, a significant reduction in the severity of F. oxysporum f. sp. lactucae by using pellets of B. carinata (reduction between 52% and 79%) and compost (reduction between 49% and 67%) was observed, while the Brassica green manure and the cattle and chicken manure provided only a partial control. Inconsistencies in Fusarium wilt management by using Brassica green manure were also reported by several authors (Blok et al., 2000; Bonanomi et al., 2007; Njoroge etal., 2008; Borrego-Benjumea et al., 2014 a). Gamliel and Stapleton (1993) indicated the ability of composted chicken manure at 10 t/ha to suppress Pythium ultimum on lettuce. In our trials chicken manure showed inconsistent results in reducing Fusarium wilt of lettuce. However, the efficacy of organic amendments in disease and pathogen control is due to several factors, among these is of great impact the microbial activity. Leak in Fusarium wilt control observed in trial two in the chicken amended soil could be a result of an increased in detection of total fungi and in a reduction in Pseudomonas population. Certainly, also the high disease severity observed in trial 1, 2 and 4 may have influenced the effectiveness in Fusarium wilt control of the different soil amendment used.
Generally, B. carinata pellet and compost had a positive effect in disease suppression after two cycles of cultivation of lettuce. The long-term impact on disease suppression of such amendments can be explained with a shifts in soil microbial population (Mitosi et al., 2009; Ferrocino et al., 2014). In our study, carried out under controlled conditions,an extended duration of Brassica and compost treatments from 30 to 60 days did not significantly affect disease severity as well as plant
growth. Brassica carinata pellet and compost applied in mixture or combined with a short period of soil solarization did not improved the level of disease management, against Fusarium wilt of basil and rocket however, significantly increased the biomass and positively affected yield (Gilardi et al. 2014 a).
In our study the highest biomass of lettuce was observed in the non –inoculated substrate amended with Brassica flour, chicken manure, and compost generally, compared with the untreated control at the end of the first cycle. This positive effect was also evident in the second cycle with chicken manure and compost amendments. Generally, the highest fresh weight of lettuce was measured at the end of the first cycle, in the treatments providing the best disease control.
In conclusion, there is a potential for the practical use of soil amendments for managing Fusarium wilt of lettuce grown in short rotations in monoculture: Brassica (pellet and flour) and compost represent a good opportunity under integrated pest management programmes, with a positive impact in reducing the inoculum potential of the pathogen after two consecutive crop cycles.
Acknowledgements
The work reported here has received funding from the European Union’s Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 261752, ‘Plant- FoodSec – Plant and Food Biosecurity, Network of Excellence’. Stefano Demarchi is kindly acknowledged for his technical support. The authors would like to thank Marguerite Jones for the language revision.
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Table 1 – List and timing of the operations carried out in 2012, 2013 and 2014.
Operation
Trial 1 Trial 2 Trial 3 Trial 4
Artificial inoculation 15-03-2012 21-06-2013 7-05-13 14-12 2013
Soil treatment with organic amendments and covering
16-03-2012 22-06-2013 8-05-13(T60)
9-06-13 (T30)
14-12-2013(T60) 13-01-2014 (T30)
Plants trasplanting (Cycle I) 15-04-12 23-07-13 6-07-13 12-02-14
Disease assessment 16-05-12 17-09-13 13-08-13 2-04-14
End of the first cycle 16-05-12 17-09-13 13-08-13 2-04-14
Fresh weight evaluation 16-05-12 17-09-13 13-08-13 2-04-14
Plants transplanting (Cycle II)
24-05-12 19-09-13 14-08-13 3-4-14
Disease assessment 22-06-12 31-10-13 24-09-13 7-5-14
End of the trial 22-06-12 31-10-13 24-09-13 7-5-14
Soil sampling to determine microbial population
22-06-12 31-10-13 -a -
a
Table 2 - Effect of different soil treatments against F. oxysporum f. sp. lactucae (FUS lat 10 ATCC RB) on lettuce (cv. Crispilla). Data are expressed as disease index 0-100 at the end of the first and second crop cycles, and as Log CFU g- 1of the selected microbial population in trial 1.
Treatment Dosage Inoculation Trial 1 bLog CFU g- 1 of soil at the end of the second
cycle*
Cycle 1 Cycle 2 F. oxysporum
f. sp. lactucae
Total fungi Pseudomonas
Non-treated control
- no 0.0 aa 0.0 a 4.67 a-d 5.71 ab
Brassica flour 250g/m2 no 0.0 a 0.0 a 4.88 b-f 6.35 c-e
B.juncea green
manure
2.0 kg/m2 * no 0.0 a 0.0 a 5.01 d-f 6.77 e
B.carinata pellet 250g/m2 no 0.0 a 0.0 a 4.55 ab 6.55 de
Cattle manure 10 kg/m2 no 0.0 a 0.0 a 5.53 g 6.39 c-e
Chicken manure 1,5 kg/m2 no 0.0 a 0.0 a 4.75 a-e 6.22 cd
Compost 10 kg/m2 no 0.0 a 0.0 a 5.08 ef 7.28 f
Inoculated non-treated
- yes 63.3 de 83.3 de 5.15 b 5.15 f 5.46 a
Brassica flour 250g/m2 yes 24.6 b 23.6 b 4.49 a 4.49 a 7.25 f
B. juncea green
manure c
2.0 kg/m2 yes 83.1 e 86.1 de 4.96 ab 4.96 c-f 6.36 c-e
B. carinata pellet 250g/m2 yes 22.9 b 29.9 bc 4.64 ab 4.64 a-c 7.68 f
Cattle manure 10 kg/m2 yes 51.4 cd 95.8 e 4.73 ab 4.73 a-d 5.95 bc
Chicken manure 1,5 kg/m2 yes 36.2 bc 54.2 cd 4.60 ab 4.60 ab 6.37 c-e
Compost 10.0 kg/m2 yes 32.5 b 74.3 de 5.18 ab 5.18 f 6.68 de
a
Values with different letters in the same column differ significantly according to Tukey’s Test (P<0.05).
b
Results were calculated as the mean Log count for the three plate replicates. c
Table 3 - Effect of different soil treatments against F. oxysporum f. sp. lactucae (FUS lat 10 ATCC RB) on lettuce (cv. Crispilla). Data are expressed as disease index 0-100 at the end of the first and second crop cycles, and as Log CFU g- 1of the selected microbial population in trial 2.
Trial 2 bLog CFU g- 1 of soil at the end of the second cycle
Treatment Dosage Inoculation Cycle 1 Cycle 2 F.oxysporum
f.sp.lactucae
Total fungi Pseudomonas
Non-treated control - no 0.0 aa 0.0 a 4.36 a 5.96 abc Brassica flour 250g/m2 no 0.0 a 0.0 a 4.95 ab 6.81 d B.juncea green manure 2.0 kg/m2 * no 0.0 a 0.0 a 4.65 ab 5.92 abc B.carinata pellet 250g/m2 no 0.0 a 0.0 a 5.15 bc 6.66 cd
Cattle manure 10 kg/m2 no 0.0 a 0.0 a 4.30 a 5.95 abc
Chicken manure 1,5 kg/m2 no 0.0 a 0.0 a 4.49 ab 5.86 abc
Compost 10 kg/m2 no 0.0 a 0.0 a 4.53 ab 6.11 bcd
Inoculated non-treated
- yes 62.1 d 50.0 b 3.23 d 4.26 a 5.95 abc
Brassica flour 250g/m2 yes 34.6 b-d 37.1 b 2.84 c 4.83 ab 5.83 ab
B.juncea green
manure
2.0 kg/m2 yes 32.9 bc 30.0 b 2.72 bc 4.86 ab 5.95 abc
B.carinata pellet 250g/m2 yes 29.6 b-d 28.8 ab 2.26 a 4.26 a 6.90 d
Cattle manure 10 kg/m2 yes 21.9 bc 44.9 b 2.36 ab 4.76 ab 5.26 a
Chicken manure 1,5 kg/m2 yes 43.8 cd 40.8 b 2.36 ab 5.71 c 5.75 ab
Compost 10.0 kg/m2 yes 27.5 bc 29.2 ab 2.53 abc 4.65 ab 6.28 bcd
a
Values with different letters in the same column differ significantly according to Tukey’s Test (P<0.05).
b
Results were calculated as the mean Log count for the three plate replicates. c
Table 4 - Effect of different soil treatments against F. oxysporum f. sp. lactucae (Fus lat 10 ATCC RB) on yield of lettuce (cv. Crispilla). Data are expressed as fresh weight at the end of the first and second crop cycle.
Trial 1 Trial 2
Treatment Dosage Inoculation Cycle 1 Cycle 2 Cycle 1 Cycle 2
Non-treated control - no 153.8 a-da 70.6 cdef 389.7 b 246.0 b-d
Brassica flour 250g/m2 no 246.9 a 105.5 bc 489.1 b 271.3 b-d B. juncea green manure 2.0 kg/m2 no 104.8 b-e 15.8 ef 231.3 b 186.0 cd B.carinata pellet 250g/m2 no 147.8 b-d 98.0 bc 480.6 b 380.9 b-d
Cattle manure 10 kg/m2 no 101.7 cde 90.1 bcd 464.3 b 68.6 d
Chicken manure 1,5 kg/m2 no 199.1 ab 142.9 ab 990.9 a 743.8 a Compost 10 kg/m2 no 184.3 abc 182.5 a 599.9 ab 520.2 ab Inoculated non-treated - yes 71.6 de 9.6 ef 298.4 b 142.9 cd
Brassica flour 250g/m2 yes 175.8 a-c 74.7 cde 297.5 b 288.1 b-d
B.juncea green
manuere
2.0 kg/m2 yes
19.7 e 10.5 ef 447.2 b 401.1 a-d
B.carinata pellet 250g/m2 yes 150.0 a-d 67.5 cdef 527.9 b 575.1 ab
Cattle manure 10 kg/m2 yes 88.2 c-e 7.3 f 514.2 b 166.1 cd
Chicken manure 1,5 kg/m2 yes 77.4 de 71.1 cdef 397.1 ab 183.2 cd
Compost 10.0 kg/m2 yes 183.5 a-c 23.7 def 652.2 ab 489.4 a-c
a
Values with different letters in the same column differ significantly according to Tukey’s Test (P<0.05).
Table 5 -Effect of different soil treatments against F. oxysporum f. sp. lactucae (FUS lat 10 ATCC RB) on lettuce (cv. Crispilla). Data are expressed as disease index 0-100 at the end of the first and second crop cycle, and as fresh weight(Trial 3).
Treatment Dosage Inoculation Ta Disease index 0-100 at the
end of
Fresh weight (g) at the end of
Cycle 1 Cycle 2 Cycle 1 Cycle 2
Non-treated control - no 30 0.0 ab 0.0 a 122.9 hi 68.3 c-g
Brassica flour 250g/m2 no 30 0.0 a 0.0 a 495.7 b-f 142.8 c-e
B.juncea green manure 2.0 kg/m2 * no 30 0.0 a 0.0 a 310.2 d-i 95.1 c-g
B.carinata pellet 250g/m2 no 30 0.0 a 0.0 a 465.3 b-g 110.0 c-g
Cattle manure 10 kg/m2 no 30 0.0 a 0.0 a 296.7 d-i 64.8 d-g
Chicken manure 1,5 kg/m2 no 30 0.0 a 0.0 a 997.2 a 571.9 a
Compost 10 kg/m2 no 30 0.0 a 0.0 a 533.6 b-f 146.7 cd
Inoculated non-treated control
- yes 30 32.2 ef 33.4 de 95.3 i 29.3 g
Brassica flour 250g/m2 yes 30 11.6 bc 12.6 bc 349.7 c-i 55.8 fg
B juncea green manurec. 2.0 kg/m2 yes 30 9.4 bc 16.6 bc 259.9 f-i 64.9 d-g
B.carinata pellet 250g/m2 yes 30 8.4 b 14.1 bc 400.8 c-h 102.9 c-g
Cattle manure 10 kg/m2 yes 30 14.7 c 17.9 bc 201.0 g-i 64.8 d-g
Chicken manure 1,5 kg/m2 yes 30 23.1 de 19.0 bc 739.2 ab 382.3 b
Compost 10 kg/m2 yes 30 10.6 bc 22.7 cd 416.2 c-g 109.4 c-g
B. carinata pellet 250g/m2 yes 60 13.1 bc 12.0 bc 553.6 b-e 75.1 c-g
B juncea green manurec. 2.0 kg/m2 yes 60 14.7 c 14.1 bc 568.8 b-d 118.4 c-f
Brassica flour 250g/m2 yes 60 14.4 bc 11.9 b 619.2 bc 117.7 c-f
Compost 10 kg/m2 yes 60 15.3 cd 12.5 bc 454.8 c-g 151.9 c
Inoculated non-treated control
- yes 60 39.7 f 37.5 e 280.6 e-i 65.6 c-g
Non inoculated control - no 60 0.0 a 0.0 a 316.2 d-i 59.3 e-g
a
T, Days from treatment application to transplanting. b
Values with different letters in the same column differ significantly according to Tukey’s Test (P<0.05).
c
Table 6 - Effect of different soil treatments against F. oxysporum f. sp. lactucae (FUS lat 10 ATCC RB) on lettuce (cv. Crispilla). Data are expressed as disease index 0-100 at the end of the first and second crop cycle, and as fresh weight(Trial 4).
Treatment Dosage Inoculation Ta Disease index 0-100 at
the end of
Fresh weight (g) at the end of
Cycle 1 Cycle2 Cycle 1 Cycle2
Non-treated control - no 30 0.0 ab 0.0 a 263.6 f-h 148.9 c-g
Brassica flour 250g/m2 no 30 0.0 a 0.0 a 614.7 a-c 430.0 ab
B.juncea green manure 2.0 kg/m2 * no 30 0.0 a 0.0 a 257.7 f-h 134.1 d-g
B.carinata pellet 250g/m2 no
30 0.0 a 0.0 a 529.7 c-e 352.6 bc
Cattle manure 10 kg/m2 no 30 0.0 a 0.0 a 316.7 e-g 126.8 d-g
Chicken manure 1,5 kg/m2 no 30 0.0 a 0.0 a 822.9 a 550.3 a
Compost 10 kg/m2 no 30 0.0 a 0.0 a 772.9 ab 351.6 bc
Inoculated non-treated control
- yes 30 59.6 d 60.9 de 155.9 f-h 89.1 fg
Brassica flour 250g/m2 yes 30 33.8 c 42.2 cd 613.8 a-c 166.4 c-g
B. juncea green manure 2.0 kg/m2 * yes 30 38.4 c 49.7 de 265.1 f-h 57.4 g
B.carinata pellet 250g/m2 yes 30 12.2 b 10.0 b 551.6 b-d 215.0 c-g
Cattle manure 10 kg/m2 yes 30 64.1 d 58.4 de 199.8 f-h 65.3 fg
Chicken manure 1,5 kg/m2 yes 30 90.3 e 84.4 e 58.8 h 67.1 fg
Compost 10 kg/m2 yes 30 36.9 c 38.1 cd 339.6 d-f 104.7 d-g
B. carinata pellet 250g/m2 yes 60 15.0 b 12.2 b 121.0 f-h 346.8 b-d
B. juncea green manure 2.0 kg/m2 * yes 60 31.9 c 20.3 bc 98.7 gh 159.2 d-g
Brassica flour 250g/m2 yes 60 30.0 c 35.9 cd 148.2 f-h 283.5 b-e
Compost 10 kg/m2 yes 60 44.1 cd 53.4 de 179.6 f-h 251.6 b-f
Inoculated non-treated control
- yes 60 44.4 cd 40.9 cde 67.6 h 164.4 c-g
Non inoculated control - no 60 0.0 a 0.0 a 122.2 f-h 170.9 c-g
a
T, Days from treatment application and transplanting. b
Values with different letters in the same column differ significantly according to Tukey’s Test (P<0.05).
c
