research article bioagents and commercial algae products

Hindawi Publishing CorporationJournal of Marine BiologyVolume 2013, Article ID 429850, 10 pageshttp://dx.doi.org/10.1155/2013/429850

Research ArticleBioagents and Commercial Algae Products as IntegratedBiocide Treatments for Controlling Root Rot Diseases ofSome Vegetables under Protected Cultivation System

Mokhtar M. Abdel-Kader and Nehal S. El-Mougy

Plant Pathology Department, National Research Centre, El-Behouth St., Dokki, 12662 Giza, Egypt

Correspondence should be addressed to Mokhtar M. Abdel-Kader; mokh [email protected]

Received 26 April 2013; Revised 6 October 2013; Accepted 25 October 2013

Academic Editor: Jakov Dulcic

Copyright © 2013 M. M. Abdel-Kader and N. S. El-Mougy.This is an open access article distributed under the Creative CommonsAttribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work isproperly cited.

Integrated commercial blue-green algae extracts and bioagents treatments against vegetables root rot incidence when used assoil drench under greenhouse and plastic house conditions were evaluated. All applied treatments reduced significantly root rotincidence at both pre- and postemergence growth stages of cucumber, cantaloupe, tomato, and pepper plants compared withuntreated check control. In pot experiment, the obtained results showed that treatments of Trichoderma harzianum or Bacillussubtilis either alone or combined with commercial algae extracts were significantly superior for reducing root rot disease for twotested vegetable plants compared with the other tested treatments as well as control. It is also observed that rising concentrations ofeither algae products, Oligo-X or Weed-Max, were reflected in more disease reduction. Promising treatments for controlling rootrot disease incidence were applied under plastic houses conditions. As for field trails carried out under plastic houses conditionsat different locations, the obtained results revealed that the applied combined treatments significantly reduced root rot incidencecompared with fungicide and check control treatments. At all locations it was observed that Weed-Max (2 g/L) + Bacillus subtilissignificantly reduced disease incidence of grown vegetables comparedwithOligo-X (2mL/L) +Trichoderma harzianum treatments.An obvious yield increase in all treatmentswas significantly higher than in the control. Also, the harvested yield in applied combinedtreatments at all locations was significantly higher than that in the fungicide and control treatments.

1. Introduction

Vegetable crops are grown worldwide as a source of nutrientsand fiber in the human diet. Fungal plant pathogens can causedevastation in these crops under appropriate environmentalconditions. Root rot in vegetables strikes quickly and thenruins a whole crop. Several fungi may cause root rot in veg-etable plants, transmitting the disease through the soil. Somecommon fungi include Fusarium, Rhizoctonia, Sclerotinia,and Pythium, each of which causes a root rot named for thespecific fungi that cause it. While the presence of one of thesefungi is the primary cause for disease, plants exposed to poorgrowing conditions, such as a soil that does not drain well,are most susceptible to root rot. The best way to avoid rootrot is by eliminating these contributing causes and practicing

sound cultivation techniques. It was reported that the soil-borne pathogens Rhizoctonia solani, Pythium ultimum, andFusarium spp. can cause severe economic losses to field andgreenhouse cucumber [1]. Also, Fusarium stem and root roton greenhouse long English cucumber (Cucumis sativus L.)cvs. Bodega and Gardon was observed at four commercialgreenhouses in Leamington, Ontario, Canada. Losses of 25 to35%, representing 2.5 ha, were noted. Fusarium spp., Rhizoc-tonia spp., and Pythium spp. were isolated from tomato plantsshowing root and crown rot symptoms [2].

Thepathogens,Alternaria solani, Fusarium solani, F. oxys-porum, Rhizoctonia solani, Sclerotium rolfsii, Macrophominaphaseolina, and Pythium sp. were isolated from cucumber,cantaloupe, tomato and Pepper plants grown in plastichouses and showing root rot disease symptoms [3]. Different

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approaches may be used to prevent, mitigate, or control plantdiseases. Beyond good agronomic and horticultural prac-tices, growers often rely heavily on chemical fertilizers andpesticides. Such inputs to agriculture have contributed signif-icantly to the spectacular improvements in crop productivityand quality over the past 100 years. The current managementstrategy relies on the intensive use of fungicides. A promisingstrategy for the replacement of chemical pesticides hasbeen the implementation of biological control. The recentdevelopment in the commercialization of biological controlproducts has accelerated this approach [4]. The applicationof biological controls using antagonistic microorganismshas proved to be successful for controlling various plantdiseases in many countries [5]. However, this is not an easymethod, and it is costly to apply; however, it can serveas the best control measure under greenhouse conditions.Trichoderma harzianum introduced to the soil was able toreduce root rot incidence of faba bean plants significantlymore than the fungicide Rizolex-T [1]. In recent years,several attempts have been made to overcome this obstacleby applying antagonistic microorganisms. Trichoderma spp.are well documented as effective biological control agentsof plant diseases caused by soil-borne fungi [2, 3, 6]. Manyinvestigators observed that the application of wheat brancolonized by T. harzianum to soil infested with R. solaniand S. rolfsii reduced the incidence of root diseases causedby these pathogens [7–9]. Furthermore, soil drenched withT. harzianum was significantly able to reduce the incidenceof bean root rot of bean and pepper wilt diseases [1, 10–12]. As for antagonistic bacteria, [13] it was found thatseed treatment with Bacillus spp. was actively controlledby three fungal root diseases of wheat. Also, Pseudomonascepacia or Pseudomonas fluorescens applied to pea seedsacted as biological control agent against Pythium damping-off and Aphanomyces root rot and was able to reduce diseasesincidence [11]. In addition, recently algae are one of the chiefbiological agents that have been studied for the control ofplant pathogenic fungi, particularly soil-borne diseases [14].Cyanobacteria (blue-green algae) and eukaryotic algae hadbeen reported to produce biologically active compounds, thatis, antifungal activity [15, 16], antibiotic and toxic activity[17, 18], against plant pathogens. Moreover, Anabaena spp.,Scytonema spp., and Nostoc spp. were reported to be efficientfor controlling damping-off as well as the growth of soil fun-gus Cunninghamella blakesleana [19–22]. Also, [15] reportedthat culture filtrates or cell extracts from cyanobacteria andalgae applied to seeds protect them from damping-off fungisuch as Fusarium sp., Pythium sp. and Rhizoctonia solani.Furthermore, in previous work of the authors [23] it wasfound that commercial blue-green algae extracts, Weed-Max(blue-green algae extracts in powder phase), and Oligo-Mix(blue-green algae extracts in liquid phase) have potentialfor the suppression of soil-borne fungi and enhance theantagonistic ability of fungal, bacterial and yeast bioagents.These results led to the suggestion that another supportingfactor is needed to raise the efficacy of the algae products.Therefore, application of the bioagents as a soil treatment inintegration with algae products could be evaluated againstroot rot incidence of various plants.

The present research focuses on finding compoundsthat are safe to humans and the environment, for example,algae, as well as bioagents which may provide an alternativecontrol against many soil- and seed-borne pathogens. Theobjective of the present work was to evaluate integrated bioa-gents, Trichoderma harzianum, T. viride or Bacillus subtilis,and Pseudomonas fluorescens, and commercial algae extract,Weed-Max or Oligo-X, against vegetables root rot incidencewhen used as soil drench under artificial infestation in potexperiment and natural infestation under commercial plastichouse conditions.

2. Materials and Methods

Evaluation of integrated bioagents, Trichoderma harzianumor Bacillus subtilis and commercial algae extract, Weed-Maxor Oligo-X, against Cucumber, Tomato, and Pepper rootrot incidence, was carried out under greenhouse and plastichouse conditions.

2.1. Tested Materials

2.1.1. Microorganisms. The bioagents fungal antagonists, thatis, Trichoderma harzianum and T. viride, as well as bacterialantagonists, that is, Bacillus subtilis and Pseudomonas fluo-rescens, obtained from culture collection unit of Plant Pathol-ogy Department, National Research Centre, Egypt, wereused in the present work. These bioagents proved their highantagonistic effect against wide spectrum of plant pathogensin many previous works at the same department. Also, highlyaggressive isolates of Fusarium solani and Rhizoctonia solaniwere used in pot experiment.

2.1.2. Preparation of Microorganisms Inocula. The fungalinocula (pathogenic or bioagent) were grown individually fortwoweeks on sand-barleymedium (1 : 1, w : w and 40%water)at 25 ± 2∘C. Meanwhile bacterial bioagents were grown onnutrient broth medium for 48 hrs at 28 ± 2∘C under shakingconditions.

2.1.3. Commercial Algae Extracts. Purchased commercialalgae extracts, that is, Weed-Max (blue-green algae extractsin powder phase) produced by Inc. Trade S.A.E. Company,Naser City, Egypt, and Oligo-X algae (blue-green algaeextracts in liquid phase) produced by Arabian Group forAgricultural Service, 114 King Fesal Street, Giza, Egypt wereused in the present study. These commercial algae extractswere used in their commercial form without analyzing theircomposition.

2.1.4. Vegetables. Vegetables seeds or transplants of Cucum-ber (Hisham cv.), Cantaloupe (Yathreb cv.), Tomato (Agyaadcv.), and Pepper (Khyrratte cv.) were used for greenhouse andplastic house trails.

2.2. Pot Experiment. Pot experiment was carried out inthe greenhouse of Plant Pathology Deptartment, National

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Research Centre, Egypt, for evaluating the efficacy of bioa-gents, Trichoderma harzianum or Bacillus subtilis, and com-mercial algae extract, Weed-Max or Oligo-X, introduced tothe soil, as soil treatments, against root rot disease incidence.Cucumber and tomato representing cucurbits and solana-ceous crops were used in this experiment as a model ofwidespread vegetable crops mainly grown under protectedcultivation system in Egypt and showed susceptibility toattack with root rot pathogens [3]. The pathogenic isolatesof Fusarium solani and Rhizoctonia solani were used. Loamysoil was artificially infested individually (at the rate of 5%w :w) with inoculum of each pathogenic fungus, throughmixing thoroughly with the soil and then filled in plasticpots (20 cm in diameter). The infested soils were then mixedthoroughly with inocula of bioagents either fungi (Tricho-derma harzianum, T. viride) or bacteria (Bacillus subtilis,Pseudomonas fluorescence) relevant to the specific treatment.The fungal inocula were added to the soil at the ratio of 5%(w : w) of soil weight, while bacterial inocula as liquid culture(3×106 cfu/mL) at the ratio of 100mL/cubic foot of soil. Algaeextracts Oligo-X (liquid phase) and Weed-Max (solid phase)were added at different concentrations, that is, 0.5, 1.0, and20.0 (mL or g/L), were added individually or combined withbioagents at the rate of 250mL/cubic foot of soil.

Another set of varied infested soils only with pathogenswas used for comparison check treatment.

The applied treatments in infested soil with either Fusar-ium solani or Rhizoctonia solani were as follows:

(1) Oligo-X(2) a mixture of Oligo-X + T. harzianum(3) a mixture of Oligo-X + T. viride(4) a mixture of Oligo-X + B. subtilis(5) a mixture of Oligo-X + P. fluorescens(6) weed-Max(7) a mixture of Weed-Max + T. harzianum(8) a mixture of Weed-Max + T. viride(9) a mixture of Weed-Max + B. subtilis(10) a mixture of Weed-Max + P. fluorescens(11) T. harzianum(12) T. viride(13) B. subtilis(14) P. fluorescens(15) infested Untreated control(16) uninfested untreated control.

Five seeds of Cucumber or Tomatowere sown in preparedartificially infested soils in each pot, and five pots were usedas replicates for each particular treatment. Percentages ofpre- and postemergence root rot incidence throughout theexperimental period were recorded. Percentage of root rotincidence at the preemergence stage was calculated as thenumber of absent seedlings relative to the number of sownseeds. Meanwhile, the percentage of root rot incidence at

the postemergence stage was calculated as the number ofdiseased plants relative to the number of emerged seedlings.Percentage of root rot incidence at preemergence growthstage was recorded after two weeks from sowing date. Mean-while, percentage of root rot incidence at postemergencestagewas calculated 45 days after emergence.This experimentwas repeated twice in order to confirm the obtained results.At the end of the experiment, survived plants were carefullypulled out from pots after being flooded with water in orderto leave the root system undamaged. Plant roots showingrot lesions in addition to the visual root rot symptoms onthe shoot system were considered diseased plants. Isolationfrom infected germinated seeds at the preemergence stageand infected plants at the postemergence stage was carriedout. Undeveloped, germinated seeds which were picked upfrom the soil and the diseased plants were washed andsterilized with 3% sodium hypochlorite and then subjectedto reisolation in order to identify the causal pathogens.

2.3. Plastic House Experiments. The tested treatments inprevious pot experiment which revealed promising resultsagainst root rot incidence were applied in plastic housesexperiments under natural infestation conditions.This exper-iment was carried out on growing vegetables under pro-tected cultivation system in commercial plastic houses ofMinistry of Agriculture and Soil Reclamation, Egypt, atDokki, Nubaria, and Haram locations. The applied inte-grated treatments were a mixture of Oligo-X (2mL/L) + T.harzianum and a mixture of Weed-Max (2 g/L) + B. subtilis.The recommended fungicide Rizolex-T 50% as transplantingdipping at the rate of 2 g/L was used as comparison treatment.The experimental plastic house consists of 6 rows eachcontains two cultivated row sites. Each cultivated row site(0.9 × 60m, width × long) was divided into 2 parts 30mlong each, and every part was considered as one replicate.Three replicates were used for each particular treatment incomplete randomized design. The proposed treatments wereprepared in laboratory of Plant Pathology Department, NRC,and sent to certain locations for soil application. The soildrenched at the cultivated row site with bioagents inocula ofT. harzianum was grown previously on sand-barley mediumat the ratio of 120 g/m2 [10] as well as inocula of B. subtiliswere grown previously on nutrient broth medium at the rateof 500mL/row (3 × 106 cfu) after [13]. Bioagents inocula wereincorporated into the top of 20 cm of the soil surface at plant-ing row sites considering relevant treatments. The preparedsolution of algaemixture was also incorporated into the samecultivated row site at the rate of 30 L/row (distributed forthe three replicates) as combined treatment.These treatmentswere applied 5 days before vegetables transplanting. Thetransplanted vegetables were Cucumber (at Dokki plastichouse location); Cantaloupe (at Nubaria location); Tomatoand Pepper (at Haram plastic house location). The culti-vated vegetables received traditional agriculture practices,that is, irrigation, fertilizers, and so forth. At all locations,the growing vegetables in the experimental plastic housesreceived traditional programs recommended by Committeeof Protected Cultivation Administration Office, Ministry


of Agriculture and Soil Reclamation, for controlling foliardiseases and harmful insects, that is, Aphids,Thrips,Whitefly,and so forth.

Monitoring and scouting of root rot incidence wererecorded up to 60 days from transplanting date. Percentageof root rot disease incidence was recorded as the number ofdiseased plants relative to the number of planted seedlingsand then the average of disease incidence in each treatmentwas calculated. At the end of growing season the obtainedaccumulated yield of cultivated vegetables for each relevanttreatment was calculated.

2.3.1. Statistical Analysis. All experiments were set up incompletely randomized design (CRD). The data collectedfrom greenhouse experiment were analyzed by MSTAT-Cprogram [24]. The means differences were compared by leastsignificant difference test (LSD) at 5% level of significance.In plastic house experiments, one-way ANOVA was used toanalyze differences between applied treatments. A generallinear model option of the analysis system SAS [25] was usedto perform the ANOVA. Duncan’s multiple range test at 𝑃 ≤0.05 level was used for means separation [26].

3. Results

3.1. Pot Experiment. Evaluating the efficacy of bioagentsand/or algae extracts as soil drench against root rot diseaseincidence was carried out in the greenhouse. Data presentedin Tables 1 and 2 showed that all applied treatments assoil drench reduced significantly root rot incidence at bothpre- and postemergence growth stages of Cucumber andTomato plants compared with untreated check control. Dataalso revealed that applied treatments of the bioagent incombination with algae extracts resulted in higher significantreduction in root rot incidence than each of them alone. Thepresented data showed that treatments of T. harzianum or B.subtilis either alone or combined with algae extracts were sig-nificantly superior for reducing root rot disease for two testedvegetable plants comparedwith the other tested treatments aswell as control. It is also observed that (Tables 1 and 2) risingconcentrations of either Oligo-X orWeed-Maxwere reflectedin more disease reduction. Presented data also showed thatthe recorded root rot incidence inT. harzianum andB. subtilisas single treatments at preemergence growth stages was 20%for Cucumber andTomato in infested soil with either F. solanior R. solani. Meanwhile, lower significant disease incidencewere recorded when these bioagents combined with algaeextracts. In this regard, root rot incidence of cucumber atpreemergence stage (Table 1) was recorded as 16.0, 12.0, and8.0% and 20.0, 16.0, and 12.0% at combined treatment of T.harzianum and Oligo-X and Weed-Max at concentration of0.5, 1.0, and 2mL/L in infested soil with F. solani and R.solani, respectively. Meanwhile root rot incidence of Tomatoat preemergence stage (Table 2) was recorded as 20.0, 16.0,and 12.0% and 20.0, 20.0, and 12.0% at the same previoustreatments in respective order. On the other hand, root rotincidence at preemergence growth stage was recorded as32.0, 36.0% and 32.0, 32.0% for Cucumber and Tomato inuntreated infested soil with F. solani or R. solani, respectively.

Similar trend was also observed concerning root rot inci-dence at postemergence growth stage. The highest reductionin disease incidence was recorded at treatments of bioagentscombined with algae extracts at concentration of 2mL/Land 2 g/L. At postemergence stage, the recorded root rotincidence of Cucumber (Table 1) at T. harzianum + Oligo-X and T. harzianum + Weed-Max treatments was 8.6, 9.0%and 8.3, 8.6% in infested soil with F. solani or R. solani,respectively. Also, in Table 2 the root rot incidence of Tomatoin infested soil with F. solani or R. solani was recorded as13.6% atT. harzianum combined treatment with either Oligo-X or Weed-Max. Announced reduction in root rot incidenceat postemergence growth stage of Cucumber and Tomato wasobserved at B. subtilis combined with Weed-Max treatments.At concentration of 2 g/L of Weed-Max combined with B.subtilis the root rot incidence recorded as 4.1, 4.1 and 9.0, 8.6%forCucumber andTomato plants in soil infestedwith F. solanior R. solani, respectively (Tables 1 and 2).

The obtained results concerning applied treatments ofbioagents alone or combined with commercial algae extractsagainst root rot incidence of some vegetables grown in artifi-cially infested soil with root rot pathogens under greenhouseconditions revealed that the most promising treatmentsfor controlling disease incidence are combined treatmentsbetween bioagents, T. harzianum, B. subtilis, and algae prod-ucts at the highest concentration tested. Therefore, thesetreatments were evaluated under natural infections in plastichouse conditions.

3.2. Plastic House Experiments. Different treatments wereevaluated against root rot incidence under plastic houses con-ditions at different locations. Combined soil drench treat-ments, Oligo-X (2mL/L) + T. harzianum and (Weed-Max(2 g/L) + B. subtilis) were applied compared with thefungicide Rizolex-T (2 g/L) as transplants dipping. Thesetreatments were carried out before Cucumber, Cantaloupe,Tomato, and pepper being transplanted. Presented data inTable 3 revealed that the applied combined treatments signif-icantly reduced root rot incidence compared with fungicideand check control treatments.

At all locations it was observed that Oligo-X (2mL/L)+ T. harzianum and Weed-Max (2 g/L) + B. subtilis reduceddisease incidence of grown vegetables compared with fungi-cide treatment and control as well. In this concern, data inTable 3 showed that no significance was observed betweenthe two applied combined treatments. Also, data showed thatthe recorded disease incidence was 5.6%, 4.8% and 6.3%,5.0% compared with 8.6%, 6.8% of Tomato, and Pepper plantat treatments, Oligo-X (2mL/L) + T. harzianum, Weed-Max(2 g/L) + B. subtilis, and the fungicide Rizolex T, in respectiveorder.Meanwhile, root rot incidences as 17.6% and 18.7%wererecorded in untreated control.

Reduction in disease incidence of Cucumber grown atDokki location (Table 3) was recorded as 86.5% and 85.8%at Oligo-X (2mL/L) + T. harzianum and Weed-Max (2 g/L)+ B. subtilis compared with 65.3% at fungicide treatments. Asfor Cantaloupe plants grown atNubaria location (Table 3) thereduction in root rot incidence was recorded as 73.0%, 74.6%,


Table 1: Effect of integrated soil treatment with algae compound and bioagents against root rot incidence of cucumber under greenhouseconditions.

Soil infestation Soil treatment

Root rot incidence (%)Preemergence Postemergence

Algae product concentration (mL/L and g/L)0.5 1.0 2.0 Mean STDEV 0.5 1.0 2.0 Mean STDEV

Fusarium solani

Oligo-X 28.0 24.0 16.0 22.6 4.98 16.6 15.7 9.5 13.9 3.15Oligo-X + T. harzianum 16.0 12.0 8.0 12.0 3.26 14.2 9.0 8.6 10.6 2.55

Oligo-X + T. viride 20.0 16.0 12.0 16.0 3.26 15.0 14.2 9.0 12.7 2.66Oligo-X + B. subtilis 16.0 12.0 8.0 12.0 3.26 14.2 13.6 8.6 12.1 2.51

Oligo-X + P. fluorescens 20.0 16.0 12.0 16.0 3.26 20.0 19.0 13.6 17.5 2.81Weed-Max 28.0 24.0 20.0 24.0 3.26 22.2 21.0 20.0 21.0 0.90

Weed-Max + T. harzianum 16.0 8.0 4.0 9.3 4.98 14.2 8.6 8.3 10.3 2.71Weed-Max + T. viride 24.0 20.0 20.0 21.3 1.88 21.0 20.0 15.0 9.8 5.15Weed-Max + B. subtilis 16.0 8.0 4.0 9.3 4.98 14.2 4.3 4.1 7.5 4.71

Weed-Max + P. fluorescens 20.0 16.0 8.0 14.6 4.98 15.0 14.2 13.0 14.0 0.82T. harzianum 20.0 15.0

T. viride 24.0 21.0B. subtilis 20.0 25.0

P. fluorescens 28.0 27.7Untreated 32.0 29.4

Rhizoctonia solani








Untreated control 8.0 8.6LSD at 5%

Infestation (I) ns 1.8Treatment (T) 4.0 1.4Concentration (C ) 2.0 2.2Between (I × T × C) 4.0 2.8

and 53.9% at treatments, Oligo-X (2mL/L) + T. harzianum,Weed-Max (2 g/L) + B. subtilis and fungicide, respectively. AtHaram location similar trend was observed for the reductionin root rot incidence of Tomato and Pepper plants.

An obvious yield increase in all treatments was signifi-cantly higher than that in the control. Also, the harvestedyield in applied combined treatments at all locations wassignificantly higher than that in the fungicide and controltreatments (Table 4). The treatments of Oligo-X (2mL/L) +

T. harzianum showed higher yield production than thosetreatments usingWeed-Max (2 g/L) + B. subtilis, and Rizolex-T. At Dokki location (Table 4) the effective treatment whichhelped increase Cucumber yield was Oligo-X (2mL/L) + T.harzianum (47.4%), followed by Weed-Max (2 g/L) + B. sub-tilis (37.8%) and Rizolex-T (32.9%), respectively. At Nubarialocation (Table 4) grown Cantaloupe in soil drenched withOligo-X (2mL/L) + T. harzianum resulted in the highestincrease in produced yield estimated as 28.6% followed by


Table 2: Effect of integrated soil treatment with algae compound and bio-agents against root rot incidence of tomato under greenhouseconditions.

Soil infestation Soil treatment

Root rot incidence (%)Pre-emergence Post-emergence

Algae product concentration (mL/L and g/L)0.5 1.0 2.0 Mean STDEV 0.5 1.0 2.0 Mean STDEV

Fusarium solani








Rhizoctonia solani








Untreated control 4.0 4.1LSD at 5%

Infestation (I) ns 2.8Treatment (T) 2.0 1.8Concentration (C ) 4.0 2.4Between (I × T × C) 4.0 4.6

treatments, Weed-Max (2 g/L) + B. subtilis and Rizolex-Twhich resulted in an increase in yield estimated as 23.0%and 13.2%, respectively. Tomato and pepper plants grown inplastic houses atHaram location (Table 4) showed an increasein produced yield estimated as (26.6%, 21.7%); (23.3%, 19.3%)at applied soil treatments Oligo-X (2mL/L) + T. harzianumand Weed-Max (2 g/L) + B. subtilis, respectively. Meanwhilelower yield increase was recorded as 6.3% and 10.1% forTomato and Pepper plants, respectively, at the fungicidetreatment.

4. Discussion

Root rot disease occurs during the growing season of veg-etable crops from seedling to flowering stages and may causepreemergence infection. So far, apart from scientific andprac-tical difficulties, there is no economic way to control the cropdiseases. The management of soil-borne plant pathogens isparticularly complex because these organisms live in or nearthe dynamic environment of the rhizosphere and can fre-quently survive a long period in soil through the formation of


Table 3: Application of algae compounds and bioagent formula against root rot disease of cucumber grown in plastic houses under protectedcultivation system at different locations.

Treatment

Root rot incidence (%)Location

Dokki Nubaria Haram HaramCucumber Cantaloupe Tomato Pepper

DI1 𝑅2 DI 𝑅 DI 𝑅 DI 𝑅

Oligo-X + T. harzianum 2.1c 86.5 3.4c 73.0 5.6c 68.1 4.8c 74.3Weed-Max + B. subtilis 2.2c 85.8 3.2c 74.6 6.3c 64.2 5.0c 73.2Rizolex-T (2 g/L) 5.4b 65.3 5.8b 53.9 8.6b 51.1 6.8b 63.6Untreated control 15.6a — 12.6a — 17.6a — 18.7a —Mean values within each column followed by the same letter are not significantly different (𝑃 ≤ 0.05).1Disease incidence calculated as the number of diseased plants relative to the whole number of examined plants in percentage.2Reduction in disease incidence calculated as disease incidence in treatment relative to disease incidence in control in percentage.

Table 4: Effect of applied algae compounds and bio-agent formula on produced yield of some vegetables grown in plastic houses underprotected cultivation system at different locations.

Treatment

Average yield Kg/rowLocation

Dokki Nubaria Haram HaramCucumber Cantaloupe Tomato Pepper𝑌1

𝐼2

𝑌 𝐼 𝑌 𝐼 𝑌 𝐼

Oligo-X + T. harzianum 299.6d 47.4 183.4d 28.6 312.6d 26.6 203.6d 21.7Weed-Max + B. subtilis 280.2c 37.8 175.5c 23.0 304.4c 23.3 199.5c 19.3Rizolex-T (2 g/L) 270.2b 32.9 161.5b 13.2 262.4b 6.3 184.2b 10.1Untreated control 203.2a — 142.6a — 246.8a — 167.2a —Mean values within each column followed by the same letter are not significantly different (𝑃 ≤ 0.05).1The obtained accumulated yield of cultivated vegetables for each relevant treatment was calculated as Kg/row.2Percentage of the increase in obtained accumulated yield of cultivated vegetables for each relevant treatment was calculated relative to yield in controltreatment.

resistant survival structures. Several commercially availableproducts have shown significant disease reduction throughvarious mechanisms to reduce pathogen development anddisease. Plant diseases need to be controlled to maintain thequality and abundance of food, feed, and fiber produced bygrowers around the world. However, the environmental pol-lution caused by excessive use and misuse of agrochemicals,as well as fearmongering by some opponents of pesticides, hasled to considerable changes in people’s attitudes towards theuse of pesticides in agriculture.Many strategies to control thisfungal pathogen have been investigated in the field [27, 28].Currently, themost effectivemethod in preventing soil-bornediseases is to mix the seed with chemical fungicides. Theapplication of chemical fungicide induces other problems,such as the harm to other living organisms and the reductionof useful soil microorganisms [29, 30]. Therefore, publicconcern is focused on alternative methods of pest control,which can play a role in integrated pest management systemsto reduce our dependence on chemical pesticides [31].

The revolutionized therapy of infectious diseases bythe use of antimicrobial drugs has certain limitations dueto the changing patterns of resistance in pathogens andthey side effects they produced. These limitations demand

for improved pharmacokinetic properties, which necessitatecontinued research for new antimicrobial compounds for thedevelopment of drugs [32]. So accordingly, pharmaceuticalindustries are giving importance to the compounds derivedfrom traditional sources (soil and plants) and less traditionalsources like marine organisms [33]. Hence, the interest inmarine organisms as a potential and promising source ofpharmaceutical agents has increased during recent years [34].Marine algae or seaweeds are a rich and varied source ofbioactive natural products, so they have been studied aspotential biocidal and pharmaceutical agents [35]. Therehave been a number of reports of antibacterial activityfrom marine plants [36] and special attention has beenreported for antibacterial, and/or antifungal activities relatedto marine algae against several pathogens [37]. Seaweedsare considered as a source of bioactive compounds as theyare able to produce a great variety of secondary metabolitescharacterized by a broad spectrum of biological activities[38] with antiviral, antibacterial and antifungal activities[39] which act as potential bioactive compounds of interestfor pharmaceutical applications [33]. Most of these bioac-tive substances isolated from marine algae are chemicallyclassified as brominated, aromatics, nitrogen-heterocyclic,


nitrosulphuric-heterocyclic, sterols, dibutanoids, proteins,peptides, and sulphated polysaccharides [37]. The antibacte-rial activity of seaweeds is generally assayed using extractsin various organic solvents, for example, acetone, methanol-toluene, ether, and chloroform-methanol [40]. Using oforganic solvents always provides a higher efficiency inextracting compounds for antimicrobial activity [41]. Sev-eral extractable compounds, such as cyclic polysulfides andhalogenated compounds, are toxic to microorganisms, andtherefore, responsible for the antibiotic activity of someseaweeds [42]. Also [36] it was revealed that the extractionof antimicrobials from the different species of seaweedswas solvent dependent; methanol was a good solvent forextraction of antimicrobials from brown seaweeds, whereasacetone was better for red and green species.

Furthermore, application of seaweeds as organic soilamendment has increased in recent years due to raisingawareness about the adverse effect of chemical pesticides [43–47]. Also, in previous study the suppression of root rottingfungi and root knot nematode of chili by a red alga Solieriarobusta has been reported [44].

The present investigation has demonstrated the antifun-gal activity of all treatments tested. This work proves thatsome algae products have potential and could be useful whenintegrated with bioagents against root rot fungal pathogens.From the earlier reports [32, 36] it is evident that some of themarine algae products have antifungal compounds which dohave the capacity to inhibit the fungal pathogens. Therefore,there is increasing interest in obtaining alternative antimi-crobial agents for use in plant disease control systems. Oneof the main procedures used in the research of biologicallyactive substances is a systematic screening for the interactionbetween microorganisms and plant products.This procedurehas been a source of useful agents to control the microbialsurvival [48]. In the present study the introduction of thebioagent T. harzianum or B. subtilis to the soil increased theefficacy of both algae products against root rot incidenceunder greenhouse and plastic houses conditions. Similarresults were also reported [10]. It was stated thatT. harzianumintroduced to the soil was able to reduce root rot incidenceof faba bean plants significantly more than the fungicideRizolex-T. Moreover, the application of biological controlsusing antagonistic microorganisms has proved to be success-ful for controlling various plant diseases in many countries[6, 49–52]. Combination between Topsin-M and drench witheither B. subtilis or B. megaterium induced more significantreduction in disease incidence and yield increase than seedcoating with bioagents and/or each treatment alone. Inaddition, Bacillus cereus has proven to have beneficial effectson crop health including enhancement of soybean yield,suppression of damping-off of tomato [53], and alfalfa [54].

5. Conclusion

The present work demonstrated that application of com-mercial algae extracts, Oligo-X and Weed-Max, combinedwith bioagents, T. harzianum and B. subtilis, as integratedsoil treatment under greenhouse and plastic houses trails,resulted in plant health and improved the obtained yields in

numerous tested vegetable crops. These treatments causeda significant reduction in root rot incidence of Cucumber,Cantaloupe, Tomato, and Pepper. Furthermore, an obviousyield increase in all applied combined treatments at alllocations was significantly higher than that in the fungicideand control treatments. It may be concluded that applicationof commercial algae products combinedwith active bioagentsis considered an applicable, safe, and cost-effective methodfor controlling such soil-borne diseases.

Conflict of Interests

The authors declare that they do not have a direct financialrelation with the twomentioned companies “El-Nile Compa-ny, Egypt, and Chemical Industrial Development Company(CID), Egypt,” that might lead to a conflict of interests.

Acknowledgment

Thisworkwas supported financially by theNational ResearchCentre Fund (NRC), Egypt, Grant no. 9050204.

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