Revista Mexicana Ciencias Agrícolas   volume 11   number 2   February 15 - March 31, 2020

DOI: https://doi.org/10.29312/remexca.v11i2.2071

Article

Control of guava cloves with plant extracts

Ernesto González-Gaona1

Héctor Silos-Espino1

Catarino Perales-Segovia1§

José Saúl Padilla-Ramírez2

Irma Guadalupe López-Muraira3

Efraín Acosta-Díaz4

1TecNM/ I. T.-EL Llano Aguascalientes. Aguascalientes-San Luis Potosí Highway km 18, El Llano, Aguascalientes, Mexico. CP. 20230. (eggaona@yahoo.com.mx; silosespino@hotmail.com). 2Experimental Field Pavilion-INIFAP. Aguascalientes-Zacatecas Highway km 32.5, Arteaga Pavilion, Aguascalientes, Mexico. CP. 20660. (jsaulprmez@yahoo.com). 3TecNM/ I. T. de Tlajomulco. Tlajomulco-San Miguel Cuyutlán Highway km 10, Tlajomulco de Zúñiga, Jalisco, Mexico. CP. 45640. (lopezmuraira@hotmail.com). 4General Experimental Field Terán-INIFAP. Montemorelos-China Highway km 31, Ex Hacienda Las Anacuas, General Terán, Nuevo León, Mexico. CP. 67400. (acostaefrain@yahoo.com.mx).

§Corresponding author: cperales55@hotmail.com.

Abstract

Extracts made by alcoholic maceration, showed the greatest inhibition of the growth of the P. clavispora fungus with respect to water maceration or infusion. In bioassays with alcoholic extracts concentrated with rotary evaporator and filtered, extracts of jaral (Cistus sp.), olives (Bidens odorata Cav.), Mesquite (Prosopis laevigata Humb. & Bonpl. Ex Willd.), paradise (Melia azedarach L.), olive tree (Olea europaea L.), trompillo (Solanum eleagnifolium Cav.), lantana (Lantana sp.), rosemary (Rosmarinus sp.), rue (Ruta graveolens L.), venadilla (Bursera simaruba (L.) SARG.), cow tongue (Rumex crispus L.) and Australian eucalyptus (Corymbia (=Eucalyptus) gummifera (Gaertn.) Hill & Johnson) showed fungal growth reductions, greater than 90%. In the field, extracts of red eucalyptus plants (Eucalyptus camaldulensis) and Australian eucalyptus (Corymbia gummifera) showed less damage than chemical synthesis fungicides evaluated. The foregoing indicates that the use of these extracts is feasible in the control of the P. clavispora fungus, reducing the environmental impact.

Keywords: Eucalyptus, Psidium guajava, bioassays, field evaluation.

Reception date: December 2019

Acceptance date: March 2020

Introduction

The scab disease of the guava is a disease that affects both fruits and leaves of the guava tree (Psidium guajava L.), in the former dark brown circular lesions (such as a startled scab of the epidermis) with the appearance of a ‘rusty nail’, while asymmetrical reddish brown spots are observed on the leaves in the middle portion around the central rib, the tender shoots curl over their bundle and the terminal buds dry and fall (Nieto, 1996; González, 2002). The effects may exceed 70% in wild plants (Farfán, 2005) and around 14% in commercial orchards (Mishra and Prakash, 1986; González et al., 2008).

The causative agent is the fungi Pestalotiopsis (=Pestalotia) and Neopestalotiopsis (Keith et al., 2006; Solarte et al., 2017), the species that affect the guava are: P. palmarum (Cooke) Steyaert, P. psidii (Pat.) Mordue, P. versicolor (Speg.) Steyaert (Montiel, 1997) and P. olivacea Guba (Mishra and Prakash, 1986); P. psidii is considered the causative agent of scab disease in the guava producing area of Aguascalientes and Zacatecas (Nieto, 1996), while Serrano et al. (2018) found that P. clavispora is the causative agent in the area of Calvillo, Aguascalientes. Farr et al. (2008), mention that P. psidii affects guavas in other regions of the world (Burma, Ivory Coast, Ecuador, Hawaii, India, Malaysia, Mozambique, Nigeria, Puerto Rico, Taiwan, Tanzania, India, Venezuela, Zambia and Zimbabwe) and report effects on Psidium guineense in Venezuela, on Psidium pomiferum in Ecuador, on Feijoa sellowiana in Italy, on Musa paradisiaca in India and on P. pomiferum in India and Nepal.

For its control chemical synthesis fungicides are applied (Kasar et al., 2006; Prakash and Pandey, 2007; Ray et al., 2007). In Calvillo, Aguascalientes, Mexico, fungicides are applied on a scheduled basis, from July to October, because the conditions of temperature and high relative humidity favor their presence and damage (González et al., 2009), are performed from three to six applications of fungicides mixed or alternated with insecticides, due to the suspicion of a vector insect (Monalonion sp. Hemiptera: Miridae) detected in the area (Serrano et al., 2018). With 7 000 ha of guava in the area, more than 10 t of pesticides would be applied only to combat this disease, which could cause collateral damage to the environment.

In the area of Calvillo, the Institute of Health of the State of Aguascalientes has reported an increase in chronic renal diseases associated with the application of pesticides in the crop, observing overexposure to Malation and Cypermethrin in seven rural communities, concluding that 9% of the Study population is at moderate risk of progression to kidney damage. The increase in urinary excretion of sodium and phosphates was correlated with the serum concentrations of Cipermethrin (Mendoza et al., 2015).

Alternative strategies to control the disease are fruit bagging (Villamizar et al., 2003; Ramirez, 2005; Morera and Blanco, 2009), the use of antagonists (Gonzalez et al., 2008) and the application of botanical fungicides. In relation to the latter, the neem (Azadirachta indica), the purple basil (Ocimum sanctum), the eucalyptus (Eucaliptus globulus L.), the mint (Menta piperita) and the horsetail (Equisetum arvense) of the which E. globulus showed a control of 89% (Mishra, 2004; Parada, 2005; Quijada and Gómez, 2005). The control of plague organisms such as guava weevil (Conotrachelus dimidiatus Ch.) with botanical extracts has been explored with good results in the

Calvillo area; however, it has not been adopted since the evaluated plants (jicama or pepper) are not produced in the area, which implies a cost to obtain them, together with the elaboration work (González et al., 2008).

In the orchards associated with guava, wild plants coexist that can be used for the management of pest organisms. The objective of this study was to evaluate extracts of plants for regional use or present in the guava orchards of the producing area of Calvillo, Aguascalientes as an alternative for the management of the disease, considering its accessibility, low investment, easy processing and low environmental impact.

Materials and methods

Collection of biological material

Vegetable material was collected from 64 broadleaf species located in and around guava orchards, such as weeds or ruderal plants on perimeter fences. The material was transferred to the Plant Health Laboratory of the Pabellón Experimental Field (CEPAB), where it was dehydrated under the shade at room temperature (Rodríguez et al., 2012) afterwards, the samples (whole plant) were ground in a hammer mill (Hamilton Beach® Custom Grind™ Deluxe model), weighed and stored in 0.5 kg plastic bottles.

Preparation of extracts

Infusions. 10 g of plant material were weighed and placed in an aluminum container with 1 L of water, to which heat was applied until boiling for 5 min, they were filtered and stored in amber jars (Biswas et al., 2013). The solutions were filtered with sterile gauze, then with Whatman No. 42 paper and subsequently taken to a rotary evaporator to remove the solvent (Dhiman et al., 2011) until leaving a third of the total extract (the stock solution). Finally, they were sterilized with 0.45 µm micropore filters. Sterile solutions were stored in amber bottles protected from light and evaporation.

Aqueous and ethanolic macerates. The extracts were obtained by the method of maceration at room temperature (27 °C) with 70% water and alcohol, the maceration consisted of making 1:4 solutions (for each gram of plant material 4 ml of solvent were added), which they were left in maceration for a period of 7 days with manual agitation twice daily for 1 min. In water maceration, electropure and boiled water was used (Biswas et al., 2013). The same infusion procedure was followed to concentrate and store the macerates.

Bioassays of effectiveness against Pestalotiopsis

The two bioassays were performed in 9.0 cm diameter petri dishes, which were filled with 20 ml of sterile PDA medium + 150 µL of each extract, once the medium solidified the pathogen was inoculated by an agar disc of 0.6 cm in diameter with active growth of the fungus, it was incubated at a temperature of 27 °C until the negative control mycelium (PDA without extract) covered the entire plate (Baños et al., 2004). The percentage of inhibition of radial mycelial growth with respect to the negative control was measured by the formula: % inhibition of radial growth = [(control-treated)/control] X 100.

To know the effect of the best form of preparation of the extracts, three forms of preparation were considered a) macerated in water; b) macerated in 70% alcohol; and c) infusions. In the first instance, 10 plants were used for domestic use (Mexican cuisine), present in urban vegetation or as weeds in the area of Calvillo, Aguascalientess. A completely randomized design was used, with 13 treatments and three repetitions. They were compared with a commercial extract (Biogober®) and two commercial products (Fractal® and Cupravit®) (Table 1), the estimated variable was the percentage of inhibition.

Table 1. Effect on the growth of the fungus Pestalotiopsis sp by plant extracts obtained in different forms.

*= mean growth in mm of three repetitions at 168 h after inoculation ± standard deviation.

In order to find plants from which to obtain a solution with an inhibitory effect on the growth of Pestalotiopsis sp., additionally the extracts obtained by the alcoholic maceration of 23 plants associated with the guava orchards were used, as well as the Australian eucalyptus and Copper oxychloride through a randomized block design with three repetitions with the percentage inhibition variable (Table 2).

Table 2. Effect on the growth of Pestalotiopsis sp. with plant concentrates associated with guava orchards.

*= Colony growth mean of the fungus Pestalotiopsis sp., followed by the same letter are not statistically different using 0.05% Tukey.

Field experiment

The experiment was carried out in the locality ‘Las Moras’ (Mesa Grande, Calvillo, Aguascalientes; 21° 47’ 09.4’’ and 102° 43’ 17.7’’ with an altitude of 1 827 meters above sea level), where an infestation of the immature fruit disease (<2 cm in diameter) and a tree with the presence of nymphs and adults of the bed bug Monalonion sp. (Hemiptera: Miridae), considered this as the disease vector.

Once the trees were selected, all the affected fruits were eliminated and the treatments were randomized considering a randomized block design with nine treatments and three repetitions, with the following treatments: 1) Biogober® (BG) a commercial product based on extracts of governor at doses of 10 cc L-1 of water; 2) Eucalyptus camaldulensis (EER) red eucalyptus extracts at a dose of 50 ml of infusion (40 g of foliage in 1.5 L of water) per 1 L of water; 3) Excerpt from governor Larrea tridentata (EG) in prepared infusion and same doses as the EER; 4) Australian eucalyptus extract Eucalyptus gummifera (EEA), prepared and same doses as treatment 2.5) Cupravit® copper oxychloride (CU) at a dose of 5 g L-1 of water; 6) Metalaxyl + Chlorothalonil with trade name Ridomil Gold® (RG) at a dose of 5 g L-1 of water; 7) Mancozeb (MZ) at 5 g L-1 of water; 8) water only; and 9) Malation insecticide (M) at a dose of 3 cc L-1 of water.

To improve the emulsion and the adhesion to the plant, 5.0 cc of Tamis® and 3 drops of Tween 20® per liter of water were added to all the preparations. The application of the treatments began when most of the fruits were approximately 2 cm in diameter and three applications of the chemicals and six of the botanists were made. At the end of the applications, all the fruit present in each tree was counted and all the affected fruits were harvested. The incidence was determined (healthy fruits - damaged fruits) and the severity determined with the following scale 0 = no damage, 1= slight 1-3 nails <10% damage, 2= moderate 5 -7 nails around 15 to 20% of damage, 3= strong> 10 nails and 40-60% damage and 4= very strong> 70% (González et al., 2009).

The data obtained were transformed to a weighted average of the infection (Townsend and Heuberger, 1943) using the following formula: PI= [∑(n*v)/CM*N]*100. Where: PI= weighted average of infection, n= number of fruits for each class on the scale, v= numerical value of each class, CM= major category, N= total number of fruits in the sample. For their analysis, the data were transformed to a square root of X+0.5 to decrease the variance and were analyzed using the SAS JMP program and the differences between means were compared using 0.05% Tukey. To determine the biological effectiveness of the treatments, Abbott's formula (1987) was applied.

%E= [IT-It/IT]*100, where:%E= percentage of effectiveness, IT= control infection, It= treatment infection.

Results and discussion

In vitro effect of the form of preparation of plant extracts on Pestalotiopsis sp.

Alcoholic maceration (Table 1) showed the greatest inhibition of fungus growth, compared to water maceration and infusion (7.6 mm), even lower than chemical treatments (Fractal and Copper oxychloride) with a growth of 13.67 and 12.67 mm. The higuerilla and olive extracts showed no outstanding effect. The commercial Biogober extract showed no significant effects in reducing fungus growth that were similar to the control with alcohol.

Regarding the bioassay of alcoholic extracts concentrated with rotary evaporator (Table 2), some extracts showed effects of fungus growth reduction greater than 90% (jaral, olives, mesquite, paradise, olive, trompillo, lantana, rosemary, rue, bandage, tongue of cow and Australian eucalyptus), similar to the copper treatment that showed an average reduction of 96.65%. The extracts with the lowest effect on the growth of the fungus were: horsetail, huache and mallow.

Evaluation of extracts in commercial gardens

The trees under treatment had an average of 1 502 tree fruits (range from 585 to 3 729), in the establishment of the experiment an average of 47 fruits with nail incidence was found, with a range of 0 to 361 fruits damaged per tree (average incidence of 3%).

Table 3 shows the average number of fruits damaged by tree, where it was observed that only the treatment with the insecticide Malathion was statistically different from the rest of the treatments. The treatments with the least number of affected fruits were Malathion and the Australian and red eucalyptus (5, 10 and 11 fruits damaged per tree representing 0.5, 0.4 and 1% damage respectively), while those with the highest number of affected fruits were: the governor and the control with water with 91 and 65 damaged fruits representing 5.3 and 4.6% damage respectively.

Table 3. Effectiveness of plant extracts for the control of Pestalotiopsis clavispora in the field.

*= means of fruits damaged by tree, means followed by the same letter are not statistically different by means of Tukey at 0.05%; **= percentage of infection according to Townsend and Heuberger, 1943; ***= effectiveness of treatments according to Abbot’s formula, 1987.

The chemical synthesis fungicides as a group showed similar damages among them with 22 damaged fruits, which is lower than that of Biogober with 28 damaged fruits (23, 23 and 22 fruits respectively for CU, RG, MZ and BG). When the data of percentage of damage with respect to the total of fruits present per tree are observed, the fruits damaged in the treatments with governor and the control with water represented 5.3 and 4.6%, whereas, in the Australian eucalyptus, red and the Malation they represent 0.4, 0.5 and 1%.

Regarding the severity (Figure 1), only the treatments of Malathion and Australian eucalyptus did not show fruits with very strong damages. In the control and in the governor’s statement there were more than 10 fruits with strong damages and more than 25 fruits with medium damages. Red eucalyptus, Australian eucalyptus and Malathion presented less than 5 fruits with light damage. In general, light damage prevailed in all treatments except for Mancozeb and Ridomil fungicides where light damage predominated or there was no trend.

Figure 1. Degree of severity in the damages caused by Pestalotiopsis sp., to guava fruits under field conditions, Aguascalientes in 2016.

The percentage of infection (PI) (Table 3) in general was low. It was 0.071 in the Australian eucalyptus (EEA) followed by the Malathion and red eucalyptus (0.154 and 0.376 respectively) and the highest percentage was observed in the governor extract (EG) with 2.031, even higher than the control with water (1.822). Of the chemical synthesis fungicides, the one with the lowest PI was the Copper-based product (CU with 0.283). The best treatments for disease control were EEA, Malathion, CU and ER with efficiencies of 99, 91, 84 and 79%.

The results are consistent with the indications of Parada (2005); Quijada and Gomez (2005) on the effectiveness of eucalyptus extracts in the control of the guava clove caused by Pestalotiopsis spp. and reinforce the use of the ethanolic extracts of this plant in the fight against plant diseases (Baños et al., 2004; Alzate et al., 2009; Cazar et al., 2014), as well as it was observed that when applying insecticides against the vector the damages caused by the disease are reduced, reinforcing the signaling of the presence of a vector of the disease in the region (Serrano et al., 2018).

Conclusions

In the bioassays, plants associated with guava orchards were found that can be used to control the disease of the guava clove, from which we can mention the extracts of jaral, olives, mesquite, paradise, olive, trompillo, rosemary, rue, venadilla, cow tongue and eucalyptus. At the field level, extracts of red eucalyptus (Eucalyptus camaldulensis) and Australian eucalyptus (Corymbia (=Eucalyptus) gummifera) plants showed similar damage percentages to the Malathion insecticide and lower than those observed with the application of chemical synthesis fungicides evaluated.

Extracts of red eucalyptus at a dose of 50 ml of infusion (40 g of foliage in 1.5 L of water) per 1 L of water applied on six occasions are considered an option for disease control without the use of chemical synthesis. The handicraft extracts of governor (Larrea tridentata) showed no efficient control of the disease while the commercial formulation based on governor was only slightly greater damage than that of synthetic fungicides. The Malathion insecticide was one of the best treatments in the control of this disease, which shows the relevance of vector control (Monalonion sp.). The use of plant extracts represents an alternative in the control of Pestalotiopsis clavispora with a lower environmental impact.

Acknowledgments

To the PhD program in Biotechnology in Agricultural Processes of the National Technological Institute of Mexico (El Llano Aguascalientes Technological Institute) for allowing me to carry out the research work and to CONACYT for the financial support of the 2018 01NACF 03186 scholarship. To Mr. Joaquín Velasco Luevano for providing us with the facilities for the development of the experiment in your orchard.

Cited literature

Abbot, W. S. 1987. Classic Paper: Abbott´s Formula. A Method of computing the effectiveness of an insecticide. J. Am. Mosquito Control Association. 3(2):302-303. https://www.biodiversitylibrary.org/content/part/JAMCA/JAMCA-V03-N2-P302-303.pdf.

Alzate, N. A.; López, V. K.; Marín, H. A. y Murillo, A. W. 2009. Evaluación preliminar de la actividad fungicida de los aceites esenciales de eucalipto (Eucalyptus tereticornis, Myrtaceae) y cáscara de naranja (Citrus sinensis, Rutaceae) sobre algunos hongos filamentosos. Revista Tumbaga. 4:59-71.

Baños, P. E.; Zavaleta, M. E.; Colinas, M. T.; Luna, R. I.; Gutiérrez, A. J. A. 2004. Control biológico de Colletotrichum gloeosporioides [(Penz.) Penz. y Sacc.] en papaya Maradol Roja (Carica papaya L.) y fisiología postcosecha de frutos infectados. Rev. Mex. Fitopatol. 22(2):198-205. http://www.redalyc.org/articulo.oa?id=61222206.

Biswas, B.; Rogers, K.; McLaughlin, F.; Daniels, D. and Yadav, A. 2013. Antimicrobial activities of leaf extracts of Guava L.) on two gram-negative and gram-positive bacteria. International journal of microbiology. Hindawi Publishing Corporation. Article ID 746165. 7 p.  http://dx.doi.org/10.1155/2013/746165.

Cazar, M. E., Villena, P.; Parra, J.; Espinoza, V.; Larriva, G. y Caldas, A. 2014. Eficacia de extracto etanólico de Eucalyptus globulus) en el control de Alternaria sp. en cultivos de col y patata. Maskana 5(1):33-41. Https://www.researchgate.net/publication/305719595. DOI:10.18537/mskn.0501.03.

Dhiman, A.; Nanda, A.; Ahmad, S. and Narasimhan, B. 2011. In vitro antimicrobial activity of methanolic leaf extract of Psidium guajava L.  J. Pharmacy and Bio. Sci. 3(2):226-229. http://dxdoi.org/10.4103/0975-7406.80776.

Farfán, F. P. D. 2005. Distribución espacio-temporal y daño causado por Pestalotia spp. En el fruto de guayaba (Psidium guajava L.) en la hoya del río Suárez. Tesis de Licenciatura. Universidad Pedagógica y Tecnológica de Colombia. Facultad de Ciencias. Escuela de Biología. Tunja, Boyacá, Colombia. 57 p.

Farr, D. F.; Rossman A. Y.; Palm, M. E. and McCray, E. B. 2008. Fungal database. Systematics Mycology and Microbiology laboratory. ARS. USDA. http//nt.ars-grin.gov/fungaldatabases/new-allview.cfm?whichone =fungushosts&thisname.

González, G. E. 2002. Enfermedades y nematodos. In: Guayaba, su cultivo en México. González G., E. J. S.; Padilla, R. L.; Reyes, M. M. A.; Perales de la C. y Esquivel, V. F. (Eds.) Libro técnico núm. 1. INIFAP-CIRNOC-Campo Experimental Pabellón. 112-127 pp. file:///C:/Users/EGG/Descargas/Guayaba%20su%20cultivo%20en%20mexico%20(1).pdf.

González, G. E.; Castillo, P. I.; Lozano, G. J.; Perales, de la C. M. A.; Padilla, R. J. S.; España L. M. P. y Pineda, D. C. 2008. Control de clavo en guayaba (Pestalotia psidii Pat.) con Trichoderma lignorum en Zitácuaro, Michoacán. In: Memorias del XXXI Congreso Nacional de Control Biológico. Sociedad Mexicana de Control Biológico. 426-429 p.

González, G. E.; Padilla, R. J. S. y Perales, de la C. M. A. 2009. Estrategias para el manejo del clavo de la guayaba (Pestalotiopsis psidii). Folleto técnico núm. 40. INIFAP-CIRNOC-Campo Experimental Pabellón. Pabellón de Arteaga, Ags. México. 29 p. file:///C:/Users/EGG/Descargas/3809%20Estrategias%20para%20el%20manejo%20del%20Clavo%20de%20la%20Guayaba.pdf.

Kasar, P.; Maity, S. S.; Bhattacharya, R.; Chowdhury, A. K. and Khatua, D. C. 2006. Occurrence of guava fruit canker in west Bengal and biossay of fungicides against pathogen. J. Hortic. No. 17. CAB Abstracts. http://www.cababstractsplus.org/abstracts/Abstracts.aspx?AcNo=200 53079049.

Keith, L. M.; Velásquez, M. E. and Francis, T. 2006. Identification and characterization of Pestaliotopsis spp. causing scab disease of guava Psidium guajava in Hawaii. Plant Dis. 90(1):16-23. https//doi.org/10.1094/PD-90-0016.

Mendoza, E. C.; González, R. C.; Martínez, S. M. C.; Avelar, G. F. J.; Valdivia, F. A. G.; Aldana, M. M. L.; Rodríguez, O. G. y Jaramillo, J. F. 2015. Estudio de exposición a Malatión y Cipermetrina y su relación con el riesgo de daño renal en habitantes del municipio de Calvillo, Aguascalientes, México. Rev. Mex. Cienc. Farmacéuticas. 46(3):62-72. https//www.Redalyc.org/articulo.oa?id=57945705007.

Mishra, A. K. and Prakash, O. 1986. Studies on diseases of fruit crops. Annual report. Central Institute of Horticulture for Northern Plains. Luknow India. 67-68 pp.

Mishra, A. K. 2004. Guava disease their symptoms, causes and management. In: Disease of fruits and vegetables. Diagnosis and Management. Naqvi, S. A. M. H. (Ed.). Kluver Academic Publisher Netherlands. 81-119 pp. file:///C:/Users/EGG/Descargas/14GuavaDiseasestheir SymptomsCausesandManagement.pdf.

Montiel, C. A. 1997. Pestalotiopsis psidii (Pat.) Mordue causante de necrosis de frutos de guayabo (Psidium guajava L.) en plantaciones de los municipios Baralt y Mara del estado de Zulia. Revista de la Facultad de Agronomía. 14(3):341-347.

Morera, M. R. y Blanco, M. H. 2009. Microorganismos asociados a frutos embolsados de guayaba Taiwanesa variedad Tai Kuo. Agron. Mesom. 20(2):339-349.

Nieto, A. D. 1996. Fisiología, bioquímica y patógenos en frutos de guayaba (Psidium guajava L.). Tesis de Doctor en Ciencias. Colegio de Postgraduados, México. 111 p.

Parada, E. R. 2005. Evaluación de sustancias convencionales (fungicidas químicos) y no convencionales (extractos vegetales) para el control del agente causal de la peca del fruto en guayaba Pestalotia versicolor Speg. en el municipio de Vélez (Santander). Tesis de Licenciatura. Universidad Pedagógica y Tecnológica de Colombia. Facultad de Ciencias. Escuela de Biología. Tunja, Boyacá. Colombia. 58 p.

Prakash, O. and Pandey, B. K. 2007. Current scenario of guava diseases in India and their integrated management. In: Proceedings first international guava symposium. Singh, G.; Kishum, R. and Chandra, E. (Eds.). Acta Horticulturae. 735(67):495-505.

Quijada, R. O. y Gómez, S. R. 2005. Desarrollo tecnológico para el manejo poscosecha de la guayaba en Colombia y Venezuela. Informe de avances de proyecto. Instituto Nacional de Investigaciones Agrícolas Centro de Investigaciones Agropecuarias del Estado Zulia-Corporación Colombiana de Investigación Agropecuaria Estación Experimental CIMPA (Programa Nacional de Procesos Industriales). Barbosa. http//:www.fontagro.org/projects/ 01-21-guayaba/III-infotec-01-021.pdf.

Ramírez, D. J. 2005. Evaluación de alternativas para el manejo integrado de P. versicolor Speg. En condiciones de campo en la provincia de Vélez, Santander. Tesis de licenciatura Ingeniero Agrónomo. Universidad Pedagógica y Tecnológica de Colombia. Facultad de Ciencias Agropecuarias Escuela de Ingeniería Agronómica. Tunja, Boyacá, Colombia. 105 p.

Ray, S. K.; Jana, M.; Maity, S. S.; Bhattacharya, R. and Khatua, D. C. 2007. Fruit diseases of guava in West Bengal. In: Proceedings first international guava symposium. G. Singh, R. Kishum, and E. Chandra (eds.) Acta Hortic. 735(69):525-531. http//doi.org/10.17660/ ActaHortic.2007.735.69.

Rodríguez, P. A.; Ramírez, A. M.; Bautista, B. S.; Cruz, T. A. y Rivero, D. 2012. Actividad Antifúngica de extractos de Acacia farnesiana sobre Fusarium oxysporum f. sp. lycopersici. Revista Científica UDO Agrícola. 12(1):91-96. file:///C:/Users/EGG/ Descargas/Dialnet-ActividadAntifungicaDeExtractosDeAcaciaFarnesianaS-4277990.pdf.

Serrano, G. C.; González, G. E.; Padilla, R. J. S. y De Lira, R.K.V. 2018. Manejo Integrado de Pestalotiopsis clavispora agente causal del clavo de la guayaba en Calvillo. INIFAP-CIRNOC-Campo Experimental Pabellón. Pabellón de Arteaga, Aguascalientes, México. Desplegable para productores número 65. 6 p.

Solarte, F. C. German, M. S. S. N. Maharachchikumbura y E. Álvarez. 2017. Diversity of Neopestalotiopsisi and Pestalotiopsisi spp., causal agents of guava scab in Colombia. Plant Dis. 102(1):49-59. https://www.researchgate.net/publication/319147557.

Townsend, G. R. and Heuberger, J. W. 1943. Methods for estimating losses caused by diseases in fungicidal treatments. Plant Dis. Reporter. 27(17):340-343.

Villamizar, Q. C.; Gómez, S. R.; Parra, G. R. y J. Bautista. 2003. Embolsado de frutos de guayaba con diferentes materiales biodegradables. Corporación Colombiana de Investigación Agropecuaria. Centro de Investigación para el mejoramiento de la Agroindustria Panelera. Programa Nacional de Transferencia de Tecnología Agropecuaria. Barbosa, Santander, Colombia. 32 p. http://bibliotecadigital.agronet.gov.co/bitstream/11348/4101/1/113.pdf.