Use of phosphites in postharvest to control anthracnose of yellow passionfruit / Uso de fosfitos em pós-colheita para o controle da antracnose do maracujá-amarelo

Brazil is the largest producer of yellow passionfruit (Passiflora edulis f. flavicarpa) and one of its production problems is the anthracnose (Colletotrichum spp.). The use of fungicides on control of postharvest diseases is a method that protects the fruits during storage. However, precautions must be taken due to fungicide toxicity. The restriction to the use of fungicides in post-harvest led a demand for alternative methods of disease control, and, the phosphite application is one of these methods. Therefore, this work aimed to evaluate the effects of fruit immersion in phosphite on postharvest control of anthracnose. Two tests were developed in vitro to assess the effect on the fungus: phosphite Mg2 (40%P2O5+6%Mg), Zn (40%P2O5+10%Zn), Ca1 (30%P2O5+7%Ca) and K1 (40%P2O5+20%K2O). For the in vivo tests, passionfruit (Gigante Amarelo), were wounded and inoculated (50L; 106conidia mL-1). Two tests were done with: Cu (25%P2O5+5%Cu), 2.5mL L-1; Zn, 2.5mL L-1; K1, 2.5mL L-1; Mg1 (30%P2O5+4%Mg), 3mL L-1; Ca1, 3mL L-1; Ca2 (10%P2O5+6%Ca), 4mL L-1; K2 (40%P2O5+20%K2O), 1.5mL L-1; Mg2 (40%P2O5+6%Mg), 1.5mL L-1; K3 (20%P2O5+20%K2O) 1.75 mL L-1; K4 (30%P2O5+20%K2O), 1.75mL L-1. Other two tests with phosphites Mg2, Ca1, Zn and K1 were with CaCl2 (2%) was developed. In addition, phosphites were tested at 25, 50, 100 and 200% of the dose: K2 (100%; 1.5mL L-1) and Ca1 (100%; 3 mL L-1). The phosphites Mg2, Ca1, K1 and Zn in vitro have reduced mycelial growth and fungus conidia production. The phosphites K1, K2, Ca1 and Zn were the ones that most reduced the size of the anthracnose lesion. There were no differences among treatments, concerning the physico-chemical fruit properties analyzed (% fresh mass loss, total soluble solids, pH and titratable acidity).

O Brasil é o maior produtor mundial de maracujá-amarelo (Passiflora edulis f. flavicarpa) e um dos problemas para sua produção é a antracnose (Colletotrichum spp.). O uso de fungicidas no controle de doenças pós-colheita é um método que protege os frutos durante o armazenamento, mas, precauções adicionais devem ser tomadas quanto à sua toxidade, presença de resíduos e a provável seleção de fungos resistentes. A restrição ao uso de fungicidas na pós-colheita cresceu e levou à procura de alternativas de controle, e, entre tais está à aplicação de fosfitos. Diante disso, este trabalho objetivou avaliar os efeitos da imersão de frutos em soluções de fosfitos no controle da antracnose em pós-colheita. Dois testes in vitro foram feitospara avaliar o efeito de fosfitono fungo: Mg2 (40%P2O5+6%Mg), Zn (40%P2O5+10%Zn), Ca1 (30%P2O5+7%Ca) e K1 (40%P2O5+20%K2O). In vivo, frutos de maracujá (Gigante Amarelo), foram feridos e inoculados (50l; 106conídios mL-1). Dois testes foram feitos com: Cu (25%P2O5+5%Cu), 2,5mL L-1; Zn, 2,5mL L-1; K1, 2,5mL L-1; Mg1 (30%P2O5+4%Mg), 3mL L-1; Ca1, 3mL L-1; Ca2 (10%P2O5+6%Ca), 4mL L-1; K2 (40%P2O5+20%K2O), 1,5mL L-1; Mg2 (40%P2O5+6%Mg), 1,5mL L-1; K3 (20%P2O5+20%K2O), 1,75mL L-1; K4 (30%P2O5+20%K2O), 1,75mL L-1. Outros dois testes com fosfitos foram com CaCl2 (2%) e Mg2, Ca1, Zn e K1. Ainda, dois fosfitos foram testados a 25, 50, 100 e 200% da dose: K2 (100%; 1,5mL L-1) e Ca1 (100%; 3mL L-1). Os fosfitos Mg2, Ca1, K1 e Zn in vitro reduziram o crescimento micelial e a produção de conídios do fungo. Os fosfitos K1, K2, Ca1 e Zn foram que mais reduziram o diâmetro da lesão causada pelo patógeno. Ca1 e K1 com CaCl2 reduziram o tamanho das lesões. Não houve diferenças significativas entre os tratamentos, quanto as características físico-químicas analisadas (% perda de massa fresca, teor de sólidos solúveis totais, pH e acidez titulável) dos frutos.

The Major Postharvest Disease of Onion and Its Control with Thymol Fumigation During Low-Temperature Storage

Onion (Allium cepa L.) is one of the major vegetable crops in Korea that are damaged and lost by pathogenic fungal infection during storage due to a lack of proper storage conditions. The aim of this study was to determine an appropriate control measure using thymol to increase the shelf life of onions. To control fungal infections that occur during low-temperature storage, it is necessary to identify the predominant fungal pathogens that appear in low-temperature storage houses. Botrytis aclada was found to be the most predominant fungal pathogen during low-temperature storage. The antifungal activity of the plant essential oil thymol was tested and compared to that of the existing sulfur treatments. B. aclada growth was significantly inhibited up to 16 weeks with spray treatments using a thymol solution. To identify an appropriate method for treating onions in a low-temperature storage house, thymol was delivered by two fumigation treatment methods, either by heating it in the granule form or as a solution at low-temperature storage conditions (in vivo). We confirmed that the disease severity was reduced up to 96% by fumigating thymol solution compared to the untreated control. The efficacy of the fumigation of thymol solution was validated by testing onions in a low-temperature storage house in Muan, Jeollanam-do. Based on these results, the present study suggests that fumigation of the thymol solution as a natural preservative and fungicide can be used as an eco-friendly substitute for existing methods to control postharvest disease in long-term storage crops on a commercial scale.

Production and Optimization of Killer Toxin in Debaryomyces hansenii Strains

ABSTRACT Postharvest diseases of fruits and vegetables result in critical losses of production in worldwide. The losses often are caused by fungi and nowadays, most fungal pathogens are controlled by several strategies such as the use of fungicides. However, most of the fungicides are chemical-based compounds and are dangerous to human health and the nature. Therefore, the discovery of healthy and reliable strategies is crucial to control of fungal pathogens. In the paper, it was aimed to evaluate and characterize yeast isolates previously isolated from dairy products for the production of killer toxin. A total of 18 yeasts have been found to produce antagonistic behavior against susceptible fungal species. All of the yeasts expressing killer character were characterized by using several molecular techniques, and isolates TEM8 and 17 identified as D. hansenii have showed the strongest antifungal activities. Improvement of killer toxin production by the yeasts also has been studied, and the highest production was found in YMB medium containing NaCl (6%) and DMSO (1000 ppm) at pH 4.0 and 20oC. The killer characters of these yeasts have indicated the potential use of the yeasts as antagonists for the control of postharvest diseases in agricultural industries.

Controle pós-colheita da antracnose do pimentão pela levedura Rhodotorula glutinis / Post-harvest control anthracnose in pepper by yeast Rhodotorula glutinis

Considerando as perdas causadas em pós-colheita pela antracnose no pimentão e à ineficácia das medidas de controle atualmente utilizadas, este trabalho teve por objetivo estudar a potencialidade antagônica in vitro e in vivo de quinze isolados de leveduras à Colletotrichum sp., agente causal da antracnose em pimentão. Foi calculada a porcentagem de inibição do crescimento do fungo dos tratamentos em relação à testemunha nos testes in vitro e determinado o tamanho da área lesionada em frutos através da mensuração do comprimento da lesão em dois sentidos diametricamente opostos nos testes in vivo. As leveduras que obtiveram o melhor resultado no controle da antracnose foram identificadas através de características macroscópicas, microscópicas, fisiológicas, bioquímicas e por taxonomia molecular, sendo os isolados de levedura 13E e 13A1, os que obtiveram as melhores respostas no controle do fitopatógeno tanto in vitro quanto in vivo, identificados como pertencentes à espécie Rhodotorula glutinis.

Considering the losses caused by post-harvest anthracnose in sweet pepper chili and ineffectiveness of control measures currently used, this study had the objective of evaluate the antagonistic potential in vitro and in vivo of fifteen isolates of yeast to Colletotrichum sp., the causal agent of anthracnose on pepper. By calculating the percentage growth inhibition of the fungus treatment compared to the control tests in vitro and determining the size of lesions via the measurement of lesion length in both directions diametrically affixed in vivo tests. Yeasts who obtained the best result in controlling anthracnose were identified by characteristic macroscopic, microscopic, physiological, biochemical and molecular taxonomy. In this study, the yeast isolates 13E and 13A1, which obtained the best results in controlling the pathogen both in vitro and in vivo of the species Rhodotorula glutinis.

The First Report of Postharvest Stem Rot of Kohlrabi Caused by Sclerotinia sclerotiorum in Korea

In March 2014, a kohlrabi stem rot sample was collected from the cold storage room of Daegwallyong Horticultural Cooperative, Korea. White and fuzzy mycelial growth was observed on the stem, symptomatic of stem rot disease. The pathogen was isolated from the infected stem and cultured on potato dextrose agar for further fungal morphological observation and to confirm its pathogenicity, according to Koch's postulates. Morphological data, pathogenicity test results, and rDNA sequences of internal transcribed spacer regions (ITS 1 and 4) showed that the postharvest stem rot of kohlrabi was caused by Sclerotinia sclerotiorum. This is the first report of postharvest stem rot of kohlrabi in Korea.

Soft Rot of Rhizopus oryzae as a Postharvest Pathogen of Banana Fruit in Korea

Soft rot on banana fruit caused by Rhizopus oryzae was identified for the first time in Korea. Colonies were white to light brown and formed numerous sporangiospores. Optimum temperature for mycelial growth was 30degrees C. Sporangia were globose and 30~200 microm. Sporangiophores were usually straight, 8~20 microm, and rhizoids usually in groups of 3~5. Columella were globose to sub-globose and 90~110 microm. Sporangiospores were sub-globose or oval and 4~10 microm. Based on its mycological characteristics, molecular analysis, and pathogenicity to host plants, this fungus was identified as Rhizopus oryzae Went & Prisen Geerligs. This is the first report of soft rot on banana caused by Rhizopus oryzae in Korea.

First Report of Rhizopus oryzae as a Postharvest Pathogen of Apple in Korea

Soft rot in apple caused by Rhizopus oryzae was found for the first time in Korea. A detailed description of the specimen is given along with its internal transcribed spacer rDNA sequence. The fungus was identified as Rhizopus oryzae based on the mycological characteristics, molecular data, and pathogenicity testing.

First Report of Botrytis cinerea as a Postharvest Pathogen of Blueberry in Korea

Gray mold of blueberry caused by Botrytis sp. is reported for the first time in Korea. A detailed description of the fungus is given, along with its rDNA internal transcribed spacer sequence. The fungus was identified as Botrytis cinerea based on mycological characteristics and molecular data.

Integrated control of penicillium digitatum by the predacious yeast Saccharomycopsis crataegensis and sodium bicarbonate on oranges

Our investigation of integrated biological control (IBC) started with an assay testing activity of the predacious yeast Saccharomycopsis crataegensis UFMG-DC19.2 against Penicillium digitatum LCP 4354, a very aggressive fungus that causes postharvest decay in oranges. Under unfavourable environmental conditions, the yeast showed a high potential for control (39.9 percent disease severity reduction) of this fungus. This result was decisive for the next step, in which S. crataegensis was tested in association with sodium bicarbonate salt, a generally regarded as safe (GRAS) substance. The yeast was able to survive at different concentrations of the salt (1 percent, 2 percent and 5 percent), and continued to grow for a week at the wound site, remaining viable at high population for 14 days on the fruit surface. The yeast alone reduced the severity of decay by 41.7 percent and sodium bicarbonate alone reduced severity of decay by 19.8 percent, whereas the application of both led to a delay in the development of symptoms from 2 to 10 days. Ingredients of the formulations were not aggressive to fruits since no lesions were produced in control experiments.

Biological control of Penicillium italicum, P. digitatum and P. expansum by the predacious yeast Saccharomycopsis schoenii on oranges

In this study we evaluated the ability of Saccharomycopsis schoenii Nadson and Krassiln (UWO-PS 80-91) as biocontrol agent against plant pathogenic filamentous fungi P. expansum Link (UFMG 01-2002), P. italicum Wehmer (LCP 61.1199), and P. digitatum (Pers.: Fr.) (LCP 984263, LCP 68175 and LCP 4354). S. schoenii was able to reduce disease severity in oranges inoculated with all fungi. Among the phytopathogens, P. digitatum LCP4354 was the most virulent whereas P. digitatum LCP 68175 was the most susceptible to predation. The yeast was able to survive for 21 days on the fruit surface and did not produce lesions on oranges. Production of antagonistic substances by S. schoenii was not detected using standard techniques. Our results point to the potential use of S. schoenii to control postharvest phytopathogens in fruits.

Este estudo avaliou a capacidade de levedura Saccharomycopsis schoenii Nadson & Krassiln (UWO-PS 80-91) em controlar o crescimento dos fungos fitopatogênicos Penicillium expansum Link (UFMG 01-2002), P. italicum Wehmer (LCP 61.1199), e P. digitatum (Pers.: Fr.) (LCP 984263, LCP 68175 e LCP 4354). S. schoenii reduziu a severidade da doença em laranjas inoculadas com todos os fitopatógenos testados. Entre estes fitopatógenos, P. digitatum LCP4354 apresentou a maior virulência enquanto que P. digitatum LCP 68175 foi o mais suscetível à predação. A levedura foi capaz de permanecer viável, sem produzir lesões na superfície dos frutos por 21 dias. Outra característica desejável observada foi a ausência de produção de substâncias antagonistas. Sendo assim, este trabalho evidência o potencial de utilização da levedura S. schoenii em protocolos de controle biológico de doenças pós-colheita em laranjas.