Monilinia fructicola (Wint.) Honey, and Rhizopus nigricans Erh., the causal organisms of brown rot and Rhizopus rot, respectively, have long been recognized as the two major causes of post-harvest rots on peach and nectarine fruits. Fruit losses of as much as 50% may occur during storage, transport, and marketing from these two diseases if effective fungicide treatments are not used. Application of fungicide suspensions as post-harvest dips have been reported to reduce losses from post-harvest rots considerably, however, more effective treatments are needed. Tests were made of three fungicides: benomyl [methyl-l-(butylcarbamoyl)-2-benzimidazole carbamate], Topsin-M [dimethyl-4,4'-ophenelenebis (3-thioallophanate) , and Botran (2,6-dichloro-4-nitroanaline) against the two post-harvest rot fungi, M. fructicola and R. nigricans, on peach and nectarine fruits and in vitro. Fruits were inoculated with an equal concentration of spores of both fungi, then treated, by dipping in the different fungicide suspensions at 0, 4, 8, and 12 hour intervals after inoculation. Three concentrations of benomyl or Topsin-M (300, 450, and 600 ~g/ml) were used in combination with corresponding concentrations of Botran (600" 900, and 1200 Ug/ml). Number of decayed fruits increased with time of treatment after inoculation up to 8 hours then leveled off. Lesion progression, however, was slower with all fungicide treatments as compared to those of the untreated check fruit. Percent of decayed fruit remained lower when treatments were applied within 4 hours after inoculation. Later application times were ineffective and fruits showed approximately the same level of infection as controls. Treated nectarines appeared to be more susceptible to the post harvest rots than peaches. This may be due to lower residues of the chemicals remaining on the smooth skinned fruit. Benomyl and Topsin-M were fungitoxic to M. fructicola in vitro but neither was effective against R. nigricans. Botran alone was fungistatic to both R. nigricans and M. fructicola, but often lost effectiveness after 96 hours. Combinations of benomyl plus Botran, or Topsin-M plus Botran, were fungitoxic to M. fructicola and fungistatic to R. nigricans. Botran alone and Botran in combination with benomyl or Topsin-M inhibited germination of M. fructicola and R. nigricans spores more effectively than benomyl or Topsin-M alone. There were no major significant differences in control provided by treatments containing benomyl or Topsin-M. Treatments using Botran with benomyl or Topsin-M did not effectively control post harvest rot when applied later than 4 hours after inoculation. In vitro tests, however, indicated either a synergistic or additive effect of the fungicide combinations against R. nigricans. / Master of Science

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The aim of the present work was to evaluate the efficiency of pre-harvest application of fungicides on control of brown rot on postharvest and verify their effect when associated with fungal antagonists, ensuring efficiency in the control of disease and quality of fruit. We evaluated the effect of application of fungicides on pre-harvest in the control of brown rot after 15 and 40 days of refrigerated storage of fruits, in addition to the association of fungicides with postharvest treatment with the fungus antagonist, Trichoderma harzianum. To do this, were established two experiments. At the first, phytosanitary programs (active ingredients) were evaluated: [1] control (application of water); [2] captan; [3] iprodione; [4] iminoctadine; [5] tebuconazole; [6] procymidone; [7] azoxystrobin; [8] difenoconazole; [9] fungicide (azoxystrobin/difenoconazole); [10] fungicide (trifloxystrobin/tebuconazole); [11] sequence iminoctadine + captana; [12] sequence of iprodione + iminoctadina; [13] sequence of tebuconazole + captan; [14] sequence of tebuconazole + iprodione. All treatments were applied in the pre-harvest phase, in recommended doses for culture. After harvesting the fruits were stored at -0.5 °C for 15 and 40 days. In the second experiment were evaluated the pre-harvest application of following products: [1] control (application of water); [2] captan; [3] iprodione; [4] iminoctadine; [5] tebuconazole. After harvesting the fruits were stored at -0.5 °C for 40 days and following, in half of the fruits of each treatment was applied the antagonist Trichoderma harzianum, through immersion. Both experiments were evaluated after exposure of fruit to 20 °C for a period that varied from four to 12 days, depending on the storage time of each experiment. The parameters evaluated were: incidence of brown rot, percentage of healthy fruits, respiratory rate, ethylene production and skin browning. Until the time of harvesting the fungicide which best controlled the brown rot was the difenoconazole, whereas, the fungicides tebuconazole and iminoctadina have satisfactory results in control of brown rot, after 15 and 40 days of refrigerated storage. The use of Trichoderma harzianum has no effect on postharvest control of brown rot, however, when associated with fungicides is effective in the control of Rhizopus stolonifer. Pre-harvest application of fungicide captan and postharvest of Trichoderma harzianum affect postharvest quality of fruits, causing skin browning. / O objetivo do presente trabalho foi avaliar a eficiência da aplicação pré-colheita de fungicidas no controle da podridão parda em pós-colheita e verificar o seu efeito quando associado a fungos antagonistas, assegurando eficiência no controle da doença e qualidade dos frutos. Para tanto, avaliou-se o efeito da aplicação de fungicidas em pré-colheita no controle da podridão parda do pessegueiro após 15 e 40 dias de armazenamento refrigerado dos frutos, além da associação de fungicidas com o tratamento pós-colheita com o fungo antagonista, Trichoderma harzianum. Para isso, foram instalados dois experimentos. No primeiro foram avaliados programas fitossanitários com os seguintes produtos (ingredientes ativos): [1] testemunha (aplicação de água); [2] captana; [3] iprodiona; [4] iminoctadina; [5] tebuconazol; [6] procimidona; [7] azoxistrobina; [8] difenoconazol; [9] fungicida (azoxistrobina/difenoconazol); [10] fungicida (trifloxistrobina/tebuconazol); [11] sequência de iminoctadina + captana; [12] sequência de iminoctadina + iprodiona; [13] sequência de tebuconazol + captana; [14] sequência de tebuconazol + iprodiona. Todos os tratamentos foram aplicados na fase pré-colheita, nas doses recomendadas para a cultura. Após a colheita os frutos foram armazenados a -0,5 ºC por 15 e 40 dias. O segundo experimento constituiu-se da aplicação pré-colheita dos seguintes produtos: [1] testemunha (aplicação de água); [2] captana; [3] iprodiona; [4] iminoctadina; [5] tebuconazol. Após a colheita os frutos foram armazenados a -0,5 ºC por 40 dias e na sequência, na metade dos frutos de cada tratamento foi aplicado o fungo antagonista Trichoderma harzianum, por meio de imersão. Ambos os experimento foram avaliados após a exposição dos frutos à temperatura de 20 ºC, por um período que variou de quatro a 12 dias, dependendo do tempo de armazenamento de cada experimento. Os parâmetros avaliados foram: incidência de podridão parda, porcentagem de frutos sadios, taxa respiratória, produção de etileno e escurecimento da epiderme. Até o momento da colheita, o fungicida que melhor controlou a podridão parda foi o difenoconazol, enquanto que, os fungicidas iminoctadina e tebuconazol apresentam resultados satisfatórios no controle da podridão parda, após 15 e 40 dias de armazenamento refrigerado. A utilização do Trichoderma harzianum em pós-colheita não apresenta efeito no controle da podridão parda do pessegueiro, entretanto, quando associado a fungicidas é eficiente no controle de Rhizopus stolonifer. A aplicação pré-colheita do fungicida captana e a utilização pós-colheita de Trichoderma harzianum afetam a qualidade pós-colheita dos frutos, causando escurecimento da epiderme.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Brown rot is the main diseases of peaches, with pre and postharvest losses. Control it is difficult because the fungus infect fruit and remain latent until conditions are favorable to its manifestation. Therefore, to understand the role of latent infection of the disease incidence and find strategies to minimize losses, with low environmental impact, is essential for sustainable crop management. This thesis consists of four papers that resulted from work with the following objectives: to study the relationship between latent infection and the occurrence of postharvest brown rot; to evaluate the effect of preharvest fungicide application on the Monilinia fructicola control during storage and marketing of peaches; to investigate the pre and postharvest applications of silicon on the brown rot control in peach. They were used peaches of Eldorado and Pepita cultivars, in field experiments involving preharvest spraying of fungicides and pre and postharvest applications of silicon and experiments in refrigerated storage conditions at -0.5 ° C. Iprodione, tebuconazole and difenoconazole are effective in brown rot control in the field conditions, while in postharvest, the incidence was controlled in 96.2% with iminoctadine. These products decreased the incidence of injuries resulting from latent infections. There is a high correlation between the presences of latent infections in preharvest with the incidence of the disease in postharvest, with most of the damage after cold storage resulting from the latent infections of Monilinia fructicola. Foliar application of 6 g L-1 sodium silicate or sodium metasilicate is effective in controlling the disease without causing phytotoxicity to the plants. Six sodium silicate applications had the same effect as six fungicides applications to brown rot control in peaches Eldorado . Postharvest sodium metasilicate application, in 6 g L-1, reduced the diseases incidence but caused fruit skin darkening. Physical defense mechanisms of the plants are affected by silicon application, because it increased the element content in the leaves and fruits, and increased skin texture. However, the effect of silicon on the biochemical defense mechanisms may involve the synthesis of polyphenols, because in the one year of search we found a higher content of these compounds in fruit treated with silicon. In general, products based on silicon, applied alone or intercalated with fungicides, control the disease in pre and postharvest, allowing a decrease in fungicide use and production cost. / A podridão parda do pessegueiro é a doença de maior importância para a cultura, com danos em pré e pós-colheita. O controle é dificultado devido à habilidade do fungo de infectar os frutos e permanecer latente até que as condições tonarem-se favoráveis à sua manifestação. Portanto, compreender o papel da infecção latente na incidência da doença, bem como encontrar estratégias que minimizem as perdas, com baixo impacto ambiental, é fundamental para o manejo sustentável da cultura. Esta tese é composta por quatro artigos científicos que resultaram de trabalhos com os seguintes objetivos: estudar a relação da infecção latente com a ocorrência da podridão parda em pós-colheita; avaliar o efeito da aplicação pré-colheita de fungicidas no controle do fungo Monilinia fructicola durante o armazenamento e comercialização de pêssegos; investigar o potencial do silício em pré e pós-colheita no controle da podridão parda do pessegueiro. Foram utilizados pêssegos das cultivares Eldorado e Pepita em experimentos a campo envolvendo pulverizações pré-colheita de fungicidas e aplicações pré e pós-colheita de produtos à base de silício e experimentos em condições de armazenamento refrigerado a 0,5 ºC. Os fungicidas iprodione, tebuconazole e difenoconazole foram eficazes no controle da podridão parda a campo, enquanto que em pós-colheita, a incidência foi controlada em 96,2% com iminoctadina. Esses produtos também reduziram a incidência de lesões decorrentes de infecções latentes. Há uma alta correlação entre a presença de infecções latentes em pré-colheita com a incidência da doença em pós-colheita, sendo a maior parte das lesões após o armazenamento refrigerado decorrentes das infecções latentes do fungo Monilinia fructicola. Aplicação foliar de 6 g L-1 de metassilicato de sódio ou de silicato de sódio foram eficazes no controle da doença sem causar fitotoxidez às plantas. Seis aplicações de silicato de sódio tiveram o mesmo efeito que seis aplicações de fungicidas no controle da podridão parda em pêssegos cv. Eldorado. A aplicação de metassilicato de sódio em pós-colheita, na dose de 6 g L-1, reduziu a incidência da doença, mas causou escurecimento da epiderme dos frutos. Os mecanismos físicos de defesa das plantas são afetados pelo Si, pois houve aumento do conteúdo do elemento nas folhas e frutos e aumento da textura da epiderme, entretanto, o efeito do silício sobre os mecanismos bioquímicos de defesa pode envolver a síntese de polifenóis, pois em um dos anos da pesquisa verificou-se maior conteúdo destes compostos em frutos tratados com silício. Em geral, produtos à base de silício, aplicados isoladamente ou intercalados com fungicidas, controlam a doença em pré e pós-colheita proporcionando redução no uso de fungicidas e no custo de produção.

Thesis (PhD(Agric))--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Postharvest decay of stone fruit in the Western Cape province of South Africa is caused primarily by Botrytis cinerea (grey mould) and Monilinia laxa (brown rot). Little is known about the relative importance and seasonal occurrence of the two pathogens in nectarine and plum orchards, the mode of penetration of fruits by M laxa, latency and subsequent disease expression by the latter pathogen. These aspects were investigated in this study. By sampling from the Unifruco Quality Evaluation Scheme and from 11 stone fruit orchards, observations were made over a 3-year period of the occurrence of grey mould and brown rot in the major stone fruit regions. Botrytis cinerea was found to be the most important pathogen causing blossom blight and postharvest decay on stone fruit. The pathogen was most prominent on early- and mid-season culti~ars. Brown rot was exclusively caused by M laxa and no evidence was found that M fructicoZa had been introduced into the region. Monilina laxa was most prominent on the later maturing cultivars. Botrytis cinerea blossom infection did not contribute directly to postharvest decay. Both surface inoculum and latent infection consistently occurred on fruit in each orchard, although at fluctuating levels. Disease expression on developing fruit was not governed by the amount of B. cinerea occurring on fruit surfaces, but by the ability of fruit to resist disease expression. The amount of B. cinerea on fruits was generally higher during spring than during summer. Monilinia laxa occurred sporadically on the blossoms of late-maturing cultivars. Immature fruit were generally pathogen-free and disease expression occurred on maturing fruit only. These findings suggest that conidia of M laxa are generally produced in orchards when fruits are approaching maturity and can penetrate and infect maturing fruit only. The behaviour of airborne M laxa conidia was subsequently studied on nectarine (cultivar Flamekist) and plum (cultivar Laetitia) fruit. For these studies, an inoculation method that simulates natural infection by airborne conidia was used. Fruit at pit hardening, 2 wk before harvest, harvest stage and after cold storage (nectarines 4 wk at -o.soC followed by 1 wk at 23°C at ±56% RH; plums 10 days at .....().5°C,18 days at 7.5°C followed by 1 wk at 23°C at ±56% RH) were dusted with dry conidia of M laxa in a settling tower. The fruits were incubated for periods ranging from 3 to 48 h at high relative humidity (2':93%, humid fruit) or covered with a film of water (wet fruit). Behaviour of the solitary conidia was examined with an epifluorescence microscope on skin segments stained in a differential stain containing fluorescein diacetate, aniline blue and blankophor. The ability of solitary conidia to colonise the fruit surface, penetrate fruit skins and to induce disease expression was determined by using a differential set of tests. For these tests, fruit were surface-sterilised (30 s in 70% ethanol) or left Unsterile. From each group, fruit were selected for isolation (skin segment test), immersed in a 3% paraquat solution (paraquat-treated fruit test) or left untreated (sound fruit test). 1be findings demonstrated that solitary conidia of M laxa behaved consistently on plum and nectarine fruit surfaces: appressorium formation and direct penetration was not observed on any of the fruit surfaces and germ tubes penetrated fruit predominantly through stomata, lenticels and microfissures in the fruit skin. The monitoring of airborne conidia revealed subtle effects of the fruits on the behaviour of solitary germlings, which could not be seen when using conidial suspensions. On both fruit types, no deleterious effect was seen on conidial and germling survival when fruit were kept humid at pit hardening, 2 wk before harvest and harvest. However, conidial and germling survival were drastically reduced by prolonged wet incubation of fruits. The findings on disease expression in the skin segment, paraquat-treated fruit and sound fruit tests clearly showed that the skin of both nectarine and plum fruits were not penetrated at the pit hardening stage, latent infections were not established and fruitsreacted resistant to disease expression. These facets on both fruit types were furthermore unaffected by wetness. The barrier capacity of the fruit skin of the two stone fruit types however differed drastically later in the season. On nectarine, fruit skins were more readily penetrated and disease expression became more pronounced when fruit approached maturity. Penetration and disease expression on ripening nectarine fruit were furthermore greatly influenced by wetness. Maturing plum fruit, on the other hand, did not display the drastic change in the barrier capacity of fruit skins as observed on nectarine. The influence of wetness on infection and disease expression was also less pronounced than on nectarine. In fact, plum fruit remained asymptomatic in the sound fruit test after inoculation and humid incubation at the 2 wk before harvest stage, harvest stage and after cold storage. Plum fruit at these stages only developed disease after a prolonged period (~12 h) of wet incubation. The paraquat fruit test revealed that these fruits became more susceptible to latent infection, but they were not as susceptible as nectarine. Collectively, these findings indicate that M. laxa fruit rot epidemics on plum and nectarine are driven by inoculum levels on fruit approaching maturity and by weather conditions prevailing during the preharvest and harvest period. However, the barrier capacity of plum skins is considerably more effective than that of nectarine fruit. Wounds would therefore play an important role in the epidemiology of M. laxa on plum fruit. Infection of fresh wounds by airborne M. laxa conidia, and by conidia and germlings that have established on fruits, was therefore investigated. Plum fruit (cultivar Laetitia) at pit hardening, 2 wk before harvest, harvest stage and after cold storage were dusted with dry conidia of M. laxa in a settling tower.- Infection of rionwounded fruit and of fresh wounds by \ the airborne conidia on dry, humid and wet plum fruit surfaces, and by conidia and germlings that have been established on fruits under the wetness regimes was then investigated. Nonwounded immature and mature fruit remained mostly asymptomatic, whereas nonwounded cold stored fruit decayed readily. Wounding drastically increased infection by airborne conidia. Immature fruits were less susceptible to wound infection by the airborne conidia than mature fruits. Conidia dispersed freshly were more successful in infecting fresh wounds than conidia that were deposited, or germlings that established, on fruit surfaces 4 days prior to wounding. This decrease in infectivity was especially pronounced on humid and even more on wet incubated fruit. This study clearly showed that in order to reduce. the incidence of brown rot, inoculum levels on fruit approaching maturity should be reduced by sanitation practices and fungicide applications. Furthermore, it is essential to protect fruits, especially. near-mature fruits, from being wounded. / AFRIKAANSE OPSOMMING: EPIDEMIOLOGIE VAN MONILINIA LAXA OP NEKTARIEN EN PRUIM: INFEKSIE VAN VRUGTE DEUR KONIDIA OPSOMMING Naoesverrotting van steenvrugte in die Wes-Kaap provinsie van Suid-Afrika word hoofsaaklik veroorsaak deur Botrytis cinerea (vaalvrot) en Monilinia laxa (bruinvrot). Min is bekend oor die relatiewe belang en seisoenale voorkoms van hierdie patogene in nektarienen pruimboorde, asook oor die infeksieweg, latensie en daaropvolgende siekte-uitdrukking van M laxa. Hierdie aspekte is in dié studie nagevors. \ \ Monsters IS oor 'n 3-jaar periode van die Unifruco Kwaliteitsevalueringskema, en ook van 11 steenvrugboorde verkry. Die voorkoms van vaalvrot en bruinvrot in die hoof steenvrugareas is so bepaal. Botrytis cinerea was die belangrikste patogeen wat betref bloeiselversenging en naoesverrotting. Verder was hierdie patogeen ook meer prominent op die vroeë- en middel-seisoen kultivars. Bruinvrot is uitsluitlik deur M Iaxa veroorsaak en geen aanduiding omtrent die moontlike voorkoms van M fructicola in Suid-Afrika is waargeneem nie. Monilinia laxa was meer prominent op die laat-seisoen kultivars. Botrytis cinerea bloeiselinfeksie het nie direk bygedra tot naoesverrotting nie. Beide oppervlakkige inokulum en latente infeksie het deurgaans, maar wel teen wisselende hoeveelhede, op vrugte in die onderskeie boorde voorgekom. Siekte-uitdrukking op ontwikkelende vrugte is egter nie beinvloed deur die hoeveelheid B. cinerea op die vrug nie, maar eerder deur die vermoë van die vrug om siekte-uitdrukking te onderdruk. Die hoeveelheid B. cinerea op vrugte was verder hoër gedurende lente as gedurende somer. Monilinia laxa het slegs sporadies op die bloeisels van laat-seisoen kultivars voorgekom. Groen vrugte was in die algemeen vry van die patogeen en siekte-uitdrukking het slegs op ryp vrugte plaasgevind. Hierdie bevindinge dui daarop dat M laxa in boorde hoofsaaklik op ryper vrugte geproduseer word. Hierdie swam infekteer ook net ryp vrugte. Die gedrag van luggedraagde M laxa conidia is bestudeer op nektarien- (kultivar Flamekist) en pruimvrugte (kultivar Laetitia). 'n Inokulasie-metode wat natuurlike infeksie deur luggedraagde konidia simuleer, is vir hierdie studies gebruik. Vrugte van die pitverharding-, twee weke voor oes-, oesstadium, asook koud-opgebergde vrugte (nektariene, 4 weke by -o.soe gevolg met 1 week by 23°C en ±56% RH; pruime, 10 dae by -O.5°e, 18 dae by 7.Soe gevolg deur 1 week by 23°C en ±56% RH), is met droë konidia in 'n inokulasietoring geïnokuleer. Die vrugte is vir periodes wat gewissel het van 3 tot 48 h geïnkubeer by hoë relatiewe humiditeit (~93% RH, vogtige vrugte), of dit is bedek met'n film water (nat vrugte). Die gedrag van die enkelspore (konidia) op die vrugoppervlak is met 'n epifluorisensiemikroskoop bestudeer. Skilsegmente is gekleur in 'n kleurstof, bevattende fluorisein diasetaat, analien-blou en blankofor. Die vermoë van die enkelspore om die vrugoppervlak te koloniseer, te penetreer en om siekte-uitdrukking te induseer, is met 'n differensiële stel toetse bepaal. Vir hierdie toetse is die vrugte oppervlakkig gesteriliseer (30 s in 70% etanol), of nie-steriel gelaat. In elke groep is vrugte geneem vir isolasie (skilsegment-to\~ts), of gedoop in "n 3% parakwat-oplossing (parakwat vrugtoets), of\, onbehandeld gelaat (onbehandelde vrugtoets ). Die. bevindinge het op die soortgelyke gedrag van M laxa enkelspore op die verskillende vrugsoorte gedui: appressoria en direkte penetrasie is nie waargeneem nie, en kiembuise het die vrugte hoofsaaklik deur huidmondjies, lentiselle en mikro-krakies .in die vrugskil gepenetreer. Deur luggedraagde spore te bestudeer, is sekere subtiele effekte van die vrug op die gedrag van enkelspore op die vrugoppervlak waargeneem. Op beide vrugtipes is geen nadelige effek op konidiurn- en kiembuisoorlewing opgemerk wanneer die vrugte onder hoë vogtoestande geïnkubeer is. Konidiurn- en kiembuisoorlewing is egter drasties verlaag hoe langer die vrugte onder nat toestande geïnkubeer is. Die bevindinge van die skilsegment-, parakwat en onbehandelde vrugtoetse het duidelik daarop gewys dat die vrugskil van nektarien en pruim nie gepenetreer is tydens die pitverhardingstadium nie, latente infeksies is nie gevorm nie, en die vrugte was bestand teen siekte-uitdrukking. Hierdie fasette op beide vrugtipes is ook nie beinvloed deur inkubasie-natheid nie. Die beskermingskapasiteit van die vrugskil van hierdie steenvrugtipes het egter drasties verskil later in die seisoen. Nektarien-vrugskille is meer geredelik gepenetreer en siekte-uitdrukking het toegeneem met rypwording. Penetrasie en siekteuitdrukking is verder in 'n groot mate deur inkubasie-natheid bevoordeel. Rypwordende pruime het egter nie so In drasties verandering in die beskermingskapasiteit van die vrugskil getoon nie. Die invloed van inkubasie-natheid op infeksie en siekte-uitdrukking was ook minder opsigtelik as op nektarien. Pruimvrugte van die twee weke voor oes-, oesstadium, en , koud-opgebergde pruime, wat onder hoë vog geïnkubeer is, het simptoomloos in die onbehandelde vrugtoets gebly. Vrugte van hierdie stadia het slegs simptome ontwikkel na periodes van langer as 12 h onder nat toestande. Die parakwat-behandelde vrugtoets het egter gewys dat die pruimvrugte meer vatbaar vir latente infeksies raak, maar steeds nie so vatbaar soos die nektarienvrugte nie. Gesamentlik dui hierdie bevindinge daarop <41tM laxa bruinvrot epidemies op pruim en nektarien afhanklik is van inokulumvlakke op rypwordende vrugte, asook die weerstoestande gedurende die vooroes- en oesstadia. Die beskermingskapasiteit van pruim vrugskille was egter aansienlik meer effektief as dié van nektarien vrugte. Wonde op vrugte sal dus 'n groter rol speel in die epidemiologic van M laxa op pruim. Infeksie van vars wonde deur luggedraagde M laxa konidia, en deur konidia en kiembuise wat reeds op die vrugoppervlak gevestig is, is gevolglik bestudeer. Pruimvrugte (kultivar Laetitia) van die pitverharding-, twee weke voor oes-, oesstadium, asook koud- \ \ opgebergde vrugte is in 'n inokulasie-toring geïnokuleer met droë M laxa konidia. .Infeksie , , van nie-gewonde vrugte en van vars wonde deur luggedraagde konidia op droë, vogtige en nat pruim vrugoppervlaktes, asook deur konidia en kiembuise wat reeds op die vrugoppervlak onder hierdie toestande gevestig is, is bepaal. Nie-gewonde groen tot ryp vrugte het meestal simptoomloos gebly, terwyl koud-opgebergde ryp vrugte wel verrot het. Wonde .het die hoeveelheid infeksie deur luggedraagde spore drasties vermeerder. Konidia wat geïnokuleer is op vrugte met vars wonde, was meer in staat om hierdie wonde te infekteer as konidia en kiembuise wat 4 dae voor wonding gevestig is. Hierdie afname in infektiwiteit was meer sigbaar op die vogtige, maar veral die nat vrugte. Hierdie studie het duidelik gewys dat inokulumvlakke op rypwordende vrugte verlaag moet word deur sanitasie-praktyke en fungisiedtoedienings. Dit is verder belangrik om vrugte, veral rypwordende vrugte, teen wonding te beskerm.

M. Tech. Agriculture / Brown rot caused by Monilinia laxa is the main pre and postharvest disease of peaches; it affects the shelf life and marketability of peaches. Increasing consumer concern regarding food safety makes it necessary to search for natural environmentally friendly alternative products for postharvest disease control. The objective of this study is to develop an environmentally friendly essential oil technology for the control of brown rot (M. laxa) in peaches at postharvest stage to replace the currently used synthetic fungicide (Iprodione)

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2016-10-13T15:32:28Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação completa Maximiliano Dini.pdf: 5135504 bytes, checksum: 0af878399c0b0f849228a9eae5e33c8d (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-01-04T14:56:39Z (GMT) No. of bitstreams: 2 Dissertação completa Maximiliano Dini.pdf: 5135504 bytes, checksum: 0af878399c0b0f849228a9eae5e33c8d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-04T14:56:39Z (GMT). No. of bitstreams: 2 Dissertação completa Maximiliano Dini.pdf: 5135504 bytes, checksum: 0af878399c0b0f849228a9eae5e33c8d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-08-29 / A cultura do pessegueiro [Prunus persica (L.) Batsch] vem crescendo em todo o mundo, devido ao aumento no consumo de frutas in natura e de seus produtos industrializados. No Brasil, em parte, o crescimento deve-se ao melhoramento genético. Essa área de pesquisa, visando a obtenção de novas cultivares que produzam frutos de qualidade, tenham alta produção, adaptação climática, e apresentem resistência às principais doenças é de muita importância para a expansão da cultura. O conhecimento dos parâmetros genéticos, fenotípicos e ambientais que influenciam direta ou indiretamente nos caracteres de importância econômica em pessegueiro são de fundamental importância para o delineamento dos programas de melhoramento desta frutífera, permitindo antever a possibilidade de sucesso com a seleção de diferentes genótipos em diferentes ambientes. O objetivo central deste trabalho foi buscar fontes de resistência à podridão-parda; estudar a segregação; estimar a herdabilidade e verificar a possível existência de efeito materno em alguns caracteres de importância econômica no pessegueiro. Foi constatada variabilidade fenotípica e segregação transgressiva, para os caracteres fenológicos estudados nas populações avaliadas. A herdabilidade para o período de desenvolvimento do fruto, data de plena floração e data de maturação, é alta a muito alta, permitindo um rápido ganho genético para estes caracteres fenológicos. A herança desses caracteres fenológicos estudados é predominantemente aditiva, e os desvios podem ser atribuídos a um possível efeito materno ou a genes de efeito maior. Foi observada a presença de segregação transgressiva para os parâmetros referentes à tonalidade da cor da polpa (ângulo Hue, croma e luminosidade), e a herdabilidade estimada foi alta, possibilitando rápido avanço genético também para este caráter. A herança da tonalidade da cor da polpa é predominantemente aditiva, e os desvios podem ser atribuídos a genes de efeito menor, sem constatar-se indícios de efeitos maternos. O ângulo Hue é o parâmetro correto para classificar e estudar a tonalidade de pêssegos e nectarinas de polpa amarela, e o parâmetro luminosidade pode ser uma opção para o estudo dos frutos de polpa branca. O uso dos três parâmetros em conjunto possibilita melhor representação deste caráter. Para os caracteres de resistência à podridãoparda em flores e frutos, nas populações estudadas, foi verificada alta variabilidade genética. As cultivares Maciel e Cerrito foram os genitores de maior resistência à podridão-parda nas flores, e transmitiram essa característica a suas progênies. As seleções Conserva 947 e Conserva 1600 foram os genitores de maior resistência à podridão-parda nos frutos, com um nível de resistência similar a ‘Bolinha’, transmitindo essa característica a suas progênies. A herdabilidade da resistência à podridão-parda nas flores (incidência e severidade) e nos frutos (diâmetro da lesão e esporulação), no pessegueiro, é média. A seleção dos genitores, baseada no fenótipo, possibilita um médio avanço genético para esta característica. / The peach culture [Prunus persica (L.) Batsch] has been growing throughout the world, due to an increase in consumption of fresh fruits and processed products. Aiming the development of new productive and adapted cultivars, with good quality fruits and disease resistance, breeding programs are partially responsible for the expansion of the culture, in Brazil. The knowledge of the genetic, phenotypic and environmental parameters that influence, directly or indirectly, on the economically important characters in peach is of fundamental importance for the fruit breeding programs, allowing to anticipate the possibility of success with the selection of genotypes under different environments. The main objective of this work was to seek sources of brown rot resistant genotypes, as well as study the segregation, estimate the heritability and verify the possible existence of maternal effect on some characters of economic importance in peach. Phenotypic variability and transgressive segregation were observed for the phenological characters studied on the evaluated populations. The heritability of the fruit development period, date of full blooming and maturity date, is high to very high, allowing a rapid genetic gain for these phenological characters. The inheritance of the studied phenological characters is predominantly additive, and the deviations can be attributed to a possible maternal effect or major genes. It was observed the presence of transgressive segregation for the parameters relating to the tonality of flesh color (Hue angle, chroma and luminance), and the estimated heritability was high, enabling fast genetic advance for this character. The heritability of this character is predominantly additive, and the deviations can be attributed to the minor genes, without observing signs of maternal effects. The Hue angle is the correct parameter to classify and study the flesh color tonality of yellow peaches and nectarines. The luminance parameter may be an option for the study of white flesh. The use of the three parameters together, enables better representation of this character. For the character brown rot resistance on flowers and fruits, a high genetic variability was verified. The cultivars Maciel and Cerrito were the parentals with higher resistance to flower blight, and they transmitted this trait to their offspring. The selection Conserva 947 and selection Conserva 1600 were the parentals with higher brown rot resistance to infection on fruit, similar to ‘Bolinha’, passing this trait to their offspring. The heritability of brown rot resistance on flowers (incidence and severity) and fruits (diameter of the lesion and sporulation), in peach, is medium. Parental selection based on phenotype, enables a genetic breakthrough for medium resistance to brown rot.

Isolates of Monilinia fructicola (Wint.) Honey obtained from stone fruit orchards in Hawkes Bay, North Island and from Californian fruit exported to New Zealand, were tested for resistance to methyl benzimidazole carbamate (MBC). Resistant isolates from the North Island had EC₅₀ values of >30,000, and most isolates from the imported fruit had of values approximately 1.5 mg a.i./l carbendazim. Sensitive isolates failed to grow on 1 mg a.i./l carbendazim. A detached peach shoot system was used in controlled conditions for estimation of values for incubation period, latent period and rate of spore production on flowers (cv Glohaven). The same variables and the rate of colonisation of host tissue were measured on fruit (cv Fantasia) in controlled conditions. An inoculum density of 1x10⁴ spore/flower or fruit greatly increased fitness in vivo compared to an inoculum density of 1x10² spore/flower (fruit). Isolates varied considerably, but there was no consistent relationship between the degrees of resistance and fitness. This was in contrast to earlier studies with dicarboximide resistant strains of M. fructicola. The survival in the field of 10 isolates resistant or sensitive to MBC or dicarboximide fungicides on twig cankers and mummified fruit was compared. The ability to produce conidia on twig cankers inoculated in late spring 1989 was maintained by all sensitive and MBC resistant isolates for at least 1 year. The production of conidia on mummified fruit inoculated in February 1990 decreased after 2-3 months in the field but some conidia were still produced on all fruit in the following spring. Dicarboximide resistant isolates produced less conidia than either the MBC resistant and the sensitive isolates. The pathogenicity and fitness of all isolates were similar to the original values after survival for 1 year. A technique was developed to produce apothecia reliably from inoculated peach (cv Black Boy) and nectarine (cv Fantasia) fruit in controlled conditions in the laboratory. The fruit were inoculated with resistant or sensitive isolates, or combinations, and were incubated for 8 weeks at 25°C (±1°C) with 12 hours photoperiod of fluorescent light (Sylvania 2x65 W, daylight) to produce mummified fruit. The fruit were then buried in moist autoclaved peat moss for 10 weeks at 25°C (±1°C) in the dark to form stromata. These fruit were then hydrated with running tap-water (total hardness (CaCO₃) = 47 g/m³ and conductivity at 20°C = 12.7 mS/m) for 72 hours. The hydrated mummified fruit were placed in moist peat moss and were incubated for 13-14 weeks at 8°C (±0.5°C) in the dark. At the end of this period, stipe initials were visible. Differentiation of stipe initials into mature apothecia occurred within 15-20 days after transfer to 12°C (±2 °C) with a 12 hour photoperiod of fluorescent and incandescent light. All isolates produced apothecia when treated in this way. A technique for isolation of ascospore sets in linear arrangement was developed for tetrad analysis of the inheritance of resistance. At least 3 hours of fluorescent and incandescent light at 12°C (±2°C) was essential to allow ascospore ejection from individual asci taken from apothecia previously maintained in a 12 hour photoperiod at 12°C (±1°C). A water film on the surface of water agar was necessary to hold a set of ejected ascospores in linear sequence. Single ascospores were obtained in sequence with the aid of a micromanipulator. Genetic analysis of MBC resistant isolates was carried out on ascospores derived from apothecia produced in the laboratory. Analysis of ascospore sets in linear arrangement and ascospore populations indicated that resistance to >30,000 mg a.i./l carbendazim (high-resistant) is governed by a single major gene and is affected by gene conversion mechanisms. Crossing over was frequent, suggesting that recombination of resistance with other characters, such as pathogenicity and fitness, may occur readily. The segregation ratio (1:1) from most resistant isolates revealed that heterokaryons containing both resistant and sensitive alleles were common in resistant populations and that resistance is dominant. Allozyme analysis of ascospore progeny through electrophoresis revealed a narrow genetic base of M. fructicola in New Zealand. The technique for reliable apothecial production in controlled conditions developed in this study provided an important step for the determination of the biology of M. fructicola strains resistant to MBC fungicides, and the complexity of its life cycle. Genetic heterogeneity in field populations can be conserved in one isolate through heterokaryosis, thus providing for adaptability of the pathogen to the changing environmental conditions. Knowledge on genetic variability, overwintering ability, pathogenicity and fitness factors may be useful for future management strategies of stone fruit brown rot. Special emphasis should be made in particular to prevent primary infection on blossoms, which would delay the establishment of recombinant strains of M. fructicola and the onset of brown rot epidemics.