Thesis (MScAgric)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Various studies revealed that Botrytis cinerea, the causal pathogen of Botrytis bunch rot, is mostly associated with pedicels, rachises, laterals and berry bases, and not with berry skins as previously understood. Provided that sufficient coverage of inner bunch parts was achieved, laboratory studies have shown that fungicides can effectively reduce the amount of B. cinerea at the various positions in bunches, and prevent infection and symptom expression at all growth stages. The same efficacy was, however, not achieved with the same fungicides when using conventional spraying methods in vineyards. Poor disease control on fruit and leaves in vineyards is attributed to inappropriate timing of fungicide applications and/or insufficient coverage of susceptible tissue. Previously, spray coverage evaluations in South Africa were based on the use of water-sensitive cards. A variety of other methods have been used to assess spray coverage in vineyards, but none of these methods could assess spray deposits on a very small, three-dimensional area of interest such as the susceptible grape bunch parts. The methods were furthermore dependent on human objectivity, which lacks quantitative measuring and speed of measurement. Suitable technology to determine spray coverage on susceptible bunch parts is, therefore, not available. The aim of this study was to develop a protocol to visualise and quantify spray deposits in grape bunches, specifically on the inner bunch parts and to use the protocol to determine the effect of different levels of spray cover on artificially inoculated B. cinerea grape bunches, in order to facilitate future determination of minimum effective coverage levels for effective B. cinerea control. A spray coverage assessment protocol using fluorometry, photomicrography and digital image analyses was developed to measure spray coverage on susceptible grape bunch parts. Among several fluorescent pigments tested, a yellow fluorescent pigment (SARDI Fluorescent Pigment) from Australia was selected on the basis of its small particle size (2.45 - 4.90 μm). Bunches were sprayed at pea size and bunch closure with different volumes of a mixture of fenhexamid and the yellow fluorescent pigment. Sprayed parts from bunches were illuminated under black light (UV-A light in the 365 nm region) and visualised under a stereo microscope at 20 x magnification. Photos of the berry skin, pedicel and rachis were taken with a digital camera (Nikon DMX 1200). Image analysis of photos was done with Image- Pro Discovery version 4.5 for Windows (Media Cybernetics) software. The total area of deposited pigment in selected areas of interest (AOI) was calculated. The percentage area covered was subsequently calculated for each AOI. Good correlation was evident between the parameters, sum of objects and percentage area covered. Bunch parts at pea size generally had higher coverage values than at bunch closure. Spray applications earlier in the season would therefore result in higher and more effective spray coverage of the susceptible bunch parts. Similar deposition trends were observed on the inner bunch parts (pedicel and rachis). These were, however, significantly different from berry skins, which had significantly higher levels of spray deposits than the inner bunch parts. The variance component analysis indicated that the highest variance was observed for berries and bunches, and substantially less for image readings. For the same accuracy, means for percentage coverage values of at least 10 bunches per treatment (1 part per bunch and 3 readings per part) will be sufficient. In order to determine the biological efficacy of different levels of spray coverage on B. cinerea incidence on grape bunches, bunches were sprayed at pea size and bunch closure with different volumes of a mixture of fenhexamid and a yellow fluorescent pigment and the percentage fluorescent pigment coverage on pedicels was determine. Bunches were subsequently dusted with dry airborne conidia of B. cinerea in a settling tower and incubated for 24 h at high relative humidity (98%). Infection was determined by estimating the amount of B. cinerea infections occurring on sprayed bunch parts with isolations on to paraquat and Kerssies mediums. Linear regressions for the part x stage combinations of percentage B. cinerea incidence on different bunch parts were fitted on mean coverage levels. An increase in spray cover caused linear reductions in levels of B. cinerea on susceptible bunch parts. Higher B. cinerea incidences were recorded at pea size. Furthermore, higher B. cinerea incidences were found on paraquat medium for both stages, than on Kerrsies medium. The information gathered from this study will be used to facilitate future determination of minimum effective coverage levels for effective B. cinerea control in grape bunches. In these validation experiments, the results clearly showed that the protocol can be used to determine the effect of different levels of spray coverage on B. cinerea incidence and that an increase in spray coverage will decrease B. cinerea incidence. The information gathered from this study will be used to facilitate future determination of minimum effective coverage levels for effective B. cinerea control in grape bunches and subsequently be used as benchmarks to evaluate spray application in vineyards. / AFRIKAANSE OPSOMMING: Vaalvrot by wingerde word veroorsaak deur Botrytis cinerea. Verskeie studies het getoon/gewys dat die oorsaaklike patogeen meestal geassosieer word met die pedisel, ragis, laterale en die korrelbasis, en nie met die korrelskil soos voorheen beweer nie. Laboratorium studies het getoon dat swamdoders wel effektief is om B. cinerea by alle trosdele te verminder en simptoomontwikkeling te voorkom tydens alle groeistadia, mits die binne-trosdele voldoende spuit bedekking ontvang het. Dieselfde effektiwiteit is egter nie gevind in wingerde met konvensionele spuittegnieke nie. Onvoldoende siektebeheer van vrugte en blare van wingerde kan toegeskryf word aan verkeerde spuit skedulering en/of swak spuitbedekking van vatbare gasheerweefsel. Evaluering van spuitbedekking is voorheen in Suid Afrika deur middel van water-sensitiewe papier gedoen. Verskeie ander metodes is al gebruik om spuitbedekking te evalueer in wingerde, maar nie een van hierdie metodes kan gebruik word om spuitbedekking op ’n baie klein, drie-dimensionele oppervlak, soos die vatbare trosdele, te evalueer nie. Verder was die tegnieke afhanklik van menslike objektiwiteit, en gevolglik ontbreek kwantitatiewe meting en metingspoed. Daar is dus nie geskikte tegnologie vir die evaluering van spuitbedekking op vatbare trosdele nie. Die doel van hierdie studie was die ontwikkeling van ‘n protokol vir die visualisering en kwantifisering van spuitbedekking op spesifiek die binne-tros dele en om die protokol dan te gebruik om die effek van verskillende vlakke van spuitbedekking op B. cinereageinokuleerde druiwetrosse te bepaal, Protokol vir evaluasie van spuitbedekking op vatbare druifdele is ontwikkel deur gebruik te maak van fluorometrie, fotomikrografie en digitale beeldanalise. Van die verskillende fluoresensie pigmente wat getoets is, is ‘n geel flouresensie pigment (SARDI Flourescent Pigment) van Australië gekies op grond van sy klein partikelgrootte (2.45 - 4.90 μm). Druiwetrosse is gespuit tydens ertjie- en trostoemaakstadia met verskillende volumes van ’n mengsel van fenheksamied en die geel fluorosensie pigment. Die gespuite druifdele is dan verlig onder swartlig buise (UV-A lig in die 365 nm spektrum) en gevisualiseer deur ’n stereo mikroskoop by 20x vergroting. Foto’s van die korrelskil, pedisel en ragis is met ‘n digitale kamera (Nikon DMX 1200) geneem. Beeldanalise is gedoen met ImagePro Discovery weergawe 4.5 vir Windows (Media Cybernetics) sagteware. Die totale area neerslag van die pigment is in geselekteerde areas bereken. Die presentasie area bedek is bereken vir elkeen van hierdie areas. Goeie korrelasie is gevind tussen die parameters aantal fluoresserende partikels en die persentasie bedekte area. Trosdele tydens ertjie-stadium het in die algemeen hoër waardes gehad as by trostoemaak. Dit blyk dus dat spuittoediening vroeg in die seisoen meer effektief sal wees vir die bedekking van vatbare trosdele. Soortgelyke bedekkings patrone is gevind by die binne trosdele (pedisel en ragis). Dit het egter betekenisvol verskil van die korrelskil, wat betekenisvol meer spuitbedekking as die binne trosdele gehad het. ’n Variasie komponent analise het getoon dat die meeste variasie gevind is tussen korrels en trosse, en heelwat minder vir die beeld analise lesings. Om dieselfde akkuraatheid te behou, is ten minste 10 trosse per behandeling (1 deel per tros en 3 lesings per deel) nodig. Vir die bepaling van biologiese effektiwiteit van verskillende vlakke van spuitbedekking op B. cinerea voorkoms op druiwe, is druiwe gespuit tydens ertjie- en trostoemaak-stadia met verskillende volumes van ’n mengsel van fenheksamied en die geel fluorosensie pigment. Die persentasie fluoresensie pigment is bepaal op die pedisels. Trosse is vervolgens geinokuleer met droë luggedraagde konidia van B. cinerea in ’n inokulasietoring en geïnkubeer vir 24 h by hoë relatiewe humiditeit (98%). Die voorkoms van B. cinerea infeksie op gespuite tros dele is bepaal deur middel van isolasies op paraquat en Kerssies medium. Liniêre regressies vir trosdeel x stadium kombinasies van persentasie B. cinerea voorkoms op verskillende trosdele is gepas vir gemiddelde bedekkings waardes. ’n Verhoging in spuit bedekking het ‘n liniêre vermindering van B. cinerea voorkoms op vatbare trosdele veroorsaak. Verder is hoër vlakke van B. cinerea op paraquat medium as op Kerssies medium vir beide die groeistadia gevind. Die kennis wat verkry is uit hierdie studie sal gebruik word om minimum effektiewe spuitbedekkingsvlakke vir die beheer van B. cinerea op druiwetrosse te bepaal.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Endocrine disrupting contaminants (EDCs) coming from households, industrial parks, wastewater (sewage) treatment and agricultural areas have been shown to pollute our freshwater systems. These contaminants may disrupt early development and reproductive systems in freshwater organisms (fish, frogs and crocodile species) as well as humans. Agricultural pesticides are shown as a large contributor to endocrine disruption activity in water catchment areas through spray drift, runoff, and/or groundwater leeching. Although South Africa is recognized as the largest consumer of agricultural pesticides in Africa, few studies have been undertaken to assess the prevalence and impact of endocrine disorders activities of pesticides in local freshwater systems. Recent studies have suggested that various agricultural pesticides, especially fungicides, might have adverse effects on the male endocrine system. There is therefore a need to test for a wider range of endocrine disrupting activities (mechanisms) in environmental waters other than conventional estrogenic (feminising) activities. Furthermore, there is a need to establish biomarkers in endemic species (bio-indicators) to show endocrine disruption in vertebrates (therefore also apply to humans). The specific objectives of the study were to: (1) describe and confirm the use of androgen-controlled breeding glands in male African clawed frogs (Xenopus laevis) as a biomarker for (anti)androgenic endocrine disruption activity (Chapter 2), (2) to investigate the premature development of breeding glands in X. laevis tadpoles (pre-metamorphic) and young froglets (post-metamorphic) (Chapter 2), (3) to investigate the disruption of male reproductive traits in adult X. laevis frogs by exposure to substances disrupting two different anti-androgenic endocrine disruption pathways (Chapter 3), (4) screen for (anti)androgenic activity of individual and binary mixtures of pesticides, which are regularly used in agricultural areas in the Western Cape Province of South Africa (Chapter 4), and (5) to test for (anti)androgenic and estrogenic endocrine disrupting activities by making use of in vitro assays as well as adult male X. laevis frogs collected from selected ponds surrounded by vineyards and fruit orchards in the Stellenbosch Winelands. The present study confirmed that male breeding glands can serve as biomarkers for (anti)androgenic endocrine disruption and that male reproductive and secondary sexual characteristics can be disrupted through two different biochemical control pathways. The study also confirmed that the expression of androgen-regulated breeding glands can be stimulated in pre-metamorphic tadpoles and immature, post-metamorphic frogs, and can thus be used for (anti)androgenic testing. The rapid testing and predictive value of an in vitro recombinant yeast screen for androgen receptor binding inhibition of selected individual or binary mixtures of pesticides was also confirmed. However, the current study showed that the predicted in vitro (anti)androgenic activity did not always correspond with in vivo (anti)androgenic biomarker outcomes. This It also confirmed that single-cell in vitro assays can be used as a first-level prediction for (anti)androgenic activities of individual or mixtures of agricultural pesticides. This study provides a better understanding for potential mixture interactions of commonly used agricultural pesticides, the hormonal control of secondary sexual characteristics in male frogs and the use of reproduction biomarkers to study long-term effects of endocrine disruptors in local water supplies. / AFRIKAANSE OPSOMMING: Endokriene versteurings-kontaminante (EVKe) wat vanaf huishoudings, industriële parke, afvalwater(riool)-behandeling en landbougebiede kom, besoedel ons varswaterstelsels. Hierdie kontaminante mag versteuring van vroeë ontwikkeling- en voorplantingstelsels in varswater-organismes (vis-, padda- en krokodil-spesies) sowel as die mens inhou. Landbou-plaagdoders word uitgesonder as ’n bydraer van endokriene versteuring-aktiwiteite in wateropvangs-gebiede deur spuitnewel, afloop-water en/of grondwater-deurvloei. Hoewel Suid-Afrika erken word as die grootste verbruiker van landbou-plaagdoders in Afrika, word min studies onderneem om die voorkoms en impak van endokriene versteurings-aktiwiteite van plaagdoders in plaaslike varswaterstelsels te ondersoek. Onlangse studies het voorgestel dat verskeie landbou-plaagdoders, veral swamdoders, nadelige uitwerkings kan hê op die manlike endokriene stelsel. Daar bestaan dus 'n behoefte om te toets vir 'n wyer verskeidenheid van endokriene versteurings-aktiwiteite (meganismes) in omgewingswater anders as konvensionele estrogeniese (vervroulikings) aktiwiteite. Verder bestaan daar ’n behoefte om biomerkers in endemiese spesies te gebruik as bio-indikators van endokriene versteuring in werweldiere (daarom ook van toepassing op die mens). Die spesifieke doelwitte van die studie het ingesluit om: (1) die gebruik van androgeen-beheerde parings- velkliere (“breeding glands”) in manlike platannas (Xenopus laevis) as 'n biomerker vir (anti)androgeniese endokriene versteuring-aktiwiteit te beskryf en bevestig (Hoofstuk 2); (2) ondersoek in te stel na die voortydige ontwikkeling van parings-kliere in X. laevis paddavisse (pre-metamorfose) asook jong paddas (post-metamorfose) as biomerkers van androgeniese (vermanlikheids) aktiwiteite (Hoofstuk 2); (3) ondersoek in te stel na die versteuring van manlike geslags-eienskappe in volwasse X. laevis paddas deur middel van blootstelling aan stowwe wat twee verskillende androgeniese endokrien reaksie-weë verteenwoordig (Hoofstuk 3); (4) toets vir (anti)androgeniese aktiwiteit van individuele en binêre mengsels van landbou-plaagdoders wat gereeld in die Westelike Provinsie van Suid Afrika gebruik word (Hoofstuk 4) en (5) te toets vir (anti)androgeniese en estrogeniese endokriene versteurings aktiwiteite deur gebruik te maak van in vitro toetse asook volwasse manlike X. laevis paddas wat uit geselekteerde damme (omring deur wingerde en vrugte boorde in die Stellenbosch wynland distrik) versamel was. Die huidige studie het bevestig dat die manlike parings-velkliere as biomerkers vir (anti)androgeniese versteuring kan dien en dat manlike voortplanting en sekondêre geslagskenmerke deur twee verskillende biochemiese beheer-weë ontwrig kan word. Die studie het verder bevestig dat die uitdrukking van androgeen-gereguleerde parings-velkliere voortydig gestimuleer kan word in pre-metamorfose paddavissies asook onvolwasse, post-metamorfose paddas. Die vinnige toetsing en voorspellingswaarde van 'n rekombinante in vitro gis toets om binding-inhibisie van die androgeen reseptor deur geselekteerde individuele of binêre mengsels van plaagdoders aan te toon is ook bevestig. Alhoewel, die huidige studie het getoon dat die voorspelde in vitro (anti)androgeniese aktiwiteit nie altyd ooreenstem met in vivo (anti)androgeniese biomerker uitkomstes nie. Hierdie studie bevestig dat enkel-sel in vitro toetse aangewend kan word as eerste vlak- en voorspelling-toetse vir (anti)androgeniese aktiwiteite van enkel of mengsels van landbou-plaagdoders. Sodoende is 'n beter begrip verkry vir potensiële mengsel-interaksies van algemeen-gebruikte landbou plaagdoders, die hormonale beheer van sekondêre geslagskenmerke in manlike paddas asook die aanwending van voortplantingsbiomerkers om langtermyn effekte van endokriene versteurders in plaaslike waterbronne te ondersoek.

Thesis (PhD(Agric))--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Despite adherence to fungicide spray schedules and label recommendations, table and wine grape producers invariably suffer crop losses when environmental conditions are conducive to fruit and foliar pathogens. Registered fungicides are effective and poor control is often attributed to: 1) improper spray timing, 2) reduced sensitivity to fungicides in the pathogen populations, and 3) poor spray deposition. Spray timing, management of fungicide resistance and the epidemiology of Botrytis cinerea have been thoroughly researched under South African conditions on grape crops. However, limited research regarding spray deposition exists in South Africa, probably due to a lack of proper spray deposition assessment protocols. To determine minimum spray deposition quantity and quality levels needed for effective B. cinerea control, bunches and leaves of table (Waltham Cross) and wine grapes (Chenin blanc) were sprayed at various stages using different volumes with a precision spray gun. A deposition assessment protocol using fluorometry, photomicrography and digital image analyses was improved. Deposition values correlated favourably with Botrytis infection. Increasing spray volume increased spray deposition; however, at a certain point, deposition quality remained constant and B. cinerea infections did not decrease significantly with increasing spray volume, indicating the importance of both spray deposition quantity and quality. Fluorescent pigment area that effected 75% control of B. cinerea infection (FPC75 values) was calculated for leaves, pedicels and receptacles at different growth stages. The FPC75 values obtained in this study can be used as benchmarks to evaluate future spray application. In order to study the optimisation of spray deposition with existing application technology (air blast and air shear sprayers) in commercial vineyards, spray deposition quantity and quality values were assessed from leaves and structural bunch parts of wine (Chenin blanc) and table grapes (Waltham Cross) and compared with FPC75 values. Spray trials were conducted at different growth stages at current best-practice recommendations, and with a range of spray volumes but with spray mixture concentration amended accordingly (i.e. fixed dosage per hectare). Spray trails indicated that deposition levels following current best-practice spray application were sub-optimal to control B. cinerea infections on bunches and leaves. Deposition values between air blast and air shear sprayers were generally similar. The air blast sprayer resulted in higher deposition levels with diluted spraying and increased spray volume; however, when dosage per hectare was kept constant, no significant differences were calculated between spray volumes (250-1000 L/ha), indicating that this sprayer can as effectively but more efficiently be used at lower spray volume. The air shear were not as efficient at higher spray volumes (>500 L/ha), but was superior at low volume concentrate application (≈250 L/ha at 4× concentration). This study clearly demonstrated the efficacy and cost-saving potential in optimising spray application with respect to application technology. / AFRIKAANSE OPSOMMING: Wingerdprodusente kan oesverliese ondervind indien omgewingstoestande bevorderlik is vir swampatogene. Siektes word onvoldoende beheer ten spyte van die nakoming van korrekte swamdoder aanbevelings. Geregistreerde swamdoders is effektief, mits die vatbare plantdele voldoende spuitbedekking ontvang. Onvoldoende siekte beheer kan gewoonlik toegeskryf word aan: 1) verkeerde spuit tydsberekening, 2) vermindere sensitiwiteit in patogeen-populasies teen swamdoders, en 3) swak spuitbedekking. Spuit tydsberekening, die bestuur van weerstand teen swamdoders en die epidemiologie van Botrytis cinerea is deeglik onder Suid-Afrikaanse toestande nagevors. Nietemin is daar beperkte navorsing oor spuitbedekking, waarskynlik weens 'n gebrek aan behoorlike spuitbedekking assesseringsprotokol. Om te bepaal hoeveel spuitbedekking (% area bedek deur fluoresserende pigment) nodig is om 75% van B. cinerea infeksies (FPC75 waardes) op vatbare wingerddele te beheer, is druiwetrosse en blare van tafel- en wyndruiwe (Waltham Cross en Chenin blanc, onderskeidelik) op verskillende groei stadiums en spuitvolumes in die laboratorium gespuit. ‘n Assesseringsprotokol van spuitbedekking op vatbare druifdele en blare is ontwikkel deur gebruik te maak van fluorometrie, fotomikrografie en digitale beeldanalise. Spuitbedekking het goed met Botrytis infeksies gekorreleer. Toenemende spuitvolume het bedekking laat toeneem, maar egter net tot 'n sekere punt, waar die kwantiteit van die bedekking nog toegeneem het, maar die kwaliteit van bedekking en B. cinerea infeksies nie beduidend toegeneem het nie. Dit is ‘n aanduiding van die belangrikheid van beide die kwantiteit en kwaliteit van spuitbedekking. Die FPC75 waardes wat in hierdie studie verkry is, kan as drempelwaardes om toekomstige spuittoediening te evalueer, gebruik word. Ten einde spuitbedekking met bestaande tegnologie (druk en waaierpomp spuitmasjiene) te optimiseer, is kommersiële wyn- en tafeldruiwe (Chenin blanc en Waltham Cross, onderskeidelik), volgens huidige spuit aanbevelings vir wingerde tydens verskillende groeistadiums en met ‘n reeks van verskillende spuitvolumes gespuit. Die konsentrasie van die spuitmengsel is dienooreenkomstig gewysig, i.t.v. ‘n vaste dosis per hektaar ongeag die spuitvolume. Bedekkingswaardes is met FPC75 waardes vergelyk en het aangedui dat kommersiële spuit aanbevelings aan produsente sal lei tot sub-optimale beheer van B. cinerea op beide blare en druiwetrosse. In die algemeen was bedekkingswaardes vir beide druk- en waaierpomp spuitmasjiene soortgelyk. Vir die waaierpomp teen verskillende spuitvolumes en aanbevole konsentrasie het ‘n toename in spuitvolumes tot hoër beddekingswaardes gelei, maar indien die dosis per hektaar van die spuitmengsel konstant behou is, is geen betekenisvolle verskille tussen spuitvolumes (250-1000 L/ha) voorspel nie. Hierdie dui aan dat die waaierpomp net so doeltreffend, maar meer effektief teen laer spuitvolumes gebruik kan word. Die drukpomp was nie so doeltreffend teen hoër spuitvolumes (> 500 L/ha) nie, maar was aansienlik beter by lae volume konsentraat toediening (≈ 250 L/ha op 4 × konsentrasie). Die studie toon duidelik die doeltreffendheid en moontlike kostebesparing moontlikhede deur bespuiting relatief tot bespuitingstegnologie te optimiseer. / Department of Plant Pathology, National Research Foundation, THRIP, Deciduous Fruit Producers’ Trust, Winetech, Bayer, BASF, Dow Agrosciences, DuPont, Syngenta, Nexus, Terason, UAP and Wenkem for financial assistance

A requeima, causada pelo oomiceto Phytophthora infestans e a pinta preta, causada pelo fungo Alternaria solani, estão entre as doenças mais importantes e destrutivas da cultura da batata no Brasil e no mundo. Considerando a importância do controle químico em sistemas integrados e a necessidade de se conhecer detalhadamente o desempenho de fungicidas e indutores de resistência visando à sustentabilidade da produção, o presente estudo objetivou caracterizar e comparar a ação preventiva, residual, curativa, anti-esporulante e resistência à chuva de fungicidas em condições controladas, bem como, avaliar em campo o potencial de controle de fungicidas e indutores de resistência e seus reflexos sobre a produtividade total e comercial de tubérculos. Todos os fungicidas promoveram elevada ação preventiva contra a requeima e a pinta preta. Os fungicidas sistêmicos ou com alta tenacidade proporcionaram controle das duas doenças até os 12 DAP, enquanto que os fungicidas translaminares até os 9 DAP. Quanto à ação curativa e anti-esporulante destacaram-se principalmente os fungicidas sistêmicos aplicados até as 24 horas após a inoculação (HAI). Os fungicidas translaminares foram capazes de inibir a requeima quando aplicados até 12 HAI e os de contato destacaram-se apenas para ação preventiva. Semelhantemente, os fungicidas sistêmicos, translaminares ou com alta tenacidade foram os menos afetados pela chuva simulada. O aumento do tempo de secagem promoveu uma maior retenção ou absorção dos produtos reduzindo o impacto negativo da precipitação. Os melhores níveis de controle, produtividade e qualidade de tubérculos foram obtidos com os fungicidas mandipropamida+clorotalonil, fluopicolida+propamocarbe, dimetomorfe+ametoctradina, mandipropamida, fenamidona+propamocarbe, bentiavalicarbe+ fluazinam, seguidos de dimetomorfe+clorotalonil mefenoxam+clorotalonil e famoxadona+ cimoxanil+mancozebe para requeima e azoxistrobina+difenoconazol, picoxistrobina, piraclostrobina+metconazol, trifloxistrobina+tebuconazol, azoxistrobina, boscalida+ piraclostrobina, iprodiona+pirimetanil e ciprodinil para pinta preta. Acibenzolar-s-metílico (ASM) reduziu a severidade da requeima e da pinta preta, porém, promoveu aumento da produtividade, apenas no campo de requeima. O fosfito de potássio (FP) também reduziu a severidade da requeima, no entanto, não influenciou na produtividade. Com exceção de mandipropamida, a adição de ASM à mefenoxam+mancozebe, cimoxanil+mancozebe e mancozebe promoveu aumento do controle da requeima, no entanto, apenas quando em mistura com mancozebe proporcionou aumento na produtividade. A adição de FP à mandipropamida, mefenoxam+mancozebe, cimoxanil+mancozebe, mancozebe e de ASM à azoxistrobina e difenoconazol não refletiu no controle da requeima, da pinta preta e na produtividade, respectivamente. Mancozebe e ASM não diferiram quanto severidade, progresso da pinta preta e produtividade, porém mancozebe+ASM foi superior ao ASM. A adição de ASM a programas de aplicação reduziu a requeima e a pinta preta e incrementou a produtividade apenas quando adicionados a programas onde prevaleceram fungicidas translaminares e de contato. O FP não influenciou nenhum dos programas testados para requeima. / Late blight, caused by the oomycete Phytophthora infestans and early blight, caused by the fungus Alternaria solani, are among the most destructive diseases of potato crops in Brazil and worldwide. Considering the importance of the chemical control on integrated systems and the need for detailed knowledge of the performance of resistance inducers and fungicides targeting the sustainability of production, the present study aimed to:1- characterize and compare the preemptive, residual, curative, antisporulative action and rain resistance of fungicides under controlled conditions; 2-: evaluate, under field conditions, the control potential of fungicides and resistance inductors and their effects on the total and commercial yield of potato tubers. All fungicides tested provided a high pre-emptive action against late and early blight. The systemic fungicides or high tenacity ones provided control of both diseases until 12 days after application, while translaminar ones until 9 days after application. As for the curative and anti-sporulative action, the systemic fungicides stand out when applied until 24 hours postinoculation, while the translaminar ones inhibited late blight when applied until 12 hours postinoculation. The contact fungicides stand out concerning pre-emptive action only. Similarly, systemic, translaminar and high tenacity fungicides were less affected by the simulated rain. An increase in drying time promoted higher retention and absorption of the products, so decreasing the negative precipitation impact. The better levels of control, yield and tubers quality were reached with the use of the following fungicides in the control of late blight: mandipropamid+chlorothalonil, fluopicolide+propamocarb, dimetomorph+ametoctradin, mandipropamid, fenamidone+ propamocarb, bentiavalicarb+fluazinam, followed by dimetomorph+chlorothalonil, mefenoxam+ chlorothalonil and famoxadone+cymoxanil+mancozeb. In the control of early blight the most efficient were: azoxystrobin+difenoconazole, pycoxystrobin, pyraclostrobin+metconazole, trifloxystrobin+tebuconazole, azoxystrobin, boscalid+pyraclostrobin, iprodione+pyrimethanil and cyprodinil. Acibenzolar-s-methyl (ASM) reduced the severity of late and early blight, but promoted an increase in the tuber yield only in late blight affected field. Potassium phosphite (Pp) also reduced the severity of late blight, although it did not have influenced the yield. Except for mandipropamid, the addition of ASM to mefenoxam+mancozebe, cymoxanil+mancozeb or mancozeb led to a better control of late blight, but only when mixed with mancozeb it promoted increase in the yield. Addition of Pp to mandipropamid, mefenoxam+mancozeb, cymoxanil+mancozeb, mancozeb and ASM to azoxystrobin, difenoconazole did not result either in the control of late and early blight or in an increase of yield. Mancozeb and ASM did not differ as for severity, progress of late blight and increasing yield, but however, mancozeb+ASM had a superior efficiency than ASM. Addition of ASM to application programs reduced late and early blight and increased yield only when added to programs in which prevailed translaminar and contact fungicides. Pp did not influenced any of the tested programs against late blight.

A Podridão Floral dos Citros (PFC), causada por Colletotrichum acutatum, foi observada em 1956/57 em Belize e relatada posteriormente em 1979. Neste mesmo ano a PFC também foi relatada no Brasil e, desde então, tem causado prejuízos todas às vezes nas quais o período de florescimento coincide com a ocorrência de chuvas. O controle da PFC é realizado principalmente por meio de pulverizações preventivas com fungicidas. O uso indiscriminado de fungicidas com o mesmo modo de ação pode selecionar indivíduos resistentes. O conhecimento da epidemiologia da PFC pode gerar informações precisas a serem utilizadas na elaboração de estratégias de manejo no campo, bem como melhorar a eficiência do controle químico da doença. Assim, foi proposto este trabalho com os objetivos de: i) caracterizar as dinâmicas temporal e espacial da PFC em pomares jovens de laranja doce; ii) avaliar in vitro a sensibilidade de isolados de C. acutatum a fungicidas e; iii) avaliar o efeito de diferentes fungicidas, intervalos de aplicação e programas de pulverização no controle da PFC no campo. A dinâmica temporal e espacial da PFC foi caracterizada em três talhões de 2 a 4 anos de idade com 500 plantas cada. Crescimento explosivo da PFC foi observado com altas taxas diárias de progresso (r) descritas pelo modelo logístico de 0,55 após chuvas e período de molhamento foliar prolongado. A PFC apresentou padrão espacial variável, inicialmente aleatório e posteriormente moderadamente agregado, indicando existir contribuição de outras fontes para a disseminação do patógeno além das chuvas com ventos. Não houve correlação entre incidência de sintomas em flores e de cálices persistentes. Os cálices persistentes não são importantes fontes de inóculo. In vitro, ensaios de sensibilidade a fungicidas demonstraram que isolados de C. acutatum coletados no Estado de São Paulo em 2008 não apresentaram resistência aos fungicidas difenoconazole e carbendazim. Em casa-de-vegetação, os fungicidas carbendazim e a mistura (trifloxistrobina + tebuconazole) apresentaram efeito significativo quando aplicados em pré-inoculação e 24 h pós-inoculação de C. acutatum, mas somente a mistura foi efetiva 48 h após a inoculação. Nos experimentos de controle químico no campo, esta mistura fungicida foi mais eficiente que os demais produtos para o controle da PFC em áreas com alta incidência da doença. Quando a proporção de flores sintomáticas atinge 100%, a redução na produção será em torno de 70% em pomares adultos de laranja Pera. Pulverizações frequentes podem ser requeridas durante todo o período de florescimento para o controle da doença, embora sejam mais importantes quando ocorrem chuvas em dois ou mais dias consecutivos com prolongamento do molhamento foliar, principalmente durante a expansão das pétalas e abertura das flores. / Postbloom fruit drop (PFD), caused by Colletotrichum acutatum, was firstly observed in Belize during 1956-1957 and subsequently reported in 1979. In the same year the disease was also reported in Brazil. PFD causes severe damage when bloom period coincides with rains. The disease is controlled primarily by preventive fungicide sprays. The repeated use of fungicides with the same mode of action can select resistant individuals. The knowledge of PFD epidemiology can generate precise information to develop efficient control strategies and improve the efficacy of chemical control. Thus, this study aimed to: i) characterize the temporal and spatial dynamics of PFD in young sweet orange orchards, ii) evaluate in vitro the baseline sensitivity of C. acutatum to fungicides and, iii) evaluate the efficacy of different fungicides, spray intervals and fungicide application schedule for PFD control. The temporal and spatial PFD-dynamics was characterized in three 2-to-4-year-old orchards with 500 trees each. High daily disease progress rates (r) described by the logistic model of 0.55 were observed after rainfall and prolonged leaf wetness. The spatial pattern of diseased trees varied considerably, initially at random and latter moderately aggregated, suggesting the contribution by other pathogen spread mechanisms, beside rain with wind. There was no correlation between the incidence of diseased flowers and the incidence of persistent calyxes. These calyxes are not important sources of inoculum. In vitro, assays demonstrated that the isolates of C. acutatum from São Paulo State were not resistant to fungicides difenoconazol and carbendazim. In the greenhouse, carbendazim and the trifloxystrobin + tebuconazol mixture showed significant effects when applied prior to inoculation or 24 h after inoculation, however only the mixture was effective 48 h after inoculation. In the field, the fungicide mixture was more effective for PFD control in orchards with high disease incidence. When the proportion of symptomatic flowers reaches 100%, yield reduction can be as high as 70% in Pera sweet orange trees. Frequent sprays may be required during bloom period to control the disease, although sprays were more important when two or more rainy days with prolonged leaf wetness occurs, especially during petals expansion and flowers opening.

Nos últimos anos, o plantio mecanizado da cana-de-açúcar vem sendo cada vez mais utilizado no Brasil. Tal sistema possui menor custo sobre o convencional e viabiliza o plantio durante o ano todo. Entretanto, a maior quantidade de ferimentos nas mudas colhidas mecanicamente e a realização de plantios em períodos frios e com umidade do solo inadequada têm aumentado a incidência da podridão abacaxi, doença causada pelo fungo Thielaviopsis paradoxa. Áreas onde esta doença é problemática apresentam muitas falhas, exigindo, em alguns casos, replantio. Thielaviopsis paradoxa penetra nas mudas através de ferimentos, o que é importante em cana-de-açúcar, uma vez que os colmos são seccionados durante o plantio. Medidas que estimulem a brotação rápida ou que protejam os ferimentos das mudas produzem excelentes resultados no controle da doença. Com o objetivo de avaliar o controle da podridão abacaxi da cana-de-açúcar por meio da pulverização de fungicidas em mudas no sulco de plantio, foram instalados quatro experimentos, sendo dois em casa de vegetação e dois no campo. Para os ensaios em casa de vegetação, utilizou-se um substrato esterilizado, composto por uma mistura de solo, areia e esterco de gado. Uma suspensão de T. paradoxa na concentração de 103 esporos/g de substrato foi incorporada dois dias antes do plantio. As avaliações foram realizadas em um período de 45 dias, determinando-se o número de plantas, a velocidade de brotação, a biomassa da parte aérea e de raízes, e a severidade da doença. No campo, um dos experimentos foi realizado sem a inoculação do patógeno, com a colheita das mudas e plantio mecanizados. No outro experimento, uma suspensão do fungo foi inoculada com pulverizador costal manual na concentração de 9 x 104 esporos/m2, e o plantio foi realizado manualmente. As avaliações foram realizadas em um período de 13 meses, determinando-se o número de plantas, a velocidade de brotação, a biomassa da parte aérea, o teor de açúcares totais recuperáveis e o rendimento. Nos quatro experimentos, os fungicidas foram pulverizados sobre as mudas imediatamente após o plantio, com pulverizador costal pressurizado com CO2. Os dados das avaliações foram submetidos à análise de variância e à análise de contrastes ortogonais. Além disso, os tratamentos foram comparados com a testemunha através do Teste de Dunnett a 5% de significância. Os resultados mostraram que a pulverização de fungicidas nas mudas controlou a podridão abacaxi da cana-de-açúcar, sendo que os efeitos dessa prática foram mais positivos em condições mais favoráveis à manifestação da doença. Os fungicidas Azoxistrobina + Ciproconazol; Azoxistrobina + Fluodioxonil + Metalaxil- M; Propiconazol; Piraclostrobina e Piraclostrobina + Epoxiconazol foram eficientes no controle da podridão abacaxi da cana-de-açúcar. Por outro lado, Carboxina + Tiram, comercialmente utilizado com essa finalidade, não foi efetivo em controlar a doença, tanto em casa de vegetação como no campo. / In the last few years, mechanized planting of sugarcane has been frequently used in Brazil. This system has a lower cost than the conventional system and enables planting throughout the year. However, the higher quantity of injuries in seedpieces harvested mechanically and the planting at low temperatures and with inadequate soil humidity have increased the incidence of pineapple disease, caused by the fungus Thielaviopsis paradoxa. Areas where this disease is problematic present stand reduction, requiring, in some cases, replanting. Thielaviopsis paradoxa penetrates the seedpieces through wounds caused due to stalk sectioning during planting. Measures which increase shoot emergence or which protect seedpieces wounds produce excellent results in the disease control. In order to assess control of pineapple disease of sugarcane through in-furrow fungicide spray application on seedpieces, four experiments were installed, two in greenhouse and two under field conditions. For the experiments in the greenhouse, substrate consisting of a mixture of soil, sand and cattle manure was used. Suspension of T. paradoxa at the concentration of 103 spores/g of substrate was incorporated two days before planting. Evaluations were done in a period of 45 days assessing number of shoots, germination speed, biomass of shoots and roots, and disease severity. In the field, one of the experiments was performed with no inoculation of the pathogen, and the seedpieces harvesting and planting were mechanized. For the other experiment, a suspension of T. paradoxa spores at the concentration of 9 x 104 spores/m2 was sprayed in the plots and the planting was performed manually. Evaluations were done in a period of 13 months assessing number of shoots, germination speed, biomass of shoots, total recoverable sugar content and yield. In the four experiments, fungicides were sprayed on seedpieces immediately after the planting with a CO2 pressurized sprayer. Data were submitted to analysis of variance and to analysis of orthogonal contrasts. Moreover, treatments were compared to control by Dunnett´s Test at 5% of significance. Results showed that in-furrow spray application on seedpieces controlled pineapple disease of sugarcane, and the effects of this practice were more positive under more favorable conditions for the disease manifestation. The fungicides Azoxystrobin + Cyproconazole; Azoxystrobin + Fluodioxonil + Metalaxyl-M; Propiconazole; Pyraclostrobin and Pyraclostrobin + Epoxiconazole were efficient for controlling pineapple disease of sugarcane. On the other hand, Carboxin + Thiram, commercially used for this purpose, was neither effective in the greenhouse nor in the field to control the disease.

O presente trabalho tem por objetivo monitorar o agrotóxico Mancozeb no solo em diferentes sistemas de plantios de tomate utilizando a metodologia de decomposição dos ditiocarbamatos (DTCs) com geração de dissulfeto de carbono (CS2). Este método é amplamente utilizado na determinação dos resíduos de DTCs em alimentos, tendo sido adaptado para trabalhar com amostras de solo artificiais e reais. O método foi avaliado utilizando amostras contaminadas artificialmente a partir de uma amostra de solo controle, proveniente da Amazônia. A contaminação foi realizada com uma solução de campo (2 g.L-1 em água) do agrotóxico Manzate 800 (Mancozeb). A partir do momento em que foram determinadas as condições ideais de operação do método de decomposição dos DTCs, analisou-se o teor de Mancozeb em amostras reais, provenientes de uma área cultivada com tomate, no Município de São José de Ubá (RJ), sob sistemas de Plantios Convencional, Mínimo e Direto. Foi possível constatar a presença de teores de Mancozeb nas amostras reais de solo em estudo, coletadas nas profundidades 0 - 5 cm; 5 - 10 cm; 10 - 20 cm e 20 - 40 cm. Os resultados mostraram que os solos provenientes dos sistemas convencional e mínimo apresentaram, na camada superficial, um teor de Mancozeb de (7,44 mg.kg-1 e 5,70 mg.kg-1) superior ao obtido no sistema direto, que apresentou teores de (1,14 mg.kg-1 e 1,95 mg.kg-1) de Mancozeb / The present work aims to evaluate Mancozeb pesticide monitoring on the ground in different systems of tomato seeding using the methodology of decomposition of dithiocarbamates (DTCs) with carbon disulfide (CS2) generation. This method is widely used to determinate DTCs residues in foods and it was adapted to work with artificial and real soil samples. The method was evaluated using artificially contaminated samples from a control soil sample proceeding from Amazônia. The contamination was carried out with a field solution (2 g.L-1 in water) of Manzate 800 (Mancozeb). From the moment the operational conditions of decomposition method of the DTCs were determined, the content of Mancozeb was analyzed in real samples proceeding from an area cultivated with tomato, in São Jose de Ubá city (Rio de Janeiro), under Conventional, Minimum and Direct systems of seeding. It was possible to evidence Mancozeb content in the real samples collected in 0 - 5 cm; 5 -10 cm; 10 - 20 cm and 20 - 40 cm depths. The results showed the soil samples proceeding from conventional and minimum systems (7.44 mg.kg-1 e 5.70 mg.kg-1) seeding presented Mancozeb content on the ground surface in higher level than the one obtained in direct system (1.14 mg.kg-1 e 1.95 mg.kg-1)

A requeima, causada pelo oomiceto Phytophthora infestans e a pinta preta, causada pelo fungo Alternaria solani, estão entre as doenças mais importantes e destrutivas da cultura da batata no Brasil e no mundo. Considerando a importância do controle químico em sistemas integrados e a necessidade de se conhecer detalhadamente o desempenho de fungicidas e indutores de resistência visando à sustentabilidade da produção, o presente estudo objetivou caracterizar e comparar a ação preventiva, residual, curativa, anti-esporulante e resistência à chuva de fungicidas em condições controladas, bem como, avaliar em campo o potencial de controle de fungicidas e indutores de resistência e seus reflexos sobre a produtividade total e comercial de tubérculos. Todos os fungicidas promoveram elevada ação preventiva contra a requeima e a pinta preta. Os fungicidas sistêmicos ou com alta tenacidade proporcionaram controle das duas doenças até os 12 DAP, enquanto que os fungicidas translaminares até os 9 DAP. Quanto à ação curativa e anti-esporulante destacaram-se principalmente os fungicidas sistêmicos aplicados até as 24 horas após a inoculação (HAI). Os fungicidas translaminares foram capazes de inibir a requeima quando aplicados até 12 HAI e os de contato destacaram-se apenas para ação preventiva. Semelhantemente, os fungicidas sistêmicos, translaminares ou com alta tenacidade foram os menos afetados pela chuva simulada. O aumento do tempo de secagem promoveu uma maior retenção ou absorção dos produtos reduzindo o impacto negativo da precipitação. Os melhores níveis de controle, produtividade e qualidade de tubérculos foram obtidos com os fungicidas mandipropamida+clorotalonil, fluopicolida+propamocarbe, dimetomorfe+ametoctradina, mandipropamida, fenamidona+propamocarbe, bentiavalicarbe+ fluazinam, seguidos de dimetomorfe+clorotalonil mefenoxam+clorotalonil e famoxadona+ cimoxanil+mancozebe para requeima e azoxistrobina+difenoconazol, picoxistrobina, piraclostrobina+metconazol, trifloxistrobina+tebuconazol, azoxistrobina, boscalida+ piraclostrobina, iprodiona+pirimetanil e ciprodinil para pinta preta. Acibenzolar-s-metílico (ASM) reduziu a severidade da requeima e da pinta preta, porém, promoveu aumento da produtividade, apenas no campo de requeima. O fosfito de potássio (FP) também reduziu a severidade da requeima, no entanto, não influenciou na produtividade. Com exceção de mandipropamida, a adição de ASM à mefenoxam+mancozebe, cimoxanil+mancozebe e mancozebe promoveu aumento do controle da requeima, no entanto, apenas quando em mistura com mancozebe proporcionou aumento na produtividade. A adição de FP à mandipropamida, mefenoxam+mancozebe, cimoxanil+mancozebe, mancozebe e de ASM à azoxistrobina e difenoconazol não refletiu no controle da requeima, da pinta preta e na produtividade, respectivamente. Mancozebe e ASM não diferiram quanto severidade, progresso da pinta preta e produtividade, porém mancozebe+ASM foi superior ao ASM. A adição de ASM a programas de aplicação reduziu a requeima e a pinta preta e incrementou a produtividade apenas quando adicionados a programas onde prevaleceram fungicidas translaminares e de contato. O FP não influenciou nenhum dos programas testados para requeima. / Late blight, caused by the oomycete Phytophthora infestans and early blight, caused by the fungus Alternaria solani, are among the most destructive diseases of potato crops in Brazil and worldwide. Considering the importance of the chemical control on integrated systems and the need for detailed knowledge of the performance of resistance inducers and fungicides targeting the sustainability of production, the present study aimed to:1- characterize and compare the preemptive, residual, curative, antisporulative action and rain resistance of fungicides under controlled conditions; 2-: evaluate, under field conditions, the control potential of fungicides and resistance inductors and their effects on the total and commercial yield of potato tubers. All fungicides tested provided a high pre-emptive action against late and early blight. The systemic fungicides or high tenacity ones provided control of both diseases until 12 days after application, while translaminar ones until 9 days after application. As for the curative and anti-sporulative action, the systemic fungicides stand out when applied until 24 hours postinoculation, while the translaminar ones inhibited late blight when applied until 12 hours postinoculation. The contact fungicides stand out concerning pre-emptive action only. Similarly, systemic, translaminar and high tenacity fungicides were less affected by the simulated rain. An increase in drying time promoted higher retention and absorption of the products, so decreasing the negative precipitation impact. The better levels of control, yield and tubers quality were reached with the use of the following fungicides in the control of late blight: mandipropamid+chlorothalonil, fluopicolide+propamocarb, dimetomorph+ametoctradin, mandipropamid, fenamidone+ propamocarb, bentiavalicarb+fluazinam, followed by dimetomorph+chlorothalonil, mefenoxam+ chlorothalonil and famoxadone+cymoxanil+mancozeb. In the control of early blight the most efficient were: azoxystrobin+difenoconazole, pycoxystrobin, pyraclostrobin+metconazole, trifloxystrobin+tebuconazole, azoxystrobin, boscalid+pyraclostrobin, iprodione+pyrimethanil and cyprodinil. Acibenzolar-s-methyl (ASM) reduced the severity of late and early blight, but promoted an increase in the tuber yield only in late blight affected field. Potassium phosphite (Pp) also reduced the severity of late blight, although it did not have influenced the yield. Except for mandipropamid, the addition of ASM to mefenoxam+mancozebe, cymoxanil+mancozeb or mancozeb led to a better control of late blight, but only when mixed with mancozeb it promoted increase in the yield. Addition of Pp to mandipropamid, mefenoxam+mancozeb, cymoxanil+mancozeb, mancozeb and ASM to azoxystrobin, difenoconazole did not result either in the control of late and early blight or in an increase of yield. Mancozeb and ASM did not differ as for severity, progress of late blight and increasing yield, but however, mancozeb+ASM had a superior efficiency than ASM. Addition of ASM to application programs reduced late and early blight and increased yield only when added to programs in which prevailed translaminar and contact fungicides. Pp did not influenced any of the tested programs against late blight.

Quando os fungicidas sistêmicos ou com ação de profundidade passaram a ser adotados como parte dos programas comerciais de manejo de doenças de plantas, duas coisas aconteceram: o controle obtido passou a ser maior, porque estes fungicidas possuem maior período de controle residual e porque têm algum poder curativo, e passou-se a observar e relatar efeitos secundários, fisiológicos destes produtos sobre as plantas tratadas. Com efeito, muitos artigos disponíveis hoje na literatura descrevem diferentes efeitos fisiológicos provenientes da aplicação de fungicidas em várias plantas cultivadas. A maior parte destes trabalhos foi conduzida sob condições de uso relativamente intenso dos fungicidas, tais como aplicações seqüenciais, ou uso em plantas em vaso em casas de vegetação. Poucos deles trazem informação clara sobre a intensidade das doenças ocorrentes, tampouco sobre o controle oferecido pelos produtos utilizados. Sob este aspecto, não é fácil estabelecer de forma confiável qual a real importância destes efeitos fisiológicos no manejo comercial das doenças das plantas cultivadas. Mas existe farto material promocional disponível proclamando os benefícios provenientes dos efeitos fisiológicos de alguns fungicidas. O objetivo dos trabalhos desta dissertação foi quantificar o máximo de efeitos secundários oriundos da aplicação a campo (em condição mais próxima possível do uso comercial) de diferentes fungicidas, sistêmicos e não sistêmicos, à cultura do feijoeiro, separando aqueles que podem ser explicados devido ao controle diferenciado das doenças daqueles que somente podem ser explicados pelo efeito fisiológico dos fungicidas. Os resultados mostraram que diferentes efeitos significativos (mudanças na taxa de fotossíntese, condutividade estomática, retenção foliar e produção) puderam ser detectados nas plantas provenientes das parcelas tratadas com fungicidas, mas todos eles podem ser bem explicados pelo controle diferenciado das doenças oferecido pelos produtos testados. Conclui-se que apesar de extensivamente testados e comprovados, os efeitos fisiológicos promovidos por alguns fungicidas não podem ser considerados fatores fundamentais para seleção dos produtos a serem utilizados para o manejo das doenças na cultura do feijoeiro, mas sim a sua capacidade intrínseca de controlar os patógenos que ameaçam esta cultura. / When systemic fungicides were incorporated to plant disease management strategies, two things started to happen: there was an increase in efficacy of diseases control, because these fungicides have longer lasting effect and some curative power, and some physiological effects caused by these fungicides started being related. Actually, many articles describe and measure physiologic effects caused by different fungicides in many plants. Most of these studies are carried out under very intensive conditions such as potted plants in greenhouses. Only few of them give clear information on disease severity in field trials, or disease control achieved by the fungicides. It is not easy to understand how important these physiologic effects are when selecting fungicides to be used in programs for disease management. But there is a lot of promotion material claiming that different fungicides promote physiologic effects that can benefit many crops, offering it as a factor to be taken into account when selecting products to be used in disease management programs. The objective of this work was to quantify as many changes as possible in the dry beans crop after the field use (as closest as possible to commercial conditions) of different fungicides, systemic and not systemic, separating those changes that could come from disease control from those that could only come from physiological effects. Results showed that under field conditions, some significant changes (photosynthesis, stomatal conductance, leaf retention, yield) were measured in the crop, but all of them could be well explained by the disease control given by the fungicides. Conclusion is that the capacity to induce physiologic effects on plants should not be considered as a critical factor to select a fungicide to be used in disease management programs by dry beans growers. For this purpose, the main driver should be the efficacy of the fungicide to control the most important diseases threatening that crop.

Research objective and experimental tasks. The study was designed to explore the incidence and severity of root and foot rots and ascochyta blight in field pea crops and to identify the measures and practices for the prevention and control of the diseases caused by the pathogens of Ascochyta complex. Experimental tasks: - To identify the susceptibility of various field pea varieties to root and foot rots and ascochyta blight under different agro-ecological conditions. - To establish the effect of meteorological factors on the severity of root and foot rots and ascochyta blight in field pea crops. - To determine the frequency of detection of pathogens of Ascochyta complex on various pea varieties. - To estimate the feasibility of control of the diseases caused by the pathogens of Ascochyta complex using seed treatment and fungicide application. - To assess the impact of seed treatment and fungicide application on field pea productivity and yield components. - To study the possible side-effect of the chemical seed treatment on the microflora of pea rhizosphere and soil. / Tyrimų tikslas ir uždaviniai. Tyrimais siekta ištirti šaknų, pašaknio puvinių ir askochitozės išplitimą bei žalingumą sėjamojo žirnio pasėliuose, nustatyti Ascochyta komplekso patogenų sukeliamų ligų prevencijos ir kontrolės priemones. Tyrimų uždaviniai: - Nustatyti įvairių sėjamojo žirnio veislių jautrumą šaknų, pašaknio puviniams ir askochitozei skirtingomis agroekologinėmis sąlygomis. - Nustatyti meteorologinių faktorių įtaką šaknų, pašaknio puvinių ir askochitozės intensyvumui žirniuose. - Nustatyti Ascochyta komplekso patogenų aptikimo dažnį ant įvairių veislių žirnių. - Įvertinti Ascochyta komplekso patogenų sukeliamų ligų kontrolės galimybę naudojant beicus ir fungicidus. - Įvertinti beicų ir fungicidų įtaką žirnių derlingumui ir derliaus komponentams. - Ištirti galimą cheminių beicų šalutinį poveikį žirnių rizosferos bei dirvožemio mikroflorai.