Propamocarb Hydrochloride Research Articles

Analysis of pesticide residues in melon using QuEChERS extraction and liquid chromatography triple quadrupole mass spectrometry

A rapid, precise and efficient method for the determination of seven insecticides (chlorpyrifos, dimethoate, deltamethrin, thiamethoxam, thiacloprid, pirimicarb and indoxacarb) and three fungicides (azoxystrobin, fluopicolide and propamocarb hydrochloride) in melon by employing quick, easy, cheap, effective, rugged and safe extraction method coupled with liquid chromatography triple quadrupole mass spectrometry was developed and validated by evaluating the accuracy, precision, linearity, limit of detection (LOD) and limit of quantification (LOQ). The average recoveries of the selected pesticides ranged from 82% to 106% with RSDr ≤6% in four fortification levels of 0.01, 0.05, 0.1 and 0.2 mg/kg. The correlation coefficient (R2) was ≥0.997 for all the selected pesticides when matrix-matched calibration standards were used. The LOD values ranged from 0.001 to 0.003 mg/kg, and the LOQ was determined at 0.01 mg/kg for all the analytes. Matrix effect was evaluated, and it was found considerable for thiamethoxam and deltamethrin (−53% and +135%, respectively). Finally, this method was applied for the residue analysis of 122 fresh melon samples collected from different market places in Thessaloniki, Greece. Among the 122 analysed samples, 32 (26% of the total no. of samples) were found to have pesticide residues. None of the samples contained residues above the European Union-Maximum Residue Levels. The most frequently detected pesticides were fluopicolide and thiamethoxam.

Evaluation of Fungicides for the Control of Peronospora belbahrii on Sweet Basil in New Jersey.

Basil downy mildew (BDM), caused by the fungus-like oomycete pathogen Peronospora belbahrii, has become a destructive disease of sweet basil (Ocimum basilicum). Without proper management, BDM can cause complete crop loss. Currently, there are no commercially available sweet basil cultivars with genetic resistance to BDM. Because BDM is a relatively new disease of basil in the United States, there are few currently registered conventional or organic fungicides labeled for its control. Fungicide efficacy trials were conducted in 2010 and 2011 at Rutgers Agricultural Research and Extension Center in Bridgeton, NJ. During both years, seven biological fungicide treatments were field evaluated, including hydrogen dioxide; extract of Reynoutria sachalinensis; Bacillus pumilus strain QST 2808; a mixture of rosemary oil, clove oil, and thyme oil; mono- and dipotassium salts of phosphorous acid; sesame oil; copper hydroxide; and a combination of sesame oil + cupric hydroxide. Six conventional fungicides evaluated included mandipropamid, fluopicolide, propamocarb hydrochloride, cyazofamid, azoxystrobin, and fenamidone. In both years, mono- and dipotassium salts of phosphorous acid provided the best control. Moderate disease suppression was provided by mandipropamid, cyazofamid, and fluopicolide compared with the control in 2010 and mandipropamid, cyazofamid, and copper hydroxide compared with the control in 2011.

Potencialidade de fungicidas biológicos no controle de requeima do tomateiro

O objetivo deste trabalho foi comparar o efeito da aplicação de fungicidas com agente biológico como alternativa do controle de requeima em tomateiro híbrido Silvety. O experimento foi conduzido em campo entre 2011 e 2012 na área experimental da Universidade Estadual do Sudoeste da Bahia, Vitória da Conquista-BA. Empregou-se o delineamento em blocos casualizados com cinco tratamentos, quatro repetições e unidade experimental constituída por 12 plantas. Os tratamentos (T) foram: T1) testemunha não pulverizada; T2) Trichoderma harzianum (2x108 conídios/mL); T3) Trichoderma longibrachiatum (2x108 conídios/mL); T4) metalaxyl-M + mancozeb (204 g/100L i.a/ha); T5) cloridrato de propamocarbe + fluopicolide (1000 g i.a/ha) e T6) dimetamorfe (75 g/100L i.a/ha), aplicados de forma preventiva aos 35, 42, 49 e 56 DAT (dias após o transplante). Avaliou-se a severidade da doença, a produtividade e seus componentes (número de frutos por planta, massa média dos frutos, produção). Os resultados da severidade foram utilizados para calcular a área abaixo da curva do progresso da requeima (AACPR). Para a comparação das médias, realizou-se a análise de variância e teste Tukey a 5% de probabilidade. Os fungicidas químicos promoveram maior proteção contra a requeima do tomateiro. Com cloridrato de propamocarbe + fluopicolide e metalaxyl-M + mancozeb foram obtidas as menores porcentagens de área foliar atacada pela requeima, de 2,6 e 4,36%, respectivamente, conforme avaliação aos 65 DAT. Os isolados Trichobio01 e Trichonemate01 apresentaram eficiência protetora contra a requeima até o 58º DAT. Propamocarbe + fluopicolide demonstrou eficiência no controle de requeima, apresentando a menor AACPR com 31,50 e um incremento médio de 47% na produtividade.

Assessment of Pesticide Residues in Karaboğaz Lake from Kızılırmak Delta, Turkey

Monitoring of pesticide residues in water and sediments was conducted for the coastal shallow Karaboğaz Lake, northern Turkey. During a one-year study period, eight pesticides (malathion, etofenprox, molinate, oxamyl, propamocarb hydrochloride, tebufenozide, linuron, piperonyl butoxide) were detected in water and in sediments, all at μg/L and μg/kg concentrations, respectively. Temporal variation in pesticide concentrations was observed. Highest pesticide concentrations in water and sediment were from tebufenozide and etofenprox, respectively. Aquatic risk assessments revealed that out of eight pesticides detected, three showed unaccaptable risk: malathion, oxamyl and etofenprox.

Pesticide Flow Analysis to Assess Human Exposure in Greenhouse Flower Production in Colombia

Human exposure assessment tools represent a means for understanding human exposure to pesticides in agricultural activities and managing possible health risks. This paper presents a pesticide flow analysis modeling approach developed to assess human exposure to pesticide use in greenhouse flower crops in Colombia, focusing on dermal and inhalation exposure. This approach is based on the material flow analysis methodology. The transfer coefficients were obtained using the whole body dosimetry method for dermal exposure and the button personal inhalable aerosol sampler for inhalation exposure, using the tracer uranine as a pesticide surrogate. The case study was a greenhouse rose farm in the Bogota Plateau in Colombia. The approach was applied to estimate the exposure to pesticides such as mancozeb, carbendazim, propamocarb hydrochloride, fosetyl, carboxin, thiram, dimethomorph and mandipropamide. We found dermal absorption estimations close to the AOEL reference values for the pesticides carbendazim, mancozeb, thiram and mandipropamide during the study period. In addition, high values of dermal exposure were found on the forearms, hands, chest and legs of study participants, indicating weaknesses in the overlapping areas of the personal protective equipment parts. These results show how the material flow analysis methodology can be applied in the field of human exposure for early recognition of the dispersion of pesticides and support the development of measures to improve operational safety during pesticide management. Furthermore, the model makes it possible to identify the status quo of the health risk faced by workers in the study area.

Chemical control of root rot complex and stem rot of greenhouse cucumber in straw-bale culture

Experiments were conducted in three different commercial greenhouses wherein cucumber (Cucumis sativus L.) cv. Kalunga F1 (Long English type) were grown in composted straw bales, heavily infested with Fusarium oxysporum Schlechtend.:Fr. f.sp. radicis-cucumerinum Vakalounakis (FORC), the causal agent of Fusarium root and stem rot of cucumber. FORC was isolated from roots and stem bases of symptomatic plants either in single infections or simultaneously with other root infecting pathogens, including species of Phytophthora and Pythium and Rhizoctonia solani Kühn AG-4. Verticillium dahliae Kleb. was obtained from individual cucumber plants showing wilt symptoms. Fungicide applications started at the beginning of fruiting time when the first symptomatic plants occurred and followed at 45-day intervals. Three fungicides, either alone or as tank-mixed combinations of 0.1% Topsin M 70WP (thiophanate-methyl 700 g kg−1) plus 0.15% Previcur 607SL (607 g L−1 propamocarb hydrochloride), or 0.1% Benomyl 50WP (benomyl 50 g kg−1) plus 0.15% Previcur 607SL, were applied to the crown and root area of cucumber plants through drip irrigation systems as drenches at a rate of 0.25 L/plant. Plant mortality was reduced by 11.1%–84.8% and 23.8%–77.7% when plants were drenched with Topsin M 70WP in combination with Previcur 607SL or Benomyl 50WP plus Previcur 607SL, respectively. In comparison, significantly lower levels of disease control were achieved when these fungicides were applied individually. Three fungicide applications during the crop season increased the inhibitory effect of the fungicide regime on the disease incidence compared to one or two treatment.

Fungicide Efficacy in Prevention of Root Rot Incited by Phytophthora cactorum and Phytophthora drechsleri in Fraser Fir Seedlings

The most serious disease problem in fraser fir (Abies fraseri) Christmas tree production is phytophthora root rot (PRR). The efficacies of six fungicide treatments in preventing PRR incited by Phytophthora cactorum and P. drechsleri in 2-year-old fraser fir seedlings were evaluated in 2010 and 2011 in central Pennsylvania. The study examined five fungicide drench treatments [dimethomorph, fosetyl-aluminum (fosetyl-Al), hydrogen dioxide, mefenoxam, propamocarb hydrochloride] and one soil spray treatment (mefenoxam) in raised planting boxes. Dimethomorph applied on 14-day intervals prevented foliar disease symptoms and mortality in fraser fir seedlings exposed to either P. cactorum or P. drechsleri. One-time application of fosetyl-Al or mefenoxam were effective at times in preventing foliar disease symptoms and mortality in fraser fir seedlings exposed to P. drechsleri but were not as effective against P. cactorum.

Biodegradation of soil-applied pesticides by selected strains of plant growth-promoting rhizobacteria (PGPR) and their effects on bacterial growth

A laboratory study was conducted to investigate the influence of four PGPR strains on the degradation of five soil applied pesticides and their effects on bacterial growth. Interactions of Bacillus subtilis GB03, Bacillus subtilis FZB24, Bacillus amyloliquefaciens IN937a and Bacillus pumilus SE34 with two concentrations of acibenzolar-S-methyl, metribuzin, napropamide, propamocarb hydrochloride and thiamethoxam in liquid culture and soil microcosm were studied. The degradation of acibenzolar-S-methyl by all PGPR tested in low and high concentration, was 5.4 and 5.7 times, respectively, faster than that in non-inoculated liquid culture medium. At the end of the 72-h liquid cultured experiments, 8-18, 9-11, 15-36 and 11-22% of metribuzin, napropamide, propamocarb hydrochloride and thiamethoxam, respectively, had disappeared from PGPR inoculated medium. Under the soil microcosm experimental conditions, the half-lives of acibenzolar-S-methyl incubated in the presence of PGPR strains spiked at 1.0 and 10.0mgkg(-1) were 10.3-16.4 and 9.2-15.9days, respectively, markedly lower compared with >34.2days in the control. From the rest pesticides studied degradation of propamocarb hydrochloride and thiamethoxam was enhanced in the presence of B. amyloliquefaciens IN937a and B. pumilus SE34. Acibenzolar-S-methyl, propamocarb hydrochloride and thiamethoxam significantly increased the PGPR growth. However, the stimulatory effect was related to the level of pesticide spiked.

Dissipation of Fungicides, Insecticides, and Acaricide in Tomato Using HPLC-DAD and QuEChERS Methodology

Excessive use of pesticides in tomato cultivation could lead to impact on environment and health. Here, dissipation rate of six widely used pesticides in growing tomatoes, namely, chlorothalonil, pymetrozine, metalaxyl-m, metalaxyl, abamectin, and propamocarb hydrochloride, was evaluated. Tomato samples were collected within 2 weeks after pesticides application, and the pesticide residues extracted by an optimized QuEChERS method and quantified by high-performance liquid chromatography combined with diode array detection. The half-life of these pesticides was found to be 2.06, 1.65, 19.8, 4.88, 1.06, and 1.29 days for chlorothalonil, pymetrozine, metalaxyl-m, metalaxyl, abamectin, and propamocarb hydrochloride, respectively. Preharvest intervals (PHI) for these pesticides ranged from 3 to 9 days, with the longest being for metalaxyl (9 days), followed by chlorothalonil and abamectin (6 days). Pymetrozine metalaxyl-m, and propamocarb hydrochloride had PHIs of 3, 4, and 4 days, respectively. Due to the immediate consumption of the tomatoes after harvest, the persistence of metalaxyl, chlorothalonil, and abamectin in the environment is expected to have an adverse health effect.

Testing the effect of routine fungicide application on ectomycorrhiza formation on Pinus halepensis seedlings in a nursery

SummaryThe fungicides benomyl, captan, hymexazol, iprodione, propamocarb hydrochloride and thiram were applied in a combined schedule to Pinus halepensis seedlings grown under nursery conditions to study their effect on mycorrhiza formation and plant growth. The inoculated fungi Pisolithus tinctorius (strains 3SR and Mx) and Lactarius deliciosus formed mycorrhizas when fungicides were applied. However, fungicide application led to a significant decrease of mycorrhizal plants with Pisolithus tinctorius strain 3SR (from 62% without fungicides to 35% with fungicides). This effect could be attributed to a direct effect of fungicides on mycelial growth. The morphometric and nutritional parameters were very similar in plants treated with or without fungicides, and no differences on sanitary status of plants were noted. The use of preventive fungicide treatments in plant production, which may have a harmful effect on the environment, is therefore questioned.

Effects of Propamocarb Hydrochloride on Mycelial Growth, Sporulation, and Infection by Phytophthora nicotianae Isolates from Virginia Nurseries.

Propamocarb hydrochloride is a systemic fungicide commonly used for control of Phytophthora diseases of nursery crops. Here we report on the effect of this compound on different growth stages of Phytophthora nicotianae, a major pathogen of numerous herbaceous and some woody ornamental plants. A total of 71 isolates were assayed for sensitivity to propamocarb at two concentrations of 1.8 mg/ml (label rate) and 10 mg/ml using clarified V8 agar as a base medium. All isolates grew at 10 mg/ml with the most sensitive isolate having 34.8% relative growth compared with growth on nonamended medium. Nine isolates were selected and further tested for mycelial growth at 0, 1, 10, 25, 50, and 100 mg/ml, and for sporangium production, zoospore motility, and germination at 0, 5, 50, 500, 5,000, and 50,000 μg/ml. EC50 values ranged from 2.2 to 90.1 mg/ml for mycelial growth, 133.8 to 481.3 μg/ml for sporangium production, 88.1 to 249.8 μg/ml for zoospore motility, and 1.9 to 184.6 μg/ml for zoospore germination, respectively. In addition, 17 selected isolates were evaluated for propamocarb sensitivity on Pelargonium × hortorum cv. White Orbit. Two days after seedlings were treated with propamocarb at 3.6 mg/ml, they were inoculated by either inverting one 5-mm-diameter plug of a 3-day-old culture or applying a 10-μl drop containing 20 zoospores onto each cotyledon. Propamocarb hydrochloride provided good protection of geranium seedlings from zoospore infections but not from mycelial infections. These results suggest that this fungicide must be used preventively for Phytophthora disease management and that mycelial growth may not be the most reliable measurement to determine the development of fungicide resistance to this compound in Phytophthora species at production facilities and in the landscape.

Phenotypic and genetic variation in Finnish potato‐late blight populations, 1997–2000

This study was conducted on potato late blight samples collected for monitoring early attacks in Finland from 1997 to 2000. Most of the 1726 Phytophthora infestans isolates were collected soon after the onset of the epidemics. Most of the isolates were tested for mating type as well as metalaxyl and propamocarb hydrochloride (HCl) sensitivity, while virulence on potato R‐gene differentials and mitochondrial DNA (mtDNA) haplotype were determined for a subset of the isolates. In half of the fields from which more than one isolate was tested, both mating types were detected, indicating strong potential for sexual reproduction. The mating types coexisted more often in organic fields or gardens than in conventional fields. The proportion of A1 mating type decreased from approximately 80% (1997 and 1998) to 22% by the year 2000. Simultaneously, the proportion of isolates resistant to metalaxyl decreased from approximately 40% to 16%. Resistance to metalaxyl was confined to the IIa mtDNA haplotype and clearly associated with the A1 mating type, as resistance was 10 times more common among A1 isolates than among A2 isolates. Resistance to metalaxyl therefore probably derives from common descent from an isolate with the IIa haplotype. Most of the regional variation in metalaxyl sensitivity was also linked to mating type, as both metalaxyl resistance and the A1 mating type were most common in the north and south‐west of Finland. In contrast to metalaxyl, only three propamocarb‐HCl‐insensitive isolates were found, but propamocarb‐HCl sensitivity decreased significantly during the study.

Selection for Fungicide Resistance Within a Growing Season in Field Populations of Phytophthora infestans at the Center of Origin

ABSTRACT The central highlands of Mexico should provide an optimal testing ground for evaluating the potential threat of selection for resistance to fungicides in the population of Phytophthora infestans. We evaluated the hypotheses that exposure to the fungicides azoxystrobin, cymoxanil, dimethomorph, fluazinam, mancozeb, metalaxyl, and propamocarb hydrochloride would lead to (i) a shift in the sensitivity distributions (i.e., selection) and (ii) a lower genotypic diversity of the population. We compared populations from unsprayed plots with populations that had been exposed to several applications of each of the fungicides within a single field season. This study provides novel baseline data and shows that the Toluca valley P. infestans population has a wide range of sensitivities to the fungicides fluazinam, cymoxanil, dimethomorph, metalaxyl, and propamocarb. Directional selection toward resistance combined with a reduction in genetic diversity of the P. infestans population was observed only for the fungicide metalaxyl. The results obtained provide direct experimental support for continuing vigilance regarding further introductions of exotic strains of P. infestans into the United States.

Deposition and redistribution of fungicides applied by air and chemigation for control of late blight in commercial potato fields

The fungicides metiram, mancozeb, metiram + triphenyltin hydroxide, propamocarb hydrochloride + chlorothalonil, dimethomorph + mancozeb, cymoxanil + mancozeb, and chlorothalonil were applied by aircraft and through center-pivot irrigation systems (chemigation) to replicated plots in commercial fields of ‘Russet Burbank’ potato. Fungicide deposition and redistribution were indirectly determined by inoculation of excised leaves withPhytophthora infestans and directly by chlorothalonil residue analysis from upper, middle, and lower crop canopies. The effectiveness of two surfactants added with fungicide and applied by aircraft, an increased water volume rate used by aircraft, and a reduced water volume used with chemigation was also determined. The addition of synthetic latex and siliconepolyether surfactants did not increase efficacy of metiram or mancozeb in controlling late blight when applied by aircraft. The protectant fungicides metiram, mancozeb, and chlorothalonil were not significantly different from dimethomorph + mancozeb, cymoxanil + mancozeb, and propamocarb hydrochloride + chlorothalonil in late blight control when applied by aircraft. However, cymoxanil + mancozeb had limited efficacy when applied by chemigation. Fungicide deposition through the canopy differed when air applications were made before or after canopy closure (row closure). Fungicides applied by aircraft prior to row closure protected the entire canopy; whereas, fungicide application after row closure initially protected the top and middle canopies, and subsequent applications and redistribution of the fungicides were needed for adequate protection throughout the canopy. The fungicides and fungicide mixtures tested were evenly deposited throughout the potato canopy with each chemigation application. Severity of late blight did not differ on leaves treated with mancozeb or chlorothalonil applied by aircraft at water volumes of 47 L/ha and 94 I/ha and then inoculated withP. infestans, nor did severity of late blight differ on inoculated leaves previously treated with chlorothalonil by chemigation at water volumes of 15,145 and 50, 571 L/ha.

Determination of residues of propamocarb in wine by liquid chromatography-electrospray mass spectrometry with direct injection

A simple, sensitive and reliable liquid chromatography-mass spectrometry method with direct injection of diluted samples is reported for the determination of propamocarb residues in wine. Red and white wines were diluted 40- and 20-fold, respectively, using water. Liquid chromatography was performed with a mobile-phase gradient and detection was by electrospray mass spectrometry in a positive ionization mode. Propamocarb was detected as the protonated molecular species at m/z 189. Using matrix-matched calibrant solutions, a calibrated range equivalent to 0.05–2.0 mg kg−1 in red and white wines and limits of detection of 0.025 mg kg−1 for white wine and of 0.05 mg kg−1 for red wine (0.00125 μg ml−1 of sample solution injected) were readily achievable. Recovery of propamocarb hydrochloride from wine spiked before dilution was in the range 91–115%. The chromatograms were free of isobaric interferences. In a small wine survey (72 samples), no residues of propamocarb were detected above 0.1 mg kg−1.

Metalaxyl 저항성 담배역병균(Phytophthora nicotianae) 방제를 위한 약제 선발

우리 나라 농가에서 담배역병 방제약제로 사용되고 있는 Metalaxyl의 약제 저항성균 발생억제 및 방제를 위한 대체 약제를 선발하기 위하여 시중에서 판매되고 있는 역병방제용 약제 중 Dimethomorph를 비롯한 5종의 약제를 구입하여 시험하였다. 실내 시험에서는 Propamocarb hydrochloride는 Metalaxyl과 유사한 반응을 보여 서로 교차저항성이 있는 것으로 조사되었으며 Oxadixyl + Mancozeb, Dimethomorph + Mancozeb 등이 실내시험 및 포장시험 결과 약효가 우수하여 Metalaxyl 대체약제로 선발되었다. Five commercial chemicals, Dimethomorph, Foseyl-Al, Oxadixyl + Mancozeb, Propamocarb hydrochloride, and Metalaxyl, were tested for control of tobacco black shank (Phytophthora nicotianae) and/or delaying buildup of the resistant population to Metalaxyl which has been used for control of the disease in Korean tobacco farms. Propamocarb hydrochloride seemed to have a cross-resistance to the Metalaxyl resistant isolates showing similar response with Metalaxyl in vitro. Meanwhile, Dimethomorph+Mancozeb and Oxadixyl+Mancozeb were selected to be the promising chemicals which are able to be alternative to Metalaxyl for the black shank control in accordance with in vitro and in field trial.

Distribution and pathogenic peculiarities of fungi of the Alternaria genus on vegetable crops in Lithuania

In 1999–2001 the investigation of Alternaria species on vegetable crops: cabbage, cucumber, tomato and carrot was carried out and fungi species were isolated from vegetables and substrata used for plant cultivation. Isolated micromycetes: Alternaria alternata, Alternaria tenuissima, Alternaria brassicae, Alternaria brassicicola, Alternaria cucurbitae, Alternaria dauci, Alternaria radicina and Alternaria solani differed in pathogenic peculiarities, frequency of occurrence and their various reaction to fungicides (a.s. azoxystrobin, dichlofluanid, Cooper hydroxide, mancozeb, propamocarb hydrochloride), plant activator Bion (benzothadiazole) and antagonistic microorganisms (Trichoderma harzianum, Streptomyces griseoviridis).

The Roles of Three Fungicides in the Epidemiology of Potato Late Blight.

Three fungicides were tested in the field for efficacy on late blight caused by Phytophthora infestans. The effects of these fungicides on epidemic development, lesion growth rate and sporulation were measured. No fungicide completely arrested epidemic development under the environmental conditions of these experiments. However, the fungicide mixture, propamocarb hydrochloride plus chlorothalonil, had the most suppressive effect of the fungicides tested. The mechanism of effect included suppression of disease progress and lesion expansion. Growth chamber studies demonstrated that 24°C compared to 10 or 16°C limited cymoxanil efficacy.

Postinfection Activity of Selected Late Blight Fungicides.

Two sets of experiments were done in the greenhouse with 'Russet Burbank' potatoes infected with Phytophthora infestans. The first determined the effectiveness of selected late blight fungicides in restricting lesion length and spore production when applied after stem lesions had occurred on potted plants. The second quantified the curative activity of selected fungicides applied 12 to 48 h after inoculation of excised leaves with P. infestans. Such information may be beneficial in selecting an effective fungicide for late blight management when symptoms of the disease are present in a field. Expansion of established stem lesions was consistently restricted by one application of either dimethomorph plus mancozeb or metiram plus triphenyltin hydroxide. Sporulation on established stem lesions was consistently inhibited by either one application of dimethomorph plus mancozeb or cymoxanil plus mancozeb. Two applications of propamocarb hydrochloride plus chlorothalonil were required to restrict lesion expansion and inhibit sporulation. Size and number of lesions and sporulation on leaflets were reduced when propamocarb hydrochloride plus chlorothalonil was applied up to 48 h after inoculation.

Foliar Fungicides as Protective Seed Piece Treatments for Management of Late Blight of Potatoes.

Fungicides receiving Section 18 emergency exemptions for management of the foliar phase of late blight of potato were evaluated as protective treatments for control of tuberborne inoculum of Phytophthora infestans in greenhouse and field studies. Three Section 18 products, Acrobat MZ (dimethomorph + mancozeb), Curzate M-8 (cymoxanil + mancozeb), and Tattoo C (propamocarb hydrochloride + chlorothalonil), when applied to the seed piece prior to inoculation with P. infestans, significantly (P ≤ 0.05) increased sprout emergence, compared with the inoculated water control. Of the three Section 18 products, Curzate M-8 was frequently the most effective. The increase in plant emergence with the protective seed piece treatment was seen with cultivars that differ in susceptibility to late blight, two genotypes (US-8 and US-11) of P. infestans, zoospore and sporangial inocula, and at different inoculation sites on the seed piece. In greenhouse studies, percent emergence with the protective seed piece treatments averaged 74% for cv. White Rose and 44% for cv. Shepody, compared with 9 and 8% for the inoculated water control of the respective cultivars. In field studies, when inoculum was placed either adjacent to or 4 cm away from the sprout, plant emergence of the inoculated water control was 12 and 36%, respectively. Application of the fungicides to the seed piece prior to inoculation increased emergence by an average of 700 and 212% for the respective inoculation sites. There was no evidence for translocation of the fungicides to the emerging foliage in concentrations high enough to prevent foliar infection from airborne inoculum of P. infestans. Control of tuberborne inoculum of P. infestans with appropriate seed piece treatments will result in an increase in plant emergence and improved crop uniformity.