Application Of Iprodione Research Articles

Effects of Peganum harmala extracts and synthetic chemical fungicides on controlling early blight of tomato in the central shaanxi plain of China

Peganum harmala, also known as wild rue, is a perennial herbaceous plant that occurs in semi-arid parts of Asia, the coastal Mediterranean region, Mexico, and the southern United States. Extracts from P. harmala are toxic to aphids and mites, and also possess antifungal activity. P. harmala extracts and four systemic commercial fungicides were initially investigated for their in vitro toxicity to Alternaria solani, the fungal pathogen of early blight of tomato. The P. harmala extracts inhibited mycelial growth and conidial germination of A. solani, but inhibition was less than for the commercial fungicides prothioconazole and iprodione. Tests in a commercial greenhouse near Jingyang County, Shaanxi Province, China, during 2020, 2021, and 2022 compared efficacy of P. harmala, alone and in combination with commercial fungicides, for suppression of early blight on tomato cv. Provence. Three applications of iprodione or prothioconazole at 7- to 10-day intervals resulted in <10% incidence of foliar symptoms on naturally inoculated plants. When a spray of P. harmala extract + prothioconazole was followed at 15-day intervals by P. harmala extract + iprodione and P. harmala extract alone incidence of foliar symptoms remained <10%. These results indicate that alternating tank mixes of prothioconazole or iprodione with P. harmala, followed by the extract alone, can extend the interval between sprays by 7–10 days and reduce dependency on synthetic chemical pesticides for control of early blight in greenhouse-grown tomatoes.

Potential the biological or chemical control of lettuce white rot and maintain productivity

The experiments were executed on the autumn and the winter of (2016 /2017, 2017/2018) seasons at Qalyub area, EL-Qalyubia governorate, Egypt. The main objective for this study to find out the efficacy of several biological and the chemical controls on growth and productivity of lettuce crop and management on white rot disease caused on Sclerotinia sclerotiorum. Thus, four treatments were applied as follow 1- the control (water application),2- Trichoderma asperellum, 3-Salicylic acid and 4- Calcium Chloride, which were evaluated and compared for the three fungicide as follow : 1- Iprodione , 2- Tebuconazole with Fluopyram and 3-Tebuconazole at the doses (85 & 100 ; 200 &100 and 50 &100 g or ml / 100L-1 respect.) . Which they tested for their ability for increasing the lettuce crop productivity and suppress mycelial growth of S. sclerotiorum pathogen by treatments were sprayed on two times on plants at (15-19 BBCH) stages by using backpack sprayer by 250 L./Fed.). Results indicated that, Iprodione applications significantly gave the highest indications of total and the Marketable yield in compared with the other experimental treatments for both seasons. Moreover, the two times of sprayes by Iprodione and Salicylic acid treatments had significantly lowered the disease incidence and disease severity and increasing the control efficiency in the both seasons. Whereas, the other treatments, Tebuconazole with Fluopyram or Tebuconazole and Trichoderma asperellum had a moderate effecacy on the lettuce crop productivety or the disease severity and incidence of Sclerotinia sclerotiorum in compared to the control treatment. In the contrast, application by Calcium Chloride had a low effect on the average yield or final yield as a mass and marketable plant in the both seasons and had insignificant effect on the disease severity or incidence of S. sclerotiorum despite low to medium recovery following applications. Finally, the control treatment was the lowest.

The response of soil and phyllosphere microbial communities to repeated application of the fungicide iprodione: accelerated biodegradation or toxicity?

Pesticides interact with microorganisms in various ways with the outcome being negative or positive for the soil microbiota. Pesticides' effects on soil microorganisms have been studied extensively in soil but not in other pesticides-exposed microbial habitats like the phyllosphere. We tested the hypothesis that soil and phyllosphere support distinct microbial communities, but exhibit a similar response (accelerated biodegradation or toxicity) to repeated exposure to the fungicide iprodione. Pepper plants received four repeated foliage or soil applications of iprodione, which accelerated its degradation in soil (DT50_1st = 1.23 and DT50_4th = 0.48 days) and on plant leaves (DT50_1st >365 and DT50_4th = 5.95 days). The composition of the epiphytic and soil bacterial and fungal communities, determined by amplicon sequencing, was significantly altered by iprodione. The archaeal epiphytic and soil communities responded differently; the former showed no response to iprodione. Three iprodione-degrading Paenarthrobacter strains were isolated from soil and phyllosphere. They hydrolyzed iprodione to 3,5-dichloraniline via the formation of 3,5-dichlorophenyl-carboxiamide and 3,5-dichlorophenylurea-acetate, a pathway shared by other soil-derived arthrobacters implying a phylogenetic specialization in iprodione biotransformation. Our results suggest that iprodione-repeated application could affect soil and epiphytic microbial communities with implications for the homeostasis of the plant-soil system and agricultural production.

Chemical Control of Alternaria Brown Spot on Mandarins Cultivars in Tunisia

Three field experiments were conducted to evaluate the efficiency of seven active ingredients (Tryfloxystrobin, Iprodione, Procymidone, Mancozebe, Propinebe, Tebuconazole and Coppersulfate), against Alternaria brown spot (ABS) caused by Alternaria alternata on Minneola, Fortune, Nova and Tangerine mandarins citrus cultivars in Tunisia. Over the three trials, citrus trees received 6, 10 and 16 fungicides sprays. The results of the present investigation demonstrated the prevention ability of Mancozebe, Iprodione and Copper sulfate according to disease incidence, fruit infection and losses caused by ABS. Furthermore, the applications of those three fungicides used in mixture reduce the ABS development. In fact, disease incidence was reduced better after an application of a mixture of Mancozebe and Iprodione compared to application of Mancozebe or Iprodione alone and after an application of an alternation of Mancozebe and Iprodione with copper sulfate. From this study, it revealed that the incidence of ABS, an emerging fungi disease on Citrus in Tunisia, could be reduced by using chemical products.

Evaluation of a Sclerotinia homoeocarpa Population with Multiple Fungicide Resistance Phenotypes Under Differing Selection Pressures.

Dollar spot, caused by Sclerotinia homoeocarpa, is one of the most significant diseases of cool-season turfgrass on golf courses. Resistance to the benzimidazole, dicarboximide, and succinate dehydrogenase inhibitor (SDHI) classes and reduced sensitivity to the sterol-demethylation inhibitor (DMI) in S. homoeocarpa populations have been widely reported in the United States. Moreover, the occurrence of S. homoeocarpa populations with multiple fungicide resistance (MFR) is a growing problem on golf courses. The present study was undertaken to evaluate the efficacy of DMI, dicarboximide, and SDHI against a S. homoeocarpa population with MFR on a Connecticut golf course fairway from 2014 to 2016. Also, because the S. homoeocarpa population consisted of four different phenotypes with differing resistance profiles to benzimidazole, dicarboximide, and DMI, in vitro sensitivity assays were used to understand the dynamics of the MFR population in the presence and absence of fungicide selection pressures. Results indicated that boscalid fungicide (SDHI) was able to provide an acceptable control of the MFR dollar spot population. Propiconazole or iprodione application selected isolates with both DMI and dicarboximide resistance (DMI-R/Dicar-R). In the absence of fungicide selection pressures, the percent frequency of DMI-R/Dicar-R or DMI and benzimidazole resistance (DMI-R/Ben-R) isolates declined in the population. Out of the four phenotypes, the percent frequency of isolates with DMI, dicarboximide, and benzimidazole resistance (DMI-R/Dicar-R/Ben-R) was the lowest in the population regardless of fungicide selection pressures. Our first report of MFR population dynamics will help develop effective strategies for managing MFR and potentially delay the emergence of future resistant populations in S. homoeocarpa.

The effects of iprodione fungicide on survival, behavior, and brood development of honeybees (Apis mellifera L.) after one foliar application during flowering on mustard.

A semifield study to assess the effects of iprodione on honeybees at label use rates was conducted on a bloom mustard crop. The present study followed the Organisation for Economic Co-operation and Development guideline 75 tunnel test and consisted of 3 groups: the iprodione-treated group, the untreated control group, and the toxic reference item group. In addition to the tunnels used for biological assessments, a tunnel was set up in the treatment and control groups to determine the level of residues in flowers, nectar, and pollen. The major endpoints to assess the effects of the application of iprodione were mortality, flight intensity, behavior, condition of the colonies, and development of the brood. Residue analysis showed that honeybees were exposed to significant residues of iprodione. However, no adverse effects were observed on overall mortality, flight intensity, behavior, or brood development of honeybees compared to control. It is concluded that iprodione does not adversely affect the health of honeybees when applied in agriculture at commercially relevant rates in a worst-case exposure scenario. Environ Toxicol Chem 2018;37:3086-3094. © 2018 SETAC.

Efficacy of different fungicides against the leaf spot of lettuce caused by Allophoma tropica

The efficacy of different fungicides, belonging to different chemical groups, was in vitro and in vivo tested in glasshouse trials against Allophoma tropica, the causal agent of a new leaf spot on lettuce. The in vitro trials showed that only a few fungicides were effective in inhibiting the mycelial growth of the four tested strains of A. tropica: the most effective fungicide, with the lowest ED50 and MIC values, was penconazole. Prochloraz, propiconazole, boscalid and fludioxonil showed low ED50 values, but high MIC values. The results from the in vivo trials showed that all the tested fungicides significantly reduced Phoma leaf spot incidence and severity, although differences were observed in the achieved disease pressure in the four trials. Generally, in the presence of an average disease severity in the untreated control, the best disease severity reduction (up to 90%) was provided 9 days after the application of fludioxonil, mancozeb, pyraclostrobin + boscalid, propiconazole and iprodione. Fludioxonil and iprodione showed a persistent effect (up to 90%) still being evident 12 days after the application. Generally, in the presence of a high disease severity in the untreated control, 9 days after the application of fludioxonil, mancozeb, iprodione and pyraclostrobin + boscalid provided a disease severity reduction up to 80%. Moreover, copper provided a disease severity reduction from 84 to 89%, applied as preventative treatment, resulting of special interest, particularly for crops grown under organic farming rules.

Antagonistic effects of nitrification inhibitor 3,4-dimethylpyrazole phosphate and fungicide iprodione on net nitrification in an agricultural soil

This study evaluated the effects of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) and fungicide iprodione on net nitrification rates and abundances of functional genes related to nitrification and denitrification in an agricultural soil. Single DMPP application or repeated iprodione applications decreased net nitrification rates in the test soil. However, when the DMPP and iprodione were applied together, they could generate antagonistic effects on the inhibitions of net nitrification rates. Repeated iprodione applications reduced ammonia-oxidizing archaea and bacteria (AOA and AOB) amoA gene abundances, while DMPP application decreased AOB amoA gene abundances only. The abundances of narG and nirK genes were negatively affected by repeated iprodione applications. Our results demonstrated that combined applications of DMPP and iprodione could generate antagonistic effects on the inhibitions of net nitrification rates and discrepant impacts on the abundances of functional genes related to soil denitrification.

Effects of fungicide iprodione and nitrification inhibitor 3, 4-dimethylpyrazole phosphate on soil enzyme and bacterial properties

Agrochemical applications may have unintended detrimental effects on soil microorganisms and soil health. However, limited studies have been conducted to evaluate the effects of repeated fungicide applications and interactive effects of different agrochemical applications on soil microorganisms. In this study, an incubation experiment was established to evaluate the potential influences of the fungicide iprodione and the nitrification inhibitor 3, 4-dimethylpyrazole phosphate (DMPP) on soil enzyme activities and bacterial properties. Weekly iprodione applications decreased the activities of all enzymes tested, and DMPP application inhibited soil urease activity. Compared with the blank control, bacterial 16S rRNA gene abundance decreased following repeated iprodione applications, but increased after DMPP application. After 28days of incubation, the treatment receiving both iprodione and DMPP application had higher bacterial 16S rRNA gene abundance and Shannon diversity index than the treatment with iprodione applications alone. Repeated iprodione applications significantly increased the relative abundance of Proteobacteria, but decreased the relative abundances of Chloroflexi and Acidobacteria. Simultaneously, bacterial community structure was changed by repeated iprodione applications, alone or together with DMPP. These results showed that repeated iprodione applications exerted negative effects on soil enzyme activities, bacterial biomass and community diversity. Moreover, relative to iprodione applications alone, additional DMPP application could alleviate the toxic effects of iprodione applications on bacterial biomass and community diversity.

Dynamics of biochemical properties associated with soil nitrogen mineralization following nitrification inhibitor and fungicide applications.

Agrochemical applications may have side effects on soil biochemical properties related to soil nitrogen (N) mineralization and thus affect N cycling. The present study aimed to evaluate the effects of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) and fungicide iprodione on soil neutral protease (NPR), alkaline protease (APR), chitinase (CHI), and their functional genes (nprA, aprA, and chiA) related to soil N mineralization. The following four treatments were included: blank control (CK), single DMPP application (DAA), weekly iprodione applications (IPR), and the combined applications of DMPP and iprodione (DI). Compared with the CK treatment, DMPP application significantly inhibited the CHI activity in the first 14 days of incubation, and iprodione applications, particularly when applied alone, decreased the NPR, APR, and CHI activities. Relative to the IPR treatment, extra DMPP application had the potential to alleviate the inhibitory effects of iprodione on the activities of these enzymes. DMPP application significantly increased aprA gene abundances after 14days of incubation. However, repeated iprodione applications, alone or with the DMPP, decreased nprA and chiA gene abundances. Relative to the CK treatment, DMPP application generated negligible effects on the positive/negative correlations between soil enzyme activities and the corresponding functional gene abundances. However, the positive correlation between the CHI activity and chiA gene abundance was changed to negative correlation by repeated iprodione applications, alone or together with the DMPP. Our results demonstrated that agrochemical applications, particularly repeated fungicide applications, can have inadvertent effects on enzyme activities and functional gene abundances associated with soil N mineralization.

Effects of nitrification inhibitor 3,4-dimethylpyrazole phosphate and fungicide iprodione on soil fungal biomass and community: based on internal transcribed spacer region

Nitrification inhibitors that impact soil nitrifying microorganisms have been widely applied in agricultural soils to enhance the efficiency of nitrogen fertilizers. However, little is known about their combined impact with other chemical applications, such as fungicides, on soil fungi. This study specifically examined the effects of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), alone or together with the fungicide iprodione, on fungi biomass and community in a typical farmland soil. Four treatments were set: (1) control of zero agrochemical applications (CK), (2) a single DMPP application (DAA), (3) repeated iprodione applications (4×IPR), and (4) combined applications of DMPP and iprodione (DAA+4×IPR). The agrochemicals were applied at the recommended intervals, and the soil samples were incubated in the dark for 28 days. During the incubation, soil sample DNA was extracted, and the effects of DMPP and iprodione applications on soil fungal internal transcribed spacer (ITS) abundances were determined with quantitative PCR (qPCR). At the end of the incubation, Illumina MiSeq method was employed to assess soil fungal community diversity and structure. DMPP application had a negligible effect on fungal ITS abundance. However, repeated iprodione applications significantly decreased fungal ITS abundances. After 28 days of incubation, the fungal ITS abundances in the 4×IPR and DAA+4×IPR treatments were 43.6 and 56.2% of that measured from the CK treatment, respectively. Shannon indices of fungal communities demonstrated the treatment-induced gradients, with the DAA+4×IPR treatment harboring the highest Shannon index. Fungal community structures following the DAA and 4×IPR treatments remained overlapping with that in the CK treatment, but repeated iprodione applications markedly enriched the family Teratosphaeriaceae. Relative to the CK treatment, fungal community structure in the DAA+4×IPR treatment was significantly changed, with the families Cephalothecaceae, Hypocreaceae, and Cordycipitaceae harboring a linear discriminant analysis value >3. DMPP application had negligible effects on soil fungal biomass, community diversity, and structure, potentially indicating that the DMPP is “bio-safe.” Conversely, repeated iprodione applications significantly decreased fungal ITS abundances. Moreover, the family Teratosphaeriaceae could be further investigated as a potential biomarker of the impacts of iprodione on soil fungi. The combined applications of DMPP and iprodione stimulated the Shannon diversity index and markedly changed soil fungal community structure.

Plant Health Characteristics of Creeping Bentgrass Affected by Strobilurin Fungicide Applications and Turfgrass Diseases

Previous research has indicated that strobilurin fungicide applications may mitigate the effects of summer heat stress on creeping bentgrass (Agrostis stolonifera L.). Two multi‐year experiments were conducted in 2011 and 2012 to evaluate plant health characteristics following strobilurin fungicide applications to creeping bentgrass putting greens. In Exp. 1, pyraclostrobin, azoxystrobin, fluoxastrobin, or trifloxystrobin were integrated within a conventional summer fungicide program. In Exp. 2, repeated applications of strobilurin fungicides were evaluated in absence of visible foliar disease. To limit foliar disease, overspray applications of chlorothalonil (2,4,5,6‐tetrachloroisophthalonitrile) and iprodione [3‐(3,5‐dichlorophenyl)‐N‐isopropyl‐2,4‐dioxoimidazolidine‐1‐carboxamide] were applied over the experimental units. The plant health characteristics evaluated were visual quality, spectral reflectance, percent green cover, and root morphology. Disease incidence and severity was also quantified visually. In Exp. 1, the nontreated control was similar to strobilurin fungicide programs in all parameters in 2011. In 2012, strobilurin fungicide programs exhibited improved normalized difference vegetation index (NDVI), ratio vegetation index (RVI), turfgrass quality, and percent green cover compared to the nontreated control. Disease severity also increased in 2012 compared to 2011. In Exp. 2, repeated applications of strobilurin fungicides did not affect measured parameters compared to the nontreated control when foliar diseases were managed with fungicides chlorothalonil and iprodione. In these experiments, differences in NDVI, RVI, turfgrass quality, and percent green cover often coincided with differences in disease severity in our evaluations. Under the conditions of these studies, applications of strobilurin fungicides have limited effects on NDVI, RVI, turfgrass quality, and percent green cover in the absence of visible disease.

Short-term effects of combined iprodione and vermicompost applications on soil microbial community structure

The use of compost amendments to bioremediate potential organic pollutants in agricultural soils has recently become an increasingly important field of research. Although several fungicides have been extensively used to control a wide range of soil-borne fungal diseases, little is known about the impact of applying these pesticides on the structure and function of microbial communities in soils amended with vermicompost. The aim of this study was to evaluate the effect of a combined treatment of iprodione and vermicompost on soil microbiological parameters under laboratory conditions. The study was carried out on agricultural and grassland soils to identify the effect of iprodione application at field rate (FR) and 10-times FR (10FR) with and without vermicompost (VCH) on iprodione breakdown, fluorescein diacetate activity (FDA), total fatty acid methyl ester (FAME) profiles, total protein content, and protein profiles by using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Our results indicate that the addition of vermicompost decreased the iprodione breakdown at days 30 and 60 in non-sterilised agricultural soil and at 60days in sterilised and non-sterilised grassland soil. Independent of vermicompost amended treatments, iprodione was found to mainly alter microbial communities after 30days of incubation. On day 30, separation between communities treated with iprodione 10FR and iprodione 10FR+VCH treatments were well defined in both agricultural and grassland soils. Within each soil type, our results showed no difference in the total protein content. However, the protein content in the grassland soil was clearly higher than in the agricultural soil. SDS-PAGE gels revealed that the treatments applied to the agricultural soil using iprodione at the highest dosages (iprodione 10FR and iprodione 10FR+VCH) resulted in an alteration of the band pattern. In conclusion, the experiments revealed that the addition of vermicompost may decrease the breakdown of iprodione in soils. Furthermore, elevated dosages of iprodione may potentially affect the microbial community structure and diversity of the soil, which may lead to the deterioration of soil quality and fertility.

Characterization of Botrytis cinerea Isolates Present in Thompson Seedless Table Grapes in the Central Valley of Chile.

Botrytis cinerea isolates from flowers and berries of Vitis vinifera 'Thompson seedless' (grapevine) were characterized in terms of two transposable elements (TEs) Boty and Flipper, random amplified polymorphic DNA (RAPD), infection levels, and resistance to iprodione. The isolates were collected from grapevines under fungicide programs of variable numbers of iprodione applications, and replicated in three Chilean Central Valley locations. Recovery was repeated from clusters collected at four phenological stages. Highest infection levels were found at bloom. Fungicide programs including one iprodione application or a combination of other fungicides were most effective for reducing gray mold symptoms. A total of 457 isolates collected from fungicide programs including only one iprodione application, and the control program, were tested for the presence of TEs. In all locations and during all phenological stages, transposa isolates (containing both TEs) were most common, followed by Boty. Vacuma isolates (containing neither TE) were identified at very low levels in two locations and only in the control treatment, and isolates with only Flipper were not detected at any time or location. Vacuma and Boty isolates were all sensitive to iprodione, while transposa isolates showed a wide range of resistance. Based on response to iprodione, the presence of TEs, and presence of vegetative-incompatibility alleles (Bc-hch), the isolates studied belong to B. cinerea Group II, a phylogenetic species within B. cinerea. Hierarchical analysis of molecular variance and genetic diversity analyses of the RAPD genotypes showed a genetic differentiation linked to location, but it was not related to geographic distance. Moreover, a genetic differentiation related to the phenological stage of grapes was also detected.

Application of thymol and iprodione to control garlic white rot (Sclerotium cepivorum) and its effect on soil microbial communities

The effect of different dosages of thymol alone, iprodione alone and combinations of thymol and iprodione on white rot disease of garlic and its impact on soil microbial community structure were investigated under greenhouse conditions. Thymol alone or in combination with the fungicide iprodione did not appear to reduce either white rot incidence or soil sclerotia density as compared to an infected control. However, iprodione alone or in combination with thymol reduced soil fungal biomass. In addition, iprodione alone decreased soil microbial activity as estimated by fluorescein diacetate (FDA). Soil bacterial community structure as estimated by phospholipid fatty acid (PLFA) profiles was also was affected by both thymol and iprodione applications. The correlation biplot of the individual PLFAs and biocide treatment indicated that the treatments with thymol alone increased cyclopropyl fatty acid (cy17:0 and cy19:0), while the treatments with iprodione alone increased some saturated and branched fatty acids (principally i16:0, a15:0 and 18:0). In addition, taking into account PLFA biomarkers, thymol applications reduced Gram-negative bacteria in soil. To our knowledge, this research is the first report about the effect of a monoterpene (thymol) on soil microflora.

Sensitivity to iprodione and boscalid of Sclerotinia sclerotiorum isolates collected from rapeseed in China

Baseline sensitivity of Sclerotinia sclerotiorum, causal agent of stem rot of rapeseed, to a dicarboximide fungicide iprodione was determined using 50 isolates (historic population) collected in 2001 from the rapeseed fields without a previous history of dicarboximide usage. The 50% effective concentration (EC 50) values to iprodione of these wild-type isolates ranged from 0.163 to 0.734 μg/ml with a mean of 0.428 μg/ml. In 2007 and 2008, 111 isolates (current population) were collected from rapeseed fields with 4–5 years of iprodione application. The EC 50 values of these 111 isolates ranged from 0.117 to 0.634 μg/ml. The historic and current populations were not significantly ( P > 0.05) different in sensitivity to iprodione. The EC 50 values of these 161 isolates to a carboxamide fungicide boscalid ranged from 0.002 to 0.391 μg/ml with a mean of 0.042 μg/ml. In the laboratory, three iprodione-resistant (IR) isolates HA17-IR, SZ31-IR, and SZ45-IR were induced from wild-type isolates HA17, SZ31, and SZ45, respectively. The EC 50 values of the IR isolates were 200-fold higher than those of the original wild-type parents. The IR isolates showed an increase in osmotic sensitivity. The IR isolate HA17-IR lost its ability to produce sclerotia, and showed a significantly lower virulence on rapeseed leaves than its parent isolate HA17. In contrast, the IR isolate SZ31-IR had a significantly higher virulence than its wild-type parent SZ31. PCR assays showed that the partial two-component histidine kinase ( os-1) gene, which is the putative target gene of iprodione, was deleted in the low virulent IR isolate HA17-IR. DNA sequence analysis showed that each of the other two IR isolates SZ31-IR and SZ45-IR had two point mutations in their partial os-1 genes. These results indicate that the mutations in os-1 gene may be associated with dicarboximide sensitivity, sclerotial development, and virulence in S. sclerotiorum.

Dissipation rates of iprodione and thiacloprid during tomato production in greenhouse

The behaviour of the insecticide thiacloprid and the fungicide iprodione was investigated in greenhouse tomato fruits, when both pesticides were applied in two different rates (normal dose-ND, and double dose-DD). Thiacloprid residues were below the already established EU MRLs (0.5 mg/kg) 2 and 7 days after ND and DD application, respectively. Iprodione residues were always below EU MRLs (5 mg/kg) in both application rates. The impact of storage on pesticide residues in tomatoes was also assessed. Significantly higher iprodione residue levels were observed during post harvest storage compared with those determined in fresh harvested tomatoes. Mean residue levels determined in fresh harvested tomatoes 12 days after iprodione application were 0.69 mg/kg whereas, in post harvest tomatoes stored for the same period was 0.86 mg/kg. On the contrary, no differences were noticed in thiacloprid residues between post harvest stored and fresh harvested tomatoes. Model equations that best describe the dissipation curves obtained from the experimental data of iprodione and thiacloprid in tomatoes showing different behaviour of the two pesticides. Half-life period of iprodione in ND treatment, calculated by the best fitted experimental data, (2nd order model) was 6.8 days, whilst for thiacloprid the best fitted to experimental data, model equation (R.F. 1st order model) gave a half-life of 1.9 days.

Preparation and Characterization of Inclusion Complex of Iprodione and β-Cyclodextrin to Improve Fungicidal Activity

The effect of beta-cyclodextrin (beta-CD) on the improvement of the fungicidal activity of iprodione has been investigated. The inclusion complexation of beta-CD with iprodione has been prepared and characterized by integrating some analytical techniques (such as electrospray ionization-mass spectrometry, differential scanning calorimetry, thermogravimetry, x-ray diffraction, and scanning electron microscopy) and molecular simulation methods. The beta-CD/iprodione inclusion complex has exhibited different spectroscopic features and properties from iprodione. The stoichiometric ratio and stability constant describing the extent of formation of inclusion complexes have been determined by phase solubility studies. The calculated apparent stability constant of the iprodione/beta-CD complex was 407.5 M-1. The obtained inclusion complexes were found to significantly improve the water solubility of iprodione, and there is a 4.7-fold increase in the presence of 13 mM beta-CD as compared with the solubility of iprodione in deionized water in the absence of beta-CD. The bioassay demonstrated that the complex displayed over two-fold increase of the fungicidal activity. In addition, the possible structure of the beta-CD/iprodione complex was proposed according to the results of the molecular dynamic simulation. The present study provided useful information for a more rational application of iprodione, diminishing the use of organic solvents and increasing its efficacy.

An Economic Analysis of Preharvest Fungicide Applications to Control Botrytis Fruit Rot in Annual Strawberries in Florida

The control of postharvest Botrytis fruit rot was evaluated during 1995-96, 1996-97, and 1997-98. Weekly applications of captan and thiram were examined at two or three different rates, respectively. Iprodione applications were combined with the captan and thiram treatments and applied alone for two peak bloom periods. Strawberry fruit were harvested and graded twice weekly for marketable yield and preharvest incidence of Botrytis fruit rot. For postharvest evaluations, fruit from four harvests were selected and stored at 4 °C, and Botrytis fruit rot incidence was recorded over 14 days of storage. Fungicide treatments reduced the incidence of preharvest Botrytis fruit rot and increased marketable yield. Marketable yield data were then used to extrapolate production into net economic returns per hectare. In 1995-96, net returns per hectare ranged from a low of $16,008 in the control treatment to a high of $20,728 for captan. In 1996-97, net returns ranged from a low of $3,655 per hectare for the control to a high of $17,985 for captan + iprodione. In 1997-98, net returns varied from -$641 per hectare for iprodione to a high of $24,215 for captan. Over the experiment's 3-year period, net returns averaged a low of $4,172 for iprodione alone to $19,074 for captan. The study concluded that, at roughly $1,000 per season, fungicide treatments represent a minor proportion of total costs, yet have large impacts on strawberry production profits.

Control of Postharvest Botrytis Fruit Rot with Preharvest Fungicide Applications in Annual Strawberry.

The control of postharvest Botrytis fruit rot was evaluated during 1997-98 and 1998-99. Weekly applications of captan and thiram were examined at two or three different rates, respectively. Iprodione applications were combined with the captan and thiram treatments and also applied alone for two peak bloom periods. Strawberry fruit were harvested and graded twice weekly for marketable yield and preharvest incidence of Botrytis fruit rot. For postharvest evaluations, fruit from four harvests were selected and stored at 4°C, and Botrytis fruit rot incidence was recorded over 14 days of storage. Fungicide treatments reduced the incidence of preharvest Botrytis fruit rot and increased marketable yield. The incidence of postharvest Botrytis fruit rot was significantly affected by harvest date, length of time in storage, and fungicide treatment. The highest rate captan and thiram treatments had the least Botrytis fruit rot and the longest storage life. Reduced-rate captan and thiram treatments generally did not provide the same control as their respective high-rate treatments. Iprodione added to either the captan or thiram treatments did not consistently reduce the preharvest or postharvest incidence of Botrytis fruit rot or increase yield. Regular, full-rate fungicide treatments appear to be necessary to control Botrytis fruit rot in Florida and to provide the storage life necessary to reach distant markets.