Application Of Benomyl Research Articles

Alterations in bee-plant-soil multitrophic interactions after fungicide soil application

Soil microorganisms play a key role in plant growth and health, and honey bees depend on plant pollen and nectar for their nutrition. Despite this clear above- and belowground connection, our knowledge about bee-plant-soil interactions is yet limited. Also, how these multitrophic interactions are affected by agricultural practices like pesticide applications is not well understood. Here we investigated possible non-target effects of soil application of the fungicide Benomyl on bee-plant-soil interactions in a greenhouse experiment with vetch (Vicia sativa L.). When plants were flowering honey bees were confined to their respective experimental soil treatments (untreated control, Benomyl and soil disinfection) in tents made from anti-insect mesh and micro-hives for foraging. At harvest, results showed that Benomyl and soil disinfection strongly affected key root and soil microorganisms essential for plant nutrition, such as mycorrhiza and rhizobia, and Gram-positive and Gram-negative bacteria, which coincided with phenotypic alterations in plant development and subsequently significant effects on honey bee nutrition and health, and finally honey production. In conclusion, our results show that soil application of the fungicide Benomyl strongly impact on bee-plant-soil multitrophic interactions, calling for further investigation on non-target effect of pesticides including multitrophic studies when evaluating environmental impacts of pesticides.

Effect of benomyl-mediated mycorrhizal association on the salinity tolerance of male and monoecious mulberry clones

Mulberry is an economically important crop for sericulture in China. Mulberry plantations are shifting inland, where they face high salinity. Arbuscular mycorrhizal fungi (AMF) reportedly enhance mulberry's tolerance to salinity. Here, we assessed if additional adaptive advantages against salinity are provided by sex differences beyond those provided by mycorrhizal symbiosis. In a pot experiment, male and monoecious plants were exposed to three salinity regimes (0, 50, and 200 mM NaCl) and two mycorrhiza-suppressed conditions (with or without benomyl application) for more than 16 months. We noticed that salinity alone significantly decreased the mycorrhizal colonization rate, salinity tolerance, K+ concentrations, and the ionic ratios of all plants. Mycorrhizal association mildly ameliorated the salt-induced detrimental effects, especially for monoecious plants, and sex-specific responses were observed. Meanwhile, both sexes had adopted different strategies to enhance their salinity resistance. Briefly, mycorrhizal monoecious plants exhibited a higher net photosynthetic rate and lower translocation of Na+ from root to shoot compared with mycorrhizal males under saline conditions. Their salt tolerance was probably due to the Ca2+/Na+ in roots. In comparison, male plants exhibited lower Na+ acquisition, more Na+ translocated from root to shoot, higher root biomass allocation, and higher N concentrations under harsh saline conditions, and their salt tolerance was mainly related to the K+/Na+ in their shoots. In conclusion, our results highlight that AMF could be a promising candidate for improving plant performance under highest salinity, especially for monoecious plants. Cultivators must be mindful of applying fungicides, such as benomyl, in saline areas.

Higher diversity and contribution of soil arbuscular mycorrhizal fungi at an optimal P-input level

As not only an indicator but also key determinants of soil health, the performance of arbuscular mycorrhizal (AM) fungi under intensive cropping systems remains incompletely understood, particularly with regard to quantitative contributions to crop phosphorus (P) acquisition and scientific managements of P-input levels. Here, we firstly investigated the diversity and vitality of AM fungi along with decreasing P-input levels from P100 (local regular rate) to P50 (50 % off) in a greenhouse experiment to explore the optimal P-input level, and further determined the apparent contribution of AM fungi to maize (Zea mays L.) P acquisition at optimal level in a field microplot experiment with root mycorrhization inhibition by benomyl application and in another pot experiment upon AM fungal inoculation in a sterilized soil. Decreasing P input decreased the amount but increased the efficiency of plant P acquisition, and increased the diversity and colonization of AM fungi, in addition to shaping the community composition. Notably, P80 (20 % off) appeared to be an optimal level that balanced mycorrhizal vitality, maize growth and P-acquisition efficiency. The apparent contribution of AM fungi to maize P acquisition determined in both field and pot experiments were approximately 36 % and 21 % at P80 and P100, respectively, while grain yields at P80 with mycorrhizae reached the level equivalent to that of P100 without mycorrhizae, indicating a replacement of 20 % of P fertilizers by adequate mycorrhizal management. It highlights that stronger AM associations by optimizing P input allow for relatively high crop P-acquisition efficiency upon high mycorrhizal benefits, favoring agricultural production in a sustainable manner with reduced dependence on inputs.

Arbuscular Mycorrhizal Fungi Mediate Grazing Effects on Seasonal Soil Nitrogen Fluxes in a Steppe Ecosystem

Grazing and arbuscular mycorrhizal fungi (AMF) influence soil nitrogen (N) cycling in grassland ecosystems. However, it remains unclear whether AMF mediate grazing effects on soil N cycling. We investigated the influence of benomyl (a broad-range fungicide) application to suppress AMF on soil N fluxes under different levels of grazing intensity in a steppe ecosystem on the Mongolia plateau. In situ soil core incubation method was used during both growing and non-growing seasons. Benomyl application to suppress AMF remarkably stimulated the net nitrification rate across all grazing intensities during the growing season. Benomyl application exerted a negative effect on soil N fluxes and/or N pools under no to moderate levels of grazing and a positive effect under heavy grazing during the growing season. The responses of amino acid and inorganic N stocks to grazing differed substantially between growing and non-growing seasons. The accumulation of amino acid in grazed plots (especially heavily grazed plots) during the non-growing season enhances the substrate availability for microbes in the early growing season of the following year. Our study provides field evidence that N losses are controlled to some extent by AMF and suggests a mechanism that grazing may affect soil N cycling through changing the AMF-plant symbiosis and therefore the interactions between AMF and other microbes. The findings improve our understanding of the effects of grazing and AMF on seasonal dynamics of different N forms and N pools in semiarid grassland.

Heavy grazing disrupts positive effects of arbuscular mycorrhizae symbiosis on community productivity and stability under low and high phosphorus conditions

We quantified the potential influence of arbuscular mycorrhizal fungi (AMF) on primary productivity and community stability and tested whether the effects of AMF depend on soil phosphorus (P) availability and grazing intensity in a semiarid grassland. We manipulated the abundance of AMF and soil P availability (P addition and no P addition) under four levels of grazing intensity. The aboveground biomass of plant species, functional groups and community, as well as community temporal stability were examined under these conditions. Under no to moderate grazing, benomyl decreased the aboveground biomass in C4 grasses and forbs, but increased the aboveground biomass in C3 grasses under low P conditions; thus no obvious changes in community primary productivity were observed. These results indicated that the mycorrhizal dependency of C4 grasses and forbs is higher than that of C3 grasses under low P conditions. However, community primary productivity was greatly enhanced by benomyl due to the increased biomasses of C3 grasses and forbs under high P conditions. Under heavy grazing conditions, benomyl increased community primary productivity under both low and high P conditions. AMF presence increased the community temporal stability by promoting the compensatory effects between plant species under no to moderate grazing conditions; whereas AMF decreased the community stability by forming a parasitic symbiosis with their plant hosts under heavy grazing conditions. Our findings demonstrate that the effects of benomyl application to suppress AMF on primary productivity and community stability are strongly mediated by soil P availability and grazing intensity, which improves our understanding for the roles of AMF-plant symbiosis on ecosystem functioning in grazed systems.

Soil labile organic carbon sequestration is tightly correlated with the abundance and diversity of arbuscular mycorrhizal fungi in semiarid maize fields

AbstractPlastic film mulching can affect soil organic carbon (C) lability in semiarid regions. Arbuscular mycorrhizal (AM) fungi represent an important route for plant‐derived C into soil and can be influenced by agricultural practices. Whether the changes of AM fungal community affect soil organic C sequestration is a fundamental question in semiarid environments. To this end, we conducted two field experiments investigating the influence of a Funneliformis mosseae inoculation and mycorrhizal‐suppression using benomyl application on maize growth, soil fractions of organic C, AM fungal parameters, including diversity profiling using the Illumina MiSeq. The results showed that AM fungal community composition was significantly altered by plastic film mulching and fungicide applications, soil organic C fractions and nitrogen were most important factors in influencing the AM fungal community. AM fungal inoculation significantly increased particulate organic C and light fraction organic C content, due to enhance dextramatrical hyphal length (EMH), glomalin content, and root biomass. Conversely, fungicide applications reduced labile organic C, possibly through decreasing EMH, glomalin content and soil AM fungal diversity. Increases in relative abundance of F. mosseae in rhizosphere soil, coupled with increases in AM fungal root colonization from F. mosseae inoculation indicates successfully established by outcompeting the existing natural AM fungal community. Plastic film mulching resulted in significant increases in maize yield and water use efficiency, and AM fungal inoculation was found to amplify the effects. Thus, AM fungal inoculation may act as an effective farming practice to improve soil organic C fractions, which can boost maize productivity.

Arbuscular mycorrhizal fungi alter plant community composition along a grazing gradient in Inner Mongolia Steppe

Arbuscular mycorrhizal fungi (AMF) have a significant influence on plant productivity and diversity in non-grazing grassland. However, the interactive effects between grazing intensity and AMF on plant community composition in natural grassland communities are not well known. We conducted a field experiment that manipulated AMF colonization and grazing intensity to study the impact of AMF suppression on plant community composition and nutrient status over 2 years (2015–2016) with contrasting rainfall levels. We found that AMF root colonization was significantly reduced by the application of the fungicide benomyl as a soil drench. Grazing intensity regulated plant community composition and aboveground biomass mainly by reducing the growth of Leymus chinensis over 2 years. AMF suppression increased the growth of Chenopodium glaucum, but it did not alter other plant species across all grazing intensities. The effects of AMF suppression on plant community composition changed along a grazing gradient considerably between years: AMF suppression increased the biomass of C. glaucum across all grazing intensities in 2015, but slightly increased it in 2016. Interactions between AMF suppression and grazing intensity altered the phosphorus concentration of Stipa grandis and Cleistogenes squarrosa in 2015 but not in 2016. AMF suppression decreased the shoot phosphorus content of L. chinensis but increased that of C. glaucum across all grazing intensities. Our results indicate that grazing intensity substantially alters aboveground community biomass and affects growth of dominant species; AMF by itself have limited effects on plant communities along a grazing gradient in typical steppe.

Phytoextraction of contaminated urban soils by Panicum virgatum L. enhanced with application of a plant growth regulator (BAP) and citric acid

Lead (Pb) contamination in soil represents a threat to human health. Phytoextraction has gained attention as a potential alternative to traditional remediation methods because of lower cost and minimal soil disruption. The North American native switchgrass (Panicum virgatum L.) was targeted due to its ability to produce high biomass and grow across a variety of ecozones. In this study switchgrass was chemically enhanced with applications of the soil-fungicide benomyl, chelates (EDTA and citric acid), and PGR to optimize phytoextraction of Pb and zinc (Zn) from contaminated urban soils in Atlanta, GA.Exogenous application of two plant hormones was compared in multiple concentrations to determine effects on switchgrass growth: indole-3-acetic acid (IAA), and Gibberellic Acid (GA3), and one PGR benzylaminopurine (BAP), The PGR BAP (1.0 μM) was found to generate a 48% increase in biomass compared to Control plants.Chemical application of citric acid, EDTA, benomyl, and BAP were tested separately and in combination in a pot experiment in an environmentally controlled greenhouse to determine the efficacy of phtyoextraction by switchgrass. Soil acidification by citric acid application resulted in highest level of aluminum (Al) and iron (Fe) in plants foliage resulting in severe phytotoxic effects. Total Pb phytoextraction was significantly highest in plants treated with combined chemical application of B + C and B + C + H.Suppression of AMF activities by benomyl application significantly increased concentrations of Al and Fe in roots. Application of benomyl reduced AMF colonization but was also shown to dramatically increase levels of septa fungi infection as compared to Control plants.

Resistencia de Mycosphaerella citri a benomil en plantaciones de cítricos de Costa Rica.

Research was carried out on 24 orange plantations in Costa Rica in order to determine the sensitivity to benomyl of Mycosphaerella citri Whiteside - fungi causing the citrus greasy spot. Only thirteen samples yielded enough ascospores to determine their sensitivity to benomyl. Twelve of the samples represented an area of approximately 4.000 ha from the Northern part of Costa Rica (the cantons of San Carlos and Los Chiles), and one was from a nonsprayed home orchard in Orosi, in the Central Valley located more than 250 km away from San Carlos. AIl of the samples from the Northem region yielded benomyl resistant ascospores, although benomyl is not normally used in those areas. Conversely, 99% of the ascospores obtained in Orosi were sensitive; this suggests that the M. citri wild population is benomyl-sensitive. It was found that 75% of the orchards sampled came from the same nursery, where the phytosanitary program includes five benomyl applications ayear. Furthermore, 10 M.citri samples obtained from this nursery were benomyl-resistant. This suggests that the benomyl-resistant isolations found in the plantations were introduced there through the nursery stock.

Manejo de la mustia hilachosa (Thanatephorus cucumeris (Frank)) en el cultivo del frijol comun (Phaseolus vulgaris L).

Several studies about web bligh control were carried out in Panama, the Dominican Republic, and Costa Rica. The pathogen´s genetic variability, bean varietal tolerance, chemical control, and sowing densities were evaluated. In Panama yield was increased through Benomyl applications and a greater sowing density. In the Dominican Republic Rhizoctonia AG 4, AG 2 2 and AG 1 groups were found. Several bean genotypes were evaluated, as well as populations from the web blight tolerant JB X MUS 14 cross. Between 20% and 40 % web blight severity was found in Costa Rica. Coverage and application of chemicals improved bean yield.

Induced Phytoextraction of Lead Through Chemical Manipulation of Switchgrass and Corn; Role of Iron Supplement

The effects of combined chemical application of benomyl, ethylenedianinetetraacetate (EDTA), and iron (Fe) (foliar and root) on lead (Pb) phytoextraction by switchgrass (Panicum virgatum) and corn (Zea mays) was examined. Switchgrass was grown in Pb-contaminated urban topsoil with the following treatments: (C) Control, (B) benomyl, (E) EDTA, (F) foliar-Fe, (BE) benomyl + EDTA, (BF) benomyl + foliar-Fe, (FE) foliar-Fe + EDTA, (BFE) benomyl + foliar-Fe + EDTA. Corn was grown in sand-culture supplemented with Pb (500 mg kg−1) with the following treatments: (C) control, (B) benomyl, (E) EDTA, (F) root-Fe, (BE) benomyl + EDTA, (BF) benomyl + root-Fe, (FE) root-iron + EDTA, and, (BFE) benomyl + root-Fe + EDTA. All treatments were replicated three times and pots were arranged in a completely randomized design. Plants were analyzed for element concentration (Fe, Zn, P, and Pb) using either inductively coupled plasma (argon) atomic emission spectroscopy (ICP-AES) or graphite furnace atomic absorption spectrometer. Iron supplementation (foliar and root) affected Pb-translocation in plants. Foliar-Fe treatment increased translocation ratio of Pb (TF-Pb) significantly compared to other treatments with the exception of plants treated with benomyl and BF. Root-Fe treatment in combination with EDTA (FE) increased TF-Pb significantly compared to other treatments. Phytoextraction was improved by the combined chemical application; plants treated with BFE treatment increased Pb-total-phytoextraction by 424% compared to Control plants.

Development and validation of benomyl birdseed agar for the isolation of Cryptococcus neoformans and Cryptococcus gattii from environmental samples.

One of the difficulties of isolating Cryptococcus neoformans and Cryptococcus gattii from environmental samples is the abundant overgrowth of other yeast and mold species that occurs on the plates. Here we report the application of benomyl to Guizotia abyssinica seed extract growth medium to improve the isolation of C. neoformans and C. gattii from environmental samples. We validated this medium by recovering C. neoformans and C. gattii from convenience soils and swabs from a region of the United States where these yeasts are endemic.

The interaction between arbuscular mycorrhizal fungi and soil phosphorus availability influences plant community productivity and ecosystem stability

Summary Arbuscular mycorrhizal fungi (AMF) can influence plant community composition and diversity. Previous research has shown that the addition of nutrients reduces the effectiveness of AMF. However, the ways in which soil nutrient availability and AMF interact and affect plant community productivity and ecosystem stability are still poorly understood. We examined the impact of AMF suppression and phosphorus (P) addition on plant diversity, community productivity and temporal stability (TS) in a field experiment. AMF root colonization and the concentration of an AMF‐specific phospholipid fatty acid were significantly reduced after application of the fungicide benomyl as a soil drench. The TS of the plant community was higher in communities without benomyl application compared with communities with benomyl application indicating that AMF contribute to the TS of plant communities. AMF suppression increased productivity at the plant species, functional group and community levels under high P addition rates. At the zero P addition rate, AMF did not affect plant community productivity, as the dominant species Artemisia frigida was more abundant in control plots with AMF, while the subdominant species Stipa krylovii was more abundant in the benomyl‐treated plots with reduced AMF abundance. Compensatory effects between C3 grasses and non‐N2‐fixing forbs were observed in the control plots with AMF along the gradient of P addition rates, but these effects were not detected among plant species in the benomyl‐treated plots under AMF suppression above an addition rate of 4.76 P2O5 m−2 year−1. Although AMF suppression did not influence the diversity of the plant communities, it did decrease the diversity of N2‐fixing forbs at the zero P addition rate and above an addition rate of 18.90 g P2O5 m−2 year−1, indicating that AMF play key roles in the maintenance of N2‐fixing forbs at these P addition rates. P addition led to biodiversity losses at application rates below 2.36 g P2O5 m−2 year−1 at the community level. Synthesis. Arbuscular mycorrhizal fungi and soil P availability interact to influence the productivity and TS of a plant community by mediating compensatory effects among plant species and functional groups.

Efficacy of paste and liquid fungicide formulations to protect pruning wounds against pathogens associated with grapevine trunk diseases in Chile

Trunk diseases are important on grapevines (Vitis vinifera L.) in most countries where grapevines are grown. In Chile, Diplodia seriata, Inocutis sp. and Phaeomoniella (Pa.) chlamydospora are the most prevalent pathogens associated with this syndrome. It has been demonstrated that fresh pruning wounds are the main infection route for fungal trunk disease pathogens. The objective of this study was to evaluate the efficacy of paste and spray fungicide applications in protecting pruning wounds against D. seriata, Inocutis sp. and Pa. chlamydospora on ‘Cabernet Sauvignon’ grapevines in two important Chilean grapevine production areas. The fungicides used in this study were benomyl, pyraclostrobin, tebuconazole, and thiophanate-methyl, which were applied as paste and liquid fungicide on fresh pruning wounds pre- and post-inoculation with mycelium plugs of the different fungal pathogens used in this study. The efficacy of the fungicides was assessed by measuring the length of the discoloration of the vascular system and percent re-isolation obtained on fresh pruning wounds. The results obtained demonstrate that infections caused by D. seriata, Inocutis sp. and Pa. chlamydospora can be significantly reduced using both paste and spray applications of benomyl, pyraclostrobin, tebuconazole and thiophanate-methyl and that the paste formulations provided a better control than spray applications. Regardless of the fungicide and application method used, the pre-inoculation treatments (performed 24 h before inoculation) resulted in better control than the 24 h post-inoculation treatments. The current study showed that Inocutis sp. can induce vascular discoloration on grapevine spurs. This study supports a broader use of benzimidazole fungicides for the control of the devastating trunk diseases in all grape productions worldwide.

Effect of Mycorrhizal Infection on Phosphorus Efficiency of Maize (Zea mays L.) Cultivars

Phosphorus is considered as one of the least available plant nutrients found in the rhizosphere. The large variation in phosphorus acquisition efficiency of different crop cultivars provides opportunities for screening cultivars that perform well on low phosphorus soil for sustainable agriculture. To assess phosphorus efficiency of maize cultivars viz.: Paras and JH 3459, a field experiment was conducted for 2 years at Indian Institute of Technology, Kharagpur, India on sandy loam soil, having pH 5.1, organic carbon 4.1 g kg−1 soil and as low as 11.2 kg ha−1 available phosphorus. Phosphorus was applied at a rate of 0 (low) and 400 kg ha−1 (high) with and without the application of fungicide Benomyl at 500 kg ha−1 for eradication of arbuscular mycorrhiza. Maize plants were harvested at 24, 48, and 74 days after sowing and final harvest was taken at maturity. In low phosphorus soil without Benomyl, cv. Paras produced 29, 18, and 69 %, while cv. JH 3459 produced 19, 9, and 57 % of their maximum shoot dry weight at 24, 48, and 74 days after sowing, respectively during the first year and the trend was same during the second year. The results indicate that relative shoot dry weight varies with growth stages and therefore, grain yield should be used to assess phosphorus efficiency. At maturity, maize cv. Paras produced 91 and 80 % while JH 3459 produced 71 and 60 % of their maximum grain yield during the first and second year respectively, proving that cv. Paras was more phosphorus efficient than cv. JH 3459. Root growth of both the cultivars was restricted under phosphorus deficiency conditions; however, cv. Paras produced 1.4–2.6 times more root length than cv. JH 3459 at different growth stages. Cultivar Paras had lower phosphorus influx than cv. JH 3459, but it was more phosphorus efficient because of more roots, lower internal phosphorus requirement and higher root length/shoot dry weight ratio. Application of Benomyl was completely effective in suppressing arbuscular mycorrhiza infections up to 48 days after sowing. Its effect started diminishing thereafter and some infection occurred, which however was significantly less than that observed in untreated plots. Thus, the yield difference between Benomyl treated and untreated plots can be attributed to arbuscular mycorrhiza. In low phosphorus soil, Benomyl application reduced the growth of cultivars by 12–45 % and the maximum reduction of growth was at 48 days after sowing. However, in high P soil, Benomyl application had no significant effect on dry matter yield of the cultivars.

Effect of Plant Species and Benomyl on Lead Concentration and Removal from Lead-enriched Soil

Some agricultural soils in North America are lead (Pb)-enriched as a result of the application of lead arsenate (PbHAsO4) insecticide. A controlled-environment experiment was conducted with Pb-enriched Canning soil series in Nova Scotia, Canada, to evaluate the remediation potential of 10 plant species in combination with the fungicide benomyl applied as a soil drench to suppress mycorrhizae. Overall, the highest biomass was provided by yellow poppy followed by Indian mustard and thorn apple. The application of benomyl increased Pb concentration in thorn apple tissue but not in the other crops. The phytoremediation potential (Pb removal with the harvested biomass) was higher with clary sage, alyssum, garden sage, and Indian mustard with benomyl treatments and lower in the Swiss chard, thorn apple without benomyl, and in the geranium with benomyl treatments. The results suggest that some plants can be used for phytoremediation of mildly Pb-contaminated soils.

Chemically Enhanced Phytoextraction of Lead-Contaminated Soils

The effects of the combined application of soil fungicide (benomyl) and ethylenediaminetetraacetic acid (EDTA) on lead (Pb) phytoextraction by ryegrass (Lolium perenne) were examined. Twenty-five pots of Pb-contaminated soil (200 mg Pb kg−1) were seeded with ryegrass and randomly arranged into the following treatments: (1) Control, (2) benomyl, (3) EDTA, (4) benomyl and EDTA (B+E), and (5) benomyl followed by an application of EDTA 14 days later (B…E). Chemicals were applied when plants had reached maximum growth. Plants were analyzed for foliage Pb concentration using inductively coupled argon plasma (ICAP) spectrometry. The synergistic effects of the combined benomyl and EDTA application (treatments 4 and 5) were made evident by the significantly (p < 0.05) highest foliage Pb concentrations. However, the foliage dry biomass was significantly lowest for plants in treatments 4 and 5. The bioaccumulation factor (BF) and phytoextraction ratio (PR) were highest for plants in treatment 5 followed by plants in treatment 4.

Biocontrol of Potato White Mold Using Coniothyrium minitans and Resistance of Potato Cultivars to Sclerotinia sclerotiorum

This study was conducted in Bahar and Lalehjin, Hamadan, Iran to assess the biocontrol efficacy of Coniothyrium minitans Campbell against potato white mold caused by Sclerotinia sclerotiorum (Lib.) de Bary under field and greenhouse conditions. In addition, the resistance of common potato cultivars against S. sclerotiorum was determined in a greenhouse experiment. After straw inoculation of six potato cultivars (Pashandi, Istambouli, Agria, Marfauna, Alpha and Spartaan) with S. sclerotiorum, the least disease severity was observed in Spartaan and Marfauna. Agria showed the most susceptibility to S. sclerotiorum. Compared with the healthy control, different concentrations of C. minitans conidia (<TEX>$10^7$</TEX>, <TEX>$10^8$</TEX> and <TEX>$10^9$</TEX> conidia/mL) reduced disease severity under greenhouse condition, and a concentration <TEX>$10^9$</TEX> was the most effective treatment. During 2008 and 2009, four field trials were conducted to evaluate the efficacy of C. minitans in different soil and aerial applications on disease incidence of potato white mold. In 2008, soil application of <TEX>$Contans^{(R)}$</TEX> WG (a commercial product of C. minitans) showed the greatest biocontrol capacity whereas soil application of solid-substrate C. minitans was found inferior when compared with other treatments in both Bahar and Lalehjin field sites. In 2009, benomyl application was the most effective treatment in reducing disease incidence in both tested field sites.

The Effects of Fungicides on Fusarium Oxysporum F. SP. Lycopersici Associated with Fusarium Wilt of Tomato

Tomato fusarium wilt is considered as one of the most important diseases of tomato both in field and greenhouse - grown tomatoes worldwide. In presented research, six fungicides; benomyl, carbendazim, prochloraz, fludioxonil, bromuconazole and azoxys- trobin, were evaluated for their efficacy against the disease casual agent Fusarium oxysporum f. sp. lycopersici in vitro and in vivo. Seven different concentration (0.0001, 0.001, 0.01, 0.1, 1, 10, 100 µg/ml) were used for assessment of their inhibitory activities against the patho- gen through mycelial growth inhibition on potato media. Four concentrations of above mentioned fungicides (0.1, 1. 10 and 100 µg/ml) were tested for controlling Fusarium wilt on tomato plants in glasshouse. Fungal radial growth was measured and median effective con- centration (EC 50 ) values (µg/ml) determined. The result of glasshouse tests revealed a different degree of efficacy of all tested fungicides in reducing disease infestation. Prochloraz and bromuconazole were the most effective fungicides against the pathogen both in vitro and in vivo, followed by benomyl and carbendazim. All other fungicides were less effective. Conserning the application date of fungicides it was shown that they were less effective when applied 7 days after tomato plant infection, compared with 1 day prior infection. No phytotoxic symptoms were observed after the application of prochloraz, bromuconazol and benomyl when used at recommended doses, especially on seedlings. However both fungicides fludioxonil and bromuconazole were shown to be phototoxic to tomato seedlings.

The fate and efficacy of benomyl applied to field soils to suppress activity of arbuscular mycorrhizal fungi

A systematic application of the fungicide benomyl was used to follow up the suppression of arbuscular mycorrhizal (AM) colonization and to determine its fungitoxic activity and persistence at different depths. Repeated applications of benomyl reduced AM colonization mainly in the upper 0-4 cm layer of the treated soils. Furthermore, AM colonization decreased with soil depth. The activity and persistence of this fungicide was reduced over small changes in depth in the first 10 cm of the soil profile beneath a semiarid herbland at Brookfield Conservation Park (South Australia). Repeated applications of the fungicide only slightly increased the levels of toxicity in the soils, probably because of biodegradation of the fungicide in soils with a recent history of exposure to the fungicide. The decline in fungicide activity at depth was correlated with a decline in the suppressive effect of the fungicide on the activity of AM fungi.