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1.
Peanut fields are monitored for pod rot, which is typically caused by Pythium spp. and Rhizoctonia solani, in order to determine need, and the type and timing of fungicide applications. Pod rot can lead to damaged peanut kernels and when damage exceeds 2.49%, substantial price reductions occur. Nine fields or tests were sampled weekly for pod rot during the 2009 through 2012 growing seasons. The sampling was conducted on fields treated uniformly with fungicides for pod rot or within large research plots with various fungicide treatments. Pythium myriotylum was the most frequently identified pathogen species, although Rhizoctonia spp. were also recovered from diseased pods at all sites. Pod rot incidence was related to percent damaged kernels at harvest in 3 of 5 sites. Collection of 304 samples (sample unit = 46 cm of row) in a field was required to estimate 1% pod rot accurately (CV = 20%). There was a linear relationship between average % pod rot in a field, and the percentage of sampling units (absence/presence) with pod rot at low disease incidences. Scouting for pod rot of peanuts to make in-season fungicide applications will be hampered by high sample number, destructive sampling of plants, frequent sampling (due to rapid increase of disease), and the poor relationship between disease during the season and kernel damage at harvest. Making one preventative application at 60–70 days after planting may be a better practice than timing the initial fungicide application based on sampling for disease. 相似文献
2.
Effect of cultural practices and fungicides on Phytophthora fruit rot of watermelon in the Carolinas 总被引：1，自引：0，他引：1
Chandrasekar S. Kousik Mike L. AdamsWilfred R. Jester Richard HassellHoward F. Harrison Gerald J. Holmes 《Crop Protection》2011,30(7):888-894
Phytophthora fruit rot of watermelon, caused by Phytophthora capsici, is an important and emerging disease in Southeastern U.S.A. The effects of two cultural practices (raised bare ground and raised plastic mulched beds) used for growing watermelon and different fungicide treatments on development of Phytophthora fruit rot were evaluated. The experiments were conducted over three years (2005-2008) at research stations in North Carolina and South Carolina, U.S.A. Fungicides were applied at weekly intervals on the diploid cv. Mickey Lee for an average of five applications. Fruit rot incidence was recorded at the end of each experiment. Fruit rot incidence in the non-treated plots was 66% across two states and six trials. Overall, the levels of fruit rot on the raised bare ground and raised plastic mulched beds were not significantly different. Based on percent disease reduction relative to the non-treated check plots, the fungicide Captan was the most effective across years and locations (range = 23-70%, mean = 57%), followed by mandipropamid (25-65%, mean = 50%), fluopicolide (24-65%, mean = 43%) and cyazofamid (0-48%, mean = 31%). Mefenoxam, the current standard treatment reduced fruit rot by 8-28% (mean = 18%). The addition of copper hydroxide to the spray mix did not significantly enhance effectiveness of Captan or mandipropamid. The variability in fungicide efficacy observed in these experiments across locations and years demonstrates the importance of environmental conditions in disease development and management. Even when the most effective fungicides are used, heavy losses may occur when conditions are highly favorable for disease development. Ultimately, effective control of Phytophthora fruit rot of watermelon will require an integrated management strategy that includes well-drained fields, water management and crop rotation in addition to fungicides. 相似文献
3.
Phosphite has been shown to suppress some diseases in different plant species but disease control in rice has not been investigated. In 2012/13 and 2013/14 potassium phosphite was sprayed at 1775 g ha−1 and 3550 g ha−1 in field plots of rice in Uruguay to determine if phosphite alone or in combination with label rates of a mixed strobilurin and triazole fungicide could be used to effectively control stem rot and aggregate sheath spot in irrigated rice. Six treatments consisting of different combinations of potassium phosphite alone or with a fungicide and an unsprayed control were assayed in one application at late-boot to early-heading. Phosphite alone in single and double rate slightly reduced severity and incidence of stem rot and produced a small yield increase over the unsprayed control. Fungicide at a 50% label rate with phosphite reduced stem rot severity and incidence to a similar level as the fungicide alone applied at the label rate. Disease severity was reduced by approximately 25% and incidence by 17–20% when compared with untreated control. Yield increase was 5% for both treatments over the unsprayed control. Fungicide combined with phosphite at single and double rates reduced stem rot severity by 40–45% and incidence by 34–38% when compared with untreated control, with yield increased by 10% over the unsprayed control and 5% over plots treated with a fungicide. These results indicate that a single application of potassium phosphite combined with fungicide can be used efficiently to manage of rice stem diseases. 相似文献
4.
5.
S. Gremillion A. CulbreathD. Gorbet B. Mullinix Jr.R. Pittman K. StevensonJ. Todd M. Condori 《Crop Protection》2011,30(6):698-704
Early and late leaf spot (caused by Cercospora arachidicola and Cercosporidium personatum, respectively) are major yield-reducing diseases of peanut (Arachis hypogaea L.) in the southeastern U.S. Effective suppression of both early and late leaf spot, collectively called ‘leaf spot’, can be reached with integrated disease management (IDM) systems utilizing peanut cultivars with moderate levels of resistance to these pathogens. A Bolivian landrace cultivar, Bayo Grande, and a series of progeny breeding lines were evaluated under two IDM systems consisting of various reduced application fungicide regimes and/or tillage treatments in field experiments over two years. In the absence of fungicides or when averaged across fungicide regimes, Bayo Grande and breeding lines had better leaf spot resistance when compared to cultivars Georgia Green, MDR-98 and C-99R in all experiments across years. The addition of three or four fungicide applications to Bayo Grande and several of the breeding lines suppressed leaf spot to levels similar to those genotypes and Georgia Green under the full regime. Conservation tillage reduced the need for fungicides in most genotypes in both years. Yields were higher for Bayo Grande and the breeding lines compared to Georgia Green in three of the four experiments across years. When compared across genotype, yields were greatest for the full season fungicide regime, except in 2002 when yields were similar for all treatments. Leaf spot severity was reduced in conservation tillage compared to conventional tillage in most varieties in the absence of fungicides. However, yields tended to be lower in conservation tillage treatments than in conventional tillage. Under conservation tillage, yields of Bayo Grande and two of the breeding lines were negatively impacted in one year and were overall lower in the other year. Several of these new Bolivian-derived genotypes show promise for use in a reduced fungicide and/or conservation tillage IDM system with the potential to lessen fungicide use compared to standard production practices while maintaining low leaf spot levels and high yields. 相似文献
6.
Leather rot, caused by Phytophthora cactorum, is one of the most important fruit-rotting diseases of strawberry worldwide. Efficacy of mefenoxam and potassium phosphite against leather rot, when applied in a post-infection fungicide program, made in response to rain events was evaluated over 3 years of testing. Post-infection treatments of potassium phosphite and mefenoxam were compared with calendar-based treatments of azoxystrobin or potassium phosphite sprayed weekly, starting at late bloom (fruit set). In order to obtain high-risk conditions for infection (splash dispersal of the pathogen and subsequent infection periods), plots were flooded until standing water was observed between the rows. Post-infection applications were made within 36 h after the initiation of a flooding event. Leather rot incidence in the untreated controls ranged from 15 to 66% over the 3 years. All fungicide treatments had significantly (P < 0.001) less leather rot incidence than in the untreated control. There were no significant differences in leather rot incidence between the different fungicide treatments. Percent control (the percentage reduction in incidence relative to the check) was as high as 100% with all fungicide treatments. Mefenoxam and potassium phosphite post-infection (after flooding) provided control equal to that obtained with a calendar-based spray program, but with from 1 to 3 fewer fungicide applications. 相似文献
7.
Preventive, watered-in applications of DMI fungicides provide control of several soilborne turfgrass diseases on golf putting greens. The objectives of this two-year field study were to determine the impact of these applications on foliar diseases, and evaluate the impact of application timing of paclobutrazol, a plant growth regulator, on disease severity and turfgrass quality. Triadimefon (1.58 kg a.i. ha−1), tebuconazole (0.82 kg a.i. ha−1), metconazole (0.43 kg a.i. ha−1), and triticonazole (0.64 kg a.i. ha−1), were applied twice in late April and May and immediately watered in to the soil profile with 5 mm of post application irrigation. Paclobutrazol (0.28 kg a.i. ha−1) was applied alone, in a tank-mix with the fungicide application, 7 days or 14 days after the fungicide application. Overall dollar spot severity, assessed as area under the disease progress curve (AUDPC), was significantly lower in fungicide treated plots than non-treated plots in both trial years. The date of threshold symptom observation (≥5 infection centers per plot), however, was not different between fungicide treated and non-treated plots in 2011. Triadimefon treated plots had lower AUDPC values than other fungicide treatments. Brown patch severity was not significantly different among treatments. Paclobutrazol applied alone did not reduce dollar spot or brown patch severity, however, paclobutrazol + fungicide treatments resulted in lower dollar spot severity than plots treated with fungicide alone. Short-lived phytotoxicity (bronze discoloration) was observed in plots treated with triadimefon or paclobutrazol + fungicide. Spring preventive fungicide applications targeted at soilborne disease control also provided residual control of dollar spot in this study. 相似文献
8.
Cylindrocladium and Rhizoctonia root rots, caused by Cylindrocladium parasiticum and binucleate Rhizoctonia spp., respectively, are common soilborne diseases observed during blueberry propagation in Georgia, USA. Six trials with artificially inoculated propagation medium were completed in a shade-house to determine the efficacy of select fungicides to control these diseases. For Cylindrocladium root rot, two trials with single-drench fungicide applications were made at the time the cuttings (southern highbush blueberry cultivar Rebel) were stuck. In two additional trials, a second drench application was added two weeks later. In all trials, fludioxonil (Medallion) significantly reduced lesion incidence and lesion length. Neither triflumizole (Terraguard) nor thiophanate-methyl (Cleary's 3336) consistently reduced lesion incidence with one application, indicating that a single application of these materials was not sufficient for disease suppression. The second fungicide application improved disease control for all fungicides. However, fludioxonil always performed statistically better than thiophanate-methyl and numerically better than triflumizole as indicated by lesion incidence, lesion length and girdling incidence. For Rhizoctonia root rot, two trials were completed, each with two fungicide applications (when cuttings were stuck and 2 weeks later). Fludioxonil and azoxystrobin (Heritage) significantly reduced lesion incidence and lesion length in both trials. Flutolanil (Prostar) reduced lesion incidence in both trials and also reduced lesion length in the second trial. Pending labeling for this use pattern, fludioxonil, which has provided good control of both diseases in our trials, may form the basis of a fungicide rotation program to supplement sanitation practices for managing Cylindrocladium and Rhizoctonia root rots in blueberry propagation. 相似文献
9.
《中国油料作物学报(英文)》2020,5(4):174-179
Southern stem rot, caused by Sclerotium rolfsii Sacc., is a destructive soil fungal disease of peanut in China and other countries. To evaluate resistant germplasm, a total of 256 peanut accessions were investigated on their resistance to southern stem rot in 3 environments by artificial inoculation. Variance analysis indicated that disease index was significantly influenced by environment, genotype and genotype × environment interactions. Peanut accessions of var. vulgaris type exhibited higher resistance to southern stem rot. Disease index was significantly negatively correlated with linoleic acid content, while positively correlated with oleic acid content. Six resistant accessions were identified, including Hua 28, Shandongzai, ICG 6326, Quanhua 7, Quanhua 9 and Guihua 836, with their disease indexes under 40 and mortality were less than 30% in the three environments. The identified resistant accessions showed the great potential to be applied in resistant peanut breeding, and would be good genetic resources for enhancing the resistance to southern stem rot. 相似文献
10.
Peanut pod rot, which can be caused by Pythium spp. and Rhizoctonia solani, is difficult to manage with fungicides. The objective of this study was to compare the effects of a calendar-based (CB) versus threshold-based (INC) fungicide application timings on pod rot incidence, yield, value of the crop, and returns minus fungicide cost. Large plot replicated trials were conducted in five fields with a history of pod rot. Pod rot was assessed weekly throughout the season following development of pods. Disease incidence was reduced by the preventative CB compared with INC or the non-fungicide treated control (NONE) in three of five sites. Disease was very low in the remaining two sites. Yield was not affected by treatment at individual sites, but in a combined analysis, INC at 1–2% incidence had higher yields than CB treated with mefenoxam or NONE. Occurrence of segregation 2 kernels, which results in a substantial reduction in price, was more frequent with INC and NONE than with CB at two sites. CB and INC had a higher value/ha than NONE, but there were no differences in return minus fungicide costs. CB had less pod rot during the season and a lower risk of segregation 2 kernels at harvest than INC. These results suggest that preventative CB applications made at early pegging should be used to manage pod rot. This recommendation is based on the reduction of risk to segregation 2 kernels, not because of a higher value/ha of the crop. 相似文献
11.
Fungicides are commonly applied as prophylactic sprays, with the expectation of increased yield and kernel quality, to control husk spot of macadamia in Australia. However, economic benefits from fungicide applications to control husk spot have rarely been quantified. We investigated the effectiveness, efficiency and economic returns of fungicide spray applications for husk spot control using three different spray application volumes and two dose rates of tank mixtures of carbendazim and cupric hydroxide under commercial macadamia orchard conditions. Husk spot incidence and severity were significantly (P < 0.001) different among the treatments and between the two years. In both years, the rate of fruit abscission was highest in the untreated control followed by low spray application volumes, but reduced with increasing spray volume. The quality and value of nut-in-shell increased when nut abscission was delayed. Poor quality and low nut-in-shell value of $2.85 kg−1 in 2010 and $2.12 kg−1 in 2011 were obtained in the untreated control trees that abscised early in the harvest period compared with the average nut-in-shell value of $2.95 kg−1 in 2010 and $2.46 kg−1 in 2011 in the fungicide treated trees. Gross margins for each fungicide treatment schedule compared to the untreated control averaged over both years showed positive contributions of 20%, 10% and 6% for the high, moderate and low dilute rate volume applications, respectively. Our data further indicates that dilute rate applications at higher volume may be more beneficial and cost-effective than concentrate rate applications in husk spot control programs. Overall, harvest yield increased by 11%–33% when husk spot was controlled using fungicide sprays compared to no fungicide spray applications. The benefit-cost ratios revealed highly significant benefits for the implementation of husk spot management programs. 相似文献
12.
Disease forecasting models assist producers in estimating the likely appearance of disease in their crops and in the selection and timing of preventative applications. The first objective of this study was to evaluate the accuracy of a weather-driven model for predicting infection by Taphrina deformans in different peach-growing areas. In 12 peach-growing areas in the Prefecture of Imathia, Greece, and over two years, the timing of initial infections differed depending on differences in the microclimate (mainly in temperatures and leaf wetness). There was a difference up to 9 days in the date of disease onset predicted by differences in the microclimate between regions. The model accurately predicted the observed differences in date of first symptom appearance. There was also a good correlation between predicted risk and observed disease severity. In addition, differences were observed among areas in the level of risk and the intensity of symptoms with a trend that areas at higher risk having a higher intensity of symptoms. The second objective of this study was to investigate advantages arising from using the model for scheduling fungicide applications against peach leaf curl. In five years of trials, the use of the model reduced the number of sprays compared to conventional spray program while achieving similar level of control. The simple rule of "spray one day before first forecasted rain after bud break" also gave good results. Trials were set up in order to determine the risk threshold for spraying based on model predictions. The results indicated that spraying only when the predicted risk was between 40 and 60 (over a maximum of 100) might be the most effective rule, but further investigations should be conducted to clarify the relationship between the predicted risk, actual peach leaf curl incidence and, more importantly, yield in order to determine the time when fungicide sprays are economically justified. 相似文献
13.
Leaf removal reduces the epiphytic populations of several filamentous fungi found on grapevine (Vitis vinifera). Consequently this practice is used to prevent foliar diseases of grapevines and rots of grapes. In this study, the effects of leaf removal on Cladosporium rot (Cladosporium cladosporioides and Cladosporium herbarum), which often affects ‘Cabernet Sauvignon’ in Chile, were characterized. The effects of leaf removal on epiphytic populations of Cladosporium spp. on grape berry surfaces and on Cladosporium rot development were investigated. Three leaf removal treatments were compared: (i) severe leaf removal, where leaves from two to three nodes above, opposite and from all nodes below clusters were removed; (ii) mild leaf removal, where leaves opposite each cluster were removed; and (iii) no leaf removal. Regardless of the leaf removal treatment, low population levels of Cladosporium spp. were detected early in the ontogenic development of grape berries which increased as the berries matured, reaching maximum populations on overripe berries. Based on our results, severe leaf removal favors the growth of Cladosporium spp. on grape berries and increases the prevalence of Cladosporium rot at harvest. This increase in Cladosporium spp. was correlated with an increase in lenticel damage in ‘Cabernet Sauvignon’ and ‘Sauvignon blanc’ vines subjected to severe leaf removal. Considering that Cladosporium rot significantly reduces yield and wine quality, farmers should avoid continuous exposure of grape clusters to sunlight in order to prevent severe outbreaks of Cladosporium rot. 相似文献
14.
不同花生品种对稻田镉富集及转运的研究 总被引：1，自引：0，他引：1
为研究湖南湘江流域稻田镉（Cd）污染治理方法,筛选稻田替代种植作物,于长沙县和湘阴市受污染稻田 改种花生,选用5个大果品种,设置2种（露地、覆膜）栽培方式,研究品种与栽培方式组合下对稻田Cd吸收、富集及 转运的影响。结果表明：稻田花生营养器官（根、茎、叶）Cd含量较高,生殖器官（果壳、籽仁）Cd含量较低,且品种间有明显差异。5 个花生品种的组织器官中Cd 含量最高的是茎（5.413~8.859mg·kg-1）,果壳和籽仁最少（0.523~ 1.326mg·kg-1）,但是籽仁Cd含量超出NY/T 1067-2006标准的规定值,食用安全存在风险。覆膜栽培尽管降低了花生茎、叶、果针、果壳及籽仁等的Cd含量,但提高了植株干物质重和Cd总积累,其中,营养器官（根、茎、叶）Cd富集系数高于2.5,生殖器官（果壳、籽仁）Cd富集系数为0.8~1.7。不同部位间Cd转移系数大小顺序为：根→茎秆>茎秆 →叶>果壳→籽仁>果针→果壳>茎秆→果针。不同品种的花生油中Cd含量范围在0.012~0.074mg·kg-1,符合标准, 因此花生油食用是安全的。以地上部单株干物质积累量及其Cd含量作为高镉积累筛选指标,5个品种中09-3106 的单株可高积累镉元素。建议在湘阴、长沙等地的Cd污染稻田进行覆膜栽培花生。 相似文献
15.
In southern Sweden, fungicide treatment of winter wheat is prevalent and recommended almost routinely against leaf blotch diseases. However, yield increases and hence the resulting net returns from fungicide use are highly variable within and between years. These variations raise questions about whether, when and how fungicides should be used. To help answer these questions, a thorough economic evaluation of fungicide use was carried out, based on results from untreated plots and fungicide-treated plots in trials in farmers' fields, 1983–2007. Scenarios with varying grain prices and costs of fungicide treatment were evaluated and examined. Doubling and tripling the grain price led to the largest impact on the net return from fungicide treatment, followed by increasing cost of the fungicide. Other costs were of minor importance. The mean net return from fungicide use was no more than 12 € ha−1 over the 25 years (2008 grain prices and costs used in calculations). Furthermore, the mean net return was negative in 10 years and less than 50% of the entries were profitable to treat in 11 years. Changes over time and changes in controllable factors (e.g. fungicide and cultivar choice, crop rotation, techniques) and uncontrollable factors (e.g. emerging and new diseases, price relations) influenced the profitability of fungicide use. Fungicide use was in fact more profitable (mean net return 21 compared with 3 € ha−1) during the latter part of the period (1995–2007) than in the earlier part (1983–1994). Improved decision support systems in a holistic framework based on sound economics are urgently needed. 相似文献
16.
Cercospora beticola, causal agent of Cercospora leaf spot (CLS) of sugar beet, is primarily controlled by fungicides. Benzimidazole and demethylation inhibiting fungicides, including carbendazim and flutriafol, have been widely used in Serbia. Since these fungicide groups have a site-specific mode of action, there is a high risk for developing resistance in target organisms, which is the most important limiting factor in Cercospora leaf spot chemical control. A rapid identification of flutriafol and carbendazim resistance can help researchers in examining the potential of different fungicide resistance management practices, as well as in selection of fungicides for use in the areas where resistance has occurred. One hundred single-conidia isolates were collected from 70 representative locations of the sugar beet production region in Serbia. Evaluation of the isolates' sensitivity was based on the reduction of mycelial growth on medium amended with 1.25 μg mL−1 flutriafol and 5 μg mL−1 carbendazim. Resistance to flutriafol and carbendazim was detected in 16% and 96% of the tested isolates, respectively. All isolates resistant to flutriafol were resistant to carbendazim as well, which is the first report of a double resistance to fungicides in C. beticola. Detection of the isolates resistant to flutriafol and carbendazim using Cleaved Amplified Polymorphic Sequence (CAPS) markers confirmed the results of the in vitro tests. The efficacy of carbendazim, flutriafol, azoxystrobin, and tetraconazole at commercially recommended doses was evaluated in field trials where sugar beet plants in plots were inoculated with a mixture of isolates either sensitive and/or resistant to flutriafol and carbendazim. Carbendazim and flutriafol efficacy was very low in plots inoculated with isolates resistant to these fungicides. Presented results will contribute to development of a pathogen population sensitivity monitoring strategy that could be used for an effective CLS management in the region. 相似文献
17.
Frogeye leaf spot, caused by Cercospora sojina, causes yield reductions to soybean (Glycine max) grown worldwide. Quinone outside inhibitor (QoI) fungicides have been effective in managing frogeye leaf spot, but the risk of selecting C. sojina strains with resistance to this class of fungicides is considered high. A QoI fungicide resistance monitoring program was initiated, in which sensitivities to azoxystrobin, pyraclostrobin, and trifloxystrobin were determined in C. sojina isolates collected prior to QoI fungicide use on soybean (baseline group) and C. sojina isolates collected from soybean fields in 2007, 2008 and 2009. For the baseline group, the mean effective fungicide concentration at which 50% of the conidial germination was inhibited (EC50) was determined to be 0.01287, 0.00028 and 0.00116 μg ml−1 for azoxystrobin, pyraclostrobin and trifloxystrobin, respectively. When mean EC50 values of 2007, 2008 and 2009 C. sojina isolates were compared to baseline C. sojina EC50 values, a small but statistically significant (P ≤ 0.05) shift towards less sensitivity was observed for trifloxystrobin in 2009. Although small (<1.5-fold), this shift in sensitivity indicates a risk of selecting for C. sojina strains with reduced sensitivity to QoI fungicides, and fungicide sensitivities should continue to be monitored in the future. 相似文献
18.
The efficacy of certain biocontrol agents were evaluated against Cephaleuros parasiticus Karst, a causal organism of red rust disease in tea plants. Spraying of systemic fungicides was found to be superior to biocontrol agents followed by algicides in controlling the disease under field condition. Dipping of shears in the solutions of fungicide, detergent or biocontrol agents failed to protect the disease spread. The study on the impact of different harvesting practices on disease development showed the highest disease incidence in continuously shear harvested fields and least in hand plucked fields. There was a reduction in disease incidence in spraying of a solution containing urea and murate of potash mixture at 1% level. The maximum green leaf yield and productivity index were recorded in biocontrol agents treated plots. Among the various group of biocontrol agents evaluated, Streptomyces sannanensis and Streptomyces griseus belong to actinomycetes was better than bacterial and fungal antagonists in terms of disease protection and increase in yield potential. Similarly, tea bush canopy architecture, physiological and biochemical parameters were also increased in plants treated with biocontrol agents. In the case of untreated control plots, the disease incidence was increased from 36% to 44.5% and the plants were found unhealthy in terms of chlorosis, stunted growth and heavy flowering with banji buds. The shoots collected from treated and untreated control plots were subjected to manufacture CTC black tea which revealed almost all the tea quality parameters were significantly improved in the treated plot over the untreated plots. 相似文献
19.
Blaire C. Colvin Barry L. Tillman Diane L. Rowland John E. Erickson Albert K. Culbreath 《Journal of Crop Improvement》2018,32(3):287-304
The indeterminate nature and underground fruiting habit of peanut (Arachis hypogaea L.) makes it a challenge to determine the optimal harvest time. The objectives of this study were (1) to gain additional information about how maturity and canopy health influence peg strength, yield, and grade and (2) to address anecdotal claims of differences in peg strength and digging losses among cultivars. Field trials were established in Citra, FL, and Tifton, GA. Two peanut cultivars (“Georgia-06G” and “Tifguard”) were grown under two fungicide programs (full program: every 14-day spraying interval; and reduced program: every 28-day spraying interval), and harvested at three different maturity levels (early, optimum, and late based on an accumulated growing degree day method). The fungicide program had a significant impact on yield only in 2013 at Citra, likely because the canopy structure was decreased because of fungal disease known as leaf spots (causal agents: Cercospora arachidicola and Cercosporidium personatum). The timing of the harvest had a significant impact on yield, grade, peg strength, and digging loss. In addition, yield, grade, peg strength, and digging losses differed between the peanut cultivars. These results show that reduced fungicide program might affect the yield because of the disease severity and that the optimal harvest time should consider the level of the defoliation. Although there was no correlation between peg strength and digging loss, over-maturity can cause more digging losses compared to optimal harvest time. Tifguard had higher digging loss than Georiga-06G. This study provides additional useful information on cultivars to growers. 相似文献
20.
Jeffrey S. Miller Nora Olsen Lynn Woodell Lyndon D. Porter Shane Clayson 《American Journal of Potato Research》2006,83(3):269-278
Potato storage tuber rots caused by the late blight and pink rot pathogens at harvest can cause severe economic losses, warranting the need for effective post-harvest fungicide applications. The purpose of this study was to evaluate the efficacy of select post-harvest fungicides in reducing tuber infections by the late blight and pink rot pathogens when applied at various post-inoculation time intervals. ‘Russet Burbank’ potatoes were inoculated by submersion in an aqueous suspension ofPhytophthora infestans orPhytophthora erythroseptica zoospores at 0, 1, 2, 4, and 6 h prior to receiving a post-harvest treatment. Products evaluated were zoxamide (various rates and formulation), phosphite (335 g a.i./MT), and a hydrogen peroxide/peroxyacetic acid mixture (HPPA, 9 g a.i./MT), all applied at 2.08 L/MT of tubers as a low pressure spray prior to storage. Zoxamide and phosphite significantly reduced late blight and pink rot incidence and severity when applied immediately after inoculation. HPPA was less effective at controlling disease development. Phosphite was effective at reducing late blight development at all time intervals up to 6 h post-inoculation (7% vs 80% in untreated). Zoxamide appeared to have good post-harvest disease control if applied soon after inoculation. The maximum time intervals between inoculation and treatment where significant reductions in pink rot incidence were observed was 0 h for HPPA (28%), 2 h for zoxamide (55%; 64 g a.i./MT) and 6 h for phosphite (13%) compared to the untreated (73%). Phosphite provided consistent disease control even when applied several h after inoculation and has potential to be a reliable post-harvest fungicide for the potato industry. 相似文献