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Epichloë typhina (Ascomycetes: Clavicipitaceae) is an endophytic fungus that infects perennial Pooid grasses and is the causal agent of choke disease. It is endemic to Europe and was inadvertently introduced ...
Citation Citation
- Title:
- Epichloë typhina (fungus) - Botanophila lobata (fly) interaction : an invasive "pollinator" system in its introduced range in western Oregon
- Author:
- Kaser, Joseph M.
Epichloë typhina (Ascomycetes: Clavicipitaceae) is an endophytic fungus that infects perennial Pooid grasses and is the causal agent of choke disease. It is endemic to Europe and was inadvertently introduced into orchardgrass seed production fields in western Oregon. Choke disease, which was first recorded in Oregon in 1996, currently infects ~90% of cultivated orchardgrass seed fields in the region, resulting in yield losses >65%. Infective propagules (i.e. ascospores) are produced sexually by the bipolar heterothallic fungus and gamete outcross has been shown to be facilitated in the wild by Botanophila spp. (Diptera: Anthomyiidae), including Botanophila lobata. The fly - fungus interaction is generally considered to be one of obligatory mutualism based on studies conducted in areas endemism. However, recent evidence suggests that the fungus is able to sexually outcross in cultivated Oregon orchardgrass fields without the aid of fly "pollinators." Additionally, ascosporic fertilization has recently been implicated as an alternative mechanism for gamete transfer and might have important impacts on fungal reproduction in Oregon. The objectives of this study were to: 1) explore how two tightly linked species, which appear to have an obligate mutualistic relationship in areas of endemism, interact in a non-native context; 2) quantitatively examine the seasonal and diurnal presence of E. typhina ascospores in a cultivated Oregon orchardgrass field; and 3) test alternative transfer mechanisms of fungal spermatia for E. typhina. To address objective 1), the spatial variability and reproductive success of E. typhina and B. lobata were estimated during surveys of ten cultivated orchardgrass fields in 2008 and four fields in 2009. Fungal distributions were spatially aggregated at five of the study sites in 2008 and three in 2009. Fly distributions were spatially aggregated at three sites in 2008 and one in 2009. Botanophila lobata density exhibited a positive linear relationship with E. typhina density, suggestive of positive density dependence of fly oviposition with fungal density. However, fungal reproductive success was not affected by fly density or fungal density within the range of distributions observed in this study. To address objective 2), airborne ascospores were monitored in a single cultivated orchardgrass field during 2008 and 2009 using a Burkard volumetric spore trap. Ascospore production began in early to middle May and continued into late July during both years of the study. Daily ascospore production exhibited a circadian rhythm, with production peaking on average at 1:08 am and 12:36 am, in 2008 and 2009, respectively. The prolonged duration and high intensity of ascospore production during the growing season suggest a large window within which new plants are at risk to infection, and within which preventative management strategies must be adopted. To address objective 3), splash fertilization, contact fertilization and B. lobata fertilization were tested in the greenhouse. Although only two replicates were completed, both contact and splash fertilization appeared to be viable mechanisms of sexual outcross for E. typhina. The results of this study strongly indicate that E. typhina can successfully reproduce without the presence of B. lobata. Splash and contact fertilization, as well as ascosporic fertilization, provide opportunities for reproduction of the fungus in absence of fly pollinators. It appears that the fly - fungus interaction has shifted from an obligatory mutualism to facultative mutualism or simple fungivory within the introduced range in western Oregon.
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Brown marmorated stink bug (BMSB), (Halyomorpha halys, Hemiptera: Pentatomidae) is an invasive species that damages numerous agricultural crops including grapes. Related damage include lower ...
Citation Citation
- Title:
- Brown Marmorated Stink Bug (BMSB), Halyomorpha halys Taint in Wine : Impact on Wine Sensory, Effect of Wine-processing and Management Techniques
- Author:
- Mohekar, Pallavi, 1985-
Brown marmorated stink bug (BMSB), (Halyomorpha halys, Hemiptera: Pentatomidae) is an invasive species that damages numerous agricultural crops including grapes. Related damage include lower berry weight with increased exposure and cracked berries as a result of BMSB feeding activity. The insect is currently detected in 43 US states including Oregon, Washington, California, and New York. The grape and wine industries in these areas hold significant economic value. BMSB damage has already resulted in major economic loss in the agricultural industry. Current data indicates that the infestation is spreading to new regions and its population density is increasing in regions where it has been detected. Surveys show BMSB in vineyards of Oregon, Virginia and New York where BMSB can damage grapes, lowering their yield and quality. When harvested with grape clusters, BMSB can introduce volatile compounds, trans-2-decenal and tridecane, into wine. Prior work has shown that the presence of these compounds alters wine sensory. In this thesis, the focus is on analyzing BMSB’s impact on wine quality and consumer preference. Additionally, this work determines the action threshold (AT) for BMSB in the vineyard, which is likely to prove important to the grape and wine industry in designing control limits and maintaining wine quality. The first contribution of this work establishes the sensory detection threshold (DT) and consumer rejection thresholds (CRT) for trans-2-decenal in red wine. Trans-2-decenal is one of the main aroma compounds in BMSB taint, having green, cilantro-like aroma characteristics that is undesirable in wine. Results conclusively show that trans-2-decenal in wine has a negative effect on its quality. In Pinot noir, consumers were able to perceive trans-2-decenal at 1.92 µg/L (DT). Consumer preference for Pinot noir and Merlot containing trans-2-decenal decreased significantly above the concentration of 4.8 µg/L (CRT). Pinot noir containing trans-2-decenal above CRT was described as green, herbal, musty and less fruity by wine professionals. Based on such findings, the use of CRT is recommended when establishing consumer tolerance levels of trans-2-decenal in wine. The second contribution relates BMSB presence in vineyard with sensory threshold of trans-2-decenal in the finished wine. Pinot noir, Merlot and Pinot gris were produced using different densities of BMSB in grape clusters. The results of this study indicate BMSB density of three per cluster can result in Pinot noir containing trans-2-decenal at its DT and below its CRT. This density can be used as AT for BMSB in the vineyard since wines made from grapes contaminated at or greater than 3 BMSB per cluster are likely to experience low preference by wine consumers. The same BMSB density can be used to devise control measures for Merlot since trans-2-decenal CRT was found to be similar for both Pinot noir and Merlot. Pinot gris was found to be free of trans-2-decenal even at BMSB density of 1 per cluster. Therefore, we believe that BMSB may not be a concern for white wines. The third contribution provides methods to reduce BMSB taint in finished wine. This can be done by modifying the winemaking process or by applying corrective measures in the wine. During winemaking, destemming and pressing were identified to be the steps responsible for increasing BMSB taint levels in wine whereas alcoholic fermentation decreases taint levels. Consequently, finished white wine was found to be free of trans-2-decenal since fermentation occurs after pressing. However, trans-2-decenal was present in finished red wine since pressing occurs after fermentation. Taint levels in finished red wine are also affected by different pressing variants (free run versus press fraction, bladder press versus basket press), with press fraction and bladder press introducing more BMSB taint compared to free run and basket press. This information will allow winemakers to adjust processing steps in order to minimize BMSB taint levels in red wines. Further reduction in taint levels was shown to be possible through the use of reverse osmosis filtration. Alternatively, oak addition can be used to mask the sensory attributes of trans-2-decenal at the risk of introducing spicy notes into wine. None of the other common fining agents tested were found to be effective against trans-2-decenal. Taken together, this thesis contributes a number of novel insights into the impact of BMSB on red and white wine. By relating consumer thresholds and descriptive analysis with chemical and wine processing, we are able to establish control densities for the pest in the vineyard, identify key processing steps and post-fermentation treatments to reduce BMSB taint. The information contained in this thesis is likely to prove valuable to the wine industry in its struggle against BMSB.
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This fifth annual Cooperative Pole Research Program report outlines our progress in the six project objectives. Improved Fumigants Sampling of previously established field tests revealed that Vorlex and ...
Citation Citation
- Title:
- Conserving energy by safe and environmentally acceptable practices in maintaining and procuring transmission poles for long service ; August 1985
- Author:
- Oregon State University, Oregon State University. Dept. of Forest Products
This fifth annual Cooperative Pole Research Program report outlines our progress in the six project objectives. Improved Fumigants Sampling of previously established field tests revealed that Vorlex and Chloropicrin continued to perform well after 15 years, while Vapam was slightly less effective. Solid methylisothiocyanate (MIT) also performed well in the field after 7 years. In additional tests, gelatin encapsulated MIT migrated through Douglas-fir heartwood with addition of moderate quantities of water to degrade the gelatin. However, in the presence of higher quantities of water or no additional water, MIT migration into the wood was slowed. In a previously established test, gelatin encapsulated MIT continues to inhibit reinfestation of poles 3 years after treatment. Pelletized MIT is a new formulation (65% active ingredient) that appears to have some promise. Preliminary tests indicate that up to 95% of the MIT is release in 24 hours, but a small quantity of MIT remains in the pellets after 63 days aeration and may pose a disposal hazard. The solid MIT formulations will permit aboveground applications, increasing the risk that MIT will come in contact with pole hardware. Preliminary tests indicate that MIT had little effect on corrosion of hot dipped, galvanized bolts attached to wood. This suggests that treatment in the crossarm zone with MIT or fumigants that produce MIT should not affect the integrity of attached hardware. i-i In addition to fumigant evaluations, we recently examined an earlier test of groundline treatments with Osmoplastic® and Hollowheart®. After 10 years, these treatments are performing reasonably well, with only a slight rise in the incidence of decay fungi in the past 4 years. We also reevaluated the effectiveness of kerfing for preventing decay and found that this process reduced the depth and width of checks, resulting in a decreased incidence of decay fungi. Kerfing appears to be a valuable method for preventing internal decay at the groundline. Cedar Sapwood Decay Control This past year, the second set of five chemicals applied to control sapwood decay were evaluated after 2 years of exposure. As in earlier evaluations using the Aspergillus bioassay, none of the chemicals approach pentachlorophenol in oil for ability to inhibit sporulation of Aspergillus niger; however, several samples from zones deep in the wood produced a slight zone of effect. This may indicate the presence of a reservoir for long-term protection against decay. Several of the chemicals including Fluor Chrome Arsenic Phenol and Ammoniacal Copper Arsenate (ACA) appear to bind to the wood and may be difficult to detect by the bioassay method. We expect to assess the effectiveness of these treatments using a soil block test. Investigations of the reliability of the Aspergillus bioassay under a variety of conditions indicated that quantity of spores, use of glass or plastic petri dishes, long-term cold storage, and the use of spray inoculum instead of flooding spores had little influence on the bioassay results with pentachiorophenol, Tributyl-tinoxide, or 3 iodo propynyl butylcarbamate; however, incubation temperature did influence assay results. The Aspergillus bioassay is a simple, effective means for estimating residual preservative levels. Bolt Holes Again this year, wood around the unprotected, control bolt holes in pole sections contained such low levels of decay fungi that evaluation of the treated poles will be delayed another year. In addition to the initial bolt hole treatments, we have begun a test to determine if gelatin encapsulated or pelletized MIT can prevent decay development in field-drilled bolt holes. The pole sections used in these tests had already begun to develop decay prior to treatment and will provide an ideal test material. Detecting Decay and Estimatin& Residual Strength of Poles Fluorescent labeled lectins used in our earlier studies detected decay fungi at low weight losses under laboratory conditions. We are currently evaluating this method for detecting fungi in increment cores removed from poles to reduce the need for culturing. Last year we identified a peak that was unique to infrared (IR) spectra of warm water extracts from decayed wood. This past year we attempted to identify the chemical responsible for this peak and found that carbonyl compounds, probably from oxidative lignin degradation, were responsible for the peak. Since brown rot fungi apparently do iv not completely metabolize lignin breakdown products, they accumulate in the decaying wood and can be readily detected by their IR spectra. Strength properties of beams cut front Douglas-fir pole sections, air-seasoned for 3 years significantly decreased although decay fungi could not be uniformly isolated from the beams. In addition, there were gradual declines in work to maximum load and modulus of elasticity, as well as increased Pilodyn pin penetration. These results suggest that some strength losses occurred during air-seasoning; however, the losses were not large and should not endanger pole users. We compared several test methods including the Pilodyn, radial compression tests, longitudinal compression tests, and the pick test for evaluating residual pole strength of the wood surface of Douglas-fir treated with combinations of funtigants or groundline wraps. The results indicate that only the pick test could accurately detect surface damage and illustrate the difficulty of detecting surface damage. This past year we evaluated several sections cut from ACA treated poles stored for a number of years to determine if they were worth salvaging. Static bending tests of beams cut from the ACA treated zone, the treated/untreated boundary, and the inner heartwood revealed ACA treated sapwood had lower MOR and longitudinal compression strength than the other zones. These results represent only a small sample, but they suggest that some strength loss occurs during ACA V treatments. More importantly, the results suggest that we could have reliably predicted beam MOR by testing small plugs removed from the poles. Small beams cut from decaying, pentachlorophenol treated Douglas-fir poles were acoustically tested for residual wood strength, then evaluated to failure in static bending. The acoustic test consisted of sending a pulsed sonic wave into the wood and recording this wave after it passed through the beam. As it moved, the wave was altered by the presence of any wood defects or decay, and these alterations create a "fingerprint" specific for that defect. Preliminary results indicated that signal analysis was highly 2 2 correlated with work to maximum load (r =.82) and MOR (r .88), suggesting that this approach to decay detection may prove more reliable than measuring of sound velocity. Initiation of Decay in Air-Seasoning Douglas-fir The results of the initial survey to determine the incidence of decay fungi in poles from widely scattered Pacific Northwest seasoning yards indicated that a variety of fungi were colonizing the wood. While most of these fungi do not pose a serious decay problem, two species, Poria carbonica and Poria placenta, became increasingly abundant with length of air-seasoning. These fungi are also the most conunon decayers of Douglas-fir poles in service. As expected, the number of fungi and the wood volume they occupied increased with seasoning time; however, this incidence varied considerably between yards, especially in poles air-seasoned for vi shorter time periods. In addition to the variation between sites, many of the decay fungi colonizing the wood appear to be monokaryons, indicating that spores landing on the wood are initiating the infestation. The distribution of fungi within the poles indicated that several of the more abundant decay fungi were present in the outer sapwood where they would be eliminated by conventional pressure treatment. The remaining fungi were most abundant in the heartwood but were more concentrated near the pole end. This suggests that exposed end grain was more readily invaded than lateral grain exposed in checks. In addition to identifying the fungi colonizing Douglas-fir, we examined the effects these fungi had on wood strength. Toughness tests indicated the presence of wide variation in decay capability of the isolates. Although there was no consistent pattern, most of the isolates did not cause substantial decay and, of those that did, only . carbonica and P. placenta were sufficiently abundant to have a large influence on wood strength. Due to the prevalence of P. carbonica and P. placenta in the inner heartwood, where they might not be eliminated in a short heating cycle, we evaluated the temperature tolerance of these two fungi in Douglas-fir heartwood blocks. These tests indicated that both fungi were eliminated by exposure to temperatures above 71°C for over 1 hour or 60°C for 2 hours. The results suggest that careful control of temperature during treatment should eliminate decay fungi and that wood treated at ambient temperatures should be heated to kill fungi that become established during air-seasoning. vii This past year was the third and final year of the decay development study. In this study, sterile pole sections have been exposed for 1, 2, or 3 years at widely scattered Pacific Northwest sites, then returned to the laboratory and extensively sampled. We are now in the process of identifying the fungi from the third year poles. In addition to examining poles prior to preservative treatment, we are also evaluating poles treated with waterborne chemicals (ACA or CCA) for the incidence of surface decay. This past year we examined twenty ACA-treated poles from a line installed in 1946. While a variety of fungi were cultured from the wood, none of the poles had evidence of substantial surface deterioration. A study was initiated on the fungal flora of fumigant treated wood because of the potential for fungi developing resistance to low levels of fumigant or the ability to actively degrade the chemical. Both of these developments could shorten fumigant retreatment cycles and increase maintenance costs. We have evaluated poles treated 7 and 15 years ago with fumigants and find markedly reduced fungal flora. Tests are continuing on the fungi isolated, and we hope to assess the effects of these isolates on long-term fumigant effectiveness.