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1114 abstracts in the database

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Displaying results 31 to 60 of 1114

Year Num Title Author
2007 31 Response Of Winter Wheat To Postemergence Herbicides Applied In The Fall A. J. Chomas*, J. J. Kells, L. F. Siler, R. W. Ward; Crop and Soil Sciences, Michigan State University, East Lansing, MI
Weed control is essential for successful winter wheat production. Winter annual weeds have increased in winter wheat, leading to increased interest in fall herbicide application as compared to the typical practice of herbicide application in the spring. Field research was conducted in 2004 and 2005 at two sites each year and at one location in 2006 in Michigan to evaluate crop response to several postemergence wheat herbicides applied in the fall. Crop injury was evaluated at harvest and yields determined at all five locations. No significant injury, height reduction or yield reduction was observed with Banvel, Harmony Extra, Stinger, or Express used at typical use rates and with typical adjuvants. 2,4-D applied at either 0.5 or 1.0 lb ai/A injured wheat in three of the five sites and reduced wheat yield at one of two sites in 2004 and 2005. Addition of non ionic surfactant to 2,4-D amine reduced wheat yield at one of five sites. Increasing 2,4-D ester rate from 0.5 to 1.0 lb ai/A reduced wheat yield at one of five sites. 2,4-D reduced plant height at both sites in 2005 however, no height reduction was observed in 2006.

2007 32 Evaluation Of Uph 103 - A Sulfosulfuron Herbicide Against Complex Weed Flora In Wheat S. D. Sharma*,1 S. S. Punia,2 M. Singh1; 1Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 2Agronomy, CCS Haryana Agricultural University, Hisar, India
Resistance Phalaris minor is a big problem in India in wheat crop. There are several herbicides in the market to combat this problem in wheat crop. The aim of screening new formulations is to avoid any resistance development with the single use of a particular herbicide. Therefore a field experiment was conducted at CCS Haryana Agricultural University, Regional Research Station, Karnal using wheat cv. PBW-343 in the year 2003-04. New herbicide formulation UPH 103, a mixture of sulfosulfuron and metsulfuron, was evaluated and compared with the other existing sulfosulfuron herbicide. All the herbicide treatments were applied at 35 days after sowing by knapsack sprayer using flat fan nozzle delivering 300 L water/ha volume. The experiment was conducted with the aim to control both grassy as well broadleaf weeds in wheat crop. It was observed that with the application of UPH 103, the number of P. minor and broadleaf weed plant and their dry weight were significantly lower than the untreated plots. There was no significant difference in crop height and length of earhead among the treatments. Similarly yield parameters viz. number of effective tillers and grain yield were significantly higher under UPH103 treatments as compared weedy plot. There was no significant difference between the two formulations of sulfosulfuron. Higher doses of UPH103 e.g. 80 and 120 g a.i. ha-1 showed phytotoxic symptoms on the growing wheat plants but this effect was recovered later and there was no loss of yield under these plots. This study showed that there was effective control of Phalaris minor and broadleaf weeds even at the lowest rate of 15 g a.i. ha-1 UPH applied in the crop. shiv901@ufl.edu

2007 33 Potential For Crop Injury And Reduced Control Of Wild Oat In Spring Wheat (Triticum aestivum) When Tank Mixing Several Fungicides With Several Common Grass And Broadleaf Herbicides. J. J. Wiersma*, B. R. Durgan, J. H. Cameron; University of Minnesota, St. Paul, MN
A randomized complete block treatment design consisting of individual and tank mixtures of the postemergence grass herbicides clodinafop & cloquintocet, fenoxaprop-P, and AEF 103060 and the broadleaf herbicide bromoxynil & MCPA applied at labeled rates, and the fungicides trifloxystrobin & propiconazole (Stratego) and azoxystrobin & propiconazole (Quilt) applied at half the labeled rate were evaluated for their potential to cause crop injury and reduce wild oat (Avena fatua) control. The experiment was conducted from 2004 through 2006 at the Northwest Research & Outreach Center in Crookston, MN on a Donaldson loam (coarse-loamy over clayey, mixed over smectitic, superactive, frigid oxyaquic Hapludoll). The experimental site had been maintained to provide an even wild oat population. The plot area was chisel plowed the previous fall and a seed bed was prepared in the spring using a field cultivator. The hard red spring wheat cv. ‘Alsen’ was solid seeded to a 4 cm depth in six 5 m strips using a double-disk press drill. The strips were separated by a 2.5 m alley. Within each strip, 2.5 m wide plots were marked. Treatments were applied to the center 1.8 m of the plot using a CO2 powered backpack sprayer equipped with 80015 flat-fan nozzles delivering 93.5 L ha-1 at 0.24 MPa. The three solid-seeded strips of Alsen formed the 3 replicates. The application was made at the 4.0 leaf stage of wheat. Crop injury on wheat was rated at 7, 14, 21, and 28 days after application. Wild oat control was evaluated at 21 and 28 days after application. Grain yield was estimated by harvesting the center 1.8 m from each plot with a plot combine. Bromoxynil & MCPA in combination with any of the three grass herbicides and either fungicide caused significantly more crop injury at 7 days after application then the three grass herbicides individually or in tank mixtures with either fungicide in two of the three years. Also, bromoxynil & MCPA in combination with the postemergence grass herbicides and either fungicide resulted in less control of wild oat at 28 days after application then the grass herbicides individually or in tank mixtures with either fungicide. The crop injury was localized to the fourth and fifth leaves and new growth did not show any injury symptoms. At 14 days after application crop injury had decreased and no crop injury was found at 21 and 28 days after application. Wild oat in plots treated with bromoxynil & MCPA in combination with any of the three grass herbicides and either fungicide showed considerable phytotoxicity (necrosis). The observed phytotoxicity in the wild oat was identical to phytoxicity that can be observed in wheat with bromoxynil. Thus, the addition of either fungicide to the tank mix caused the additional crop injury of the bromoxynil & MCPA. Furthermore, the observed necrosis in the wild oat may explain the observed reduced control of wild oat as the necrosis caused by the bromoxynil & MCPA may have reduced uptake or translocation of either of the three grass herbicides. The crop injury at 7 and 14 days after application and the reduced control of wild oat had no effect on final grain yield.

2007 34 Seasonal Distribution And Relative Density Of Weeds In Fruit And Nut Nurseries Treated With Methyl Bromide And Alternate Fumigants A. Shrestha*,1 G. Browne,2 B. Lampinen,3 S. Schneider,4 L. Simon,5 T. Trout6; 1Statewide IPM Program, University of California, Parlier, CA, 2USDA-ARS, Davis, CA, 3University of California, Davis, CA, 4USDA-ARS, Beltsville, MD, 5University of California, Berkeley, CA, 6USDA-ARS, Fort Collins, CO
Perennial fruit and nut nurseries in California have relied on methyl bromide (MB) for broad-spectrum pest control, including year-long weed suppression. With the phase-out of MB, alternate fumigants are being explored in these nurseries. Shifts in fumigant usage may have important implications for weed management at nurseries. Therefore, we examined a hypothesis that use of fumigant alternatives to MB will result in species composition shifts in weed communities. Field studies were conducted in 2005 at nurseries in Hickman and Le Grand, CA to test the effect of MB and alternate fumigants on weed emergence. The treatments included: Control (no tarp); MB (98:2), 448 kg/ha, std HDPE; iodomethane:picloran (50:50), 448 kg/ha, std HDPE; Telone II, 380 kg/ha, std HDPE; Telone C35, 600 kg/ha, std HDPE; Inline 600 kg/ac, std. HDPE; and Telone C35, 600 kg/ha, VIF. The experimental design was a randomized complete block with four replications. Seasonal distribution and relative densities (density of a species/total weed density X 100) were determined from weed evaluations made during winter, spring, summer, and fall. No major differences in the relative densities of weed species were observed. However, Telone II appeared weaker than the other fumigants on burr clover (Medicago sp.). The relative density of fluffy-seeded weeds such as Conyza sp., Sonchus sp., and common groundsel (Senecio vulgaris) of the Asteraceae family was generally lower in the control (undisturbed plots) than the fumigated plots. Similarly, the relative density of burr clover (Medicago sp.) was also generally lower in the control plots. None of the fumigants provided adequate control of this species and cheeseweed (Malva sp.). This indicated that additional control measures would be required for these species. All the fumigants generally provided similar control of other weed species. Although weed species composition were generally similar between the fumigated plots, the results of this study may have been affected by the resident seed bank and the historical use of MB in these plots. Continuous long-term monitoring may be needed to ascertain weed species shifts.

2007 35 Weed Control Efficacy And Crop Safety For Beet, Spinach And Swiss Chard Herbicides J. O'Sullivan*, R. Grohs, R. Riddle; Plant Agriculture, University of Guelph, Simcoe, ON, Canada
The objective of this research was to identify herbicides, sequentials and tank mix combinations that will provide improved efficacy against weeds in beets, spinach and Swiss chard. Herbicides were evaluated for crop safety and weed control efficacy. Field studies were established, as a randomized complete block design with four replications, at the Horticultural Research Station, Simcoe, Ontario in 2005 and 2006. Beets, spinach and Swiss chard were planted on May 25, 2005 and on June 5, 2006. Herbicide treatments were applied with a small plot sprayer (200 L/ha, 240 kPa) at 1X and 2X the registered label rate (or manufacturer recommended rates for herbicides not yet registered). Untreated check plots were included. Visual injury at 21 days after herbicide application, crop yield, and percent weed control was determined. Data was analyzed by analysis of variance and means were compared using Fisher’s protected least significant differences at the 0.05 level of probability. All crops were severely injured by flucarbazone-sodium and linuron. Beets and Swiss chard were tolerant of other herbicides except triflusulfuron-methyl and desmedipham plus phenmedipham (injury >10% at 1X). Spinach was the most sensitive crop and was also injured by pyrazon (post), ethofumesate, clopyralid and dimethenamid. Only s-metolachlor and pyrazon (pre) at 1X application rates were safe on this crop. In many cases there were no significant yield reductions, despite the significant injury noted. Several herbicides gave good to excellent control of broad-leaf weeds and had yields comparable to weed-free control plots.

2007 36 Nutsedge (Cyperus sp.) Control In Highbush Blueberries (Vaccinium corymbosum) D. A. Boelk*, C. F. Fouche; Cooperative Extension, Univ of CA - Davis, Stockton, CA
Highbush blueberries are a recent addition to the crop mix in the Central Valley of California. Yellow and purple nutsedge are becoming pernicious weeds in this newer commodity. The perennial nature of the crop encourages the growth and proliferation of nutsedge amongst the plants on the berm and eventually in the lanes between rows. There is not currently an herbicide labeled for blueberries in California that adequately controls nutsedge, though a few will suppress the growth and spread for a limited time. Our study chose to look at several pre- and post- emergent herbicides, some of which are newly acquiring blueberries on their labels. Applications of pre-emergent herbicides were made in spring of 2006 and post-emergent herbicides were applied in summer of 2006. The experiment was implemented at three sites under two different watering regimes. Preliminary evaluation shows a marked benefit in nutsedge suppression out to 32 DAT with the application of Permit (halosulfuron)and with Rely (glufosinate) out to 21 DAT.

2007 37 Resistance To Foliar Herbicides In Long-term Experiments In Orchards R. A. Bulcke*, E. G. Mechant; Weed Science Unit, Ghent Univ., Ghent, Belgium
In four long-term experiments (EXP 1, 2, 3 and 4 respectively) in apple and pear orchards at three sites in Belgium, one or more of the foliar herbicides amitrole, paraquat and glufosinate-ammonium, were applied each year on the same plots. In EXP 1, amitrole (10 kg ai ha-1) applied at the end of winter over the 1961 - 1995 period, soon allowed a dense stand of annual meadowgrass (Poa annua). As all meadowgrass that had overwintered, was killed by the herbicide applied postemergence, it was not suspected to be resistant. In the mid-eighties, rather by chance, resistance of this population to amitrole applied through the soil was detected. So, the short soil residual activity of amitrole is likely to have played an important role in the selection of this resistant biotype. Comparable responses of another resistant Poa annua biotype collected in EXP 4 [amitrole (3.8 kg ai ha-1) applied once a year over the 1997-2004 period] further support this hypothesis. In EXP 2, following amitrole (2.5 kg ai ha-1, three to four times a year, 1964 - 2005), resistance evolved in creeping bentgrass (Agrostis stolonifera). Following application of paraquat (1 kg ai ha-1, three to four times a year) [EXP 2 (1970-2005) and EXP 3 (1987-1999)], there was a sudden appearance of a resistant biotype of American willowherb (Epilobium adenocaulon), a species that had not been recorded before on treated plots. Where glufosinate-ammonium (1 kg ai ha-1; EXP 2; 1979-2005) was applied three to four times a year, no resistance could be recorded so far. robert.bulcke@ugent.be

2007 38 Three Methyl Bromide Alternatives Being Developed In Georgia A. S. Culpepper*,1 A. L. Davis,1 T. M. Webster,2 A. W. MacRae,1 D. L. Langston3; 1Crop and Soil Sciences, University of Georgia, Tifton, GA, 2USDA-ARS, Tifton, GA, 3Plant Pathology, University of Georgia, Tifton, GA
The experiment was conducted in the spring of 2006 at The University of Georgia Ponder Research Farm located near TyTy, Georgia. Soil was a sandy loam with 92% sand, 6% clay, and 2% silt with 1% organic matter and pH of 6.5. A natural population of purple nutsedge (Cyperus rotundus) was present at 21 plants per meter square. Treatments included five fumigant options applied under three mulches. Fumigant options included 1) MB: methyl bromide plus chloropicrin (67:33, 392 kg/ha), 2) MIDAS: methyl iodide plus chloropicrin (50:50, 392 kg/ha), 3) DMDS: dimethyl disulfide plus chloropicrin (79:21, 701 L/ha), 4) Telone II/chloropicrin/Vapam: Telone II (112 L/ha) followed by chloropicrin (168 kg/ha) followed by Vapam (701 L/ha), and 5) no fumigant. Fumigants are expressed in broadcast rates but actually were applied only in the bed. Mulch options included low density polyethylene (LDPE), metalized smooth, or virtually impermeable film (VIF). Fumigants were applied on February 22, 2006 and ‘Heritage’ bell pepper was transplanted 20 d later. Plants were placed 30 cm apart down the row and 38 cm apart across the row with two rows on an 81 cm bed top. Plots were one bed (15 cm tall) by 8 m in length. Nutsedge Control: MB injected under LPDE mulch controlled purple nutsedge 98% at harvest. Control was similar with MIDAS and DMDS. The Telone II/chloropicrin/Vapam treatment was less effective than MB, but control was still 92%. In this treatment, nutsedge emerged on the outside two inches of the bed shoulder suggesting a fumigant placement issue. Applying MB, MIDAS, or DMDS under VIF or metalized mulch could not improve control. However, these mulches did improve control by the Telone II/chloropicrin/Vapam system to 99%. Pepper Response to Fumigants: At 18 days after fumigating, plant holes were poked and pepper were hand transplanted 2 d later. At 40 d after transplant, fumigant impact on plant growth was only noted with MIDAS under VIF (60% stunting) and metalized mulch (30% stunting). Pepper Yield: U.S. Fancy fruit were harvested five times. All fumigant alternative systems, except for MIDAS under VIF, produced pepper fruit number and weights equal to or greater than that of the standard MB under LDPE mulch. Yields from MIDAS under VIF were less than those of MB because of early-season fumigant injury. Summary: Preliminary results indicate alternatives to methyl bromide may exist for nutsedge control and pepper yield in Georgia. However, future studies across diverse environments and in large acreage on-farm trials are needed to confirm these results. Also, the multiple year affect of these alternative fumigants on pest pressures is not known, but is currently being studied.

2007 39 Screening For Preemergence Herbicides For Use In Basil (Ocimum Basilicum L.). L. Brandenberger*, L. Wells, B. Havener, D. Valdez; Oklahoma State University, Stillwater, OK
Screening for preemergence herbicides for use in basil (Ocimum basilicum L.). Due to the lack of labeled preemergence herbicides for herbs, the objective of this study was to identify and begin development of preemergence herbicides for use in basil. The study was completed in spring 2006 at the Oklahoma Vegetable Research station in Bixby, Oklahoma. Study design was a randomized block with four replications including 21 herbicides in 26 treatments and untreated and weeded checks. On 5/23/06 two pre-plant incorporated treatments were applied and incorporated then basil was direct seeded in 1 row on 12 inch row centers with three other plant species in three adjacent rows. Preemergence treatments were applied on 5/24/06 to the plots planted on 5/23/06 then irrigated with 0.5 inch of overhead irrigation. Plots received a total of 25 lbs/acre of nitrogen on 7/10/06. Crop injury and efficacy ratings were recorded on 6/20/06 and yield on 7/28/06. Eleven treatments (Carfentrazone + S-metolachlor, Glyphosate + S-metolachlor, Prodiamine, Flufenacet, S-metolachlor alone, S-metolachlor + Ethofumesate applied post, KIH 485, Prometryn, Dimethenamid-P, Oxyfluorfen and Sulfentrazone) resulted in 93 to 100% control of Palmer amaranth (Amaranthus palmeri S. Wats.). Basil was very sensitive to a majority of the herbicides that were included in the study. Only Linuron at 0.1 and 0.2 lb ai/acre, Flucarbazone-sodium, and Sulfentrazone had injury ratings less than 50%. Treatments that had fresh yields that were equal or better than the weeded check included 24,272 lb/acre for Sulfentrazone, 17,831 lb/acre for Flucarbazone-sodium, 16,803 and 15,937 lb/acre for Linuron at 0.1 and 0.2 lb ai/acre, 12,783 lb/acre for Ethofumesate at 0.5 lb ai/acre, and 12,191 lb/acre for Clomazone at 0.375 lb ai/acre.

2007 40 Identifying Weeds and Mint in Hyperspectral Images Using Spectral Vegetation Indices M. S. Gumz*,1 L. L. Biehl,2 S. C. Weller1; 1Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 2ITaP, Purdue University, West Lafayette, IN
Peppermint and spearmint are grown as high value essential oil crops in the Midwestern U.S. (IN, MI, and WI) and the Pacific Northwest (OR, WA, MT, and ID). Remote sensing-based site-specific weed management offers great potential to decrease weed control costs by simplifying weed detection and producing site specific herbicide application maps. If weed species in peppermint and spearmint fields could be consistently identified from spectral reflectance characteristics, this should reduce or eliminate the need for ground referencing when interpreting remotely sensed images. In the past, we used reflectance data obtained by a handheld spectroradiometer from mint and key weed species to develop spectral vegetation indices (SVIs) for differentiating species. Our objective in these studies was to apply SVIs calculated from spectroradiometer reflectance data to apparent reflectance data calculated from airborne hyperspectral images to determine which method had the highest accuracy for differentiating between mint and weeds in the image. Data obtained from a hyperspectral image have more variation than data from a handheld spectroradiometer due to atmospheric disturbances and the larger areas being sampled (fields compared to plots). However, airborne imagery is the fastest and most economical method to obtain reflectance data for production fields. SVI calculations were made from experimental field plots of peppermint, spearmint, giant foxtail, white cockle, tall waterhemp, Powell amaranth, common lambsquarter, and velvetleaf. SVIs based on simple ratios of reflectance values in the near infrared and green portions of the spectra accurately differentiated between peppermint and weed species, while simple ratios of near infrared and red reflectance values accurately differentiated between spearmint and weed species. Absolute values of SVIs varied between spectroradiometer and image calculations; however, the ratio of mint to weed SVI values was approximately 2 to 1 in both instances. This 2X difference in SVI values can be used to identify weedy areas of a mint field in a hyperspectral image and allow accurate targeting of postemergence herbicide application which would reduce costs and increase efficiency of weed management for growers.

2007 41 Response Of Seeded And Transplanted Yellow And Zucchini Squash (Cucurbita pepo) To S-metolachlor Applied At Planting Or Postemergence L. M. Sosnoskie*, A. L. Davis, A. S. Culpepper; Crop and Soil Sciences, University of Georgia, Tifton, GA
Concerns regarding crop sensitivity limit the use of herbicides in cucurbit production. Field experiments were conducted in 2004 and 2005 at the University of Georgia's Ponder Farm to evaluate the effects of s-metolachlor on summer squash (Cucurbita pepo L.) fruit number and weight per plot. Treatment variables were combined factorially and included: herbicide rate and application method (non-treated control, 0.5 pt/A-preemergence (PRE), 1 pt/A-PRE, 0.5 pt/A-PRE followed by 0.5 pt/A-postemergence over-the-top (POST) at 3 wks after planting, 0.5 pt/A-POST at 3 wks, 1 pt/A-POST at 3 wks), planting method (direct seeded and transplanted) and crop (yellow and zucchini squash). Plots were kept weed free throughout the growing season to avoid yield reductions effected by inter-specific competition. Visual estimates of crop stunting were taken throughout the season and fruit were harvested 12 times. Data were combined over years and subjected to mixed models analysis of variance (ANOVA). Injury symptoms were evident for both crops within 4-5 weeks of all PRE, PRE-POST and POST herbicide applications, although crop stunting was less severe when s-metolachor was applied POST. Averaged across crops and planting methods, early season (harvests 1-3) yields (number of marketable fruit per plot) were reduced by 37, 43 and 47%, as compared to the nontreated check, when s-metolachlor was applied at 0.5 pt/A-PRE, PRE-POST and 1 pt/A-PRE (P<0.05). Similarly, early season fruit weights (lbs per plot) were reduced by 38, 47 and 60%, as compared to the control, when s-metolachlor was applied at 0.5 pt/A-PRE, PRE-POST and 1 pt/A-PRE, respectively (P<0.05). Early season yields (both fruit number and fruit weight per plot) achieved using POST applications did not differ significantly from the non-treated check. Data taken from later harvest dates indicate that plants were beginning to recover from herbicide injury by the completion of the study. Although early season fruit number and weight per plot were influenced by planting method and crop variety, both seeded and transplanted yellow and zucchini squash appear to be tolerant to s-metolachlor at 0.5 and 1.0 pt/A when applied POST. Crop herbicide sensitivity limits in-row broadleaf weed control options in cucurbits; these results suggest that postemergence applications of s-metolachlor can be adopted for use in summer squash production.

2007 42 Weed Control And Tomato Yield Following Three Conservation-Tillage Cover Crop Systems M. Saini*,1 A. J. Price,2 T. S. Kornecki,2 A. Caylor3; 1Agronomy and Soils, Auburn University, Auburn, AL, 2USDA ARS, Auburn, AL, 3North Alabama Horticulture Substation, Cullman, AL
Currently, tomato (Lycopersicon esculentum L.,) production systems typically utilize conventional tillage, plastic mulch, and multiple herbicide applications to keep fields weed free. An experiment was conducted in 2005 and 2006 at the North Alabama Horticulture Experiment Station located in Cullman, AL. A similar experiment was conducted in 2006 at George Washington Carver Agricultural Experiment Station of Tuskegee University at Tuskegee, AL. Three conservation-tillage systems utilizing Trifolium incarnatum L., Raphanus sativus L., and Secale cereale L. as winter cover crops were compared to a conventional black polythene mulch system for weed control and tomato performance. All four systems were evaluated with and without herbicides. Herbicide treatments included a preemergence (PRE) application of metalochlor (8.54 kg a.i./ha) either alone or followed by an early postemergence (POST) metribuzin (4.48 kg a.i./ ha) application and a late POST application of clethodim (2.24 kg a.i./ ha). The covers were terminated two weeks prior to tomato transplanting with glyphosate applied at 1.12 kg a.i./ ha. All covers were flattened with a mechanical roller/crimper prior the chemical termination. At Cullman in 2005, none of the three cover crops or the plastic mulch were sufficient in controlling weeds without herbicides. Plastic mulch with both PRE plus POST applications provided greater than 98% control of all weeds except Yellow nutsedge (Cyperus esculentus) (91%). In 2006, rye when evaluated without herbicides provided better control than the polythene mulch. It also provided better weed control when only PRE herbicides were used. For all treatments evaluated in 2006 the POST application did not result in any significant increase in weed control compared to treatments having only preemergent applications. In Tuskegee, Rye without any herbicide provided the best control of Virginia buttonweed (Diodia virginiana) (96.8%), Yellow nutsedge (98%) and Smallflower morningglory (Jacquemontia tamnifolia) (98%). Whereas, rye alone proved inadequate in controlling Large crabgrass (Digitaria sanguinalis), it required both the post treatments to control this weed in most cases. Rye provided better overall weed control than other covers in Tuskegee. Corresponding Author Email: priceaj@auburn.edu

2007 43 Weed Control In Cantaloupe, Honeydew Melon, And Watermelon With Preemergence Herbicides. W. T. Lanini*,1 M. E. McGiffen2; 1Plant Sciences, University of California, Davis, Davis, CA, 2Botany and Plant Sciences, University of California, Riverside, Riverside, CA
Melons have only a few registered herbicides available for weed control. The objectives of this study were to evaluate honeydew, cantaloupe and watermelon tolerance and weed control efficacy with several new or non-registered herbicides. On May 25, 2004 and May 23, 2005, seed of 6 cantaloupe, 4 honeydew melon varieties, and one watermelon was planted into pre-irrigated beds. Herbicide treatments were applied on May 28 in both years, and included clomazone at 0.43 or 0.56 kg ai ha-1, metolachlor at 1.50 kg ai ha-1, rimsulfuron at 0.035 kg ai ha-1, halosulfuron at 0.053 kg ai ha-1, rimsulfuron plus halosulfuron at 0.035 plus 0.053 kg ai ha-1, sulfosulfuron at 0.060 kg ai ha-1, and untreated. The entire plot area was sprinkle irrigated (0.30 inches) to incorporate the herbicides immediately after treatment. Weed control and crop injury was visually evaluated several times after application. Melon stand was measured three weeks after treatment by counting all emerged melon plants in each plot. Cantaloupe and watermelon were harvested twice in 2004 and four times in 2005, picking all mature melons, and recording number of fruit and total weight for each variety in each plot. Honeydew melons matured later and were harvested a single time in both years. Melon stand and phytotoxicity was not influenced by herbicide treatment in 2004 but stand was reduced by almost 50% by sulfosulfuron treatment in 2005, and got progressively worse as the season progressed. Crop injury in 2005 was also evident in the metolachlor plots, but by five weeks after treatment, the melons had recovered from this treatment. At 14 DAT, all herbicide treatments, except halosulfuron were providing acceptable control, with metolachlor providing almost complete weed control in 2004. In 2005, weed control was generally reduced compared to 2004, with clomazone and metolachlor providing less than 70% control. All treatments seemed to reduce common lambsquarters (Chenopodium album). Clomazone suppressed lambsquarters slightly more than other treatments. All treatments reduced purslane (Portulaca oleracea) presence except halosulfuron. Grass presence was more common in halosulfuron and clomazone plots. Melon yields differed among among varieties in both years. Among cantaloupe, ‘Ocotillo’ and ‘Impac’, had the highest yield, while ‘Oro Rico’ and ‘Durango’ were the lowest yielding. ‘Emerald’ and ‘Saturno’ were the highest yielding among the honeydew melons, while ‘HoneyAce’ and ‘SantaFe’ were the lowest yielding. In 2004, herbicide treatment did not influence melon yield, but in 2005, melon yields were reduced in sulfosulfuron treated plots and increased in metolachlor plots. Clomazone, metolachlor, rimsulfuron and halosulfuron were relatively safe on melons when applied postplant, preemergence. Rimsulfuron and sulfosulfuron were the most consistent in controlling weeds. Except for sulfosulfuron, melon yields were not decreased by herbicide treatment.

2007 44 Non-Pungent Jalape?o Peppers: Weed Control and Yields. Charles L. Webber III*, USDA, ARS, SCARL; James W. Shrefler, Oklahoma State Univ.; and Vincent M. Russo, USDA, ARS, SCARL; Lane, OK. C. L. Webber*,1 J. W. Shrefler,2 V. M. Russo1; 1USDA, ARS, SCARL, Lane, OK, 2Oklahoma State Univ., Lane, OK
Unknown to most consumers, non-pungent jalape?o peppers are used for making commercial picante sauces (salsas). The non-pungent jalape?o peppers produce the required jalape?o flavor along with the appropriate texture necessary for picante sauce. Capsaicin is added during processing to produce the various levels of pungency (i.e. high, medium, and mild). These peppers have a potential for outstanding yields in Oklahoma, but additional research is required to determine the crop safety of certain herbicides when used specifically for weed control in non-pungent jalape?o peppers. The objectives of this research were to determine the weed control efficacy and crop safety of a combination of preplant incorporated herbicides on transplanted non-pungent jalape?o peppers. A field study was conducted during the summer of 2005 on 91-cm wide raised beds at Lane, OK. The herbicides in the study included napropramide (2.2 kg ai/ha), clomazone (1.1 kg ai/ha), bensulide (6.7 kg ai/ha), and trifluralin (1.1 kg ai/ha) used separately, and in combination with one of the other herbicides. All herbicides were applied preplant incorporated just prior to transplanting on 6 May 2005. Pace 105 non-pungent jalape?o peppers were transplanted on 6 May 2005 with a 46-cm spacing between plants within the rows. Fruit were harvested on 21 July 2005, 76 days after transplanting. Plants treated with only clomazone produced the greatest yields (16.4 mt/ha) compared to plants treated with the other herbicides used individually, although it was not significantly greater than napropramide (9.2 mt/ha). Four of the five top yielding herbicide treatments included the use of clomazone. The tank mixture of napropramide and bensulide produced the second greatest yield (16.2 mt/ha). Weed interference in the weedy-check reduced yields by 86% compared to the weed-free treatment’s 17.5 mt/ha. These results demonstrate that clomazone used individually or in combination with certain other herbicides, can maintain non-pungent jalape?o yields equivalent to weed-free levels.

2007 45 Influence of Purple Nutsedge Density and Time of Removal on its Interference with Watermelon J. Morales-Payan*; Horticulture, University of Puerto Rico, Mayaguez, Mayaguez, PR
The effects of Cyperus rotundus density and time of removal on watermelon yield were determined in field experiments. Watermelon fruit yield and number were negatively affected by C. rotundus interference. In general, watermelon fruit yield and size decreased as C. rotundus densities were higher and when C. rotundus was removed later in the season. C. rotundus densities lower than 50 plants/m2 competing with the crop season-long did not significantly reduce watermelon yield. Removal of C. rotundus later than 5 weeks after crop emergence did not result in improved yield. Watermelon yield loss was as high as 85% when competing season-long with 300 C. rotundus plants/m2.

2007 46 Cyperus rotundus Interference with Rambutan During the Nursery Stage J. Morales-Payan*; Horticulture, University of Puerto Rico-Mayaguez, Mayaguez, PR
Control/Tracking Number: 07-P-365-WSSA Activity: Poster Current Date/Time: 3/10/2006 10:48:24 AM Cyperus rotundus is a common weed in fruit crop nurseries where soil is used as a component of the substrate to grow seedlings. Nursery experiments were conducted to determine the effects of C. rotundus density and time of removal on height and stem diameter of rambutan seedlings for rootstock. C. rotundus densities were 0 to 10 plants/container. Times of C. rotundus removal were 10 to 60 days after rambutan emergence. There was a general trend of shorter and thinner rambutan seedlings as density increased and as the time the crop and the weed grew together was longer. These results indicate that increased C. rotundus density and time of removal may prolong the nursery stage in rambutan by delaying the seedling growth.

2007 47 Herbicide Screening in a Garden Rose Field Nursery B. D. Hanson*; Water Management Research Unit, USDA-ARS, Parlier, CA
The garden rose industry in the US, which is primarily located in California and Arizona, produces 35 million rose bushes annually for retail sale. Weed control in garden rose nurseries generally depends on preplant soil fumigation with methyl bromide, hand labor, and a few registered herbicides. The phaseout of methyl bromide, increasing labor costs, and recent shortages in the available labor force increases the need for alternative weed management. Trials were initiated in 2005-06 to screen several herbicides for efficacy and crop safety in newly planted hardwood rose cuttings. Preliminary results indicate several promising candidates for further research. These include PRE applied thiazopyr, and POST-directed applications of flumioxazin, rimsulfuron, and imazosulfuron. Several other compounds, including sulfentrazone, halosulfuron, penoxulam, foramsulfuron, carfentrazone, and lactofen may provide acceptable efficacy and safety with alterations in application rate, placement, or timing. Mesotrione, oxyflourfen, bromacil, and S-metolachlor did not have acceptable safety or efficacy at the rates tested. This research is ongoing and is being expanded to include other compounds and rose production techniques.

2007 48 Flazasulfuron for Overseeding Safety and Poa annua Control K. C. Hutto*,1 B. J. Brecke,1 J. B. Unruh2; 1Agronomy, University of Florida, Jay, FL, 2Environmental Horticulture, University of Florida, Jay, FL
Poa annua is a difficult to control weed species in overseeded bermudagrass. Postemergence herbicides highly efficacious on Poa annua also cause tremendous injury to commonly used overseeding turfgrasses like perennial ryegrass. Research conducted in the fall of 2005 evaluated flazasulfuron applications prior to overseeding for Poa annua control and overseeding safety. Flazasulfuron at 0.05 kg ai/ha applied 4 to 6 wk prior to overseeding (WPO) caused minimal injury (<14% injury) to perennial ryegrass 60 days after treatment (DAT). Flazasulfuron applied 2 WPO or less caused unacceptable perennial ryegrass injury 60 DAT (>20% injury). By 90 DAT, 0.03 and 0.05 kg/ha flazasulfuron caused 40 and 63% perennial ryegrass injury, respectively when applied 2 WPO. Perennial ryegrass injury increased to 58 and 86% injury, respectively for these same treatments applied 1 WPO. No injury was observed for 0.01 kg/ha flazasulfuron applied 2 or 1 WPO. Unacceptable perennial ryegrass injury was observed 139 DAT when 0.03 and 0.05 kg/ha flazasulfuron was applied 2 WPO or less. All treatments provided good Poa annua control (90% control) 139 DAT. However, by 175 DAT all treatments provided less than 65% Poa annua control. Flazasulfuron applications made 4 WPO or earlier did not significantly injure perennial ryegrass or reduce ryegrass color, quality or density compared to the untreated. However, applications made this early did not provide season long Poa annua control.

2007 49 Bermudagrass Control in Cool-Season Turfgrass J. B. Willis*, S. D. Askew; Virginia Tech, Blacksburg, VA
There is no selective control for bermudagrass [Cynodon dactylon (L.) Pers.] in cool-season turfgrass. Bermudagrass is an aggressive and persistent weed that is difficult to control and decreases turf aesthetics. Fenoxaprop and triclopyr are used for bermudagrass suppression, however long term control is unreliable. Recent work has indicated sequential applications of mesotrione control some perennial grass weeds in cool-season turfgrass and may be effective toward bermudagrass. Three trials were conducted in 2005 and 2006 in Blacksburg, VA to evaluate herbicide combinations for selective bermudagrass control in cool-season turf. Research sites consisted of Kentucky bluegrass (Poa pratensis L.) and perennial ryegrass (Lolium perenne L.) turf, and was maintained as a golf course fairway at 2 cm mowing height. All sites are naturally infested with common bermudagrass, with 30 to 50% cover at initiation. The experimental design was a randomized complete block with three replications. Treatments were arranged in a factorial with two application scenarios and seven herbicide treatments. The two application scenarios were herbicide treatments applied either two or three times in both spring and fall. The first spring treatment was applied at 60% bermudagrass greenup and successive applications were made at three-week intervals. Fall applications were applied 9, 6, and 3 weeks prior to expected senescence. The seven herbicide treatments were all possible combinations of fenoxaprop-P, tricolpyr, and mesotrione at 246, 1123, and 140 g ai/ha, respectively. A nontreated control was included for comparison, making a total of 15 treatments. For all herbicides and combinations, three applications significantly reduced bermudagrass cover more than two applications. When applied alone, mesotrione controlled bermudagrass equivalent to fenoxaprop-P and triclopyr, however none of the herbicides applied alone controlled common bermudagrass at acceptable levels. Equivalent levels of control and differing mode of action indicate mesotrione could hold promise as a tank-mix partner for controlling bermudagrass. Treatments reducing common bermudagrass cover to below 10%, one year after treatment (YAT) were viewed acceptable. Acceptable treatments were mesotrione plus triclopyr, triclopyr plus fenoxaprop-P, and mesotrione plus triclopyr plus fenoxaprop-P, with 9, 5, and 2% bermudagrass cover 1 YAT, respectively. In stressful conditions these treatments injured perennial ryegrass as much as 35%, however, injury was short lived, and turfgrass recovered by 3 weeks after application.

2007 50 Absorption, Translocation, and Metabolism of Prohexadione Calcium in Annual Bluegrass (Poa annua), and Three Turfgrass Species M. J. Goddard*, J. B. Beam, S. D. Askew; Virginia Tech, Blacksburg, VA
Prohexadione calcium is an experimental turfgrass growth regulator that selectively controls or suppresses annual bluegrass in desirable turfgrass such as creeping bentgrass (Agrostis stolonifera), Kentucky bluegrass (Poa pratensis), and perennial ryegrass (Lolium perenne). To help explain interspecific differences in turfgrass and weed response to prohexadione Ca, two laboratory trials were conducted to measure 14C-prohexadione Ca absorption, translocation, and metabolism in these four species. Annual bluegrass, ‘Penncross’ creeping bentgrass, ‘Prosport’ perennial ryegrass, and ‘Kelly’ Kentucky bluegrass were transplanted from field grown plants thinned to one tiller and one fully expanded leaf and placed in 0.25% Hoagland solution in the greenhouse with average nighttime and daytime temperatures of 20 and 30 C, respectively. Plants acclimated for 1 week before treatment. Foliar absorption and translocation were determined by applying three one-microliter droplets of treatment solution to the newest fully expanded leaf blade on each plant. Annual and Kentucky bluegrass absorbed more prohexadione Ca than creeping bentgrass and perennial ryegrass when averaged over harvest timing and trial. Neither translocation out of the treated leaf or metabolism of prohexadione Ca differed between species. When averaged over species and trial, 22% of recovered prohexadione Ca was metabolized within 1 HAT, and plants metabolized an additional 0.7% each additional hour for a period of 48 hours. Previous research indicates that annual and Kentucky bluegrass growth is suppressed more by prohexadione Ca than creeping bentgrass and perennial ryegrass. Increased prohexadione Ca absorption partially explained this trend in the current study.

2007 51 Herbicide Alternatives for Atrazine and Simazine in Christmas Tree Plantations M. W. Marshall*,1 B. H. Zandstra,1 R. J. Richardson2; 1Horticulture, Michigan State University, East Lansing, MI, 2Crop Science, North Carolina State University, Raleigh, NC
Weed control remains an important practice in Christmas tree production. Simazine and atrazine are the first and third, respectively, most widely used preemergence herbicides in Michigan Christmas tree production. Both herbicides provide excellent control of numerous broadleaf weed species; however, concern from atrazine and simazine movement into groundwater sources may limit their future use. In addition, development of weed resistance to these modes of action may also limit their utility. Field studies were initiated in 2005 and repeated in 2006 to evaluate potential replacement herbicides for weed control in Douglas fir (pseudotsuga menziesii). Premergence treatments were applied on April 19, 2005 and April 11, 2006 which included atrazine (0.84 kg/ha) plus simazine (0.84 kg/ha), flumioxazin (0.28 kg/ha), mesotrione (0.28 kg/ha) plus simazine (0.84 kg/ha). Postemergence treatments were applied on June 23, 2005 and May 23, 2006 which included clopyralid (0.28 kg/ha), mestrione (0.28 kg/ha) plus crop oil concentrate (1% v/v), trifloxysulfuron (9.9 g/ha) plus non-ionic surfactant (NIS) [0.25% v/v], rimsulfuron (34.8 g/ha) plus NIS, and imazethapyr (34.8 g/ha) plus NIS. Herbicides were applied in water at a carrier volume of 187 L/ha with a pressure of 207 KPa. Experimental design was a randomized complete block design with 4 replications and individual plot sizes of 5.5 by 7.6 m. Weed control and Douglas fir injury ratings were evaluated 8 weeks after treatment (WAT), 12 WAT, and 16 WAT on a 0 to 100% scale with 0 indicating no control or injury and 100 equal to weed or crop death. In 2005, atrazine plus simazine and mesotrione plus simazine provided greater than 96% horseweed (Conzya canadensis) and hoary alyssum (Berteroa incana) control 8 WAT and greater than 91% hoary alyssum control 16 WAT. In contrast, trifloxysulfuron, provided only 8% hoary alyssum control 8 WAT. In addition, hoary alyssum control with rimsulfuron was 81% 8 WAT. Douglar fir injury, regardless of treatment, was less than 5% 16 WAT. In 2006, atrazine plus simazine and mesotrione plus simazine provided excellent control (>95%) of hoary alyssum and common catsear (Hypochoeris radicata). Initial Douglas fir response to mesotrione, trifloxysulfuron, rimsulfuron, and imazethapyr was greater in 2006; however, it grew out of the injury by 16 WAT. Mesotrione shows promise as a preemergence alternative to atrazine and simazine. In addition, imazethapyr, rimsulfuron, and mesotrione applied postemergence provided good to excellent control of common broadleaf weeds found in Christmas tree plantations.

2007 52 A General Phenological Growth Stage Key For Describing Trees And Woody Plants G. A. Finn*,1 V. Peterson,1 A. E. Straszewski2; 1Product Technology, Dow AgroSciences, Indianapolis, IN, 2Proport Services, Newbury, United Kingdom
The extended BBCH scale (BBCH = Biologische Bundesantalt Bundessortenamt and CHemische Industrie, Germany) is a system for the uniform coding of phenologically similar growth stages for plants, based on the Zadoks decimal code used in cereals. Detailed plant-specific descriptions and decimal codes are presented for the phenological growth stages of woody species. The scale uses eight of the 10 principal stages, starting with sprouting/bud development (stage 0) and ending with dormancy (stage 9). The secondary stages are numbered 0 to 9, being related to the ordinal or percentile stages of growth. This BBCH-compliant scale represents a single, standardized growth stage key for describing the growth of leaf-bearing and needle-bearing woody plants and promotes the adoption of the use of BBCH scales more widely.

2007 53 Dogfennel (Eupatorium capillifolium) Size At Application Impacts Herbicide Efficacy. B. A. Sellers*,1 J. A. Ferrell2; 1Range Cattle Research and Education Center and Dept. of Agronomy, University of Florida, Ona, FL, 2Agronomy, University of Florida, Gainesville, FL
Dogfennel is a significant weed in Florida pastures, reaching heights greater than 2 meters. Traditionally, ranchers have mowed dogfennel to reduce seed production and spread. However, a timely herbicide application may be more cost effective as fuel prices continue to rise. Experiments were conducted to determine the impact of dogfennel height on herbicide efficacy. Locations were chosen based on uniform dogfennel density, and dogfennel plants were treated at 38, 76, and 152 cm tall with the following herbicides: triclopyr & fluroxypyr at 0.42 & 0.14, 0.53 & 0.17, 0.63 & .21, & 0.84 & 0.28 kg ai/ha, triclopyr at 1.1 kg/ha, 2,4-D amine & dicamba at 0.72 & 0.25 and 1.2 & 0.43 kg/ha, and triclopyr + 2,4-D amine & dicamba at 0.56 + 0.36 & 0.13 kg/ha. All treatments were applied with an air-pressurized ATV sprayer equipped with 11003 Turbo Teejet nozzles calibrated to deliver 281 L/ha. All treatments were mowed 60 days after application to evaluate regrowth 1 year after treatment. When applied to 38 cm dogfennel, all treatments were similar, providing >85% control 30 days after treatment (DAT) except for 2,4-D amine & dicamba at 0.72 & 0.25 kg/ha, which provided 79% control. By 60 DAT, dogfennel control was similar across treatments, providing greater than 92% control. Applying these herbicides to 76 cm dogfennel, resulted in similar trends, however, triclopyr & fluroxypyr at 0.53 & 0.17 kg/ha or higher and triclopyr alone provided >90% control 30 DAT. At 60 DAT, all herbicide treatments provided >90% control. It took longer to achieve similar levels of control when these treatments were applied to 152 cm dogfennel. At 30 DAT, triclopyr & fluroxypyr at 0.84 & 0.28 kg/ha provided the highest level of control at 85%, while all other herbicide treatments provided <80% control. Triclopyr & fluroxypyr at application rates at and greater than 0.53 & 0.17 kg/ha provided >90% control 60 DAT of 152 cm dogfennel, while all other treatments provided 80% or greater control. However, 0.72 & 0.25 kg/ha 2,4-D amine & dicamba provided only 64% control. One year after application of these treatments to 38 and 76 cm dogfennel resulted in >85% control. Delaying herbicide applications until dogfennel plants were 152 cm tall resulted virtually no control with 2,4-D amine & dicamba at 0.72 & 0.25 kg/ha one year after treatment, and control with the low rate of triclopyr & fluroxypyr was unsatisfactory (66%). All other treatments provided >85% control one year after treatment. Applying these herbicides earlier in the year when dogfennel plants are less than 76 cm tall will result in increased herbicide efficacy at reduced cost compared to applying these herbicides to larger dogfennel.

2007 54 Comparison Of Aminopyralid And Other Herbicides On Weed Control In Grass Pasture D. D. Lingenfelter*, W. S. Curran; Crop and Soil Sciences, Penn State University, University Park, PA
From 2004 to 2006, aminopyralid was compared to and in combination with 2,4-D, dicamba, metsulfuron, and triclopyr to determine the impact on control of several weed species in grass pastures in central Pennsylvania. Depending on the location and year, herbicides were evaluated for control of plumeless thistle (Carduus acanthoides), Canada thistle (Cirsium arvense), curly dock (Rumex crispus), common burdock (Arctium minus), dandelion (Taraxacum officinale), and smooth bedstraw (Galium mollugo). Treatments were applied in late May to early June with a hand-held or ATV-mounted boom sprayer that delivered 187 L/ha. In 2006, treatments also were applied in mid-July in a smooth bedstraw study. Aminopyralid was applied at 0.07 to 0.123 kg ae/ha, 2,4-D at 0.41 to 1.1lb ae/ha, dicamba at 0.28 to 0.56 lb ae/ha, metsulfuron at 0.011 to 0.02 lb ai/ha, and a triclopyr plus 2,4-D premix at 1.69 to 2.53 lb ae/ha. Plots were replicated and randomized and measured 3 m wide by 9 or 23 m long. Late season ratings revealed that treatments containing aminopyralid almost always provided greater than 90% control of Canada thistle and 95% or greater control of plumeless thistle. In contrast, 2,4-D, dicamba, metsulfuron, and the triclopyr plus 2,4-D premix alone or in combination with each other ranged from 73 to 83% control of Canada thistle and 80 to 100% control of plumeless thistle. In 2004, aminopyralid-containing treatments provided 95 to 99% control of curly dock and common burdock, while the other treatments provided similar control of curly dock and from 77 to 99% control of common burdock. In 2004 and 2005, aminopyralid alone or in combination with 2,4-D provided 73 to 93% control of dandelion, whereas treatments containing metsulfuron provided 84 to 99% control. In 2006, aminopyralid alone or in combination with 2,4-D provided 97 to 100% control of smooth bedstraw when applied either in late May or mid-July. The triclopyr plus 2,4-D premix applied in late May provided 65% control of smooth bedstraw, whereas the later application provided 96% control. Regardless of timing, metsulfuron provided only 23 to 28% control of smooth bedstraw. Aminopyralid will provide an additional option for weed control in grass pasture and will be particularly helpful for control of troublesome weeds such as thistle species, dock species, common burdock, and smooth bedstraw to name a few.

2007 55 Gorse (Ulex europaeus) Infestations In Hawaii And New Zealand Display Similar Patterns Of Resource Exploitation From Altered Landscapes. J. J. K. Leary*,1 D. A. Peltzer,2 N. V. Hue,3 D. Borthakur1; 1Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, HI, 2Landcare Research, Lincoln, New Zealand, 3Tropical Plant and Soil Science, University of Hawaii at Manoa, Honolulu, HI
Gorse is a woody leguminous shrub that is endemic to Western Europe and the Mediterranean, but has become a major cosmopolitan weed with infestations existing in at least 10 countries. To determine the effects of gorse infestations in different geographical locations, separate field analyses were conducted on Mauna Kea, Hawaii and Bank’s Peninsula, New Zealand. At both sites, three experimental units were identified and consisted of a high-density gorse population (HD) zone and an adjacent low-density gorse population (LD) zone. Furthermore, the LD zones in Hawaii were areas with young pioneer gorse individuals in early succession, while the LD zones of New Zealand were former infestations in late succession. Soil, plant, and bacterial samples were collected from all zones at both locations. Soil nutrient status was the best indicator of gorse impacts on the landscape. Soil pH was significantly lower in the HD zones for both sites. Concentrations of Ca and Mg were also significantly higher in the LD zones for both sites, while Al concentrations were significantly higher in the HD zones. Plant Al concentration was significantly higher only in the LD zone in New Zealand, but not in Hawaii. This was the only significant difference for all tissue nutrients for both sites. This suggests that changes to the soil are dependent on gorse plant densities (i.e. infestation) and reversion of soil nutritional status may be a successional trait of the landscape. This work also suggests that Al accumulation by gorse in late succession may be an indicator of decline. Bradyrhizobium isolates from Hawaii and New Zealand do not share the same Box-PCR marker profiles, while gorse and koa (Acacia koa) Bradyrhizobium isolates do. This indicates that gorse does not require specific host-symbiont relationships for symbiosis and is compatible with a wide range of indigenous Bradyrhizobium for effective nitrogen fixation. The lack of specificity for root mutualists (Bradyrhizobium) may play a major role in the cosmopolitan success of gorse invasion. Regardless of the geographic location, soil nutrition and symbiosis appear to be important factors to consider when developing preventative or responsive control strategies.

2007 56 Invasive Potential of Ornamental Pear (Pyrus calleryana), Beefsteak Plant (Perilla frutescens), Asiatic Smartweed (Polygonum caespitosum) and Mulberry Weed (Fatoua villosa) in the Midwestern United States. P. B. Trewatha*; Department of Agriculture, Missouri State University, Springfield, MO
A survey of midwest horticulture, weed science, extension, conservation and natural resource personnel was conducted to estimate the extent of establishment of naturalized wildland plantings of four Asian-native species: ornamental pear, beefsteak plant, asiatic smartweed and mulberry weed throughout the midwest. Results indicated that ornamental pear, documented as being increasingly found in wild populations in the eastern U.S., is also appearing as wild seedlings at a number of sites in Missouri, Illinois and Kentucky. Asiatic smartweed is also quite widespread in Ohio, Iowa, Minnesota, Missouri and Illinois in turf and in moist wildland areas (open woods, stream and riverbanks). Beefsteak plant is found along disturbed open woodland trails, as well as appearing as an urban and cultivated crop weed in Missouri, Ohio, Iowa, Illinois and Minnesota. Mulberry weed is more sporadically located, but has been identified growing as far north as Minnesota. Documentation on sites and invasive predictor characteristics for each species will be presented.

2007 57 Evaluation Of Herbicides For Phragmites Management In Connecticut Marshes T. L. Mervosh*,1 D. Roach2; 1Valley Laboratory, Connecticut Agricultural Experiment Station, Windsor, CT, 2All Habitat Services, LLC, Madison, CT
Common reed or phragmites [Phragmites australis (Cav.) Trin.] has become the dominant weed in many Connecticut wetlands. This invasive, rhizomatous grass is displacing cattails (Typha sp.) and other native plants in these ecosystems. We conducted experiments to evaluate the efficacy of herbicides with aquatic use registrations for managing phragmites in a freshwater marsh in Manchester, CT (Experiment 1; 2004-05 ) and in a brackish marsh in Old Saybrook, CT (Experiment 2; 2005-06 ). In both marshes, the study areas were prepared in early spring by mowing down dry standing stalks of phragmites. Plots in both experiments were arranged in a randomized complete block design with three replicates. Plot dimensions were 10 ft by 25 ft in Experiment 1, and 20 ft by 20 ft in Experiment 2. Untreated alleyways 10 ft in width surrounded all plots. In Experiment 1, treatments containing the herbicides glyphosate and/or imazapyr in varying doses were sprayed over the top of phragmites-dominated plots at one of three application timings: early June, mid August or late October 2004. In Experiment 2, treatments containing glyphosate, imazapyr and/or triclopyr in varying doses were sprayed over the top of phragmites-dominated plots at one of three timings: early June, late June or early September 2005. For the early June treatments both years, phragmites was an average of 3 to 4.5 ft tall, and herbicides were applied using a hand-held spray boom while walking through the plots. For later treatment timings, phragmites was 8 to 13 ft tall. Herbicides were applied from nozzles attached to an elevated platform mounted on an amphibious all-terrain vehicle that was driven in the alleyways. Plots were evaluated periodically for up to 16 months after treatment application for phragmites height, stem density, vigor, injury symptoms, and for the presence of other vegetation. In Experiment 1, June treatments that included imazapyr, alone or in combination with glyphosate, provided better long-term control of phragmites than treatments that included only glyphosate. All herbicide treatments applied in August 2004 provided nearly complete control of phragmites throughout 2005. The October treatments were applied too late in the season to be effective. In Experiment 2, treatments were more effective when applied in September 2005 than when applied in June. Regardless of application timing, treatments containing glyphosate or imazapyr were better than treatments containing only triclopyr at reducing phragmites growth in 2006. Combinations of triclopyr with either glyphosate or imazapyr were effective. Plots will continue to be evaluated for phragmites and other plant species that emerge.

2007 58 Evaluation Of Penoxsulam For Water Hyacinth [Eichhornia crassipes (Mart.) Solms] and Giant Salvinia (Salvinia molesta Mitchell) Control. R. J. Richardson*, A. P. Gardner; Crop Science, North Carolina State Univ., Raleigh, NC
Water hyacinth and giant salvinia are invasive aquatic weeds that are established and problematic in many parts of the southern United States. Greenhouse trials were conducted to evaluate water hyacinth and giant salvinia control with penoxsulam applied in-water or as a foliar application. With in-water treatments, penoxsulam was applied at 0, 2, 5, 10, and 20 ppb. Penoxsulam was applied at 0, 5, 10, 25, 50, 100, and 200 g/ha plus 0.25% non-ionic surfactant in foliar trials. Plants were rated weekly on a 0 to 100% scale, with 0% equal to no weed control and 100% equal to complete plant death. At approximately five weeks after treatment, plants were harvested for fresh weight determination. In addition, root length and hyacinth plant number were recorded with the in-water trial. In the in-water trial, control of both weeds was 41 to 95% across treatments. Dry weight, root length, and plant number with penoxsulam treatments were reduced from that of the untreated control with three of the four herbicide rates evaluated. Giant salvinia dry weight was reduced with all penoxsulam in-water rates to no more than 44% of untreated weights. In the foliar application trial, water hyacinth control was 71 to 97% and giant salvinia control was 43 to 94%. Penoxsulam at 25 g/ha controlled water hyacinth 92% and giant salvinia 82%. In conclusion, penoxsulam can effectively control both water hyacinth and giant salvinia.

2007 59 Information Discovery From Canada Thistle Control Research Data By Using Association Rule Mining J. Zhou*, C. G. Messersmith, J. Davidson-Harrington; North Dakota State University, Fargo, ND
Data-mining is a process that uses several data analysis concepts to discover patterns and relationships in databases that may be used to make valid predictions. Association rule mining, which is a data-mining task, finds interesting association relationships among a large database. To use Canada thistle control as an example, an association rule mining function has been developed based on North Dakota weed field research data, but the function with limited modification can mine other databases. The association rules are statements in the form “in xx% cases, if the minimum temperature 1 d before treatment is lower than a F, the maximum temperature 1 d after treatment is higher than b F, the minimum temperature 1 d after treatment is less than c F, ¼ then the control of Canada thistle is higher than yy%”. Each rule has two value measures, support and confidence, that describe the frequencies of the occurring pattern (rule) and strength of implication of the rule. One goal of association rule mining is to identify correlation relationships among weed control and affecting factors that need to be addressed and perhaps researched further.

2007 60 WeedSOFT®: A Tool for Teaching IWM Principles L. Bills*, A. R. Martin, M. Bernards; University of Nebraska, Lincoln, NE
WeedSOFT® is a set of free, Web-based applications designed to teach IWM principles. It is a regional project currently involving nine North-central states: Illinois, Indiana, Kansas, Michigan, Missouri, Nebraska, Ohio, Pennsylvania, and Wisconsin. The WeedSOFT® tools include the following: ADVISOR, EnviroFX, and PastureADVISOR. The foundation of this set of tools is ADVISOR - an application to evaluate weed management systems based on crop and weed specific information. ADVISOR assesses both early and late season yield loss due to weed competition under various weed management approaches. The user may select different weed management systems and make side-by-side comparisons. In addition, several “learning modules” are provided to clarify various weed management principles. These modules cover resistance management, application timing, environmental factors, and influences of crop growth stages. EnviroFX will assess the relative leaching and groundwater contamination potential of herbicides for a given soil classification. PastureADVISOR evaluates herbicide treatment options for pasture and range land based on weed species, forage species and forage use. More modules and applications will be added as they are developed and become available.



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