Effect of Xanthomonas campestris pv. poae (JT-P482) on the Growth and Seed Production of Annual Bluegrass (Poa annua L.).
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Abstract:
To ascertain the most effective use of Xanthomonas campestris pv. poae (JT-P482) treatment for the control of annual bluegrass (Poa annua L.), pot-experiments in the greenhouse and in the field were conducted from 1993 to 1994. JT-P482 appeared to have merit as a management tool for the reduction of annual bluegrass growth, tiller numbers and seed production. Greenhouse experiments indicated that a 20°C/15°C day/night temperature regime enabled JT-P482 to effectively produce heavy wilting or plant death at cell concentrations higher than 108cfu/ml. This effectiveness continued for 3 months after the initial treatment. In the field pot experiments, applications of JT-P482 in early winter alone (December 1) and in spring alone (April 10), at cell concentrations of 108 and 109cfu/ml were very effective in suppressing seed production (77-85% and 84-88%, respectively). Moreover treatments administered in early winter and again in spring were found to significantly suppress (over about 85%) annual bluegrass seed production even at 107cfu/ml concentrations. However, of all concentrations (106 to 109cfu/ml), 108 and 109cfu/ml were most effective in suppressing seed production (about 94%). If seed suppression of 85% or more is considered to be acceptable for practical purposes, 109cfu/ml concentration in the early winter treatment, 108 and 109cfu/ml concentrations in the spring treatment, and concentrations higher than 107cfu/ml in repeated treatments can be highly effective.Keywords:
Poa annua
Tiller (botany)
Seed treatment
Wilting
Many plants become limp or droop through heat, loss of water, or disease. This is also known as wilting. In this paper, we examine plant wilting caused by bacterial infection. In particular, we want to design a metric for wilting based on images acquired of the plant. A quantifiable wilting metric will be useful in studying bacterial wilt and identifying resistance genes. Since there is no standard way to estimate wilting, it is common to use ad hoc visual scores. This is very subjective and requires expert knowledge of the plants and the disease mechanism. Our solution consists of using various wilting metrics acquired from RGB images of the plants. We also designed several experiments to demonstrate that our metrics are effective at estimating wilting in plants.
Wilting
Wilt disease
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Poa annua (annual bluegrass) is a major weed problem in winter turfs. It is a cosmopolitan and well adapted weed in most turfgrass settings. Cultural management programs to control or eliminate Poa annua are either limited or unsuccessful. Sulfentrazone herbicide was applied to perennial ryegrass turf (as overseeded bermudagrass) which had high levels of Poa annua infestation (45%-75%) at 0.125, 0.250 and 0.375 lb. AI/A. There was essentially a limited response of Poa annua to Sulfentrazone at these rates when applied on March 7, 1997. EMBARK LITE (Mefluidide) was applied once at 0.125 lb. AI/A and caused some initial discoloration to the turf at 10 DAT. At 25 DAT percent control of Poa annua (seed heads) reached 90% or greater which declined to 58% on April 15 (40 DAT). Turfgrass color was enhanced from the single application of Mefluidide at 25 and 40 DAT on golf course rough turf maintained at a mowing height of 1.50 inches. Sulfentrazone exhibited minimal or no effect on Poa annua when applied as a post emergence treatment.
Poa annua
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Annual bluegrass (Poa annua L.) samples were collected from several areas of Japan from 1991 to 1993. Eighty-nine isolates of Xanthomonas-like bacteria which caused wilting of annual bluegrass leaves upon artificial inoculation were isolated. Isolates were separated into two groups according to the pathogenicity demonstrated by leaf clipping inoculation. Ten isolates including JT-P482 as the representative isolate caused severe wilting of the whole plant, and 79 isolates including JT-P192 as the representative isolate caused mild wilt symptoms and/or pale-yellow discoloration limited to leaf blades. Pathogenicity and bacteriological properties of present isolates were compared with those of Xanthomonas campestris pv. graminis, X. c. pv. phlei, X. c. pv. arrhenatheri, X. c. pv. poae and X. c. pv. "poannua". Regardless of differences in their pathogenicity, present isolates of both types were identified as X. c. pv. poae on the basis of host-specificity and bacteriological properties.
Wilting
Bacterial wilt
Poa annua
Ralstonia solanacearum
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Poa annua
Trifolium repens
Repens
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Abstract Annual bluegrass ( Poa annua L.) plants were grown in a mature Merion Kentucky bluegrass sod and in monostands to determine the optimum cutting height for annual bluegrass in terms of shoot competition. Shoot dry weight and tiller number measurements were made on annual bluegrass plants maintained at cutting heights of 1.25, 2.54, 3.75, 5.08, and 6.25 cm. Cutting height significantly influenced the shoot dry weight and tiller number of annual bluegrass with 2.54 cm being the optimum cutting height. In addition, mowing annual bluegrass at a height of 2.54 cm significantly increased the shoot density over both higher and lower cutting heights when grown in a monostand. The optimum cutting height for annual bluegrass in terms of shoot competition was 2.54 cm.
Tiller (botany)
Poa annua
Dry weight
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Sulfentrazone herbicide was applied to bermudagrass turf, prior to overseeding at 0.125, 0.250 and 0.375 lbs. AI/A. Sulfentrazone did not inhibit emergence of perennial ryegrass when applied two days before overseeding. Plots ranged from 92-100% cover (of perennial ryegrass) from December to the end of March (last evaluation). Turfgrass color was noticeably less at the 0.375 lb. AI/A rate, but not significantly different from that of the lower rate application treatments. Pre-emergence weed control based on non-overseeded controls ranged from 51-100% across Sulfentrazone treated turfs, from December 1996 to late March, 1997. The percent reduction in Poa annua due to overseeding (comparison of non-overseed vs. overseed controls) was 90%, 61% 67% and 65% in December, January, February and March, respectively. Initial screening shows favorable activity for Poa annua control, especially at the 0.375 lb. AI/A rate. Further evaluation is needed to assess Poa annua suppression from Sulfentrazone and its potential interaction with overseeding, before cultural management programs can be devised for Poa annua control in an overseed program.
Poa annua
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ABSTRACT Genotypic differences for canopy wilting have been reported for soybean [ Glycine max (L.) Merr.], but no wilting data have been published, and mechanisms for differences remain unresolved. In field studies in 2002 and 2003, differences for wilting among 19 genotypes were consistent across years. Plant introductions (PI 416937 and PI 471938) were among the slowest wilting genotypes, and breeding lines (93705‐34 and 93705‐95) were among the fastest wilting. Row spacing (18 vs. 80 cm wide) did not affect wilting, indicating that lateral rooting did not contribute to genotypic differences. In a separate field study, volumetric soil water content at 15‐ and 50‐cm depths was generally greater for slow‐wilting PI 416937 than for fast‐wilting 93705‐95. Wilting for both genotypes responded similarly to soil water content ( r 2 = 0.63–0.74). In a growth chamber study, transpiration declined similarly for fast‐ and slow‐wilting genotypes in response to soil water deficit. Wilting response to soil water was the same for slow‐wilting PI 416937 and fast‐wilting genotypes 93705‐34 and A5959. Slow‐wilting 93705‐36 began wilting at a lower soil water content than did PI416937, 93705‐34, and A5959, indicating that more than one mechanism may be responsible for slow wilting.
Wilting
Permanent wilting point
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Plant growth regulators (PGRs) are commonly applied for annual bluegrass (Poa annua L.) suppression but various PGR regimens may be more applicable in creeping bentgrass (Agrostis palustris Huds.) management than exclusive applications. Two field experiments in Riverton, NJ investigated various regimens of paclobutrazol ((⁺/-)-(R*,R*)-b-[(4-chlorophenyl) methyl]-a-(1, 1-dimethyl)-1H-1,2,4,-triazole-1-ethanol) (PB) and trinexapac-ethyl ([4-(cyclopropyl-[a]-hydroxymethylene)-3,5-dioxo-cyclohexane carboxylic acid ethyl ester]) (TE) for Poa annua control in creeping bentgrass golf course fairways. Over four years, Poa annua coverage was greater in the spring compared to summer and fall. In the first experiment, Poa annua reductions from initial populations were 22 and 30% in untreated turf and turf treated only with TE, respectively. Reductions in Poa annua were ≈ 55% for turf receiving PB with and without TE applications. In the second experiment, PB reduced Poa annua populations to approximately half those of the untreated plots but combinations with TE did not enhance turf quality or Poa annua suppression. Routinely applying PB at 0.14 kg/ha every 3 weeks provided similar Poa annua control to single applications of 0.56 kg/ha while both regimens gave better control than PB at 0.28 kg/ha applied in the spring and fall. Overall, PB will be an effective tool for suppressing Poa annua in creeping bentgrass fairways for northeastern golf courses; however, tank mixing TE with PB will likely not enhance these effects.
Poa annua
Agrostis
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Annual bluegrass(Poa annua L.) is a problem weed that is very difficult to control on golf courses. There are some reasons that make Poa annua such a difficult weed to be controled. One of these reasons is this plant's ability to reproduce its seed even under stressful conditions. Another reason is its adaptation to low mowing heights. Above all things, the greatest competitive advantage of Poa annua is its genetic diversity. Generally, Poa annua is a bunch type and annual type cool-season grass, but some types act as weak perennials and have stolons. There has been much research on controlling annual bluegrass in golf course turf with chemical and cultural techniques. This research has been conducted for more than 85 years. There has been some progress in controlling some types of Poa annua, but these methods have not been successful on every biotype. Among all of the techniques, Roundup ready creeping bentgrass has the most promise of controlling the diverse types of Poa annua. Roundup ready bentgrass is capable of tolerating the effects of Roundup(glyphosate) while it kills other plants including Poa annua. By using this new technology, we can make Poa annua free greens, tees, and fairways.
Poa annua
Stolon
Agrostis
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