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Although dicamba-resistant crops can provide an effective weed management option, risk of dicamba off-site movement to sensitive crops is a concern. Previous research with indeterminate soybean identified 14 injury criteria associated with dicamba applied at V3/V4 or R1/R2 at 0.6 to 280 g ae ha−1. Injury criteria rated on a 0 to 5 scale (none to severe), along with percent visible injury and plant height reduction, and canopy height collected 7 and 15 d after treatment (DAT) were analyzed using multiple regression with a forward-selection procedure to develop yield prediction models. Variables included in the 15 DAT models (in order of selection) for V3/V4 were lower stem base lesions/cracking, plant height reduction, terminal leaf epinasty, leaf petiole droop, leaf petiole base swelling, and stem epinasty, whereas for R1/R2 variables were lower stem base lesions/cracking, terminal leaf chlorosis, leaf petiole base swelling, stem epinasty, terminal leaf necrosis, and terminal leaf cupping. To validate the models, experiments including the same dicamba rates and application timings used in previous research were conducted at two locations. For the variables specific to each model, data collected for the dicamba rates were used to predict yield. For the V3/V4 15 DAT model, predicted yield reduction (compared with the nontreated control for dicamba at 0.6 to 4.4 g ha−1) underestimated or overestimated observed yield reduction by an average of 1 and 3 percentage points. For 8.8 g ha−1, predicted yield reduction overestimated observed yield reduction by 8 points and for 17.5 g ha−1 by 20 points. For the R1/R2 15 DAT model, predicted yield reduction for 0.6 to 4.4 g ha−1 overestimated observed yield reduction by an average of 3 to 5 percentage points. For dicamba at 8.8 g ha−1, predicted yield reduction underestimated observed yield reduction by 8 points and for 17.5 g ha−1 overestimated by 6 points.

Taro literature was examined for information about taro starch and as a guide to the growth of interest in the material world-wide. The properties of taro starch are presented, as available from the literature and supplemented by new observations on thermal stability and microscopy. The significance of particle size is considered as it relates to the fields of application of starches other than as foods, and especially in the plastics and related industries. The economics of starch application as a filler-extender is considered and consideration given to the emergence of special features of starch fillers not obtained from traditional mineral fillers or wood-flow. This is exemplified by a detailed examination of the economics and technology of the starch-filled biodegradable polyethylene carrier bag plant which has been operating for 2½ years at Nelson in England. Process economics between countries are considered, as given to extensions of the work into other fields of plastics production now at an advanced stage of industrial trial.

Degradation of buried low-density polyethylene has been reported but only in the composting garbage environment. Evidence is offered linking the initial stage of the breakdown with the transfer by diffusion of unsaturated lipids from the compost to the polymer associated with the generation of peroxides by autoxidation.

Bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) is a ubiquitous bacterial signalling molecule produced by diguanylate cyclases of the GGDEF-domain family. Elevated c-di-GMP levels or increased GGDEF protein expression is frequently associated with the onset of sessility and biofilm formation in numerous bacterial species. Conversely, phosphodiesterase-dependent diminution of c-di-GMP levels by EAL- and HD-GYP-domain proteins is often accompanied by increased motility and virulence. In this study, we individually overexpressed 23 predicted GGDEF, EAL or HD-GYP-domain proteins encoded by the phytopathogen Pectobacterium atrosepticum strain SCRI1043. MS-based detection of c-di-GMP and 5′-phosphoguanylyl-(3′-5′)-guanosine in these strains revealed that overexpression of most genes promoted modest 1–10-fold changes in cellular levels of c-di-GMP, with the exception of the GGDEF-domain proteins ECA0659 and ECA3374, which induced 1290- and 7660-fold increases, respectively. Overexpression of most EAL domain proteins increased motility, while overexpression of most GGDEF domain proteins reduced motility and increased poly-β-1,6-N-acetyl-glucosamine-dependent flocculation. In contrast to domain-based predictions, overexpression of the EAL protein ECA3549 or the HD-GYP protein ECA3548 increased c-di-GMP concentrations and reduced motility. Most overexpression constructs altered the levels of secreted cellulases, pectinases and proteases, confirming c-di-GMP regulation of virulence in Pe. atrosepticum. However, there was no apparent correlation between virulence-factor induction and the domain class expressed or cellular c-di-GMP levels, suggesting that regulation was in response to specific effectors within the network, rather than total c-di-GMP concentration. Finally, we demonstrated that the cellular localization patterns vary considerably for GGDEF/EAL/HD-GYP proteins, indicating it is a likely factor restricting specific interactions within the c-di-GMP network.

Field experiments were conducted during 1996 and 1998 to determine the effect of atra- zine, bentazon, atrazine + bentazon, the amine salt of 2,4-D, and bromoxynil on broadleaf signalgrass and barnyardgrass control when applied in mixture with sethoxydim. Herbicide combinations were applied with crop oil concentrate, crop oil concentrate + ammonium sulfate, or BCH 815. Bentazon and atrazine + bentazon reduced broadleaf signalgrass and barnyardgrass control by sethoxydim. Bromoxynil reduced barnyardgrass control but had no affect on broadleaf signalgrass control. In- cluding ammonium sulfate with crop oil concentrate or substituting BCH 815 for crop oil concentrate increased barnyardgrass and broadleaf signalgrass control by sethoxydim when applied with benta- zon. Ammonium sulfate and BCH 815 increased barnyardgrass control when sethoxydim was applied with bromoxynil but did not affect control when sethoxydim was applied with atrazine + bentazon. Atrazine and the ammonium salt of 2,4-D did not reduce barnyardgrass and broadleaf signalgrass control by sethoxydim regardless of adjuvant. Nomenclature: Atrazine, 6-chloro-N-ethyl-N'-(l-methylethyl)-1,3,5-triazine-2,4-diamine; bentazon, 3-(1-methylethyl)-(lH)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide; bromoxynil, 3,5-dibromo-4-hy- droxybenzonitrile; sethoxydim, 2-(1-(ethoxyimino)butyl)-5-(ethylthio)propyl)-3-hydroxy-2-cycloh- exen-l-one; 2,4-D, (2,4-dichlorophenoxy)acetic acid; barnyardgrass, Echinochloa crus-galli (L.) Beauv. #3 ECHCG; broadleaf signalgrass, Brachiaria platyphylla (Griseb.) Nash #, BRAPP Additional index words: Antagonism. Abbreviations: COC, crop oil concentrate; POST, postemergence.

Field studies were conducted over 2 yr to evaluate rhizome johnsongrass control with tank mixtures and sequential applications of bromoxynil at 1.7 kg ai/ha and the graminicides clethodim, fluazifop-P, and quizalofop-P. When compared with the graminicide alone, bromoxynil reduced johnsongrass control 28 days after treatment (DAT) 20, 36, and 55% when applied in combination with clethodim, fluazifop-P, and quizalofop-P, respectively. Application of bromoxynil 7, 3, and 1 d before or 1, 3, and 7 d after all graminicides reduced antagonism when compared with the bromoxynil plus graminicide mixtures. Based on johnsongrass control 28 DAT, antagonism was precluded when bromoxynil was applied 3 d before clethodim and 7 d before fluazifop-P and quizalofop-P. Application of bromoxynil 3 and 7 d after quizalofop-P and 7 d after clethodim also precluded antagonism. The antagonistic tank mixtures of bromoxynil and graminicides reduced cotton yield 17% because of reduced johnsongrass control compared with graminicides alone. A 3-d or greater application interval between bromoxynil and the graminicides was necessary to maximize cotton yield.

Six herbicides were evaluated for their effects on Pythium root rot and growth of sugarcane in greenhouse experiments and on in vitro mycelial growth rate of Pythium arrhenomanes. Pendimethalin and atrazine were most inhibitory to mycelial growth, but neither reduced root rot severity. Asulam, atrazine, and metribuzin were not phytotoxic to sugarcane and did not affect root rot symptom severity in clay loam or silt loam field soils. Atrazine and metribuzin increased shoot number, and atrazine increased total shoot weight for treated plants in silt loam soil. Glyphosate, pendimethalin, and terbacil were phytotoxic to sugarcane. These herbicides increased root rot severity, but the extent to which growth reductions resulted from increased disease severity or from direct herbicide injury was not clear. Adverse effects on plant growth and root rot severity were greater in clay loam than in silt loam soil. The results suggest that sugarcane injury from some herbicides is compounded by increased severity of root rot.

Field experiments were conducted from 1993 to 1995 to compare weed control by the isopropylamine salt of glyphosate at 0.21, 0.42, 0.63, and 0.84 kg ae/ha applied at three stages of weed growth. Weed control by glyphosate applied at these rates alone or with ammonium sulfate at 2.8 kg/ha was also evaluated. In other experiments, potential interactions between glyphosate and acifluorfen, chlorimuron, and 2,4-DB were evaluated. Velvetleaf, prickly sida, sicklepod, pitted morningglory, entireleaf morningglory, palmleaf morningglory, and hemp sesbania were controlled more easily when weeds had one to three leaves compared with control when weeds had four or more leaves. Glyphosate controlled redroot pigweed, velvetleaf, prickly sida, sicklepod, and barnyardgrass more effectively than pitted morningglory, entireleaf morningglory, palmleaf morningglory, or hemp sesbania. Increasing the rate of glyphosate increased control, especially when glyphosate was applied to larger weeds. Greater variation in control was noted for pitted morningglory, palmleaf morningglory, prickly sida, and velvetleaf than for redroot pigweed, sicklepod, entireleaf morningglory, or hemp sesbania. Ammonium sulfate increased prickly sida and entireleaf morningglory control but did not influence sicklepod, hemp sesbania, or barnyardgrass control. Acifluorfen applied 3 d before glyphosate or in a mixture with glyphosate reduced barnyardgrass control compared with glyphosate applied alone. Chlorimuron did not reduce efficacy. Mixtures of glyphosate and 2,4-DB controlled sicklepod, entireleaf morningglory, and barnyardgrass similar to glyphosate alone.

Excitatory amino acids are an important cause of cell death in the hypoxic and ischaemic brain. Neuronal glutamate stores are depleted rapidly in hypoxia, but alanine production rises under such conditions and has been suggested to be a potential precursor of glutamate. To test this hypothesis, we have investigated amino acid metabolism using 13 C NMR with superfused guinea pig cortical slices subjected to varying degrees of hypoxia. During severe hypoxia, brain slices metabolising 5 mM [2- 13 C]pyruvate exported [2- 13 C]alanine into the superfusion fluid. The metabolic fate of alanine during normoxia and hypoxia was tested by superfusion of brain slices with 10 mM glucose and 2 mM [2- 13 C, 15 N]alanine. Metabolism of exogenous alanine leads to the release of aspartate into the superfusion fluid. The pattern of labelling of aspartate indicated that it was synthesised via the glial-specific enzyme pyruvate carboxylase. 13 C-labelled glutamate was produced with both normoxia and hypoxia, but concentrations were 30-fold lower than for labelled aspartate. Thus, although substantial amounts of glutamate are not synthesised from alanine in hypoxia, there is significant production of aspartate, which also may have deleterious effects as an excitatory amino acid.

Introduction. Chemistry and biochemistry of polymer biodegradation. Particulate starch based products. Biopolyesters. Recycling technology for biodegradable plastics. Test methods and standards for biodegradable plastics. Geletanized starch products. Index.

Qualite et valeur alimentaire des fourrages d'Andropogon gerardi et Panicum virgatum en fonction de la maturation et des organes consideres

Two trials were conducted to determine the influence of monensin on live weight gain and efficiency of forage utilization of calves grazing Bermudagrass. In trial 1, 32 calves, weaned at an average age of 238 days and 250 kg, were grazed on "Coastcross I" Bermudagrass from July 20 to October 13. Eight steers and eight heifers were randomly assigned to one of two treatments: 200 mg monensin/head/day or 0 mg monensin/head/day fed in a .01 kg/head/day diet of pelletized 14% protein feed. Both groups were stocked at 15.3 head/ha. Monensin-fed calves gained .52 kg/head/day, while the control-fed calves gained .42 kg/head/day (P < .10). Average daily gains (ADG) of steers (.54 kg) were greater (P < .05) than those of heifers (.40 kg). Forage to gain ratio estimates were 15:1 and 19:1 for calves on monensin and control paddocks, respectively. In trial 2, 48 steer calves, averaging 265 days of age and 260 kg, were randomly assigned to each of two replicates of the following grazing treatments: common Bermudagrass only (P), Bermudagrass + .91 kg/head/day 14% protein feed (PF) or Bermudagrass + .91 kg/head/day feed + 200 mg monensin/head/day (PFM). ADG were .45, .47 and .68 kg for steers fed P, PF and PFM, respectively. The monensin-fed calves showed a 45% improvement in ADG (P < .05). Estimated forage to gain ratios for calves fed P, PF and PFM were 20:5:1, 19:1 and 13:1, respectively. The use of 200 mg monensin/head/day improved calf gains by 23 to 45% and increased estimated feed efficiencies by 21 to 36% on Bermudagrass pastures. The improvement in gain for heifers fed monensin was 28.6%, while steers gained 18.4% more when fed monensin.

Mixtures of Mowiol [an industrial plasticized poly(vinyl alcohol)] and corn starch have been examined by scanning electron microscopy (SEM); their impact and crossbreaking strengths, as well as their flexural moduli, measured. The results show fracturing as well as pitting with increased corn starch in Mowiol. The starch granular sizes (determined randomly for a number of samples) fluctuated between 10 and 22 μm, without some definite trend in the distribution. However, a certain degree of uniformity of granular size distribution appears to be achieved with an increase in the starch content of Mowiol. Both the impact and crossbreaking strength decreased with increase in starch, while the flexural modulus increased as the starch content increased. The impact of these observations on the resultant Mowiol/starch composites has been discussed. That transformed poly(vinyl alcohol) is likely to be an invaluable engineering material is not in doubt.

Brassica sp. may serve as high energy forage crops at times when forage availability may be limited. Field studies were conducted in the Northeast to assess forage yield and quality of 'Sirius' turnips (Brassica rapa L.) and 'Perko' rape (B. napus L.) planted on a Hagerstown silt loam (fine, mixed, mesic Typic Hapludalf) soil in late May (1978) and late April (1979). Preemergence herbicides including metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy- l-methylethyl) acetamide], pendimethalin [Nl-ethylpropyl)-3,4 dimethyl-2,6-dinitrobenzeneamine], and nitrofen [2,4-dichlorophenyl p-nitrophenyl ether] were applied alone and in various combinations to determine effectiveness in reducing weed competition. Forage yields of turnips and rape 100 days after seeding were generally not affected by the herbicide treatments. However, associated weed yields in both turnips and rape were significantly reduced with all herbicide treatments applied. Pendimethalin applied at 2.2 kg ha−¹ was phytotoxic to both turnips and rape reducing yields 67 and 17%, respectively, as compared to the untreated control. Forage dry matter yields of turnips and rape with adequate weed control were as high as 5068 and 6711 kg ha−¹, respectively. In 1978, turnip whole plant crude protein (CP) concentration was highest (227 g kg−¹) where pendimethalin was applied at 2.2 kg ha−¹. The 2nd year CP levels for turnip leaves were similar for all herbicide treatments, but root levels were highest where pendimethalin at 2.2 kg ha−¹ was used. The high rate of pendimethalin severely inhibited root development resulting in smaller roots with higher CP. Rape CP levels in 1978 were generally highest where herbicides were used, but in 1979, rape CP was not affected by herbicide application. Averaged across herbicide treatments, turnip (whole plant) and rape CP levels averaged 121 and 106 g kg−¹, respectively. In vitro dry matter disappearance for turnips and rape were similar averaging 898 g kg−¹ and were not affected by herbicide application. Results indicate that appropriate preemergence herbicides will reduce early season weed competition and will enhance early production of turnips and rape. The high production potential and the high dry matter digestibility 100 days after seeding warrant consideration of turnips and rape for use as supplemental summer forage crops.