Effect of Application Time on the Efficacy of Sclerotinia sclerotiorum as a Mycoherbicide for Cirsium arvense Control in Pasture

An experiment was conducted in sheep-grazed pasture in three regions of New Zealand over three years to evaluate the effect of application time on the efficacy of a dry granule myceliumon-wheat formulation of Sclerotinia sclerotiorum for the biological control of Cirsium arvense . At each site, the experimental mycoherbicide was applied to a previously untreated plot in each month of the year for three years at a dose of 50 g m -2 . Applications made during the spring and early summer months of October, November and December significantly reduced the ground cover of C. arvense for 67, 67 and 44%, respectively of these applications. Reduced ground covers ranged from 38 to 81% of the cover on untreated plots. Applications in late summer and autumn were less effective. Correlations of ground cover by C. arvense with climate parameters suggested that free moisture promoted treatment efficacy, but that intense rainfall after treatment reduced efficacy through wash off. The importance of leaf wetness for the efficacy of the mycoherbicide was confirmed by comparing disease development and mortality in C. arvense shoots with and without enhanced moisture levels under field conditions. A water miscible formulation applied as a slurry was less dependent upon leaf wetness than the dry granule formulation.     

A Comparison of Auxotrophic and Wild Strains of Sclerotinia sclerotiorum Used as a Mycoherbicide Against Californian Thistle ( Cirsium arvense )

Two auxotrophic mutant strains of Sclerotinia sclerotiorum were tested in the greenhouse for pathogenicity on Cirsium arvense (Californian thistle) with and without amino acid amendments. An arginine auxotrophic mutant, with an amendment of the amino acid, followed an identical disease progress curve to that of the wild strain of the pathogen from which it was derived. However, when deprived of the amino acid amendment it was still highly pathogenic. A leucine auxotrophic mutant demonstrated poor pathogenicity without a leucine amendment, but improved pathogenicity with the addition of the amino acid. However, both of these treatments were inferior to the two wild strains tested and the arginine auxotroph with and without amendments. A field experiment was conducted on C. arvense stems in permanent pasture to compare the pathogenicity of amended auxotrophic strains and wild strains of S. sclerotiorum applied as a granule in a wheat-based carrier. The two wild strains gave significant reductions in thistle cover within 3 months of treatment, and subsequent reductions in thistle stem height and density during the following season. There was no evidence that the auxotrophic strains reduced thistle cover in the season the treatments were applied, but they did reduce subsequent stem density in the following spring. To determine disease carry-over associated with the wild and auxotrophic strains of the pathogen, rape was planted into subplots over the next three consecutive seasons. Despite substantial populations of sclerotia being present in the soil, especially in the first season after treatment of the thistles, no disease of rape caused by S. sclerotiorum was detected over the three seasons in any of the plots. Sclerotium populations of S. sclerotiorum in the soil declined by over 50% between 20 and 32 months after treatment, but there was no decline over the subsequent 12 months. The trial demonstrated that the auxotrophic strains were less field fit compared with the wild strains and that the presence of inoculum and a susceptible host to S. sclerotiorum were not the only prerequisites for disease development. It was concluded that use of a trap crop following treatment is not a suitable method for determining the risk of using this pathogen as a mycoherbicide in pasture.     

Vigour control, an integrated approach to cane, pest and disease management in red raspberry (Rubus idaeus)

The first flush of young canes of red raspberry (Rubus idaeus) was removed at different dates in spring, using the contact herbicide dinoseb. In comparison with untreated plots, cane removal increased fruit yield, controlled excessive cane vigour, and improved the health status of vegetative canes in a plantation infested by raspberry cane midge (Resseliella theobaldi). At the end of the growing season vegetative canes on treated plots were shorter and thinner, and sustained less physical injury than those on untreated plots. Access to the fruit at harvest was also improved. Reduced competition between fruiting and vegetative canes increased yield in the year of treatment by an average of 35%. Yield was not affected by date of cane removal, but growth of replacement cane was reduced below optimum when first flush cane was removed after mid-May. The later the canes were removed, the less was the incidence of pest and diseases. Cankers and lobate vascular lesions (‘patches’) resulting, respectively, from the feeding of first and second generation midge larvae (with associated fungi) affected fewer canes in treated than in untreated plots. Significantly fewer live larvae of R. theobaldi were recovered in the following winter from soil in plots treated on or after 11 May than from untreated plots. The main effect of vigour control on R. theobaldi and midge blight was that replacement canes provided fewer egg-laying sites (natural splits) than did the first flush canes on untreated plots. The incidence of spreading vascular lesions (‘stripes’) attributed to Leptosphaeria coniothyrium infecting either physical wounds (cane blight) or midge feeding wounds (midge blight) was substantially less in treated than untreated plots. Cane botrytis (Botrytis cinerea) and spur blight (Didymella applanata) were also less common in treated plots. Interactions between vigour control and pest and disease incidence are discussed in relation to the efficient management of cv. Glen Clova in eastern Scotland.     

Persistence of foraging chickens on grasshopper populations: a case study in Northwest China

Chickens were allowed to forage for one growing season (June–September) on plots containing substantial numbers of grasshoppers. When compared with untreated areas, plots where foraging occurred for just one season had significantly (P < 0.05) fewer grasshoppers for five years, though there was no difference in density in the sixth year.     

Periods of organogenesis in mono- and bicyclic annual shoots of Juglans regia L. (Juglandaceae)

The organogenetic cycle of shoots on main branches of 4-year-old Juglans regia trees was studied. Mono- and bicyclic floriferous and vegetative annual shoots were analysed. Five parent annual shoot types were sampled between October 1992 and August 1993. Organogenesis of summer growth units was monitored between 16 Jun. and 3 Aug. 1993. Variations over time in the number of nodes, cataphylls and embryonic green leaves of terminal buds were studied. The number of nodes of parent shoot buds was compared with the number of nodes of shoots derived from parent shoot buds. The spring growth units of mono- and bicyclic shoots consist exclusively of preformed leaves which were differentiated, respectively, during the spring flush of growth (mid-April until mid-May) or the summer flush of growth (mid-June until early August) in the previous growing season. Thus, winter buds may consist of flower and leaf primordia differentiated in two different periods during annual shoot extension. The summer growth units of bicyclic shoots consist of preformed leaves that were differentiated in spring buds during the spring flush of growth in the current growing season. Bud morphology is compared between spring and summer shoots.     

Natural Fusarium Grain Infection Level in Wheat, Barley and Oat after Early Application of Fungicides and Herbicides

In Norway, early application of fungicides against cereal leaf diseases (before Zadoks 60) is common practice amongst farmers. Whether this procedure has any effect on Fusarium infection of the mature grain has been little investigated. To evaluate effects on Fusarium grain infection, cereal grains were sampled during 1996, 1997 and 1998 from 12 field trials where early spraying against fungal diseases in spring wheat, spring barley and oats was carried out. Percentage infected grains and frequency of different Fusarium species was analysed in every grain sample. The effect of fungicides, glyphosate and postemergence herbicides on Fusarium grain infection was studied. Significant increase in Fusarium infection was detected in fungicide‐treated plots compared with untreated plots. Fusarium avenaceum and F. tricinctum were the most frequent species detected. The internal ranking of Fusarium species remained the same after spraying. No significant effects were found on the level of Fusarium infection after glyphosate treatment in autumn or herbicide treatment during the growing season.     

Absence of effects from immunocontraception on seasonal birth patterns and foal survival among barrier island wild horses

Despite a large body of safety data, concern exists that porcine zonae pellucidae (PZP) immunocontraception--used to manage wild horse populations--may cause out-of-season births with resulting foal mortality. Our study at Assateague, Maryland indicated the effects of immunocontraception on season of birth and foal survival between 1990 and 2002 on wild horses from Assateague Island. Among 91 mares never treated, 69 (75.8%) of foals were born in April, May, and June (in season). Among 77 treated mares, 50 (64.9%) were born in season. Of 29 mares foaling within 1 year after treatment (contraceptive failures), 20 (68.9%) were born in season. Of 48 mares treated for greater than 2 years then withdrawn from treatment, 30 (62.5%) of 48 foals were born in season. There were no significant differences (p <.05) between either treatment group or untreated mares. Survival did not differ significantly among foals born in or out of season or among foals born to treated or untreated mares. Data indicate a lack of effect of PZP contraception on season of birth or foal survival on barrier island habitats.     

不同有机物覆盖对冷凉地区苹果园土壤水温环境及速效养分的影响

为了探究不同有机物覆盖对冷凉地区果园土壤理化性质的影响,在‘寒富’苹果园设置了杂草、稻草、玉米秸秆、粉碎枝条4个覆盖处理,对比分析了各处理果园土壤水分、养分等指标的变化.结果表明: 有机物覆盖增加了土壤含水量,以干旱季节最为明显;减缓了春季土壤温度上升速度,不利于果树前期生长,但降低了夏季土壤的最高温,提高了秋冬季土壤的最低温;提高了土壤的pH值,以玉米秸秆覆盖处理最为明显,减轻了土壤酸化,使土壤pH接近中性;不同程度提高了土壤有机质含量,以杂草覆盖处理最为明显.覆盖还增加了土壤碱解氮、速效磷、速效钾含量,但稻草覆盖处理碱解氮含量低于对照.     

Controlling ‘bois noir’ disease on grapevine: does the timing of herbicide application affect vector emergence?

Bois noir is an important grapevine yellows disease that can cause serious economical losses in European grapevine production. Hyalesthes obsoletus Signoret (Hemiptera, Cixiidae) is the principal vector of bois noir in Switzerland and stinging nettle (Urtica dioica) is its favourite host plant species in vineyards. As bois noir disease can hardly be cured and direct control measures against H. obsoletus are ineffective, viticultural control practices target stinging nettle, the actual reservoir and source of both the pathogen and its vector. Currently, it is recommended to apply herbicides against stinging nettle at the end of the season to kill developing H. obsoletus nymphs. To verify if this late period of herbicide application is justified, stinging nettle patches were treated with glyphosate in the autumn, in the spring or were left untreated as a control. Herbicide applications at both dates controlled the growth of stinging nettle very well in the subsequent summer, although the autumnal treatment was slightly more efficient. To study glyphosate’s direct impact on the development of H. obsoletus nymphs, emergence traps were placed directly in the centre of treated and untreated stinging nettle patches. There was no significant difference among the three treatments in the total number of adults emerging. Thus, an aerial application of glyphosate in either spring or autumn did not inhibit the nymphs’ development on the roots of stinging nettle in the soil. Our results challenge current recommendations of applying herbicides against stinging nettle at the end of the season and suggest that stinging nettle could also be controlled in spring, alike other viticultural weeds.     

Prey availability,pesticides and the abundance of orchard spider communities

In a 4 year study, in southern England, the abundance of apple orchard canopy spiders and their potential prey was manipulated using two pest management strategies based on broad spectrum (highly toxic both to spiders and pests) and selective (moderately toxic to spiders but highly toxic to pests) insecticides in the first part of the growing season. The spider community was left to develop freely afterwards. Apple orchard plots untreated by pesticides served as control.The effect of insecticides was detrimental to spider populations as the treatments coincided with the peak abundance of adults in May and early June. Within adults, the treatments were harmful to female spiders, whereas, male spiders were much less affected. As a result the proportion of males increased in all of the sampled spider families.The use of selective insecticides resulted in a higher spider abundance compared to the use of broad spectrum compounds while the highest spider abundance was found in the pesticide free trees, i.e. three significantly different spider abundance levels were produced in spring. Spider abundance began to increase unequally between the treatments afterwards and became identical in the two pesticide treated plots due to the immigration of juveniles from surrounding habitats. However, a similar equalisation of abundance was not observed between the pesticide treated plots and untreated control. Analysing the abundance pattern of potential prey in the plots of the studied orchard we concluded that the post-disturbance increase in spider abundance was regulated by prey availability.     

Effects of aldicarb persistence on field populations of Heterodera schachtii

In field trials in 1976 and 1977 various granular formulations of aldicarb (2–8 to 12.8 kg a.i. ha^-1) were applied to sugar-beet fields infested with Heterodera schachtii . The levels of toxic residues of aldicarb and of H. schachtii populations in the soil were monitored at intervals throughout the sugar-beet season.
A severe drought in 1976 seriously affected the field trials and although aldicarb levels were maintained in the soil no aldicarb treatment proved effective in controlling H. schachtii; this was probably due to lack of mobility of the pesticide in the soil. In 1977, the final nematode populations in plots treated with 2.8 or 11.2 kg a.i. ha^-1 added incrementally through the growing season to simulate the effect of a controlled release formulation were not significantly different from those of untreated plots. In contrast treatment at drilling with fast-releasing formulations at all application rates did promote control of H. schachtii populations. No significant increase in yield was found on any trial after treatment with aldicarb.
The value of controlled release formulations of aldicarb for the control of H. schachtii populations over the growing season has not been proven.     

The integration of host resistance with fungicides in the control of oat powdery mildew

Treatment of seed with the systemic fungicides triadimenol plus fuberidazole as Baytan significantly decreased powdery mildew in field experiments involving eight oat cultivars differing widely in their resistance to the disease. This was so up to growth stage G.S. 61 (Zadoks) even in a year of high mildew incidence, although the effect diminished after flowering. Significant (P≥ 0.001) interactions between fungicide treatments and cultivars occurred in each of three years at nearly all assessment times. In years of high mildew incidence (1983 and 1984), susceptible cultivars developed similar levels of mildew in seed-treated and untreated plots by about flowering time, although cultivars with adult plant resistance (APR) had significantly less mildew when seed-treated than when left untreated. Later, as the APR was fully expressed and the fungicide effectiveness was declining, similar mildew levels were recorded on treated and untreated plots. Untreated APR cultivars generally had less mildew than treated susceptible cultivars and in a year of late and light mildew, APR alone provided good protection. Seed treatments combined with foliar sprays of tridemorph as Calixin almost completely controlled mildew except on very susceptible cultivars late in the season in high mildew years. Over all cultivars, seed treatment gave yield advantages of 5.3% (1983) and 6.6% (1984) but in 1982, a year of low mildew, the response was small. The possible influence of integrated host resistance and fungicides in stabilising the pathogen population at economically unimportant levels and the environmental benefit of using host resistance to minimise fungicide usage is discussed.     

Effects of foliar applications of fungicides during plant growth on grain development and grain germinability in spring barley

In 1990 and 1991 grain samples of spring barley were obtained from plots in which fungal diseases were controlled until ear emergence using fungicide sprays, and from comparable plots which had received no fungicide applications. The grain was stored at 10^oC, and tested for germination at intervals during storage. Grain from plots treated with fungicide consistently exhibited more dormancy than grain from untreated plots. In 1992, grain development was monitored from anthesis to harvest-ripeness in treated and untreated plots of cvs Blenheim, Camargue and Tyne. In cvs Blenheim and Camargue, grains in fungicide-treated plots had a greater dry weight at harvest-ripeness, and dehydrated later in development than grains in untreated plots. Neither of these differences was observed in cv. Tyne. Possible interpretations of the effects of fungicide treatment of the parent plant on the physiology of the grain are discussed.     

Demographic consequences of increased winter births in a large aseasonally breeding mammal (Bos taurus) in response to climate change

1.?Studies examining changes in the scheduling of breeding in response to climate change have focused on species with well-defined breeding seasons. Species exhibiting year-round breeding have received little attention and the magnitudes of any responses are unknown. 2.?We investigated phenological data for an enclosed feral population of cattle (Bos taurus L.) in northern England exhibiting year-round breeding. This population is relatively free of human interference. 3.?We assessed whether the timing of births had changed over the last 60 years, in response to increasing winter and spring temperatures, changes in herd density, and a regime of lime fertilisation. 4.?Median birth date became earlier by 1·0 days per year. Analyses of the seasonal distribution of calving dates showed that significantly fewer calves were born in summer (decline from 44% of total births to 20%) and significantly more in winter (increase from 12% to 30%) over the study period. The most pronounced changes occurred in winter, with significant increases in both the proportion and number of births. Winter births arise from conceptions in the previous spring, and we considered models that investigated climate and weather variables associated with the winter preceding and the spring of conceptions. 5.?The proportion of winter births was higher when the onset of the plant growing season was earlier during the spring of conceptions. This relationship was much weaker during years when the site had been fertilised with lime, suggesting that increased forage biomass was over-riding the impacts of changing plant phenology. When the onset of the growing season was late, winter births increased with female density. 6.?Recruitment estimates from a stage-structured state-space population model were significantly negatively correlated with the proportion of births in the preceding winter, suggesting that calves born in winter are less likely to survive than those born in other seasons. 7.?This is one of the first studies to document changes in the phenology of a year-round breeder, suggesting that the impact of climate on the scheduling of biological events may be more extensive than previously thought and that impacts may be negative, even for species with relatively flexible breeding strategies.     

Side-Effects of Field Applications of 'Propiconazol' and 'Captafol' on the Composition of Non-target Soil Fungi in Spring Barley

The results show great seasonal variation in number and composition of the fungi isolated from the upper soil layer, especially owing to an increased isolation of primary saprophytic fungi during the late growing season. Before fungicide treatment no statistically significant difference was measured between the number of isolated fungi from the examined soils. During the treatment period significantly fewer fungi were isolated from plots treated with ‘captafol’ or ‘propiconazol’ than from the untreated plots. The differences between untreated and treated plots were not statistically significant 30 days after the last treatment. The ecotoxicological effect on the total isolated fungal flora thus seems negligible. However the fungi responded differen, tly to treatment with ‘captafol’ and ‘propiconazol’. None of the fungi were significantly affected for more than a month when treated with ‘propiconazol’. The number of primary saprophytic fungi (Cladosporium spp., Alternaria spp., Epicoccum purpurascens, and Stemphylium sp.) and Sphaeropsidales, however, was significantly reduced for more than a month when treated with ‘captafol’.     

Reproductive seasonality in a free-ranging troop of stumptail macaques (Macaca arctoides): A five-year report

Seasonality in births and fertile matings are reported for a stumptail macaque group living on an island for a period of five years: 1975–1979. During this period 26 births occurred of which 24 represent infants conceived on the island. While births and fertile matings occurred throughout the year 21% of the births were concentrated in March, 34% in June and July and 17% in November. Additionally 63% of the births occurred during the rainy season. Of the 24 infants, 4 died during the first year of life thus yielding a reproductive success of 83%. The sex ratio at birth for the five years was 1:1 corrected to 1:1.2 with the four deaths. The mean interval between fertile matings for females was 19 months and 2 days and the mean age for first conception was 4 years and 5 months. The pattern of birth and breeding seasonality was markedly similar to that of the parent troop while in Puerto Rico.     

Response of Grassland Birds in Sand Shinnery Oak Communities Restored Using Tebuthiuron and Grazing in Eastern New Mexico

Sand shinnery oak (Quercus havardii) communities are a unique component of grassland bird habitat in eastern New Mexico and have been impacted by human activities for decades. These communities are frequently managed with livestock grazing and herbicide application for shrub control, strategies that potentially can be used to restore the historical shrub–grass composition of this plant community. During spring migration and the breeding seasons of 2004 and 2005, we compared density and community structure of grassland bird species among four combinations of tebuthiuron application and grazing treatments that were being evaluated for restoration of shinnery oak communities. We performed biweekly point transects on sixteen 65‐ha study plots in these communities. Density of all avian species combined did not differ between grazed and ungrazed plots. Tebuthiuron‐treated plots had a 40% higher average density for combined species than untreated plots. There was a 41% higher average density of all species during spring 2005 than 2004, but density was similar during the breeding season of both years. These trends were predominantly influenced by densities of migratory Cassin’s Sparrow (Aimophila cassinii), which were greater in tebuthiuron‐treated plots in both years. Densities of resident Meadowlarks (Sturnella spp.) exhibited little response to tebuthiuron or grazing treatments. Avian species richness, evenness, and diversity were only minimally affected by the tebuthiuron and grazing treatments. This study occurred over a period of highly variable precipitation, so future assessments, spanning longer wet–dry cycles and maturing plant communities, may be necessary to completely determine avian response to these restoration efforts.     

Suppression of Plutella xylostella and Trichoplusia ni in cole crops with attracticide formulations

The three key lepidopteran pests of cole, Brassica oleracea L., crops in North America are diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae); cabbage looper; Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae); and imported cabbageworm, Pieris rapae (L.) (Lepidoptera: Pieridae). Two species-specific pheromone-based experimental attracticide formulations were evaluated against these pests: LastCall DBM for P. xylostella and LastCall CL for T. ni. No LastCall formulation was available against P. rapae. Laboratory toxicity experiments confirmed the effectiveness of each LastCall formulations in killing conspecific males that made contact. In replicated small plots of cabbage and collards in central Alabama, over four growing seasons (fall 2003, spring 2004, fall 2004, and spring 2005), an attracticide treatment receiving the two LastCall formulations, each applied multiple times at the rate of 1,600 droplets per acre, was compared against Bacillus thuringiensis. subspecies kursatki (Bt) spray at action threshold and a negative untreated control. Efficacy was measured by comparing among the three treatments male capture in pheromone-baited traps, larval counts in plots, and crop damage rating at harvest. LastCall provided significant reductions in crop damage comparable to Bt in three of the four seasons. Efficacy of LastCall was dependent upon lepidopteran population densities, which fluctuated from season to season. In general, reduction in crop damage was achieved with LastCall at low-to-moderate population densities of the three species, such as typically occurs in the fall in central Alabama, but not in the spring when high P. rapae population pressure typically occurs in central Alabama. Significant reductions in pheromone trap captures did not occur in LastCall plots, suggesting that elimination of males by the toxicant (permethrin), rather than interruption of sexual communication, was the main mechanism of effect.     

LEAF DIMORPHISM IN POPULUS TRICHOCARPA

Critchfield , William B. (Pacific SW Forest & Range Expt. Sta., Berkeley, Calif.) Leaf dimorphism in Populus trichocarpa. Amer. Jour. Bot. 47 (8) : 699–711. Illus. 1960.—In Populus trichocarpa and other species of Populus, each tree bears 2 kinds of leaves, referred to here as “early” and “late” leaves. Both leaf types are present on all long shoots. They differ in many features of external morphology, including petiole length, size and occurrence of marginal glands, venation, and stomatal distribution. This type of foliar dimorphism has its origins in a pronounced difference in leaf ontogeny. The early leaves originate in the developing bud and overwinter as embryonic leaves. The first late leaves are also present in the winter bud, but as arrested primordia, and succeeding late leaves are initiated at the tip of the growing shoot and develop uninterruptedly to maturity during the growing season. A similar correlation between leaf form and the circumstances of leaf ontogeny appears to be a common feature of many other instances of heterophylly. The expansion of the pre-formed early leaves is almost completed by late spring, when the first late leaves begin to grow rapidly. The formation of late leaves may then continue until late in the season. The rapid elongation of the stem does not begin until the first late leaves expand. Elongation is restricted to shoots producing late leaves. Consequently, the early leaves are confined to short shoots and the base of long shoots; adventitious shoots and the upper part of long shoots bear only late leaves. Certain other woody plants with long and short shoots also exhibit a restriction of elongation to those shoots on which a second set of leaves is produced.