积雪草漆斑病病原鉴定及室内药剂筛选

近年来,在广西各地积雪草种植基地,出现一种为害极重的病害,该病害病原菌主要为害积雪草叶片、叶柄,可致使叶片大面积枯死,该病害发生普遍、侵染期长,严重影响积雪草药材的品质和产量。该研究采用常规组织分离法从积雪草病叶上分离病原菌并根据柯赫氏法则验证其致病性;通过菌落特征、菌株形态及ITS序列分析鉴定病原菌;在室内利用生长速率法测定10种杀菌剂对该菌的抑制活性。结果表明：为害积雪草叶片的病原菌为泛生漆斑菌( Myrothecium inundatum);该菌侵染性强,接种至健康积雪草叶片后24 h即可发病,并迅速扩展引起叶片萎蔫;杀菌剂60％唑醚?代森联水分散粒剂、45％恶霉灵?甲霜可湿性粉剂、1.8％辛菌胺醋酸盐水剂、80％代森锰锌可湿性粉剂室内对积雪草漆斑病病原菌的抑菌率均在98％以上,抑菌效果极强,建议在生产中轮换应用防治积雪草漆斑病。15％咪鲜胺微乳剂、70％甲基硫菌灵可湿性粉剂和10％苯醚菌酯悬浮剂对该病原菌的抑菌率也均在92％以上,抑菌效果良好,在生产中可酌情考虑使用。     

Sequential testing scheme for the assessment of the side-effects of plant protection products on the predatory bug Orius laevigatus

This paper describes a number of test methods, to beused in a sequential scheme, for testing the side-effects ofplant protection products on anthocorid bugs. Orius laevigatuswas used as test species. A `worst case' laboratory method wasdeveloped for evaluating the effect on mortality of the nymphsand the reproduction of the adults. An extended laboratory methodgives information on the effect of pesticides on adults undermore natural conditions. A semi-field test is executed in smallplots under field (glasshouse) conditions. Finally a field testsimulates the conditions in a commercial crop. For harmfulchemicals, both a laboratory and a semi-field persistence testwas developed to determine the safety period after which thepredatory bugs can be re-introduced in the greenhouse withoutbeing adversely affected. The total result of this sequentialscheme should indicate whether, and with what restrictions, aparticular pesticide can be implemented in IPM programs in whichO. laevigatus is used for control of western flower thrips(Frankliniella occidentalis). Twenty-two pesticides were testedincluding five fungicides, twelve insecticides and fiveacaricides. The fungicides captan, carbendazim, sulphur, thiram,tolylfluanid and the insecticides or acaricides pymetrozine,pyriproxyfen, tebufenozide and hexythiazox were harmless in the`worst case' laboratory test and thus did not need furthertesting. Imidacloprid, diafenthiuron, lufenuron, tebufenpyrad,abamectin, pyridaben and bifenthrin were harmful in thesemi-field test and should, in the tested concentrations, betternot be used simultaneously with the predatory bug. Theinsecticide dichlorvos was found harmful but short-lived in thepersistence test; it should be used before the introduction ofthe predatory bug O. laevigatus only when a safety period of 7days is respected. Pirimicarb was slightly toxic in thesemi-field test but short-lived. In IPM programs this aphicideshould be used at a low application frequency.     

Effects of Selected Fungicides and the Timing of Fungicide Application on Beauveria bassiana-Induced Mortality of the Colorado Potato Beetle (Coleoptera: Chrysomelidae)

Four fungicides used for controlling foliar diseases of potato (Solanum tuberosum) were evaluated under field and laboratory conditions for their effects on the infectivity and sporulation of Beauveria bassiana when used as a control for the Colorado potato beetle, Leptinotarsa decemlineata (CPB). We investigated the direct effects of fungicides on B. bassiana-induced CPB mortality and the effect of time between fungicide and B. bassiana application. Effects of fungicide on conidial survival in the soil and on foliage were examined in the field. Significantly more larval mortality was observed when larvae were sprayed with B. bassiana than with the water control. Fungicide had no significant effect on larval mortality in the field. In the laboratory, survival of larvae was significantly lower among larvae fed fungicide-treated foliage. B. bassiana-induced mortality in the laboratory was observed only when larvae were fed foliage treated with copper hydroxide or water. Larvae fed mancozeb- or chlorothalonil-treated foliage experienced high mortality regardless of B. bassiana treatment. While there was no significant effect of fungicide on B. bassiana sporulation on cadavers in the field, a pattern emerged that indicated higher proportions of cadavers producing conidia in plots sprayed with water or copper hydroxide than in plots sprayed with chlorothalonil or mancozeb. Survival of B. bassiana conidia in the soil and on foliage was significantly greater in plots treated with copper hydroxide or water than in plots treated with mancozeb or chlorothalonil. Fungicides such as copper hydroxide may be less deleterious to the fungus than mancozeb and chlorothalonil.     

Laboratory method for testing side-effects of pesticides on the rove beetleAleochara bilineata — Adults

Tests were conducted in glass cells containing moistened sand sprayed with the concentration recommended for the pesticide or with demineralised water (controls). Adult females (1–2 weeks old) ofA. bilineata were placed on the fresh residue in the cells and provided daily with fresh fly eggs as food. The duration of the test was 5 days, mortality being recorded every day. The side effects of the pesticide were expressed as reduction in egg production ofA. bilineata during the whole test period. Results permitted classification of the pesticides according to the 4 categories of harmfulness used by the IOBC working group. 23 pesticides were tested, and the reproducibility of the test appeared to be satisfactory. Generally, insecticides/acaricides had a pronounced effect on the beetles whereas fungicides and herbicides were less detrimental. Exceptions were the insecticides Tedion V 18 and Kilval, classified as harmless, and the fungicides Morestan, Pomarsol forte and Afugan rated as moderately harmful. Among growth regulators Prosevor 85 was highly detrimental while Cycocel Extra and Rhodofix had no effects. Excepting Morestan, Pomarsol forte and Ustinex PA the pesticides did not affect the hatching of eggs. The work was financed by the Danish Environmental Protection Agency.     

Compatibility of Chemical Disease and Insect Management Practices Used in New York Vineyards with Biological Control by Anagrus spp. (Hymenoptera: Mymaridae), Parasitoids of Erythroneura Leafhoppers

Toxicity to Anagrus spp. of fungicides and insecticides used in grape production was assessed with laboratory and field bioassays. Field-equivalent rates of fungicides were relatively nontoxic to Anagrus spp. adults in laboratory bioassays. In bioassays with field-weathered residues, sulfur (9600 ppm) caused elevated mortality of adults for 14 to 21 days posttreatment. Residues of microencapsulated methyl parathion (600 and 1200 ppm) increased mortality relative to the control up to 43 days posttreatment. Duration of elevated mortality of adults exposed to carbaryl was dose dependent and ranged from 14 (at 1200 ppm) to >43 days (at 4800 ppm). Residues of carbaryl and methyl parathion applied over parasitized eggs had little effect on emergence, but may have delayed development. In a field trial, adults trapped in carbaryl-treated plots were significantly reduced starting 3 weeks after treatment. Subsequent lower trap catches may have been related to effects of residues on Anagrus spp. adults or to lower leafhopper egg densities in treated plots.     

Effects of 37 fungicides on the rove beetleAleochara bilineata (Col.: Staphylinidae) in the laboratory

Effects of 37 fungicides — several of which were mixtures — on adult females of the rove beetle,Aleochara bilineata, were investigated in the laboratory. The pesticides were tested in concentrations equivalent to the highest recommended dosages for practical use. Mortality, egg production and hatch of the eggs were recorded. Most fungicides had no serious effect on any of the parameters measured. Among the morpholine and dithiocarbamate fungicides, several had adverse effects on egg production and/or hatch of the eggs laid. Furthermore, chinomethionate and pyrazophos were found to be toxic at the dosages used. Results are compared to results obtained with other species of beneficial arthropods in the laboratory. The importance of including several species in the assessment of pesticide side effects as well as the importance of measuring sublethal effects are stressed.

---

Résumé Des expériences de laboratoire ont été faites pour étudier les effets de 37 fongicides (dont plusieurs étaient des mélanges) sur les femelles adultes d'Aleochara bilineata. Les pesticides ont été testés à des concentrations équivalant aux plus fortes doses recommandées pour l'usage agricole. La mortalité, la production et l'éclosion des œufs ont été étudiées. La plupart des fongicides n'ont pas d'effet important sur aucun des paramètres retenus. Parmi les fongicides à base de morpholine et de dithiocarbamate, plusieurs avaient un effet contraire sur la production et l'éclosion des œufs. En outre le chinométhionate et le pyrazophos se sont révélés toxiques aux doses utilisées. Les résultats ont été comparés à d'autres résultats obtenus avec d'autres espèces d'auxiliaires au laboratoire. L'importance d'inclure plusieurs espèces dans l'évaluation des effects secondaires des pestieides ainsi que l'importance de mesurer les effets sublétaux sont soulignées.

     

铁皮石斛锈病病原鉴定及药剂筛选

为了明确铁皮石斛锈病的病原菌种类,筛选其有效防治药剂,通过对云南瑞丽铁皮石斛种植基地调查,运用形态学并结合分子生物学方法对病原菌进行鉴定,选用4种杀菌剂进行田间药效试验。结果表明,铁皮石斛锈病由真菌鞘锈菌(Coleosporium sp.)引起,发生期为每年2～11月,鞘锈菌的夏孢子直接侵染铁皮石斛叶片,以冬孢子越冬。10%苯甲·丙环唑悬浮剂450 mL·hm-2与75%肟菌·戊唑醇水分散粒剂300 g·hm-2的防效显著高于其他两种药剂,3次药后防效分别为82.16%和82.88%,这2种药剂可作为防治铁皮石斛锈病的有效药剂。     

Effects of 20 fungicides on the infectivity of conidia of the aphid entomopathogenic fungus Erynia neoaphidis

The effect of 20 fungicides on theinfectivity of conidia of the entomopathogenicfungus, Erynia neoaphidis, were assessedin the laboratory. After projection on broadbean leaves, conidia were treated withfungicides applied at their recommended fieldrate. Afterwards, the infectivity of theseinocula was assessed using an aphid bioassay.Four fungicides, carbendazim, kresoxym-methyl, nuarimol and thiophanate-methyl reduced the infectivity of the conidia by less than 25% and can be considered harmless for this aphid pathogen. Propiconazole was a little more toxic, with 37% reduction. Other products reducedinfectivity by between 50% and 100%. These are, from the least to the most toxic:flutriafol, prochloraz, epoxyconazole,iprodione, hexaconazole, triadimenol,azoxystrobine, cyproconazole, cyprodynil,flusilazole and tridemorph. Chlorothalonil,fenpropimorph, spiroxamine and tebuconazoletotally inhibited infectivity of the fungi. Analysis of the results according to chemicalclass showed that the benzimidazoles were theleast toxic for E. neoaphidis and themorpholines the most toxic. Effects oftriazoles and strobilurines were variable, withreduction ranging from 37% to 100% fortriazoles and from 17% to 68% forstrobilurines.     

The effects of some commonly-used foliar fungicides on Collembola in winter barley: laboratory and field studies

Four commonly-used cereal foliar fungicides were screened for their laboratory toxicity against the symphypleone collembolan, Sminthurinus aureus. A proportional hazards analysis of time-survival curves following the fungicide treatments showed that carbendazim, propiconazole, pyrazophos and triadimenol significantly increased the laboratory mortality of S. aureus. The organophosphorus fungicide pyrazophos caused high levels of mortality of S. aureus in the laboratory so a field evaluation of the effects of this fungicide on a wider range of Collembola was undertaken in winter barley. Comparison of the effects of pyrazophos with those of the broad-spectrum insecticide dimethoate in the field revealed both compounds to have similar activity against some Collembola. Of the 11 species caught only the four symphypleone species exhibited these effects but the numbers of three symphypleone species were reduced to zero 4 wk after treatment with pyrazophos. The effects of pyrazophos and dimethoate were, however, not detectable in individual species after 11 wk.     

Mesoherbivores reduce net growth and induce chemical resistance in natural seaweed populations

Herbivory on marine macroalgae (seaweeds) in temperate areas is often dominated by relatively small gastropods and crustaceans (mesoherbivores). The effects of these herbivores on the performance of adult seaweeds have so far been almost exclusively investigated under artificial laboratory conditions. Furthermore, several recent laboratory studies with mesoherbivores indicate that inducible chemical resistance may be as common in seaweeds as in vascular plants. However, in order to further explore and test the possible ecological significance of induced chemical resistance in temperate seaweeds, data are needed that address this issue in natural populations. We investigated the effect of grazing by littorinid herbivorous snails (Littorina spp.) on the individual net growth of the brown seaweed Ascophyllum nodosum in natural field populations. Furthermore, the capacity for induced resistance in the seaweeds was assessed by removing herbivores and assaying for relaxation of defences. We found that ambient densities of gastropod herbivores significantly reduced net growth by 45% in natural field populations of A. nodosum. Seaweeds previously exposed to grazing in the field were less consumed by gastropod herbivores in feeding bioassays. Furthermore, the concentration of phlorotannins (polyphenolics), which have been shown to deter gastropod herbivores, was higher in the seaweeds that were exposed to gastropod herbivores in the field. This field study corroborates earlier laboratory experiments and demonstrates that it is important to make sure that the lack of experimental field data on marine mesoherbivory does not lead to rash conclusions about the lack of significant effects of these herbivores on seaweed performance. The results strongly suggest that gastropods exert a significant selection pressure on the evolution of defensive traits in the seaweeds, and that brown seaweeds can respond to attacks by natural densities of these herbivores through increased chemical resistance to further grazing.     

CEN/TC 216: its role in producing current and future European disinfectant testing standards

CEN, the European Committee for Standardization, is a legal association comprising of National Standards Bodies (e.g. AFNOR, BSI, DIN) responsible for the production of European Standards (ENs) which are designed to facilitate the exchange of goods and services through the elimination of technical barriers to trade. CEN/TC 216 was conceived in the late 1980s with the scope Standardization of the terminology, requirements, test methods including potential efficacy under in-use conditions, recommendations for use and labelling in the whole field of chemical disinfection and antiseptics. Areas of activity include agriculture (but not crop protection chemicals), domestic service, food hygiene and other industrial fields, institutional, medical and veterinary applications. Following a meeting in 1990, the Technical Committee (TC) delegated its work to four Working Groups (WG); a Horizontal Working Group (HWG) and three Working Groups responsible for the Medical (WG1), Veterinary (WG2) and Food Hygiene, Domestic and Institutional (WG3) market sectors. Whilst the three WGs could develop test methods to assess bactericidal and fungicidal product activity, specialist Task Groups of the HWG have been established to provide specific guidance on viruses, spores, surface tests, ring trials and to harmonize methodology. The main objective of TC/216 is to produce test methods in a sequential, three phase mode. In Phase 1, the ability of a product to demonstrate bactericidal, fungicidal or sporicidal activity is tested. Phase 2 tests are divided into two steps. Step 1 tests are suspension tests to determine bactericidal, fungicidal, virucidal or sporicidal activity under laboratory conditions that simulate practical conditions. Step 2 tests are other laboratory tests e.g. handwash, handrub or surface tests that are more representative of in-use conditions. Phase 3 tests hope to give guidance to product users as to how to undertake suitable field trials. To date, eight standards have been produced and another 18 are in the final stages of development. WG1 has been the most prolific with 18 test methods under development whilst WG2 and 3 have six and three tests, respectively. Following production of standard test methodologies, the major issues for CEN/TC 216 are concerned with assessing the performance of the tests in practice, especially their statistical reliability. In addition, standards are being further harmonized and guidelines being developed to help product manufacturers and users select the appropriate tests for appropriate fields of use.     

Effects of wheat foliar fungicides on the aphid endoparasitoid Aphidius rhopalosiphi DeStefani-Perez (Hym., Aphidiidae) on glass plates and on plants

Abstract: The side-effects of several fungicides used in wheat to control disease at heading growth stage were assessed on the aphid parasitoid Aphidius rhopalosiphi by tests conducted in the laboratory on glass plates and in the greenhouse on young wheat plants. Very few formulations containing only one active ingredient (carbendazim, cyproconazole or epoxyconazole) or combinations of two (carbendazim + cyproconazole, carbendazim + hexaconazole) were harmless to A. rhopalosiphi in the glass-plate tests. There was no apparent synergism between fungicides tested in combinations. The parasitoid mortalities in tests carried out on plants were less and chlorothalonil, epoxyconazole, fenpropidin, fenpropimorph, flusilazole, flutriafol, prochloraz, tebuconazole, tridemorph and a number of combinations (carbendazim + flutriafol, chlorothalonil + cyproconazole, epoxyconazole + tridemorph, chlorothalonil + hexaconazole, chlorothalonil + flutriafol, cyproconazole + prochloraz, epoxyconazole + fenpropimorph, fenpropimorph + propiconazole, propiconazole + tridemorph, triadimenol + tridemorph) were harmless or only slightly harmful to the aphid parasitoid. Several combinations (carbendazim + epoxyconazole, carbendazim + fenpropimorph, carbendazim + flusilazole, carbendazim + tebuconazole, chlorothalonil + fenpropimorph, chlorothalonil + flusilazole, fenpropimorph + fenpropidin, fenpropimorph + prochloraz, fenpropidin + propiconazole, fenpropidin + tebuco nazole, tebuconazole + triadimenol) were toxic for wasps on plants. The parasitoid mortalities were less on plants than on glass plates but the wasps spent less time on treated leaves and in some cases parasitism of aphids was reduced to a large extent. These results suggest that in addition to study of the direct effects of pesticides on beneficial insects (mortalities, reduction of fertility) their effects on the behaviour of the insects should also be studied. Products that induced a repellent effect need further testing in field or semi-field conditions. However, many fungicide combinations that have little or no effect on A. rhopalosiphi can protect wheat against a wide range of diseases and the results obtained in this study indicate that an appropriate and effective protection of wheat at earing growth stage can be achieved with products that have no effects on aphid parasitoids.     

Influence of strobilurin compounds on the development of Puccinia horiana

The effectiveness of 5 strobilurin fungicides: Acanto 250 SC, Amistar 250 SC, Discus 500 WG, Signum 33 WG, Zato 50 WG and Score 250 EC (triazole-standard) in the control of Puccinia horiana was tested on chrysanthemum cv. Melba Blane. Number of pustules per leaf was observed before treatment, as well as 2 and 4 weeks after treatment. Additionally, after 4 weeks, their influence on plant growth, size of pustules and eventually phytotoxicity were assessed. Plants were sprayed preventively and curatively 4 times at weekly intervals. In preventive programme after 4 weeks of investigations, average of about 1.5 spot per leaf was recorded on control plants. Disease symptoms did not appear on chrysanthemums protected by fungicides Signum 33 WG at concentration 0.18% and Zato 50 WG at concentration 0.015%. In case of the other tested fungicides only sporadically pustules on single leaves were noticed (over 95% of them were browned, dried and crumbled). On control plants more than 46% of leaves was infected but in case of the other investigated fungicides it was only 3-7%. Diameter of spots on plants protected with: Score 250 EC, Acanto 250 SC and Discus 500 WG was similar as on the leaves of control plants. On plants protected with Amistar 250 SC the diameter of pustules was significantly lower than on control plants. In curative programme after 4 weeks of tests, leaves of control plants had about 4 spots per leaf. On leaves sprayed with Score 250 EC at concentration 0.05% there were 4 times less spots than on control plants. Chrysanthemums treated with tested strobilurin fungicides had about 2 times less pustules than on control plants. Diameter of spots on control plant leaves was 3.6 mm and was similar as on chrysanthemums protected with tested fungicides. On leaves of control plants all pustules were active without visible changes or damage but in case of the investigated fungicides almost 100% of them were browned, dried and crumbled. After 4 weeks of experiment, a measured height of control plants was about 125 mm and was similar to the height of plants protected with tested fungicides except Signum 33 WG, which stimulated plant growth. None of tested compounds showed phytotoxic effect.     

Effect of Temperatures on Dormancy and Germination in Three Species in the Lamiaceae Occurring in Northern Wetlands

In the temperate region temperature is the main factor influencing the germination period of plant species. The purpose of this study was to examine effects of constant and fluctuating temperatures on dormancy and germination under laboratory and field conditions in the three wetland species Lycopus europaeus, Mentha aquatica and Stachys palustris. The results should give indications if the temperature-dependent regulation of dormancy and germination is phylogenetically constrained. Tests for germination requirements showed a minimum temperature for germination of 9 °C in Mentha and 12 °C in Lycopus and Stachys, and a maximum temperature of 33 °C for Lycopus and 36 °C for Mentha and Stachys. Fluctuating temperatures promoted germination in all three species but the amplitude required for high germination (>50%) differed: it was 8 °C in Mentha, 10 °C in Stachys and 14 °C in Lycopus (mean temperature 22 °C). The effect of temperatures on the level of dormancy was examined in the laboratory by imbibing seeds at temperatures between 3 °C and 18 °C for periods between 2 and 28 weeks, as well as by a 30-month burial period, followed by germination tests at various temperatures, in light and darkness. In the laboratory only low temperatures (≤12 °C) relieved primary dormancy in seeds of Lycopus, while in Mentha and Stachys also higher temperatures lead to an increase of germination. Dormancy was only induced in Lycopus seeds after prolonged imbibition at 12 °C in the laboratory. Buried seeds of all species exhibited annual dormancy cycles with lower germination in summer and higher germination from autumn to spring. Exhumed seeds, however, showed considerable differences in periods of germination success. Dormancy was relieved when ambient temperatures were below 12 °C. Ambient temperatures that caused an induction of dormancy varied depending on species and test condition, but even low temperatures (8 °C) were effective. At high test temperatures (25 °C) in light, exhumed seeds of all three species showed high germination throughout the year. The three species showed various differences in the effects of temperatures on dormancy and germination. Similarities in dormancy and germination found among the species are in common with other spring-germinating species occurring in wetlands, so it seems that the temperature dependent regulation of dormancy and germination are related to habitat and not to phylogenetic relatedness.     

Evaluation of some fungicides for seed treatment and foliar application in management of damping-off of seedlings and blight of rapeseed caused by Alternaria brassicae

Eighteen fungicides were first evaluated for their effects on growth of Alternaria brassicae and for ascertaining their fungicidal and fungistatic natures in artificial cultures. The chemicals emerging fungicidal in action, were later evaluated for their efficacy as seed treatment and foliar application in the management of damping-off of seedlings and blight of rapeseed separately. Of 18 fungicides tested, six fungicides, viz., Dithane M-45, Dithane Z-78, Ziram, Difolatan-80, Blitox-50 and Benlate completely inhibited the growth of the pathogen and were fungicidal in action. Thiram and Brestan-60, which also caused total growth inhibition, were, however, fungistatic. Benlate (0.1 %) followed by Dithane M-45 was best seed-dressing fungicide for controlling damping-off of seedlings. Dithane M-45 (0.2%) followed by Dithane Z-78 as foliar spray was most effective for controlling the blight and increasing the yield in field trials.     

Effect of fungicides on survival of Rhizobium on seeds and the nodulation of bean (Phaseolus vulgaris L.)

The survival of Rhizobium leguminosarum biovar phaseoli on seeds of bean was tested, using the cultivar Carioca. The seeds were treated seven days before inoculation with Benlate, Vitavax, Banrot, Difolatan or Ridomil fungicides. The rhizobial strains used were: CIAT 899, CPAC 1135 and CIAT 652. Strain CIAT 899 showed greater survival on the seed with fungicide than the other strains. Two hours after the contact with fungicides strains CIAT 652 and CPAC 1135 had significantly lower numbers of rhizobia than the treatment without fungicide. The Benlate and Banrot fungicides had the greatest effect on survival of rhizobial strains. There was a drastic mortality of the two strains, CIAT 652 and CPAC 1135, on seeds treated with Benlate and Ridomil. Under field conditions, granular inoculation produced fewer nodules, but a similar total nodule weight as seed inoculation. Serological tests (ELISA) showed that seed treatment with Benlate in connection with seed inoculation reduced drastically the occurrence of inoculated strains in nodules, while the same fungicide treatment and inoculation applied in the seed furrow did not affect the survival of the inoculated strain.     

Local redistribution of fungicides on leaves by water

Local redistribution of various fungicides applied as large or small droplets to detached broad-bean leaflets was examined by laboratory bio-assay with Botrytis fabae and by leaf-printing techniques. The results showed that fungicidal particulate and soluble material will spread in water from the initial deposits and that the protected areas on leaves inoculated after washing were often much greater than on unwashed leaves. The extent of redistribution was related to the inherent toxicity, physical form, duration of weathering and tenacity of the fungicides. The effects of formulating copper oxychloride and zineb fungicides with surface-active agents and adhesives seemed due to differences in the tenacity of the deposits. Results indicated that similar types of redistribution would occur in the field, but the possible importance of the electrokinetic theory of redistribution was not proven.     

Citrus limonoid effects on Colorado potato beetle larval survival and development

The effects of citrus limonoids, applied topically to potato (Solanum tuberosum L. var. Katahdin) foliage, on Colorado potato beetle (Leptinotarsa decemlineata) (Say) (Chrysomelidae) larval development, growth, and survival were quantified in laboratory assays and a small-plot field test. In laboratory assays, survival, development rate, and body weight decreased with increasing limonoid concentration, however these measures of larval response did not significantly differ among varying periods of limonoid exposure (three, six, or nine days). Significant limonoid application concentration and frequency effects on survival, development rate, and defoliation were observed in the field test. These results indicate the potential utility of lethal and non-lethal effects of citrus limonoids for management of the Colorado potato beetle.     

Evaluation of fungicides and biocontrol products for the control of Phytophthora root rot of hydrangeas

Abstract

Phytophthora root rot is one of the most important diseases in almost all hydrangeas of nursery production. In this study, the efficacy of fungicides and biocontrol products against Phytophthora root rot of hydrangea was assessed in greenhouse and field experiments. Treatments used in field or greenhouse experiments were RootShield PLUS⁺, MBI110, IT-5103, Grotab, OxiPhos, TerraClean 5.0?+?TerraGrow program, Segovis, Pageant Intrinsic, Empress Intrinsic and Subdue Maxx. Pots/plots were inoculated with Phytophthora nicotianae grown on rice grains, sterilised rice grains were used for negative controls. After the trials, plant growth data (total plant weight, root weight, plant height, plant width) were recorded, and roots were assessed for disease severity using a scale of 0–100%. The treatments most effective in reducing Phytophthora root rot severity were Segovis, Empress Intrinsic, Subdue Maxx, TerraClean 5.0?+?TerraGrow program in both greenhouse and field experiments. This study will help nursery producers make proper management decisions by using recommended fungicides and biocontrol products of this study in a rotation or alone to manage Phytophthora root rot of hydrangea.     

The impact of sulfur on the reproductive success of <Emphasis Type="Italic">Anagrus</Emphasis> spp. parasitoids in the field

Pesticides targeted at pest species have often been demonstrated to have strong adverse effects on the survival of biological control agents in short-term laboratory bioassays; however, studies examining the influence of pesticides on the actual reproductive success of biological control agents in the field are rare. Because natural enemy reproduction is often directly tied to biological control success, effects of pesticides on reproduction are of central importance. Here we use a new technique to examine the influence of sulfur, a fungicide widely used in grape production, on the reproductive success of Anagrus erythroneurae (Hymenoptera: Mymaridae) and Anagrus daanei (Hymenoptera: Mymaridae), egg parasitoids of the grape leafhopper, Erythroneura elegantula (Homoptera: Cicadellidae). Sulfur has previously been shown to be highly toxic to Anagrus spp. in short-term laboratory and field bioassays, creating the expectation that sulfur should also reduce Anagrus reproductive success in the field. Surprisingly, in two studies, the first comparing the oviposition success of Anagrus collected live in paired sulfur-treated versus untreated vineyards and the second comparing the lifetime reproductive success of Anagrus collected at the end of their lives in unpaired sulfur-treated versus untreated vineyards, we found no effect of sulfur on parasitoid reproductive success. In this system, traditional short-term assays of laboratory toxicity do not appear to predict effects on parasitoid reproductive success, suggesting that demographic approaches to assessing the disruptive effects of pesticides may have an important role in designing IPM programs.