The behavioural response of slugs and snails to novel molluscicides, irritants and repellents

The behavioural response of the slug Deroceras panormitanum (Lessona and Pollonera) and the snail Oxyloma pfeifferi (Rossm?ssler) to novel molluscicides was investigated in choice and no-choice experiments. Low-light video-recording in combination with automated tracking and event recording was used to identify the repellent and irritant effects of (1) cinnamamide, (2) copper ammonium carbonate, (3) a mulch, (4) a horticultural ground-cover matting impregnated with a copper formulation and (5) urea/formaldehyde. In the no-choice experiments the products had a stronger irritant effect on the snails than on the slugs. All products tested except the mulch significantly reduced the locomotor activity of both the slugs and snails. The most effective product, cinnamamide, reduced snail locomotor activity by 94% and track length by 96%. The overall repellent effect of the treatments in the choice experiments was stronger in the slugs; where presence, locomotor activity and track length in the treated area were significantly reduced by all products. The avoidance of treated areas exceeded 95% with the mulch (for slugs) and with copper ammonium carbonate (for snails).     

Toxic and excitatory effects of the molluscicide metaldehyde on the biofouling bivalve Dreissena polymorpha Pallas

The zebra mussel, Dreissena polymorpha Pallas, is a biofouling freshwater pest for which alternative control methods to the use of chlorine are sought. Metaldehyde, a molluscicide used primarily for control of terrestrial slugs, has also been shown to have efficacy and specificity in the control of aquatic snails. To test its potential for zebra mussel control, we investigated its effects on zebra mussel viability and on contractility of siphon/mantle muscle preparations in vitro. Metaldehyde caused zebra mussel mortality within 48 h at concentrations of approximately 0.1 and 0.2 g litre⁻¹. The same concentrations of metaldehyde activated a complex, excitatory response in previously quiescent siphon/mantle preparations but did not modify the contractile responses of the preparations to acetylcholine. The relatively low level of toxicity of metaldehyde to zebra mussels, compared to its toxicity to snails and slugs, and the difficulty of applying this relatively insoluble molluscicide in the aqueous environment suggest that metaldehyde would not be an effective zebra mussel control agent. © 2000 Society of Chemical Industry     

安徽省潜山县栝蒌根结线虫发生危害及大田药效试验

为了有效防治栝蒌根结线虫，调查了安徽省潜山县栝蒌根结线虫及其发生，并分析了栝蒌根围土壤线虫的组成。通过线虫形态学鉴定，认为潜山栝蒌上的根结线虫为Meloidogyne incognita。栝萎根围土壤中有口针线虫占调查总量的50．7％，根结线虫2龄幼虫（J2）占31．8％。对当年栝萎J2在土壤表、中、下层的分布和年发生调查结果表明，J2在各层的分布量因月份不同而不同，并分别于3月初到9月中旬问出现2次虫口高峰；防治试验结果表明，除有机肥外，各试验小区在施药后49天J2虫口相对减退率在89．6％以上；施药后124天，克线丹和1．8％阿维菌素处理的小区增果率为250％～480％，收到很好的防效。     

土壤处理对西洋参根际线虫数量动态的影响及对防治茎线虫根腐病的效果

 Root rot of American ginseng (Panax quinquefolium) caused by Ditylenchus destructor is a novel disease found recently in Beijing area. The effects of three soil treatments (fumigating with chloropicrin, chloropicrin + lvfeng organic manure and nematicide fosthiazate) on the number of rhizospheric nematodes, survived plants, root yield and root rot of 3-year ginseng plant were compared. The effects were also investigated at the second year after treatment. The results indicated that the number of parasitic nematodes in rhizosphere of treated soil reached the peak value in late June to early July as the soil temperature raised in the growing season. Compared with the regular treatment, the number of plant parasitic nematodes was reduced while non-plant parasitic nematodes increased. The number of non-plant parasitic nematodes in the soil treated with chloropicrin + lvfeng organic manure was 2 times than that treated with chloropicrin only. The ratio of non-parasitic to parasitic nematodes of three treatments was higher than the control. Percent of survived plants was 94.8%-96.4% and diseased root was decreased obviously. The control efficacy was more than 89% at the first year after treatment. The survived plants and plot yield of ginseng increased significantly and the control efficacy was around 40% at the second year. The best of the three treatments was by chloropicrin + organic manure.     

Effects of three microbial broth cultures and an organic amendment on growth and populations of free living and plant-parasitic nematodes on banana

The effect of 24 treatment combinations of cultures of Streptomyces costaricanus sp. nov. (ATCC55274), Bacillus thuringiensis (ATCC55273) and a strain of Paecilomyces marquandii, nematicide (cadusaphos), and/or wheat mash on growth and response of potted banana plants (Musa AAA) and populations of Radopholus similis, Helicotylenchus multicinctus and free living nematodes were studied in Río Frío, Costa Rica. The best plant responses (height, leaf numbers, healthy root weight), lowest numbers of plant parasitic nematodes and highest numbers of free living nematodes were observed for treatments containing wheat as a component. Two treatments, viz. wheat + Streptomyces costaricanus (200-ml culture) and wheat + P. marquandii (200-ml culture), gave the overall best results. Numbers of free living nematodes increased up to 1500-fold only for treatments containing wheat. Significant positive correlations existed between numbers of free living nematodes and shoot weight, healthy root biomass, plant height, and leaf numbers. Non-wheat treatments, including nematicide only, gave the poorest responses in general. Observations of nematodes sampled 50 days following planting in wheat-containing treatments showed most of the free-living nematodes ( 90%) to be infected by nematophagous fungi (species not recorded). The results show that an organic amendment to soil, with or without a microbial component, can be an effective inducer of processes that regulate plant-parasitic nematode populations in soil.     

Characteristics of infestation of sweet potato by sweet potato weevil Cylas formicarius (Coleoptera: Apionidae)

Studies were conducted to examine the characteristics of infestation of vines of sweet potato plants by the sweet potato weevil, Cylas formicarius (F.). The use of terminal tender vine cuttings, taken even from heavily weevil‐infested sweet potato, to grow a new crop and planting such a crop in plots surrounded by barriers to reduce weevil migration from the outside to the newly planted area, produced a practically weevil‐free crop. On the contrary, crop planted to old vine cuttings in an open field was severely damaged by the weevil. Consequently, crop planted using tender vine cuttings produced significantly more root yield than the one planted to old vine cuttings, irrespective of whether the planting was done in an open field or in an insect‐protected field. Sweet potato weevil infestation of 1‐ to 8‐week‐old plants increased significantly with plant age. The insect preferred sweet potato roots over sweet potato vines when both plant parts were available for infestation. Dipping the vine cuttings for 30 min in carbofuran solution prior to planting protected the newly planted sweet potato crop for up to 6 weeks after planting.     

Influence of Ring Nematode Infestation and Calcium, Nitrogen, and Indoleacetic Acid Applications on Peach Susceptibility to Pseudomonas syringae pv. syringae

ABSTRACT Two field experiments were conducted to study the effects of added nitrogen, calcium, and indoleacetic acid, in the presence or absence of ring nematodes (Mesocriconema xenoplax), on susceptibility of peach to bacterial canker. When noninfested soil was inoculated with ring nematodes, peach tree susceptibility to bacterial canker infection caused by Pseudomonas syringae pv. syringae was dramatically increased after a period of 2 years. However, no evidence was found that ring nematode infestation increased tree water stress or, in turn, altered plant calcium uptake. Soil fumigation with methyl bromide prior to planting in a commercial orchard significantly reduced both nematode populations and peach tree susceptibility to bacterial canker infection when compared with nonfumigated treatments. In both experiments, tree susceptibility, as measured by canker length following inoculation of stems with P. syringae pv. syringae, was negatively correlated with plant tissue nitrogen content and positively correlated with tissue calcium content. A principal components analysis showed that tissue nitrogen and calcium levels were negatively correlated, and that high-nitrogen, low-calcium tissues were less susceptible to bacterial canker than low-nitrogen, high-calcium tissues. These results indicate that the increased susceptibility of peach to P. syringae pv. syringae under nematode infestation conditions is mediated by both nutritional effects (primarily nitrogen) and nutritional-independent effects, but do not support previous reports of beneficial effects of calcium for reducing bacterial canker.     

Substantial reductions in winter wheat diseases caused by addition of straw but not manure to soil

Over a period of 3 years, five agronomically distinct crops of winter wheat were grown in plots in which straw (1 kg m⁻²), manure (4 kg m⁻²) or nothing were incorporated into the soil. Plant establishment and height, but not leaf area per tiller, were lower in straw-treated plots. Fertilizer regimes differed between years. Soil and leaf nitrogen were recorded; there was no obvious link between N and any disease or soil amendment. The numbers of leaf layers scorable for disease were similar in all treatments. At the end of the season, plants from straw-treated plots had consistently reduced septoria tritici blotch (caused by Mycosphaerella graminicola ), powdery mildew [caused by Erysiphe ( Blumeria ) graminis ], brown rust (caused by Puccinia recondita ) and foot rot (caused by Fusarium spp.). Early on, M. graminicola was worse in straw-treated plots. In manure-treated plots, P. recondita was reduced but effects on other diseases were inconsistent and slight. A fungicide, chlorothalonil, was applied in one crop; its effects did not interact with those of other treatments. Mycosphaerella graminicola was not suppressed by straw in outdoor pot experiments. Late in the season, straw-treated plants had significantly higher leaf silica ( P  < 0·01). In a glasshouse experiment, plants supplied with silicon had less E. graminis infection ( P  < 0·001) and higher leaf silica, but effects on M. graminicola were inconsistent. A prior inoculation of M. graminicola primed plant defences against a subsequent attack of E. graminis , but only in the presence of adequate Si. It is postulated that straw acts in the field by increasing Si availability.     

Effect of prior tillage and soil fertility amendments on dispersal of Phytophthora capsici and infection of pepper

Organic soil amendments including composted cotton gin trash, composted poultry manure, an incorporated rye-vetch green manure, or synthetic fertilizer were applied to subplots, and main plots were either tilled frequently or surface-mulched in experimental field plots between 1997 and 2004. Soil from each replication of the tillage and fertility treatments was sampled in August of 2001, 2002, and 2003, brought to the greenhouse, and infested with Phytophthora capsici to study the effect of previous soil treatments on disease incidence and dispersal of the pathogen. Both the previous tillage and fertility amendments affected the incidence of disease and dispersal of the pathogen. Final disease incidence, AUDPC and the distance of pathogen spread were significantly greater in soils with previous surface mulch applications than in frequently tilled soils. Final disease incidence, AUDPC and the distance of pathogen spread were also significantly higher in soils amended with cotton gin trash, than rye-vetch green manure, poultry manure, or synthetic fertilizer. Soils amended with cotton gin trash had higher soil water content, lower bulk density, higher humic matter content, higher porosity and higher levels of mineralizable N, than soils with other fertility amendments. Soil water content, soil porosity, humic matter content, and net mineralizable levels nitrogen were positively correlated and bulk density was negatively correlated with final incidence of disease.     

Field experiments to investigate long-term effects of repeated applications of MCPA, tri-allate, simazine and linuron: II. Crop performance and residues 1969–78

In four field experiments begun in 1963, each of four herbicides was applied to plots planted wilh the same crop each year. The annual treatments were: MCPA at 17 kg/ha to barley (Hordeum sativa Jess) and wheat (Triticum aestivum L.) at growth stage 15. tri-allate at 17 kg/ha pre-emergcnce to barley and wheat, simazine at l7kg/ha pre-emergence to maize (Zea mays L.) and linuron in two applications of 084 kg/ha pre- and post-emergence to carrots (Daucus carota L.). MCPA did not affect growth or yield of either barley or wheat. In general tri-allate also did not aftect the crops although wheat yield was depressed in 1978, wheat 1000 grain weight was reduced in 1972 and barley germination percentage was increased in 1973. Simazine did not influence the height, yield or appearance of maize. Linuron normally produced no effect on carrot yield, density and size. However, in 2 years when the post-emergence application was late, density but not yield was lower than in control plots. There was no accumulation of residues of any of these compounds in the soil. Rates of loss were similar to those predicted on ihe basis of laboratory experiments. In a fifth experiment these herbicides were applied twice per year (3 times in the case of linuron) at double the rales above on each occasion to bare plots. These applications ceased in 1968 (1969 for MCPA) but residues were monitored until 1972 except in the case of MCPA. Disappearance rates were similar to those in the cropped plots and residues were largely confined to the top 10 cm. The plots treated with MCPA had developed an enhanced ability lo degrade il prior to 1968. This persisted for 5 years after the final application.     

Soil suppressiveness against the disease complex of the soybean cyst nematode and sudden death syndrome of soybean

The ecology of the complex of soybean cyst nematode (SCN) and sudden death syndrome (SDS) of soybean was investigated under soybean monoculture in two field experiments from 2003 to 2007. Initially, susceptible soybean 'Spencer' was planted while inoculating Fusarium virguliforme into nonfumigated or preseason-fumigated plots (methyl bromide, MB, at 450 kg/ha), and SCN and SDS were monitored. In one field, SCN population densities declined in nonfumigated but increased in fumigated plots. After years of limited SDS in 2003 and 2004, SDS developed later in nonfumigated than fumigated plots. In 2006 in the greenhouse, nondisturbed or disturbed soil cores (10-cm diameter, 30-cm depth) from field plots received two two-level factors: (i) nonfumigated or fumigated (1,070 kg/ha MB); and (ii) noninoculated or inoculated with 9,000 second-stage juveniles of SCN. At harvest, nonfumigated cores from nonfumigated plots had fewer nematodes and less SDS regardless of disturbance or inoculation than the corresponding fumigated cores and any cores from fumigated plots. In the second field, SCN became detectable after 2003 during the monoculture in nonfumigated plots and lagged in fumigated plots; both treatments had low levels of SDS. Exploiting the suppressiveness of the first field could allow for biological control of SDS and SCN in soybean production.     

Green manures and crop sequences influence potato diseases and pathogen inhibitory activity of indigenous streptomycetes

ABSTRACT A 2-year field trial was conducted to determine the effects of green manures and crop sequences on potato scab and Verticillium wilt. In addition, indigenous streptomycete densities and in vitro pathogen inhibitory activity were measured and their relationships to plant disease were determined. Green manures (buckwheat, canola, or fallow controls) were tested in conjunction with three crop sequences (alfalfa-potato, cornpotato, and potato-potato). Compared with fallow controls, tubers grown in buckwheat-treated soil had significantly lower Verticillium wilt ratings, and tubers grown in buckwheat- or canola-treated soil had greater yields. Potatoes grown in soil planted to corn or alfalfa the previous year had significantly lower Verticillium wilt and potato scab ratings as well as higher yields than potatoes grown in soil previously planted to potato. Streptomycetes from soils collected from green manure-treated plots tended to have greater in vitro pathogen inhibitory activity than streptomycetes from fallow-treated plots. Furthermore, streptomycete pathogen inhibitory activity was frequently negatively correlated with plant disease and positively correlated with potato yield. These results indicate that green manure treatments may contribute to active management of the pathogen inhibitory activity of the streptomycete community to achieve plant disease control.     

Methyl bromide and PCNB for sclerotium crown rot control in iris

Methyl bromide (MB) at rates of 500, 1000 and 1500 kg/ha, Terraclor 75 WP (PCNB) at 150 and 300 kg/ha, and combinations of the two, were studied for control ofSclerotium rolfsii prior to iris cultivation. Sclerotia buried 10 cm deep in soil were all killed by MB at 500 kg/ha; at greater depths higher doses were required. Bulbs harvested from PCNB- and PCNB + MB-treated plots were healthy; 75% of the bulbs in control plots were infected at harvest. When MB was used alone, the soil became re-infested (2–6% diseased plants). Bromide toxicity, correlated with the MB dose applied, appeared 41/2 months after planting; leaves yellowed and senesced prematurely. MB treatments also reduced bulb size, and residual phytotoxicity was found when the bulbs from treated plots were planted in the following year.     

Seed dressings to control slug damage in oilseed rape

Slugs are major pests of oilseed rape that are poorly controlled by conventional bait pellets. A series of laboratory experiments investigated the potential of seed-dressings to control slug damage in this crop. Four compounds: metaldehyde, methiocarb, cinnamamide and 3,5-dimethoxycinnamic acid (DMCA) were tested at a range of doses for phytotoxicity and ability to reduce damage by Deroceras reticulatum (Müller). Metaldehyde and methiocarb were not phytotoxic at any doses, whereas all doses of cinnamamide and DMCA were. All compounds reduced slug damage, but metaldehyde and methiocarb consistently performed better than cinnamamide and DMCA. Metaldehyde and methiocarb seed-dressings were compared with baited pellets containing the same active ingredients at recommended field doses. The seed-dressings protected plants from damage by D reticulatum and Arion subfuscus (Draparnaud) as well as, or better than, baited pellets. We therefore recommend that metaldehyde and methiocarb should be field-tested as seed dressings to control slugs in oilseed rape.     

旱地夏闲期秸秆覆盖和种植绿肥对冬小麦水分利用及养分吸收的影响

以夏季裸地休闲为对照,研究了免耕条件下小麦秸秆覆盖和种植豆科绿肥及二者混合对旱地冬小麦产量、作物水分利用、氮磷钾养分吸收的影响。结果表明,秸秆覆盖和种植绿肥对冬小麦籽粒产量和生物量无影响,但秸秆覆盖作物耗水量较对照增加10 mm,种植绿肥则减少11 mm,水分利用效率却无显著变化;夏闲期种植绿肥和秸秆覆盖+种植绿肥使小麦籽粒吸氮量分别降低6.0%和6.6%,差异显著,吸磷量降低5.9%和6.2%,籽粒吸钾量降低了7.9%和7.9%。可见,一年的秸秆覆盖和种植绿肥对冬小麦产量没有显著影响,但秸秆覆盖使小麦生育期耗水量增加而种植绿肥使之降低,种植绿肥和秸秆覆盖+种植绿肥使小麦对氮磷钾养分吸收有所降低。     

Evaluation ofAmaranthus sp. andVernonia amygdalina, and soil amendments with poultry manure for the management of root-knot nematodes on eggplant

The suppressive effect of vernonia (Vernonia amygdalina), amaranth (Amarathus sp.) and poultry manure on root-knot nematodes (RKNs) (Meloidogyne spp.) infecting eggplant (Solanum macrocarpon) was studied at two sites in southern Benin naturally infested with these nematodes. After 3 months, soil and root-inhabiting RKN populations were significantly less (P≦0.05) in the plots cropped with vernonia, amaranth, and eggplant amended with poultry manure (PM) at the rate of 40 t ha⁻¹ as compared with the rate of 20 t ha⁻¹ and with the control. Poultry manure was more effective after 2 months than after 3 months. Overall, vernonia was the most effective treatment affecting RKN populations in the roots and the soil. The use of these treatments in nematode management through rotation and co-planted crops is discussed. http://www.phytoparasitica.org posting August 6, 2008.     

不同药剂和不同施药方法防治农田灰巴蜗牛效果评价

一些蜗牛常栖息在高大植株上活动为害, 为探索其有效防治方法, 分别在玉米田及美国红枫( Acer rubrum L . )园选用5种杀软体动物剂进行喷雾法(在玉米田仅对植株喷雾、在美国红枫园对树体和地面喷雾)和撒粒法的防效对比试验。重复测量方差分析结果表明：26%四聚?杀螺胺悬浮剂1.125 L/hm2、45%三苯基乙酸锡可湿性粉剂1.125 kg/hm2、70%杀螺胺乙醇胺盐可湿性粉剂0.75 kg/hm2、40%四聚乙醛悬浮剂1.125 L/hm2喷雾防治灰巴蜗牛( Bradybaena ravida )的效果均显著高于6%四聚乙醛颗粒剂7.5 kg/hm2地面撒粒的防效。不同药剂不同施用方法的防治效果随用药后时间的增加而降低。用药后第3天, 4种喷雾处理在美国红枫上的防效均在90%左右, 在玉米上的防效在80%左右。当蜗牛在高大的植株上栖息为害时, 可用上述药剂按750 L/hm2的药液用量对植株均匀喷雾, 必要时同时进行地面喷雾防效更佳。     

The control of Penicillium corymbiferum on crocus and its effect on corm production

Crocus corms with different amounts of infection by Penicillium corymbiferum were planted in field plots in October 1982 and harvested in the following July. Differences in infection at planting had no effect on the development of the disease on harvested stored corms. Corms with 40–60% surface area infected by P. corymbiferum at planting had a reduced mean weight of harvested corms and yield (kg corms harvested per kg corms planted) compared with corms with 4–10% surface area infected at planting. Dipping corms in benomyl, captafol, tnancozeb or thiram solutions after harvesting failed to control the disease. The severity of disease was increased by damage occurring before storage and was reduced by delaying harvesting.     

The effect of DD and dazomet treatments on nematode populations at various depths in the soil and on the transmission of soil-borne tobacco rattle virus to gladiolus

The relation between log dosage of DD injected at 15 cm depth or of dazomet applied to the soil surface (all in November 1971) and probit mortality ofRotylenchus and trichodorids in the top 20 cm of a field on sandy soil was found to be linear. Dosage increase efficiencies of both chemicals against both nematode species were medium to high. Superficial application of dazomet was very effective against the nematodes that would have survived if only a low dosage of DD had been injected at 15 cm depth. Injection of 40 ml or 80 ml DD per m² at 15 cm depth killed all nematodes between 20 cm and 60 cm deep. Gladiolus planted in the spring of 1972 grew better, flowered earlier and produced more weight of corms on treated than on untreated plots. The poor growth on the untreated plots cannot be ascribed to direct damage by nematodes or to the effect of TRV transmitted to the plants by the viruliferous trichodorids occurring in these plots in high densities. Symptoms of TRV infection in plants grown in 1973 from the corms harvested in the 1972 experimental field showed that only DD treatments had reduced the rate of TRV transmission considerably. However, even the highest dosages of DD had only reduced it from 26% (on untreated plots) to about 8%. Most probably, this residual TRV infection was due to transmission by trichodorids that had survived in soil layers below 60 cm depth. Therefore, soil treatment with nematicides, cannot prevent TRV transmission to gladiolus sufficiently where viruliferous trichodorids occur at great depths, as is the case in many sandy soils having a low water table.     

Regression Analyses for Evaluating the Influence of Bacillus cereus on Alfalfa Yield Under Variable Disease Intensity

ABSTRACT We developed and tested regression methods to exploit the variability in disease inherent in field experiments, and applied the methods to evaluate strains of Bacillus cereus for biocontrol efficacy. Four B. cereus strains were tested for their effect on alfalfa (Medicago sativa) performance in 16 field trials planted during 1993 to 1996 at multiple sites in Wisconsin. To evaluate performance of the strains, we used the ratio of (metalaxyl response)/(untreated control response) as a measure of disease intensity within the experiments. The ratio of (Bacillus response)/(untreated control response) was then regressed as a function of disease intensity. The slope of the resulting line provides a statistical test to compare performance of the Bacillus strain with that of the untreated seed (H(o): slope = 0) and metalaxyl controls (H(o): slope = 1). Under conditions in which disease occurred, forage yield of plots planted with seed treated with B. cereus strain AS4-12 exceeded yield from the untreated control plots (P = 0.002) and was similar to yield of plots planted with metalaxyl-treated seed (P = 0.14). Yield gain associated with AS4-12 and metalaxyl seed treatment averaged 6.1 +/- 2.8% (+/-standard error) and 3.0 +/- 2.8%, respectively. In contrast to the regression approach, means analysis by analysis of variance did not detect differences among treatments. Three other B. cereus strains either did not increase alfalfa yield or increased yield less than did AS4-12. Metalaxyl and three of the Bacillus strains increased seedling emergence, but the improved stands were not predictive of increased forage yield. In six additional studies conducted for one season in 1997, AS4-12 enhanced yield of two cultivars at diverse locations in Wisconsin, but there was an apparent cultivar-location interaction. A strong correlation between response to AS4-12 and metalaxyl treatment suggests that these treatments controlled similar pathogens, most likely the oomycete pathogens Phytophthora medicaginis and Pythium spp.