Effects of timing and method of application of Penicillium oxalicum on efficacy and duration of control of Fusarium wilt of tomato

The effects of timing and method of application of Penicillium oxalicum on the control of fusarium wilt of tomato were investigated. Application of P. oxalicum to tomato seedlings in seedbeds reduced disease caused by Fusarium oxysporum f.sp. lycopersici in a growth chamber by 45–49% and in glasshouse experiments by 22–69%. Disease suppression was maintained for 60–100 days after inoculation with the pathogen in the glasshouse. No disease reduction was observed in tomato plants where P. oxalicum was applied to seeds. Treatment with P. oxalicum did not affect the population of F. oxysporum f.sp. lycopersici in the rhizosphere.     

Mode of action of etoxazole

The mode of action of the 2,4-diphenyl-1,3-oxazoline acaricide/insecticide etoxazole has been argued to be moulting inhibition, but experimental results supporting this hypothesis are lacking. This study investigated the effect of etoxazole on chitin biosynthesis in the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). Etoxazole induced moulting defects in fall armyworm larvae similar, if not identical, to those caused by benzoylphenylureas, a well-known class of insecticidal chitin biosynthesis inhibitors. Furthermore, in contrast to untreated larvae, the chitin content in the integuments of larvae several days after treatment did not differ from that in freshly ecdysed individuals, thus suggesting strong chitin biosynthesis inhibition in vivo. A more detailed investigation of the inhibitory potential by incubating cultured integument pieces from larvae of S. frugiperda with [14C]N-acetyl-D-glucosamine, a radiolabelled chitin precursor, revealed I50 values of 2.95 and 0.071 microM for etoxazole and triflumuron respectively. The incorporation of radiolabel into potassium hydroxide-resistant material was inhibited by etoxazole in a dose-dependent manner. Based on these results, it is concluded that the acaricidal and insecticidal mode of action of etoxazole is chitin biosynthesis inhibition.     

图们江干流区间流域径流变化特征

以图们江干流区间为研究对象，应用Mann-Kendall非参数检验法分析干流区间4个水文站点径流年际与年内变化趋势。在此基础上，采用R/S分析方法分析年径流、季节径流和月径流变化趋势在未来的可持续性，利用Mann-Kendall突变检验方法分析各水文站点年径流、季节径流和月径流发生突变的年份。结果表明：图们江干流区间各水文站径流年际和年内变化趋势均与干流径流变化趋势一致，呈下降趋势，非汛期径流下降的贡献主要来自春季和冬季径流的下降；Hurst指数表明，上游径流变化趋势的持续性最强，下游的持续性相对较弱；1985年是图们江干流区间年径流发生突变的年份，且降水量也发生了变化，可以推测降水量可能是径流不断减少的重要因素。     

Effects of avirulent bacteriocin-producing strains of Pseudomonas solanacearum on the control of bacterial wilt of tobacco

Root systems of tobacco dipped in suspensions containing 2 × 10⁹ colony forming units (CFU)/ml of avirulent bacteriocin-producing strains (ABPS) of Pseudomonas solanacearum and assayed immediately after planting in steam-sterilized soil had 8 × 10⁶ CFU/root system of ABPS. The bacterial population declined to an average of 5·3 × 10⁵ CFU/root system after 30 days. Roots of seedlings dipped in bacterial suspensions of ABPS were more effectively protected against wilt caused by P. solanacearum than those dipped in suspensions of an avirulent nonbacteriocin-producing strain (ANBPS). Lipopolysaccharide (LPS) isolated from one ABPS (121) inhibited the attachment of bacteria on roots by 70% but had no effect on the reduction of wilt, whereas bacterial cells significantly reduced the disease severity as compared to LPS or water treatment. In steam-sterilized soil containing a 1:1 mixture (5 × 10⁵ CFU/g of oven-dried soil) of ABPS 121 or 237 and the virulent strain K-60, ABPS 121 reduced multiplication of the virulent strain in soil and in the rhizosphere of seedlings. When roots of seedlings were dipped in a suspension of 2 × 10⁹ CFU/ml of ABPS before planting, root colonization by the virulent strain added to steam-sterilized soil at 2 × 10⁶ CFU/g of oven-dried soil was significantly reduced. When roots were dipped in a suspension of ABPS and assayed 20 days after planting, 98% of the bacterial population was found in the original zone of inoculation and only 2% was detected in new growths of the root system. Plants which were grown in soil infested with ABPS 121 or K-60 had both strains present at variable populations along all sections of roots.     

嘧啶胺类杀菌剂的作用机制

本文介绍了几种嘧啶类杀菌新品种（ｐｙｒｉｍｎｅｔｈａｎｉｌ，嘧菌胺ｍｅｐａｎｉｐｙｒｉｍ，ｃｙｐｒｏｄｉｎｅｌ）的作用机制，该类药剂在离体条件下对病菌的抗菌性很弱，但用于寄主植物上却表现很好的防治效果，该类药剂能抑制病菌甲硫氨酸的生物合成和细胞壁降解酶的分泌，从而影响病菌侵入寄主植物。     

The mode of action of chlomethoxyfen

Chlomethoxyfen [5-(2, 4-dichlorophenoxy)-2-nitroanisole] has been widely used as a pre-emergence herbicide in rice in Japan, where it is known as chlomethoxynil. It is effective against many annual weeds and some perennials, including Eleocharis acicularis and Sagittaria pygmaea. The activity of chlomethoxyfen is only slightly affected by water movement because of its low water-solubility. It is more toxic to shoots than roots and is rapidly absorbed by roots, with limited translocation to upper parts of the plants. The demethylated derivative, which was presumed to be conjugated with plant materials, was identified as the major metabolite in plants. Several other metabolites were also detected in soils and animals. Chlomethoxyfen increases phenylalanine ammonia-lyase activity in plants under light conditions, resulting in the accumulation of the biphenyl-2-ol content. The biochemical basis of the light requirement of diphenyl ether herbicides is also discussed.     

Reassessment of the Role of Saprophytic Activity in the Ecology of Thielaviopsis basicola

ABSTRACT The ability of Thielaviopsis basicola to survive saprophytically in soil was investigated using root tissue from susceptible hosts as organic substrates. Inoculum densities were lower in soils amended with root tissue than in nonamended controls after 2 and 4 weeks of incubation. The greatest decrease occurred in soils containing the highest concentration of root tissue or in soils in which root tissue included the soluble components of the living root. Reproduction by T. basicola also was examined in axenic media containing either killed root pieces or various carbohydrates as the sole carbohydrate source. T. basicola utilized killed root tissue as a carbohydrate source in axenic media, particularly in cultures in which root tissue included the soluble components. Enzymatic activities of T. basicola, however, did not result in maceration of the root tissue. T. basicola utilized sucrose and cellobiose, but did not utilize structural carbohydrates such as cellulose, hemicellulose, or pectin. Based on the absence of significant saprophytic ability, T. basicola should be classified ecologically as an obligate parasite.     

Azomethines of sec-butylamine for the control of penicillium decay of oranges

Imines, synthesised by the reaction of sec-butylamine (SBA, 2-amino-butane) with pentan-2-one, heptan-2-one, octan-2-one, undecan-2-one, benzaldehyde and 2-furaldehyde, were evaluated as vapour-phase treatments to prevent the infection of oranges by Penicillium digitatum. All the imines provided decay control equivalent to SBA when they were introduced into the fruit container at a rate equivalent to 16.4 mg SBA litre^?1 air volume. The carbonyl compound component of the imines, tested alone at a five-fold higher rate, did not reduce fruit decay. All the imines were stable in the gaseous state in dry air. The imines of pentan-2-one and undecan-2-one were hydrolysed rapidly in a humid environment, indicating that their action against P. digitatum was due to the release of SBA into the atmosphere around the fruit. The instability of the imines of the aliphatic ketones makes them unsuitable as generators of SBA in packages. The imines derived from benzaldehyde and 2-furaldehyde were stable in moist air, but were hydrolysed to a significant degree on moist filter paper, especially at pH < 7. These aromatic imines were absorbed from the atmosphere by the fruit and were hydrolysed rapidly in water, and in a buffer solution that represented the environment in fresh injuries on fruit. Apparently all the imines tested generated SBA in the fruit environment, and this SBA accumulated at potential infection sites, where it prevented the development of decay.     

Demonstration of calcium salts in excretory corpuscles of larval stages of trematodes

Calcium salts were demonstrated by Kóssa's method in excretory corpuscles of five species of cercariae and six species of metacercariae. The interference of calcium salts in excretory corpuscles in Gomori's method for the detection of alkaline phosphatase is discussed.     

Accumulation of hyperparasites of Rhizoctonia solani by addition of live mycelium of R. solani to soil

Addition of live mycelium ofRhizoctonia solani to three slightly, acid sands collected in winter from a field after a previous potato crop resulted in accumulation of hyperparasites and less infestation of sprouts of infected seed potatoes. A similar effect was observed in alkaline marine sandy loam soils, but only after a second addition of live mycelium. The predominant hyperparasite in these experiments wasVerticillium biguttatum.     

2018年我国小麦赤霉病菌对多菌灵抗性检测

以多菌灵为主的苯并咪唑类杀菌剂一直是小麦抽穗扬花期防控赤霉病的主要手段之一。本研究对2018年我国主要麦区采集的1 464株赤霉病菌菌株进行多菌灵抗性分子检测。共检测出多菌灵抗性菌株97株,抗性频率为6.63%,同时发现抗性菌株以F167Y突变频率最高,其次为E198Q和F200Y。通过比较不同省份间多菌灵抗性发生频率发现,长江中下游麦区赤霉病菌群体抗性频率明显高于黄淮麦区群体。本研究相比之前研究中的抗性频率大幅度上升,表明在多菌灵的选择压力下,多菌灵抗性种群发展迅速。为防止抗性群体的进一步发展,致使多菌灵防治赤霉病失效,应采用混配、复配药剂、不同作用机理的杀菌剂交替轮换使用来防治小麦赤霉病。     

土壤中花蓟马蛹的检测方法

本文对花蓟马属（Frankliniella）蛹期在土壤中存在的状态以及存在的时间进行了描述,并用直接镜检、干燥漂浮镜检、生物饲养检测等方法对土壤中蓟马蛹的检测方法进行了初步研究.生物饲养法能有效检出存在于土壤中的花蓟马蛹.     

Sprinkling irrigation enhances production of oospores of phytophthora infestans in field-grown crops of potato

ABSTRACT Two field experiments were conducted to study the effect of overhead sprinkling irrigation on oospore formation by the late blight fungus Phytophthora infestans in potato. Total rain (natural + sprinkling) accumulated in treatments of experiment 1 (winter 1997 to 1998) were 765, 287, and 219 mm and treatments of experiment 2 (winter 1999 to 2000) were 641, 193, and 129 mm. Sporangia from 11 isolates of P. infestans were combined in eight pairs, seven of A1 and A2 and one of A2 and A2 mating type, and were sprayed on field-grown potato crops (42 plants per plot at 7 m(2) each) and examined for their ability to form oospores in the host tissues. In experiment 1, oospores were recorded in a total of 132 of 1,680 leaflets (7.9%), 24 of 105 stems, and 2 of 90 tubers. In experiment 2, oospores were recorded in 40 of 519 leaflets (7.7%), but not in any of the 90 stems or the 45 tubers examined. Both the proportion of leaflets containing oospores and the number of oospores per leaflet increased with time after inoculation and were dependent on the rain regime, the position of leaves on the plant, and the isolate pair combination. In both field trials, increasing the rainfall significantly enhanced oospore production in leaves. Leaf samples collected from the soil surface had significantly more oospores than those collected from the midcanopy. Two pairs in experiment 1 were more fertile than the others, whereas the pair used in experiment 2 was the least fertile. The total number of oospores per leaflet usually ranged from 10 to 100 in experiment 1, but only from 2 to 10 in experiment 2. Maximal oospore counts in the field were 200 and 50 in experiments 1 and 2, respectively, but ranged from approximately 2,000 to 12,000 oospores per leaflet in detached leaves in the laboratory. We concluded that P. infestans can produce oospores in the foliage of field-grown potato crops, especially when kept wet by regular overhead sprinkling irrigation, but production was far below that in the laboratory.     

新农药呋喃虫酰肼在土壤降解研究

本文研究了其在3种土壤中有氧环境下的降解情况。呋喃虫酰肼在3种土壤中的降解速率大小依次为河南黄土〉吉林黑土〉江西红土,其降解半衰期分别为315、365、213d,降解遵循一级动力学方程。根据国内农药在土壤中的残留划分标准,呋喃虫酰肼属于较难降解类农药。比较呋喃虫酰肼在非灭菌与灭菌的吉林黑土、江西红土和河南黄土中的降解情况表明,药剂在非灭菌土中降解明显加快,分析可能是土壤中微生物对呋喃虫酰肼的降解具有显著的影响。     

Digital Image Analysis of Internal Light Spots of Appressoria of Colletotrichum acutatum

ABSTRACT The initial penetration process of appressoria of Colletotrichum acutatum on almond leaves was studied using digital image analysis of light micrographs and scanning electron microscopy. For image analysis, a series of sequential, partially focused digital micrographs of appressoria was analyzed to generate a single, completely focused montage image with a continuous in-focus depth of field. In studies on the development of the internal light spot (ILS), we observed that 50.4% of the appressoria formed an ILS after leaves were inoculated and incubated for 12 h at 20 degrees C, and that this increased to 95.8% after 24 h. Comparative image analyses of appressoria with and without ILSs using depth relief mapping and line profile software options showed that the ILS had a depth relief that was below that of the leaf surface. Depth relief analysis in the ILS region during incubation revealed an increase in depth in this area of up to 1.8 mum in some of the appressoria. A comparative morphological study of the ILS in montage images and the penetration pore of appressoria in scanning electron micrographs showed similar shapes and dimensions of the two structures in the appressorium. Light micrographs of histological sections confirmed fungal penetration and internal vesicle formation in almond leaves within 36 h after inoculation and incubation at 20 degrees C. This study represents the first direct evidence that the ILS in appressoria corresponds to the penetration pore and the developing penetration peg using a rapid, digital image analysis technique.     

Effects of crop rotation and removal of crop debris on the soil population of two isolates of Verticillium dahliae

Microsclerotia of Verticillium dahliae are produced in large numbers on senescing parts of host plants and remain viable in the soil for many years. Changes in the population density, i.e. density of microsclerotia, in the soil were measured in micro-plots using two isolates of V. dahtiae , specific to either field bean or potato, several crop sequences comprising potato, field beans and barley, and either the removal of aerial debris of the crops or incorporation into soil.
Potato was more susceptible to the potato isolate and field bean more susceptible to the field bean isolate. Removal of debris of potato and field bean reduced numbers of microsclerotia in the soil in the subsequent years, but removal of barley straw had no effect. Initially non-infested control micro-plots became infested, probably by the growth of potato roots into the naturally infested subsoil. The rate of increase of the microsclerotial population in the non-infested control micro-plots was larger than in the initially infested treatments, because more colonized debris was produced. It is concluded that removal of aerial debris of host crops is important to reduce the soil population of V. dahtiae.     

First record of Drosophila suzukii in the areas of the Republic of Cyprus not under the effective control of the government of the Republic of Cyprus

In this paper, the authors report the first record of Drosophila suzukii Matsumura (Diptera: Drosophilidae) in the areas of the Republic of Cyprus not under the effective control of the government of the Republic of Cyprus. This pest was found in September 2016 on Prunus armeniaca L. in Morfou and identification of the pest was carried out by the first author.     

宁夏不同地区农田土壤矿质氮的空间变异特征

在宁夏灌区和旱区共计选定肥力水平不同的30块农田,分别采集了0~120 cm深土壤剖面样品和小麦植株样品,测定了土壤铵、硝态氮含量和小麦地上部含氮量,分析了土壤矿质氮的空间变异性及其与小麦吸氮量的关系。结果表明,在0~120 cm深土壤剖面中,NH4-N、NO3-N和矿质氮含量及其累积量,灌区土壤显著高于旱区土壤,测点之间存在极显著差异,变异系数相当高。但在土层间不论灌区还是旱区变化不明显,在剖面上下分布比较均匀。矿质氮含量在土层间存在着正相关。在0~120 cm深土壤剖面中,矿质氮累积量在灌淤土、黑垆土、黄绵土和灰钙土间差异较大,平均分别为370.0、155.1、117.5和61.0 kg/hm2。其累积量与小麦籽粒产量、生物学产量、地上部总吸氮量之间呈极显著正相关,表明土壤较深层次的矿质氮对作物吸氮量也具有重要贡献。     

Variability of Cryptostroma corticale, the causal fungus of sooty bark disease of sycamore

The rate at which 19 isolates of Cryptostroma corticale grew on 3% malt agar varied considerably but the growth of each isolate was optimal at 25°C. The isolates also varied considerably in their ability to grow in young sycamores ( Acer pseudoplatanus ) in the glasshouse and in 15-year-old trees in the field. Growth rates on agar and in the host were not related but isolates which grew most rapidly in young sycamores in the glasshouse had the greatest tendency to become black on Sabouraud dextrose agar and on malt agar. The results did not support the hypothesis that the 1976–77 outbreak of sooty bark disease in England was associated with a more virulent strain of the fungus.     

Effect of Population Density of Pseudomonas fluorescens on Production of 2,4-Diacetylphloroglucinol in the Rhizosphere of Wheat

ABSTRACT The role of antibiotics in biological control of soilborne pathogens, and more generally in microbial antagonism in natural disease-suppressive soils, often has been questioned because of the indirect nature of the supporting evidence. In this study, a protocol for high pressure liquid chromatography/mass spectrometry is described that allowed specific identification and quantitation of the antibiotic 2,4-diacetylphloroglucinol (Phl) produced by naturally occurring fluorescent Pseudomonas spp. on roots of wheat grown in a soil suppressive to take-all of wheat. These results provide, for the first time, biochemical support for the conclusion of previous work that Phl-producing fluorescent Pseudomonas spp. are key components of the natural biological control that operates in take-all-suppressive soils in Washington State. This study also demonstrates that the total amount of Phl produced on roots of wheat by P. fluorescens strain Q2-87, at densities ranging from approximately 10(5) to 10(7) CFU/g of root, is proportional to its rhizosphere population density and that Phl production per population unit is a constant (0.62 ng/10(5) CFU). Thus, Phl production in the rhizosphere of wheat is strongly related to the ability of the introduced strain to colonize the roots.