Bud necrosis,a storage disease of tulips. III. The influence of ethylene and mites

Experiments demonstrated that bud necrosis in tulip bulbs is caused by mites that penetrate the flower bud during storage. This penetration is only possible if the buds, which are normally closed, are open at their tips. Such buds were found after administration of ethylene (3 ppm) during storage at 20°C shortly after lifting and in Red Champion also after storage at higher temperatures (20 to 23°C) in ethylene-free atmospheres. Open buds, caused by ethylene, resulted from unequal growth inhibition of the young leaves and stamens. The difference in sensitivity of both organs to ethylene decreased during storage. later on, the growth inhibition of stamens and leaves became equal, and the buds remained closed. Then ethylene caused blasting of the flower buds. Open buds in Red Champion, caused by higher storage temperatures, resulted from aberrant differentiation of the tips of the young leaves.The production of ethylene by tulip bulbs infected withFusarium oxysporum f.tulipae was measured and proved to be sufficiently high to cause open buds in non-infected bulbs stored in the same room if ventilation is not adequate. The highest production of ethylene, averaging 140 l/24 h/bulb was found at a storage temperature of 20°C.Samenvatting Proeven toonden aan dat kernrot in tulpebollen wordt veroorzaakt door mijten (Rhizoglyphus echinopus Fumouze & Robin enTyrophagus spp.) als deze tijdens de bewaring in de bloemknoppen binnendringen (Tabel 2 en 3). Dit konden mijten alleen bij knoppen die aan de top open waren; normaal zijn de knoppen gesloten. Open knoppen ontstonden door blootstelling van de bollen aan ethyleen (3 dpm) bij 20°C vlak na het rooien (Tabel 1 en Fig. 2) en bij bollen van Red Champion ook door bewaring bij hoge temperaturen (20 tot 23°C) in een ethyleen-vrije atmosfeer. Dit laatste berustte op een afwijkende differentiatie in de top van de pas aangelegde bladeren (Fig. 3). Ethyleen kon open knoppen doen ontstaan, doordat de lengtegroei van de jonge bladeren sterker werd geremd dan die van de meeldraden (Fig. 1). De snellere groei van de binnenste delen van de knop resulteerde dan in open knoppen. Het verschil in gevoeligheid van beide organen voor ethyleen was het grootst vaak na het rooien en nam af gedurende de bewaring. Later in het seizoen (na augustus) was de remming van meeldraden en jonge bladeren gelijk (100%) en ontstonden geen open knoppen meer. Ethyleen veroorzaakte toen verdroging van de bloemknoppen.De door ethyleen geïnduceerde groeiremming was ten dele reversibel. De groei van de jonge bladeren herstelde gedeeltelijk; de groei van de meeldraden geheel, tenzij verdroging van deze organen had plaats gehad als gevolg van blootstelling aan ethyleen laat in het seizoen. Door het verschil in reversibiliteit van de groeiremming van meeldraden en loofbladen kan de toename van de mate van knopafwijking tijdens verdere bewaring na de toediening van ethyleen verklaard worden (Tabel 1).De ethyleenafgifte van bollen die metFusarium oxysporum f.tulipae waren geïnfecteerd, is gemeten. De geproduceerde hoeveelheden ethyleen bleken afhankelijk te zijn van de bewaartemperatuur. Gemiddeld werd de grootste hoeveelheid gevonden bij 20°C, namelijk: 140 l per dag per bol (Fig. 4). Deze hoeveelheid blijkt voldoende te zijn om in slecht geventileerde ruimten bij bollen die niet doorFusarium zijn aangetast, bovengenoemde abnormale groei te veroorzaken.     

Genital lesions in an outbreak of caprine contagious agalactia caused by Mycoplasma agalactiae and Mycoplasma putrefaciens

This paper reports on the genital lesions observed in adult male and female goats from a commercial flock in the Extremadura region of southwestern Spain, following an outbreak of contagious agalactia syndrome caused by Mycoplasma agalactiae and M. putrefaciens. Although both species were isolated from several organs, M. putrefaciens was the only agent isolated from the genital lesions reported here, characterized by desquamative salpingitis and cystic catarrhal metritis in females and by testicular degeneration in males. Mycoplasma putrefaciens was isolated from the testes of only one of the males examined.     

甘肃省泾川县三元杂交肉牛生长发育的研究报告

本研究测定并对比研究了德秦黄、德利黄、德西黄、利西黄、利秦黄等三元杂交牛及二元杂交牛初生 ,3月龄、6月龄、1 2月龄、1 8月龄的生长发育指标 ,结果表明 :三元杂交牛比二次杂交牛体尺、体重均有较大幅度的增长、初步筛选出适宜泾川养殖习惯的较佳杂交组合。在农户饲养条件下 ,三元杂交初生重 38kg,比二元杂交牛提高 1 2 .8%～ 5 6.6% ;1 8月龄母牛体重 377.8kg,提高 1 5 .2 %～94.1 % ;1日龄～ 1 8月龄日增重 5 2 8.2 g,增长 9.2 %～ 68.7% ;管围提高幅度为 2 4 .1 %～ 32 .3% ;臀围为 1 .7%～ 32 .3% ;体高为 2 .9%～ 1 5 3% ,体斜长为 5 .5 %～ 1 3.9% ,胸围为 1 1 .4%～ 2 0 .5 %。尻长为 5 .1 %～ 1 1 .8% ,腰角宽为 0～ 2 1 .4% ,髋宽为 0～ 3%。适宜的杂交组合为德秦黄、德利黄、德西黄。三元杂交牛 6～ 1 2月龄生长发育受阻 ,主要是饲料营养水平低所致 ,建议从 2月龄开始用优质饲草和配和配合饲料 ,1 8月龄体重达到 40 0 kg以上 ,再经 3个月育肥 ,2 1月龄达到体重 5 0 0 kg的出栏标准。     

Risk assessment models for wheat fusarium head blight epidemics based on within-season weather data

ABSTRACT Logistic regression models for wheat Fusarium head blight were developed using information collected at 50 location-years, including four states, representing three different U.S. wheat-production regions. Non-parametric correlation analysis and stepwise logistic regression analysis identified combinations of temperature, relative humidity, and rainfall or durations of specified weather conditions, for 7 days prior to anthesis, and 10 days beginning at crop anthesis, as potential predictor variables. Prediction accuracy of developed logistic regression models ranged from 62 to 85%. Models suitable for application as a disease warning system were identified based on model prediction accuracy, sensitivity, specificity, and availability of weather variables at crop anthesis. Four of the identified models correctly classified 84% of the 50 location-years. A fifth model that used only pre-anthesis weather conditions correctly classified 70% of the location-years. The most useful predictor variables were the duration (h) of precipitation 7 days prior to anthesis, duration (h) that temperature was between 15 and 30 degrees C 7 days prior to anthesis, and the duration (h) that temperature was between 15 and 30 degrees C and relative humidity was greater than or equal to 90%. When model performance was evaluated with an independent validation set (n = 9), prediction accuracy was only 6% lower than the accuracy for the original data sets. These results indicate that narrow time periods around crop anthesis can be used to predict Fusarium head blight epidemics.     

Herbicide resistance in Aster squamatus conferred by a less sensitive form of acetolactate synthase

A biotype of Aster squamatus (Sprengel) Hieronymus with suspected resistance to the ALS-inhibiting herbicide imazapyr was detected in a chicken farm in the province of Seville, Spain, which had been treated once a year with imazapyr for 10 years. Resistance to imazapyr in this biotype was studied using dose-response experiments, absorption and translocation assays, metabolism studies and ALS activity assays. The rate of imazapyr required to inhibit A squamatus growth by 50% (ED50) was 15 times higher for the R (resistant) than for the S (susceptible) biotype. Cross-resistance existed for the ALS-inhibitors imazamox, imazethapyr, amidosulfuron, nicosulfuron, rimsulfuron, triasulfuron and tribenuron, but not for bensulfuron. Control of A squamatus using alternative herbicides was poor with clopyralid, intermediate with quinclorac, amitrole and MCPA, and excellent with 2,4-D, glufosinate and glyphosate. Absorption of [14C]imazapyr increased over time for both the R and S biotypes, and translocation from the treated leaf to shoots and roots was similar in both biotypes, with most of the radioactivity remaining in the treated leaf. No metabolites of imazapyr were detected in either biotype. Sensitivity of the ALS enzyme (target site) to imazapyr was lower for the R biotype (I50(R) = 4.28 x I50(S)). The mechanism of imazapyr resistance in this R biotype appears to be an altered ALS conferring decreased sensitivity to imazapyr at the whole-plant level.     

Evaluating processing temperature and feeding value of extruded-expelled soybean meal on nursery and finishing pig growth performance

We conducted two experiments comparing the use of extruded-expelled soybean meal (EESoy) to solvent-extracted soybean meal (SBM) in swine diets. In Exp. 1, the objective was to determine the optimal processing temperature of EESoy for nursery pig growth performance. Pigs (n = 330, 13.2 +/- 2.3 kg of BW) were fed a control diet containing SBM with added fat or one of five diets containing EESoy extruded at 143.3, 148.9, 154.4, 160.0, or 165.6 degrees C. All diets were formulated on an equal apparent digestible lysine:ME ratio. From d 0 to 20, no differences were observed (P > 0.32) in ADG or ADFI (average of 544 and 924 g/d, respectively). However, gain:feed ratio (G/F) improved (quadratic, P < 0.01, range of 0.56 to 0.60) with increasing processing temperature, with the greatest improvement at 148.9 degrees C. In Exp. 2, the objective was to determine the feeding value of EESoy relative to SBM with or without added fat for growing-finishing pigs in a commercial production facility. A total of 1,200 gilts (initially 24.5 +/- 5.1 kg of BW) was used, with 25 pigs per pen and eight replications per treatment. Dietary treatments were arranged in a 2 x 3 factorial, with two sources of soybean meal (SBM or EESoy) and three levels of added fat. Pigs were phase-fed four diets over the experimental period and added fat (choice white grease) levels were 0, 3.4, and 7% initially, with the added fat levels decreasing in the next three dietary phases. Energy levels were based such that the higher energy in EESoy (with or without added fat) was calculated to be equal to that provided by SBM with added fat. From 24.5 to 61.2 kg, pigs fed EESoy had greater (P < 0.07) G/F than those fed SBM. Increasing added fat in either EESoy- or SBM-based diets increased G/F (linear, P < 0.0003). From 61.2 to 122.5 kg, ADG and G/F were unaffected in pigs fed EESoy and/or increasing added fat (P > 0.10). For the overall growing-finishing period, ADG was unaffected (P > 0.61) by increasing energy density of the diet; however, ADFI decreased (P < 0.05) and G/F increased (P < 0.02, range of 0.37 to 0.40) as energy density increased with either EESoy or added fat. Carcass leanness was not affected by dietary treatment. These results indicate that EESoy should be extruded at 148.9 to 154.4 degrees C, and that increasing dietary energy density by using EESoy and/or added fat improves feed efficiency in finishing pigs reared in a commercial environment.     

A review of porcine reproductive and respiratory syndrome virus in Dutch breeding herds: population dynamics and clinical relevance

Understanding the spread of porcine reproductive and respiratory syndrome virus (PRRSV) in pig populations is essential to the development of effective PRRS prevention and control strategies. Moreover, knowledge of the field dynamics of PRRSV in pigs will provide insights into the clinical relevance of PRRS, and will enable the targeting of interventions. This review of PRRSV includes discussion on the occurrence of outbreaks, the persistence of infection and the fade-out of infection in Dutch breeding herds. The dynamic character of PRRSV infections in endemically infected herds and the relevance of the disease under Dutch field conditions are also highlighted. Furthermore, several strategies aimed at controlling the spread of PRRSV are discussed.