Foot Rot Research Articles

Assessment of Carrier Materials to Formulate Trichoderma Harzianum Bio-Fungicide for Controlling Foot and Root Rot Disease of Brinjal in Seed Bed

Efficacy of eight different carrier materials and their combinations were tested to formulate a suitable Trichoderma harzianum based bio-fungicides for controlling foot and root rot diseases of brinjal caused by Sclerotium rolfsii in tray soil as well as seed bed soil under net house condition of Bangladesh Agricultural Research Institute (BARI). The results from a series of experiments revealed that four combination of carrier materials based T. harzianum bio-fungicides such as (1) wheat bran + rice bran, (2) wheat bran + mustard oil cake (MOC) + rice bran, (3) khesari bran + rice bran, and (4) khesari bran +MOC+ rice bran were suitable for controlling the soil borne foot and root rot disease (S. rolfsii) of brinjal in tray soil as well as seed bed soil conditions.

Selenium Supplementation Restores Innate and Humoral Immune Responses in Footrot-Affected Sheep

Dietary selenium (Se) alters whole-blood Se concentrations in sheep, dependent upon Se source and dosage administered, but little is known about effects on immune function. We used footrot (FR) as a disease model to test the effects of supranutritional Se supplementation on immune function. To determine the effect of Se-source (organic Se-yeast, inorganic Na-selenite or Na-selenate) and Se-dosage (1, 3, 5 times FDA-permitted level) on FR severity, 120 ewes with and 120 ewes without FR were drenched weekly for 62 weeks with different Se sources and dosages (30 ewes/treatment group). Innate immunity was evaluated after 62 weeks of supplementation by measuring neutrophil bacterial killing ability. Adaptive immune function was evaluated by immunizing sheep with keyhole limpet hemocyanin (KLH). The antibody titer and delayed-type hypersensitivity skin test to KLH were used to assess humoral immunity and cell-mediated immunity, respectively. At baseline, FR-affected ewes had lower whole-blood and serum-Se concentrations; this difference was not observed after Se supplementation. Se supplementation increased neutrophil bacterial killing percentages in FR-affected sheep to percentages observed in supplemented and non-supplemented healthy sheep. Similarly, Se supplementation increased KLH antibody titers in FR-affected sheep to titers observed in healthy sheep. FR-affected sheep demonstrated suppressed cell-mediated immunity at 24 hours after intradermal KLH challenge, although there was no improvement with Se supplementation. We did not consistently prevent nor improve recovery from FR over the 62 week Se-treatment period. In conclusion, Se supplementation does not prevent FR, but does restore innate and humoral immune functions negatively affected by FR.

Observing lame sheep: evaluating test agreement between group-level and individual animal methods of assessment

AbstractFor on-farm sheep welfare assessment, a reliable, simple and robust method is required to assess the level of flock lameness. This study examined the level of test agreement for two binary lameness scoring systems for sheep. The first was a group-level lameness assessment of sheep performed on ungathered sheep at pasture and was termed group observation method (GOM). The second method of lameness assessment was performed after gathering of the sheep and involved close observation of the gait of individual sheep in a handling pen and was termed individual animal gait assessment (IAGA). Following individual gait assessment, each sheep was also examined for the presence of specific foot and limb lesions: white line lesions (WL); inter-digital dermatitis (ID); footrot (FR); contagious digital dermatitis (CODD); toe granuloma (TG); and joint swellings (JS). A total of 3,074 sheep were assessed from 40 flocks in North England and Wales by one assessor. Test agreement between the assessment methods was found to be good as judged by linear regression and Bland-Altman plots. The method of group observation identified a slightly higher proportion of lame sheep compared to the individual animal examination and also appeared to be a more feasible on-farm method of observation. Over half of the sample sheep were identified with WL but this did not appear to be associated with a high level of lameness (as assessed by IAGA) with just under 12% of sheep with WL being identified as lame. In contrast, the percentage of lame sheep was most closely associated with CODD and over 80% of animals with this lesion were scored as lame.

Selenium Supplementation Alters Gene Expression Profiles Associated with Innate Immunity in Whole-Blood Neutrophils of Sheep

Footrot (FR) is a common, contagious bacterial disease of sheep that results in lameness and significant economic losses for producers. We previously reported that sheep affected with FR have lower whole-blood (WB) selenium (Se) concentrations and that Se supplementation in conjunction with routine control practices accelerates recovery from FR. To determine whether oral Se-yeast administered at supranutritional levels (>4.9 mg Se/week) alters the ability of sheep to resist or recover from FR infection, 60 ewes with and 60 ewes without FR were drenched once weekly for 62.5 weeks with 0, 4.9, 14.7, or 24.5 mg organic Se-yeast (30 ewes per treatment group). Footrot prevalence and severity were measured at 0, 20, 28, 40, and 60 weeks of Se supplementation. Genomic expression of eight WB-neutrophil genes for selenoproteins and seven WB-neutrophil genes for proteins involved in innate immunity was determined at the end of the treatment period using SYBR Green and quantitative polymerase chain reaction methodology. Supranutritional Se-yeast supplementation successfully increased Se status in sheep but did not prevent FR. Supranutritional Se-yeast supplementation increased WB-neutrophil expression of genes involved in innate immunity: L-selectin, interleukin-8 receptor, and toll-like receptor 4, which were or tended to be lower in ewes affected with FR. Furthermore, supranutritional Se-yeast supplementation altered the expression of selenoprotein genes involved in innate immunity, increasing selenoprotein S and glutathione peroxidase 4 and decreasing iodothyronine deiodinases 2 and 3. In conclusion, supranutritional Se-yeast supplementation does not prevent FR, but does alter WB-neutrophil gene expression profiles associated with innate immunity, including reversing those impacted by FR.

Reference Gene Selection for Quantitative PCR Studies in Sheep Neutrophils

Reference genes are essential for studying mRNA expression with quantitative PCR (qPCR). We investigated 11 potential neutrophil reference genes (RPL19, GAPDH, ACTB, B2M, HPRT, G6PD, TFRC, PGK1, YWHAZ, SDHA and GYPC) for sheep under disease conditions of foot rot (FR) and with or without Se supplementation. Initial screening was based on gene expression level (<28 Cq cycles) and variability (SD < 1.5 Cq cycles) and excluded TFRC, GYPC and HPRT from further analysis. Expression stability of the remaining genes was evaluated using four software programs: geNorm, NormFinder, BestKeeper and the comparative delta Cq method. The neutrophil reference genes, G6PD, YWHAZ, GAPDH, RPL19 and SDHA, consistently ranked among the top five most stable genes under these experimental conditions. The SDHA gene expression was not stable in FR-diseased sheep receiving Se treatment and, thus, cannot be recommended as a reference gene. The commonly used genes, PGK1, ACTB and B2M, were not reliable reference genes, underscoring the need to validate neutrophil reference genes under different experimental conditions. Multiple references genes rather than a single gene may provide more robust and reliable results. The best pair of reference genes was SDHA/G6PD in healthy sheep and GADPH/YWHAZ in FR-diseased sheep.

Participatory surveillance of livestock and poultry diseases in Agidi development area of Nasarawa state Nigeria

A participatory surveillance of livestock and poultry diseases was carried out in Agidi Development Area of Nasarawa State among 123 farmers, 29 of the respondent were female, while 94 were male. Open-ended interviews were utilized where necessary to clarify information that needed clarifications by the respondents; physical examination of the some affected animals and it surroundings were carried out during the surveillance. The following diseases were established in the study area: Peste des peptits ruminants, Foot rot, helminthosis, mite/lice/flea infestation, tick infestation, bloat, Orf (Contagious ecthyma), poison, mange, Newcastle disease, fowl pox, coccidiosis, infectious bursal disease (Gumboro), chronic respiratory disease, African Swine Fever (ASF), abortion, Dystocia, sudden death, foot and mouth disease, Fascioliasis, trypanosomosis, black quarter disease, babesiosis, and wounds. Some of these diseases have specific period (season) of outbreak, while some occurs at all season. Analysis of data indicated that Newcastle disease was the most important disease of poultry, Peste des peptits ruminants was the disease that lead to high mortality in small ruminants, while African Swine Fever (ASF) is the most devastating disease of pigs, and Lice/flea infestation is the most common disease to poultry, small ruminants and pigs, in the study area.

Evaluation of microbial products for the control of zucchini foot and root rot caused by Fusarium solani f. sp. cucurbitae race 1.

Microbial products containing bacteria (Cedomon [ Pseudomonas chlororaphis MA342, PC-MA342], Mycostop [ Streptomyces sp. K61, SG-K61], Proradix®Agro [ Pseudomonas sp. DSMZ13134, PS-DSMZ13134]) and fungi (Clonotry [ Trichoderma harzianum and Clonostachys rosea , TH+CR], Remedier [ T. asperellum ICC012 and T. gamsii ICC080, TA-ICC012+TG-ICC080], Rootshield WP [ T. harzianum T22, TH-T22]) were tested for efficacy against Fusarium solani f. sp. cucurbitae race 1 (FSC7 strain) on zucchini. They were applied to seeds (S), plant growth substrate (PGS) and both (S+PGS) in a growth chamber experiment, and to PGS, transplantation soil mixture (TSM) and both (PGS+TSM) in a greenhouse experiment. FSC7 was inoculated in PGS at sowing time in the growth chamber and in TSM at transplant in the greenhouse. In the growth chamber, the most effective products were Cedomon (S and S+PGS treatments), Rootshield (PGS treatment) and Proradix (S+PGS treatment), reducing the disease by 39.7, 43.1, 25.8 and 36.4%, respectively. In the greenhouse, all tested products applied to PGS reduced the disease severity and more markedly when applied to PGS+TSM. In the PGS and PGS+TSM treatments, Cedomon was the most effective product showing a disease decrease by 42.4 and 59.5%, respectively. The data obtained in vivo were consistent with the ability of the antagonists to colonize zucchini rhizosphere and with their inhibitory effects on the growth of the pathogen in in vitro assays. The bacteria caused the greatest growth inhibition of FSC7 showing abnormal morphology, while Trichoderma spp. parasitized FSC7 hyphae. Bacteria were the most active in reducing pathogen colony growth through antibiotic metabolites. All antagonists produced exo- and endochitinase enzymes. Trichoderma strains showed greater levels of β-N-acetylhexosaminidase and endochitinase, whereas SG-K61 was the most active producer of chitin 1,4-β-chitobiosidase. These results indicate that the studied bioproducts have potential for an effective management of zucchini Fusarium foot and root rot through rhizosphere competence and several mechanisms exerted by their microbial ingredients.

Why are sheep lame? Temporal associations between severity of foot lesions and severity of lameness in 60 sheep

AbstractWe investigated the temporal associations between the severity of foot lesions caused by footrot (FR) and the severity of lameness in sheep. Sixty sheep from one farm were monitored for five weeks. The locomotion of each sheep was scored once each week using a validated numerical rating scale of 0-6. All feet were then examined, FR was the only foot lesion observed; the severity of FR lesions was recorded on a scale from 0 to 4. Sheep had a locomotion score &gt; 0 on 144/298 observations. FR lesions were present on at least one foot on 83% of observations of lame sheep but also present on 27% of observations where sheep were not lame; 95% of these sheep with a lesion but not lame had FR score 1. The results from a linear mixed model with locomotion score as the outcome were that the mean (95% CI) locomotion score of 0.28 (0.02, 0.53) in sheep with no lesions increased by 0.35 (0.05, 0.65) in sheep with FR score 1 or 2 and by 1.55 (1.13, 1.96) in sheep with FR score &gt; 2 at the time of the observation; indicating that as the severity of the lesion increased, the severity of lameness increased. One week before an FR score &gt; 2 was clinically apparent, sheep had a locomotion score 0.81 (0.37, 1.24) higher than sheep that did not have an FR score &gt; 2 in the subsequent week. One week after treatment with intramuscular antibacterials the locomotion score of lame sheep reduced by 1.00 (0.50, 1.49). Our results indicate a positive association between severity of FR lesions and locomotion score and indicate that some non-lame and mildly lame sheep have footrot lesions. Treatment of even those mildly lame will facilitate healing and probably reduce the spread of infection to other sheep in the same group.

Higher whole-blood selenium is associated with improved immune responses in footrot-affected sheep

We reported previously that sheep affected with footrot (FR) have lower whole-blood selenium (WB-Se) concentrations and that parenteral Se-supplementation in conjunction with routine control practices accelerates recovery from FR. The purpose of this follow-up study was to investigate the mechanisms by which Se facilitates recovery from FR. Sheep affected with FR (n = 38) were injected monthly for 15 months with either 5 mg Se (FR-Se) or saline (FR-Sal), whereas 19 healthy sheep received no treatment. Adaptive immune function was evaluated after 3 months of Se supplementation by immunizing all sheep with a novel protein, keyhole limpet hemocyanin (KLH). The antibody titer and delayed-type hypersensitivity (DTH) skin test to KLH were used to assess humoral immunity and cell-mediated immunity, respectively. Innate immunity was evaluated after 3 months of Se supplementation by measuring intradermal responses to histamine 30 min after injection compared to KLH and saline, and after 15 months of Se supplementation by isolating neutrophils and measuring their bacterial killing ability and relative abundance of mRNA for genes associated with neutrophil migration. Compared to healthy sheep, immune responses to a novel protein were suppressed in FR-affected sheep with smaller decreases in FR-affected sheep that received Se or had WB-Se concentrations above 250 ng/mL at the time of the immune assays. Neutrophil function was suppressed in FR-affected sheep, but was not changed by Se supplementation or WB-Se status. Sheep FR is associated with depressed immune responses to a novel protein, which may be partly restored by improving WB-Se status (> 250 ng/mL).

A within farm clinical trial to compare two treatments (parenteral antibacterials and hoof trimming) for sheep lame with footrot

From observational studies, farmers who use parenteral antibacterials to promptly treat all sheep with footrot (FR) or interdigital dermatitis (ID) have a prevalence of lameness of <2% compared with a prevalence of 9% lameness reported by farmers who treat lame sheep by trimming affected feet. We tested the hypothesis that prompt treatment of sheep lame with naturally developing FR or ID with parenteral and topical antibacterials reduces the prevalence and incidence of lameness with these conditions compared with less frequent treatment with trimming of hoof horn and applying topical antibacterials. A further hypothesis was that reduction of ID and FR would improve productivity. A lowland sheep flock with 700 ewes was used to test these hypotheses in an 18-month within farm clinical trial with four groups of ewes: two intervention and two control. The duration and severity of lameness was used to categorise sheep into three weighted scores of lameness (WLS): never lame (WLS0), mildly lame/lame for <6 days (WLS1) and severely or chronically lame (WLS2). The intervention reduced the prevalence of lameness due to FR and ID in ewes and lambs and the incidence of lameness in ewes. The WLS was also significantly lower in sheep in the intervention groups. Ewes with a higher WLS were subsequently significantly more likely to have a body condition score <2.5 and to have lame lambs. Significantly more ewes lambed and successfully reared more lambs that were ready for slaughter at a younger age in the intervention versus control groups. There was an increase in the gross margin of £630/100 ewes mated in the intervention group, including the cost of treatment of £150/100 ewes mated. We conclude that prompt parenteral and topical antibacterial treatment of sheep lame with ID and FR reduced the prevalence and incidence of these infectious conditions and led to improved health, welfare and productivity.

Characterization of Smallholder Sheep and Goat Farming in Bauchi, Northeastern Nigeria

The study was conducted to investigate and describe the smallholder sheep and goat production in Bauchi. Data collated was subjected to simple descriptive statistics. The results showed that majority (61.25%) of the farmers were males, and mainly adults (85.00%) attaining the age of twenty five years or more. About 57.00% of the farmers sourced their foundation stock through purchase while others obtained them through inheritance (7.20%), gift (13.60%) and other sources (27.20%). Farmers kept more sheep (58.75%) than goats (41.25%). The results also revealed that the extensive/ free-range (53.75%) was the predominate system of rearing sheep and goats. This was followed by those who practised the semi-intensive system (30.00%). The rest (16.25%) being for the farmers who used the improved production system. Farmers used various shelter conditions for keeping their animals; concrete house (21.25%), mud (23.75%), pen/tethering (35.00%) and no provision of housing (20.00%). However, majority of the farmers (65.00%) breed their animals through uncontrolled natural breeding method, while others relied on the natural controlled breeding method. There was no single farmer that was practising the artificial means of breeding. Most animals (52.23%) had poor body condition score (BCS 1 & 2), 39.03% average, 8.38% and 0.36% fat and obese respectively. Only about 30.0% of the farmers had all-year round feed and water supply to the animals and the rest complained of scarcity of either feed or water at point in time. There was a large number (63.75%) of farmers who give feed supplements, and a lot of farmers (51.25%) have no veterinary services in the business of keeping sheep and goats. The results showed that the major ectoparasites in the area were ticks, fleas and lice with incidence rates of 46.52, 19.79 and 10.34%, respectively. About 23.35% of the animals were free from these parasites. Disease occurrence showed that enteritis, foot rot, fracture/ dislocation, helmenthosis, mange/scabies, nutritional disorder, PPR, pneumonia and others having incidence rates of 8.39, 13.55, 3.87, 25.80, 5.16, 7.10, 20.65, 5.80 and 9.68%, respectively. These diseases occurred mainly (49.68%) in both dry and wet seasons. Others occur only in the dry (20.00%) or wet (30.32%) seasons. The average amount spent annually on diseases was generally less than ₦500 per animal. The study showed that animals under small – holder farming are exposed to numerous hazards, characterized by poor housing and nutrition, high incidence of diseases, poor breeding methods, among others. It is, therefore, suggested that great improvement in the husbandry of these animals should be realized if these constraints are successfully removed to enhance their productivity.

Farmers’ practices and factors associated with the prevalence of all lameness and lameness attributed to interdigital dermatitis and footrot in sheep flocks in England in 2004

The aim of this study was to investigate whether the risk factors associated with all causes of lameness in sheep differed from those associated with the lesion specific causes of lameness, interdigital dermatitis (ID) and footrot (FR). A total of 809 randomly selected English sheep farmers participated in a postal survey in 2005. Data were requested on their management of lameness in 2004 and whether this had changed from 2003 and the prevalence of all lameness, and lameness caused by ID and FR. The farmer ability to recognise ID and FR was assessed from their responses to a written and pictorial description. On 443 farms where both ID and FR were correctly named by the farmer, the mean prevalence of all lameness, and lameness caused by ID and FR were 10.0% (95% CI: 8.9, 10.8), 6.5% (95% CI: 5.8, 7.3) and 3.1% (95% CI: 2.8, 3.6), respectively. The mean prevalence of all lameness on all 809 farms was not significantly different at 10.2% (95% CI: 9.2, 11.0). The data were analysed using negative binomial regression models with the three outcomes farmer estimated prevalence of all lameness and lameness caused by ID or FR in 2004. Farmers who changed management of sheep between 2003 and 2004 were excluded from the analysis, thus all fixed effects were the farmers’ managements in 2003 and 2004 to ensure that the management was in place for at least one year before the prevalence estimates. Routine foot trimming ≥once/year compared with no routine foot trimming was significantly associated with an increased prevalence of all lameness (prevalence ratio (PR) = 1.34), ID (PR = 1.50) and FR (PR = 1.35). Footbathing was also significantly associated with increased prevalence of all lameness (PR = 1.67), ID (PR = 1.68) and FR (PR = 1.76). A stocking density of >8 ewes/ha was associated with a significantly increased prevalence of all lameness (PR = 1.26) and ID (PR = 1.39). There was a significantly lower prevalence of FR (PR = 0.73; PR = 0.70, respectively) on farms in the North East and South East of England. Separating lame sheep at pasture was associated with a decreased prevalence of all lameness and ID (PR = 0.75; PR = 0.73) and location of the farm in South East England was associated with a lower prevalence of all lameness and ID (PR = 0.75; PR = 0.71, respectively). We conclude that management factors associated with all lameness, and lameness attributed to ID and FR are similar.

Practicalities of lameness management in sheep

STAGE 1 MAKE THE CORRECT DIAGNOSIS (SPEAK A COMMON LANGUAGE) The common foot conditions are interdigital dermatitis (ID) (Fig. 2), footrot (FR) (Fig. 3), contagious ovine digital dermatitis (CODD) (Fig. 4), toe granuloma (Fig. 5), toe abscess (Fig. 6) and shelly hoof (Fig. 7) (illustrated and described at www.warwick.ac.uk/go/sheeplameness). In recent work at Warwick we highlighted that not all farmers

Effect of Carrier Media on Population Fluctuation of Trichoderma harzianum (MTCC5179) in Black Pepper ( Piper nigrum L.) Rhizosphere and their Interaction with Soil Microflora and Fauna

Trichoderma harzianum is used as a biocontrol agent to manage Phytophthora foot rot of black pepper ( Piper nigrum L.) in India. Several organic materials such as sorghum, neem cake, decomposed coir pith and farmyard manure are used both as multiplication and carrier media for T. harzianum . The effect of these carrier media on the population build up of T. harzianum in black pepper rhizosphere and their effect on microflora and fauna was studied. The organic materials increased the population of introduced T. harzianum and also increased populations of fungi, bacteria, microarthropods and nematodes. In case of sorghum, there was a sudden spurt in the population of saprophytic nematodes and mycophagous mites within 15 days followed by a succession of predatory mites and nematodes. The unspent carbohydrate and mycelial form of T.harzianum in sorghum perhaps helped in the population build up of soil microarthropods and nematodes, which in turn affect the biocontrol efficiency of the introduced organism.

Naming and recognition of six foot lesions of sheep using written and pictorial information: A study of 809 English sheep farmers

In 2005, 3000 questionnaires were sent to a random sample of English sheep farmers from a list kept by the English Beef and Lamb Executive (EBLEX) to investigate whether farmers could correctly name six common foot lesions in sheep from a characteristic picture and a written description. The lesions were interdigital dermatitis (ID), footrot (FR), contagious ovine digital dermatitis (CODD), shelly hoof, foot abscess and toe granuloma. In addition, farmers were asked to report the total percent of lame sheep in their flock in 2004 and the percent of this lameness attributable to each of the six lesions listed above. The overall response percentage was 44 with a useable response of 32%. Fifty-nine farmers out of 262 (23%) who answered all six questions named all six lesions correctly. This was greater than expected by chance. The same questionnaire of six lesions was presented at a meeting of specialist sheep advisors, primarily veterinarians, 37/47 (79%) responders named all six lesions correctly. From the six lesions listed above, the percent correctly named by farmers was approximately 83%, 85%, 36%, 28%, 65% and 43% and the percent incorrectly attributed to another lesion was 5%, 47%, 10%, 13%, 35% and 7%, respectively. The most commonly used incorrect name was FR, with farmers tending to name any hoof horn lesion as FR. A comparison of the distribution of sheep lame by a lesion correctly named compared with the same lesion incorrectly named as FR suggested that farmers recognised lesions but did not name them correctly; the distribution of lameness fitted the pattern for the correctly named lesion rather than the pattern of lameness attributed to FR. The results were validated with farm visits and a repeatability study of the questionnaire. The mean farmer-estimated prevalence for all lameness was 10.4%; with 6.9%, 3.7%, 2.4%, 1.9%, 0.9% and 0.8% of the sheep lame with ID, FR, CODD, shelly hoof, foot abscess and toe granuloma respectively from respondents who correctly named these lesions. Whilst ID and FR were the most prevalent causes of lameness in most flocks it is possible that in up to 17% flocks the primary cause of lameness was a different lesion.

SEM Investigation about Hyphal Relationships between Some Antagonistic Fungi against «Fusarium» spp. Foot Rot Pathogen of Wheat

Wheat foot rot caused by Fusarium species is a worldwide wheat disease against which the use of biocontrol agents is of increasing interest. Mycoparasitic activities of a strain of five antagonistic fungi, Gliocladium roseum (GR11), Penicillium frequentans (PF), Trichoderma atroviride (TA312), T. longibrachiatum (TL9) and T. harzianum (TH144), against three pathogens, Fusarium culmorum, F. graminearum and F. nivale, were studied by scanning electron microscopy (SEM). SEM observations suggested that the outcome of interaction between antagonist and pathogen occurred when intimate contact was established between hyphae triggering a series of events in pathogen degradation. The interaction between Trichoderma spp. and Fusarium spp. revealed that the mycoparasitic hyphae were usually attached longitudinally to the hyphae of the pathogens; hyphal coilings, hooks, pincer-shaped structures, short contact branches and hyphal depressions were also present. GR11 and PF hyphae grew mainly parallel to the pathogen causing its hyphal depression. The parasitic action of the antagonists shown with the formation of pincers, hooks and other structures leading to cell disruption, goes some way towards explaining their mode of action in the biological control of the pathogens studied.

Characterization of Phytophthora citrophthora and P. inundata associated to foot and root rot of citrus trees in Chile

Citrus production has increased considerably in Chile to about 17300 ha mainly planted with lemon, mandarin, and sweet orange. Although irrigation managements have improved and tolerant rootstocks have been commonly used, Phytophthora foot rot (gummosis) and root rot occur frequently. Symptoms included slow decline, moderate leaf chlorosis, reduced growth, lack of tree vigor and dieback. These symptoms were associated to extensive canker lesions and gummosis at the base of the trunk, and root rot, often extending from the main roots into the feeder roots. The frequent outbreaks of Phytophthora diseases in Chilean citrus groves motivated this survey to characterize the species of Phytophthora associated to foot and root rot. A total of 27 pathogenic isolates of Phytophthora were obtained in 2003 and 2004. Morphologically, 20 isolates were identified as P. citrophthora ; however, they were distinctively divided into sterile and fertile isolates. The latter were morphologically similar to P. citrophthora sensu lato but, they induced oospore production when pairing against P. cinnamomi A2. These fertile isolates exhibited a 98% match with several P. citrophthora strains and were considerably less aggressive than sterile isolates. Phytophthora inundata , a relatively new described species, was identified on the basis of analysis of the ITS regions of rDNA. Isolates of P. inundata were weakly pathogenic on citrus and, possibly were found as secondary pathogen without importance on foot and root rot development on citrus trees. Therefore, P. citrophthora was the cause of foot and root rot found on Chilean citrus groves, planted in temperate and relative dry weather conditions. The isolation and pathogenicity of P. citrophthora on Citrus macrophylla and Carrizo citrange , considered resistant rootstocks, could be suggesting that these isolates have overcome resistant genes associated with Phytophthora resistant citrus rootstocks. La produccion de citricos ha aumentado considerablemente en Chile, con alrededor de 17300 ha, principalmente destinadas a la produccion de limon, mandarin y naranjo. La pudricion del pie (gomosis) y la pudricion de las raices ocurren frecuentemente. Esto a pesar que el manejo del agua de riego ha mejorado y se han introducido portainjertos tolerantes. Los sintomas de esta enfermedad consisten en un lento y progresivo decaimiento, clorosis foliar moderada, menor crecimiento, escaso vigor y muerte parcial de ramas y ramillas. Estos sintomas estan asociados con la presencia de cancros y gomosis en la base del tronco y podredumbre radical, que compromete raices primarias y secundarias. La ocurrencia relativamente frecuente de focos de esta enfermedad en huertos citricos en la zona central de Chile, motivo esta investigacion que tuvo el proposito de caracterizar las especies de Phytophthora asociadas a este sindrome. Se obtuvo 27 aislamientos de Phytophthora entre 2003 y 2004. Morfologicamente, 20 aislamientos se identificaron como P. citrophthora entre los cuales se identificaron aislamientos esteriles y fertiles. Los aislamientos fertiles fueron morfologicamente indiferenciables de P. citrophthora sensu lato pero, desarrollaron oosporas al aparearlos con P. cinnamomi A2 y presentaron 98% de similitud al compararlos molecularmente con P. citrophthora . Los aislamientos fertiles fueron relativamente menos agresivos que los esteriles. Phytophthora inundata , corresponde a una especie recientemente descrita en el mundo, identificada sobre la base de la caracterizacion de la region ITS del rADN. Los aislamientos de P. inundata fueron debilmente patogenicos en citricos y posiblemente tienen secundaria importancia en el desarrollo de esta enfermedad. Por lo tanto, segun los resultados obtenidos en esta investigacion P. citrophthora es la causa de la pudricion del pie y de las raices en huertos citricos chilenos, generalmente plantados en zonas templadas y relativamente secas. El aislamiento y patogenicidad de P. citrophthora obtenida desde Citrus macrophylla y Carrizo citrange, considerados como portainjertos resistentes, sugiere una posible perdida de resistencia de estos portainjertos.

Disease resistance in Merino sheep. II. RFLPs in Class IIMHC and their association with resistance to footrot

Restriction fragment length polymorphism (RFLP) within the Major Histocompatibility Complex (MHC) Class II region was examined in 83 sheep. Two restriction enzymes (TaqI and PvuII) and two human cDNA probes (DQα-folke and DRβ-malta) were used to probe Southern blots from all sheep. In addition, a second human DRβ probe (signe) and the restriction enzyme, EcoRI, were used for 15 sheep to match previously published polymorphism in sheep using the same probe/enzyme combination. All sheep were part of an experiment in which footrot was experimentally induced and then controlled through vaccination with an homologous rDNA pilus vaccine. The four main probe/enzyme combinations detected extensive polymorphism; in total 74 bands were detected of which only 2 were present in all sheep. A similar level of polymorphism was also seen with the EcoRI/DRβ-signe probe/enzyme combination, which was greater than previously published for sheep, cattle or goats. After accounting for cross-hybridising bands, the sheep DRβ region appeared to be more polymorphic than the DQα region. Similarly the TaqI restriction enzyme revealed more polymorphism than the PvuI enzyme (40 and 34 bands respectively). For all 74 bands, 7 main clusters were identified both within and across probe/enzyme combinations. After removing bands/clusters which were of extreme frequency (< 0.10 and > 0.90), a total of 53 bands/clusters were analysed for their potential association with footrot and antibody responses. One band was significantly associated with susceptibility to footrot over the 27-week period during which footrot was measured. In addition, two single bands and one cluster were significantly (P > 0.001) associated with residual footrot infection after vaccination. Nine bands/clusters were associated with antibody titre during infection, and one cluster with antibody titre after vaccination. These results suggest a possible involvement for genetic polymorphism within the ovine Class II region in variation in response to footrot. ZUSAMMENFASSUNG: Krankheitsresistenz bei Merinos, II. RFLP's in Klasse II MHC und ihre Verbindung mit der Moderhinkeresistenz Restriktionsfragmentlängenpolymorphismus (RFLP) innerhalb des Haupthistokompatibilitätskomplexes (MHC) Klasse II Region wurde bei 83 Schafen untersucht. Zwei Restriktionsenzyme (TaqI und PvuII) und zwei humane cDNA-Sonden (DQα-folke und DRβ-malta) wurden für Southern blots bei allen Schafen verwendet. Zusätzlich wurde eine zweite humane DRβ-Sonde (signe) und das Restriktionsenzym EcoRI bei 15 Schafen zum Vergleich mit früher publizierten Polymorphismus mit den selben Enzym/Sondenkombinationen durchgeführt. Alle Schafe waren Teil eines Versuches, in welchem Moderhinke experimentell induziert und dann durch Vaccination mit homologer rDNA-pilus vaccine bekämpft worden war. Die 4 Enzym/Sondenkombinationen entdeckten extensiven Polymorphismus. Insgesamt 74 Banden wurden entdeckt, wovon nur zwei in allen Schafen vorhanden waren. Ein ähnliches Ausmaß von Polymorphismus wurde auch mit der EcoRI/DRβ-signe Enzym/Sondenkombination entdeckt, das größer war als bisher für Schafe, Rinder oder Ziegen publiziert. Nach Berücksichtigung der Kreuz-Hybridisierungsbande scheint die Schaf-DRβ-Region stärker polymorph als die DQα-Region zu sein. Ähnlicherweise zeigte das TaqI Restriktionsenzym mehr Polymorphismus als das PvuII Enzym (40 bzw. 34 Bande). Bei allen 74 Banden wurden sieben Hauptkluster identifiziert, sowohl innerhalb als auch über Enzym/Sondenkombinationen. Nach Entfernung von Banden/Kluster mit extremen Häufigkeiten (< 0,10 bzw. > 0.9) wurden insgesamt 53 Bande/Kluster hinsichtlich ihrer potentiellen Verbindung mit Moderhinke und Antikörperreaktion analysiert. Ein Band war signifikant mit Moderhinkeempfindlichkeit während der 27-Wochenperiode assoziiert. Zusätzlich waren zwei einzelne Bande und ein Kluster signifikant (p > 0,001) assoziiert mit Moderhinkeinfektion nach der Impfung. 9 Band/Kluster waren mit Antikörperspiegel während der Infektion verbunden und ein Kluster mit Antikörperspiegel nach Impfung. Die Ergebnisse deuten auf Zusammenhang des genetischen Polymorphismus innerhalb der ovinen Klasse II-Region mit Variabilität im Moderhinkeverlauf.

Disease resistance in Merino sheep: I. Traits indicating resistance to footrot following experimental challenge and subsequent vaccination with an homologous rDNA pilus vaccine

Clinical and serological responses were monitored in sheep following experimental challenge with footrot and subsequent vaccination with an homologous rDNA pilus vaccine. Twenty-two clinical indicators of footrot were identified to describe differences between feet, between sheep, between flocks, and over time. All eleven between-sheep indicators were significantly correlated with each other (0.47 to 0.96). However, analyses of liability on a underlying scale showed that those indicators with several categories, such as the number of feet affected or underrun, were most useful: the data strongly indicated that increasing grades of severity reflect a single underlying variable. The proportion of sheep affected and/or underrun (i.c.e. prevalence) was the most suitable indicator of flock differences. Repeatability of footrot scores over time was relatively low (0.36 to 0.56 prior to vaccination; 0.02 to 0.30 after vaccination), highlighting the need for repeat observations to describe differences in footrot over time. A need was shown to incorporate spontaneous or induced healing following vaccination in scoring systems for footrot. Serological assays detected an increase in antibody titres during infection, but antibody titres were not sufficiently correlated with clinical indicators (0.34 to 0.61) to justify their use as indicators of footrot. K-agglutination titres were moderately to highly correlated with Pili ELISA assays (0.69 to 0.86), but the two types of assay are not interchangeable. On balance, K-agglutination is the most appropriate measurement of antibody response for all types of footrot studies. This set of initial analyses has shown large phenotypic variation in all important footrot indicators. Subsequent studies will investigate the extent to which there is genetic variation in these indicators, with the aim of determining the feasibility of incorporating resistance to footrot into breeding programmes. The traits defined and described in this paper from the basis of a large scale investigation into genetic and phenotypic aspects of resistance to footrot. ZUSAMMENFASSUNG: Krankheitsresistenz bei Merinos. I. Moderhinkeresistenz nach experimenteller Infektion und Impfung mit homologer rDNA-pilus vaccine Klinische und serologische Reaktionen wurden nach experimenteller Infektion von Schafen mit Moderhinke und folgender Impfung mit homologer rDNA-pilus vaccine verfolgt. 22 klinische Symptome wurden identifiziert um Unterschiede zwischen Füßen, zwischen Schafen, Herden und Zeitspannen zu beschreiben. Alle elf "zwischen Schaf" Symptome waren signifikant miteinander korreliert (0,47 bis 0.96). Die Analysen der Liabilität auf zugrundeliegender Skala zeigt allerdings, daß Symptome mit mehreren Kategorien, wie etwa Zahl der befallenen Füße, am nützlichsten waren: Die Daten weisen darauf hin, daß steigende Erkrankungsgrade eine zugrundeliegende Variable wiedergeben. Der Anteil der befallenen Schafe und/oder lose Klauen gaben am besten Herdendifferenzen wieder. Wiederholbarkeit von Moderhinke über einen Zeitraum war relativ niedrig (0,36 bis 0,56 vor der Vaccination; 0,02 bis 0,30 nachher), wodurch Notwendigkeit wiederholter Beobachtungen der Moderhinke deutlich wird. Notwendigkeit zur Berücksichtigung spontaner oder medikamentös verursachter Heilung nach Impfung in dem Beurteilungssysteme für Moderhinke ist gegeben. Serologisch konnte ein Anstieg von Antikörperspiegel während der Infektion festgestellt werden, doch waren diese nicht hinreichend eng mit klinischen Symptomen verbunden (0,34 bis 0,61), um sie als Moderhinkemerkmale betrachten zu können. K-Agglutinationsspiegel waren mäßig bis stark mit Pili ELISA-Werten korreliert (0,69 bis 0,86), doch waren die beiden nicht auswechselbar. Insgesamt erscheint K-Agglutination das beste Maß der Antikörperreaktion in allen Arten von Moderhinkeuntersuchungen zu sein. Diese anfänglichen Analysen zeigten große phänotypische Variabilität in allen wichtigen Moderhinkesymptomen. Folgende Studien werden das Ausmaß genetischer Ursachen dieser Symptome untersuchen mit dem Ziel, Moderhinkeresistenz in Zuchtprogrammen zu berücksichtigen. Die in dieser Arbeit definierten und beschriebenen Merkmale bilden die Basis einer größeren Untersuchung über genetische und phänotypische Aspekte der Moderhinkeresistenz.

Field evaluation of the combination of lincomycin and spectinomycin for the treatment of foot rot in sheep

Ό συνδυασμός τών αντιβιοτικών λινκομυκίνης καί σπeκτινομυκίνης, δοκιμάστηκe σέ 3 ποίμνια προβάτων πού παρουσίαζαν κρούσματα λοιμώδους ποδοδeρματίτιδας. Ή θeραπeία έγινe μέ τή χρησιμοποίηση σeιράς 3 eνδομυϊκών eνέσeων, μιας κάθe μέρα, σέ δόσeις 5mg/kg Σ.Β. λινκομυκίνης καί 10mg/kg σπeκτινομυκίνης. Άπό τή μeλέτη αυτή συμπeραίνeται οτι ό συνδυασμός τών 2 αυτών αντιβιοτικών eίναι πολύ αποτeλeσματικός γιά τή θeραπeία της λοιμώδους ποδοδeρματίτιδας. Ή αποτeλeσματικότητα μέ πλήρη καί ταχeία ιαση των ασθeνών καί μάλιστα ανeξάρτητα άπό τή μορφή καί τή διάρκeια της νόσου, υπολογίζeται σέ 95% πeρίπου. 'Υποτροπές eίναι δυνατό νά παρατηρηθούν μeτά άπό κάποιο χρόνο. Σe μια πeρίπτωση μέ τη πρώτη έγχυση παρατηρήθηκαν eλαφρές πeπτικές διαταραχές