Fertilizer-induced pathogenicity of mycorrhizal fungi to sweetgum seedlings

One isolate of Glomus clarus, two of G. etunicatus, and one of G. claroideum, obtained from plants growing on abandoned stripmine sites in Kentucky, and an isolate of G. fascicutatus known to stimulate growth of various woody plants, were evaluated for their influence on growth of sweetgum seedlings in a mixture of sand and stripmine soil. Soils were supplemented with various rates of a complete slow-release fertilizer. Throughout the growth period, G. fasciculatus, and most of the stripmine isolates, stimulated growth at low fertilizer rates. At higher fertilizer rates, including the level optimum for non-mycorrhizal plants, the stripmine isolates inhibited plant growth. After 14 weeks, plants inoculated with one of the four stripmine isolates overcame the early growth depression, and those inoculated with a second isolate appeared to be overcoming the growth depression. G. fasciculatus was not inhibitory at any fertilizer rate. Root colonization by all three isolates evaluated was inhibited by the highest fertilizer rate, but this effect was not related to growth inhibition of plants. The other two isolates colonized roots at an extremely low rate (< 1%). Sporulation of all the stripmine isolates, but not G. fasciculatus, was also inhibited by the highest fertilizer rate. The G. fasciculalus isolate used in this study may be atypical of mycorrhizal fungi occurring randomly in nature in its mutualistic or neutral effect on plants under a wide range of growth conditions.     

A mycorrhizal pathogen (Glomus macrocarpum Tul. & Tul.) of tobacco: effects of long- and short-term cropping on the mycorrhizal fungal community and stunt disease

A crop rotation experiment was conducted on two adjacent tracts of land differing in long-term croppin history (30 year in tall fescue pasture or 3 year in sorghum-sudangrass hybrid (SSGH).. Short-term crops were 2 years in tobacco or low-endophyte (Acremonium coenophialum Morgan-Jones & Gams) tall fescue. Tobacco was grown on all plots in Year 3, and data relating mycorrhizal stunt disease of tobacco and populations of the stunt pathogen, Glomus macrocarpum Tul. & Tul., and of other members of the mycorrhizal fungal community, were taken. Disease incidence was highest with SSGH-tobacco and lowest with fescue-fescue, the other two combinations being intermediate. Mycorrhizal colonization was related to disease occurence. At the beginning of the season, populations of G. macrocarpum were equally high in land with a long-term history of SSGH, regardless of its short-term history; but at the end of the season, populations of G. macrocarpum among the four treatments were proportional to the incidence of disease. Populations of four mycorrhizal fungal species which were high in land with a short-term history of fescue were depressed by production of tobacco. Monocropping of tobacco appeared to narrow the diversity of the mycorrhizal fungal community and increased the proportion which is pathogenic, the overall result being lower productivity of soil for tobacco. Crop rotation of tobacco with fescue decreased the proportion of the mycorrhizal fungal community which is pathogenic and maintained productivity of soil for tobacco.     

Fertility-mycorrhizal-isolate interactions in production of containerized pin oak seedlings

Slow-release fertilizer rates (0, 1.1 and 4.5 kg/m³ of 14 N-6 P-11.6 K Osmocote) and isolates of the ectomycorrhizal fungus Pisolithus tinctorius (Pers.) Coker and Couch affected growth and mycorrhizal development on pin oak (Quercus palustris Meunchh.) seedlings. Mycorrhizae developed on all inoculated seedlings after 8 weeks regardless of fertility regime. Through the first 14 weeks, the best mycorrhizal development occurred on all inoculated seedlings fertilized at the lower fertilizer rate. The higher fertilizer rate delayed mycorrhizal development. However, after 18 weeks there were no significant differences in mycorrhizae on inoculated seedlings receiving fertilizer. Inoculated, non-fertilized seedlings had significantly less mycorrhizae than fertilized seedlings throughout the experiment. Only one isolate increased seedling growth, and only at the higher fertilizer rate. No differences in plant height were found among non-inoculated control and inoculated seedlings at the low fertilizer rate.     

Protection of lambs with a purified metabolite of exsheathed third-stage Haemonchus contortus larvae

Helminth-free lambs (approx 4 months old) were inoculated SC with a purified metabolite of exsheathed third-stage Haemonchus contortus larvae. The metabolite was obtained from in vitro cultivation and was identified as XL3FA1. After 3 periodic XL3FA1 inoculations, lambs were challenge exposed with H contortus. Multiple vaccinations with XL3FA1 did not inhibit the development of worm populations in the lambs; however, worm egg production seemed to be inhibited.     

Comparison of postoperative pain after ovariohysterectomy by harmonic scalpel-assisted laparoscopy compared with median celiotomy and ligation in dogs

OBJECTIVE: To compare the effects of postoperative pain after ovariohysterectomy by harmonic scalpel-assisted laparoscopy (HALO) and traditional ovariohysterectomy (OVH) in dogs. STUDY DESIGN: A randomized, blinded, prospective study. SAMPLE POPULATION: Sixteen, purpose-bred, intact female, Beagle dogs. METHODS: Dogs were divided into 2 groups: Group 1 (8 dogs), which had OVH by HALO, and Group 2 (8 dogs), which had traditional OVH. Physiologic data, abdominal nociceptive threshold scores, and University of Melbourne pain scores (UMPS) were recorded at 2, 6, 12, 24, 48, and 72 hours after surgery. Blood samples for measurement of plasma cortisol, glucose, and creatine phosphokinase (CPK) concentrations were collected at the time of the incision, and 2, 6, 12, 24, 48, and 72 hours after surgery. RESULTS: No significant surgical complications occurred. The HALO mean surgical time was significantly longer (55.7 minutes) than traditional OVH (31.7 minutes). No significant differences were observed between groups for the pain measures of heart rate, respiratory rate, temperature, CPK, and glucose concentrations. The OVH group had significantly higher mean plasma cortisol levels at hour 2 after surgery than the HALO group (P=.0001). The mean UMPS were significantly higher in OVH than the HALO group at all postoperative times (P=.0001). The mean nociceptive threshold measurements revealed significantly higher tolerated palpation pressures in HALO than OVH at all postoperative times, except hour 72 (P=.0002). CONCLUSIONS: Dogs appeared to be in less pain with HALO than OVH. The harmonic scalpel coagulated ovarian and uterine vessels completely with minimal collateral damage to surrounding tissues. CLINICAL RELEVANCE: HALO is a safe alternative to OVH and offers a minimally invasive and less painful method of surgery.     

Outcomes of dogs presented for cataract evaluation: a retrospective study

Two hundred and forty-four dogs were evaluated for cataracts at the University of Tennessee from January 2001 to December 2002. Fifty-four canine breeds were affected. Odds ratios for cataracts were significantly higher for six purebred dogs (including the cocker spaniel, miniature schnauzer, toy poodle, Boston terrier, miniature poodle, and bichon frise) compared with mixed-breed dogs. One hundred fifty-nine dogs did not have cataract surgery. The most common reason for dogs not having surgery was retinal degeneration (n=66).     

Diagnosis of chronic active hepatitis in a miniature schnauzer

A 12-year-old male castrated miniature schnauzer was presented with a history of abdominal distension. Serum biochemical analysis and abdominal ultrasonography indicated hepatic disease. A wedge biopsy provided a diagnosis of chronic active hepatitis. A therapeutic regime was initiated to improve the quality of life and slow the progression of this disease is described.