Effect of temperature and water variables on the juvenile growth of lucerne and red clover

Plants of three cultivars of lucerne ( Medicago sativa L.) and of red clover ( Trifolium pratense L.) were grown at four levels each of water availability and temperature in all combinations to evaluate these factors as determinants of plant growth. Plants grew in conventional plant growth chambers from age 2 to 4 weeks with the roots held between layers of polyester cloths that held a volume of nutrient solution which was adjusted at 24-h intervals by flushing and blotting the cloths. The experimental design consisted of two growth chamber runs at each of four temperatures. Within each run, water treatments and the species-cultivar combination were arranged In four replicates of a split-plot design with water treatment as whole plot and species-cultivars as subplots.
Plant response variables over all treatments were significant (P < 0·05) for temperature and water for shoot weights, root weights, shoot/root ratios and number of roots. Cultivars within species had no significant difference in response lo the treatments, but species differences were significant for alt response variables except shoot/root ratio.     

Competition among seedlings of phalaris, subterranean clover and white clover in diallel replacement series mixtures

Phalaris, subterranean clover and white clover were grown together in binary, diallel replacement series mixtures at (day/night) 15/10 or 24/19°C under long-day conditions, and cut at 2- or 4-weekly intervals. Analysis of white clover mixtures was confined to 15/10°C due to losses of seedlings prior to imposition of treatments at 24/19°C.
With white clover at 15/10°X, seedling losses occurred after the first harvest, the greater losses occurring in mixtures where subterranean clover was the major component. The de Wit analyses showed that subterranean clover excluded its companions, whereas phalaris and white clover competed for slightly different niches resulting in over-yielding. Gleeson McGilchrist analyses showed that subterranean clover and phalaris were more aggressive than white clover under infrequent cutting, but that white clover was more aggressive as a major than as a minor component of a mixture under frequent cutting. Between phalaris and subterranean clover [he pattern of competition at 24/19°C differed from that at 15/10°C only in the more rapid development of subterranean clover and consequent swing to phalaris dominance.
We conclude that the seedlings of white clover and subterranean clover are suited to combination with phalaris because phalaris is not too aggressive towards white clover, and is tolerant of the aggressiveness of subterranean clover. The survival of only a few seedlings of white clover in mixtures with subterranean clover may be sufficient for long-term growth provided some perennation occurs after the senescence of subterranean clover.     

Mycotic dermatitis with digital gangrene and osteomyelitis,and protozoal intestinal parasitism in Marlborough green geckos (Naultinus manukanus)

CASE HISTORY: Thirty adult Marlborough green geckos (Naultinus manukanus) were collected from Stephens Island and held over winter, prior to their translocation. Five adult geckos developed skin lesions after husbandry changes affected the humidity of their enclosures. Two geckos underwent ecdysis and recovered. One animal died and two others progressively worsened and were presented for treatment.

CLINICAL AND PATHOLOGICAL FINDINGS: The geckos were in poor body condition and had multiple black powdery lesions and solitary raised white nodules on their skin. Both geckos died despite topical and supportive treatment. Histopathology showed the skin nodules contained branching non-septate hyphae infiltrating necrotic epidermal tissue, and associated dermal inflammation. There was necrosis of several digits and mycotic osteomyelitis. Mucor ramosissimus was cultured from skin biopsies from each animal. Large numbers of motile protozoa, resembling Trichomonas, and another unidentifiable, were recovered from fresh faecal smears, and Nyctotherus sp protozoa were present in the lumen of the intestine of one animal post mortem.

DIAGNOSIS: Mycotic dermatitis with digital gangrene and osteomyelitis due to Mucor ramosissimus, and enteric protozoal parasitism with Trichomonas sp and Nyctotherus sp.

CLINICAL RELEVANCE: The clinical course and pathological findings of mycotic dermatitis in two Marlborough green geckos involved in a wildlife translocation in New Zealand are reported, and also the first record of the Marlborough green gecko as a host for the enteric protozoa Trichomonas sp and Nyctotherus sp.     

The incidence of mycoplasma in pet and colony maintained cats

Previous information on the incidence of feline mycoplasma is reviewed, and the results recorded of an attempt to isolate mycoplasma from the throats and conjunctiva of 254 cats, 237 of which were from three unrelated cat colonies, and seventeen of which were household pets. The animals examined varied in age from a few hours to 15 years. Mycoplama felis and M. gatae were commonly recovered, and over 80 % of adult cats were found to be infected. Analysis of these results and examinations post-mortem of fifteen kittens and young cats failed to reveal any evidence that either organism was associated with clinical disease. Résumé. Les données existantes sur l'incidence du mycoplasme félin ont été examinées et on a enregistré les résultats d'une tentative d'isoler le mycoplasme de la gorge et des conjonctives de 254 chats dont 237 venaient de trois colonies félines sans rapports entre elles et dont 17 étaient des animaw domestiques. Les animaux examints Ctaient d'âges différents, allant de quelques heures à 15 ans. Les Mycoplame felis et M. gatne ont été souvent retrouvés et on constata que plus de 80% des chats adultes étaient infectés. L'analyse de ces résultats et les autopsies de quinze chatons n'ont pu révéler aucun signe indiquant que l'un ou l'autre de ces organismes soit lié à une maladie clinique. Zusammenfassung. Es wird eine Übersicht über frühere Informationen über die Häufigkeit von Mycoplasma bei der Katze geliefert und das Ergebnis eines Versuchs mitgeteilt, Mycoplasma aus Schlund und Bindehaut von 254 Katzen zu isolieren, von denen 237 aus drei nicht zusam-menhängenden Katzenkolonien stammten und 17 Katzen Haustiere waren. Das Alter der untersuchen Tiere lag zwischen wenigen Stunden und 15 Jahren. Mycoplasma felis und M. gatae wurden allgemein gefunden, und es stellte sich heraus, dass über 80% der erwachsenen Katzen infiziert waren. Die Analyse dieser Ergebnisse und die Autopsie von 15 jungen und sehr jungen Katzen lieferte keinerlei Anhaltspunkte, dass einer der Organismen mit klinischen Erkrankungen im Zusammenhang stand.     

The effect of methyl bromide fumigation on rhizomania inoculum in the field

The first outbreak of rhizomania disease in the UK occurred in 1987 and was limited to a single sugar-beet crop in Suffolk. In an attempt to prevent the spread of this disease, the crop was first destroyed by herbicide. In 1988, to reduce the level of rhizomania still present in the soil, the field was treated with methyl bromide at a rate of 900 kg/ha prior to seeding for permanent pasture. Levels of methyl bromide were monitored during the fumigation. A mean concentration time product of 5500 mgh/1 was achieved after 72 h at the soil surface and of 3300-4100 mg-h/1 at a soil depth of 0.3 m after 24 h. Soil samples were taken from five plots across the field before and after fumigation. In the plot with the highest initial inoculum levels, further samples were taken at three depths down to 0.61 m. Sugar-beet seedlings were grown in all soil samples as a bait test for rhizomania inoculum. The presence or absence of Polymyxa betae was observed by microscopical examination, and an enzyme-linked immunoassay was used for the detection of beet necrotic yellow vein virus (BNYVV). The results showed that the methyl bromide treatment had reduced rhizomania inoculum and BNYVV in the soil to levels that were undetectable by the procedures used.     

Phenotypic plasticity of Ammannia spp. in competition with rice

The annual broadleaved weeds Ammannia auriculata Wild, and A. coccinea Rottb. are widespread and competitive in California rice ( Oryza sativa L.) fields. We studied Ammannia spp. biology in a greenhouse pot experiment. Weeds were grown alone and in competition with rice (cv. M–202), and harvested six times over 122 days. Compared with growth alone, competition reduced Ammannia spp. total plant dry weight (DW), shoot DW and leaf area in all but the first harvest. However, weed height differed at only one harvest (85 days after planting). Ammannia spp. responded to competition with increased shoot:root DW ratios, increased stem:other shoot DW ratios, decreased stem diameters, fewer but elongated internodes and fewer branches. This suggests that light capture was more important than nutrient capture for maintaining Ammannia spp. growth. The weeds appear to lodge easily in rice fields because competitive growth responses make them top heavy and unstable. Weed seed DW declined by 97% in competition, which showed the importance of crop interference to Ammannia spp. control. Plasticity may help Ammannia spp. to escape common control practices (e.g. high crop plant densities or early herbicide application), and probably contributes to its widespread distribution. Thus, Ammannia spp. plasticity should be more fully considered when designing management strategies.     

Sugarbeet rhizomania in England1

Concern about the introduction of rhizomania to UK heightened when the disease was confirmed in The Netherlands in 1983. A series of precautionary measures supported by legislation was quickly enacted to reduce this risk. Extensive surveys of harvested beet and of growing crops failed to reveal any infection until 1987 when a single isolated outbreak was found near Bury St Edmunds in Suffolk. Plants in the affected field showed typical rhizomania symptoms and laboratory tests confirmed the presence of beet necrotic yellow vein furovirus (BNYVV). Further investigation of isolates from the outbreak field revealed the presence of beet soil-borne furovirus in addition to BNYVV and sometimes both were present in mixed infections. Intensive surveys in the immediate area of the outbreak, both by field inspections of growing crops and by soil bait testing, confirmed infection only in the one field and the margin of the adjacent field. Immediate containment measures were followed by soil sterilization with methyl bromide to minimize the movement of infection from the area. Surveys of beet will continue, but results to date suggest that the distribution of the disease is limited in extent.     

Growth, development and nutrient accumulation in Senecio vulgaris L. and Chenopodium album L.

Growth, development and nutrient accumula tion in Chenopodium album and Senecio vulgaris grown in pure and mixed stands were investi gated through several experiments conducted under glasshouse conditions. Results showed that the two weeds were different in their growth, development and tissue concentration and accu mulation of mineral elements. The mean concen trations of nitrogen, phosphorus, potassium, calcium and magnesium in shoots of C. album were higher than those of S. vulgaris, while root concentrations of nitrogen, potassium and mag nesium were lower for C. album. Marked dif ferences between the two weed species in their responses to different potassium levels were found. C. album had a high specific requirement for potassium while the reverse was true for S. vulgaris. The competitive ability and accumula tion of nutrients by C. album appeared to be greatly dependent on the availability of high potassium levels in the media.