On the spatial distribution of citrus tristeza virus disease

The spatial spread of citrus tristeza virus (CTV) disease was studied using data from two infected groves. Statistical analysis indicated a spatial grouping of infected trees. A gamma distribution was fitted to the empirical distribution of the distances between nearest infected neighbors. The findings suggest that, after locating a newly infected tree, additional inspections to detect CTV should be carried out mainly on trees within 14 m of that tree.     

Correlations of stomatal conductance with hydraulic, chemical and environmental variables in five urban tree species

Recent findings suggest that stomatal conductance (g_s) may be as closely linked to plant chemical variables as to hydraulic variables. To test this in an urban field setting, we examined seasonal g_s in relation to a number of plant and environmental variables in five temperate, deciduous tree species. Stomatal conductance was generally more closely correlated with abscisic acid concentrations in xylem sap than with shoot water potential, shoot osmotic potential, pH of xylem sap or environmental variables. Seasonal g_s was mostly poorly correlated with shoot water potential and osmotic potential. Among environmental variables, PPFD accounted for most variability in g_s. We tested a model, developed previously in maize, that describes regulation of g_s by abscisic acid concentration of xylem sap with leaf water status acting to modify stomatal sensitivity to the abscisic acid signal. This model explained somewhat more variation in g_s than abscisic acid concentrations alone. Response surface models, especially those incorporating environmental variables, were most successful at explaining g_s. Our findings with urban trees are consistent with the theory of regulation of g_s by root-sourced abscisic acid.     

Diphenhydramine Intoxication in a Dog1

We report a case of diphenhydramine intoxication in a dog. A five month old intact male Labrador Retriever was presented after ingesting approximately 36 diphenhydramine tablets (50 mg/tablet; approximate ingested dose of 1800 mg or 67 mg/kg). Physical examination findings included severe ataxia, profound disorientation, severe continuous spastic muscle tremors, hyperthermia, tachycardia, tachypnea, and hyperesthesia. The dog was unresponsive to intravenous diazepam and phenobarbital, but rapidly responded to an intravenous bolus and subsequent continuous infusion of guaifenesin and supportive fluid therapy. The serum diphenhydramine level on admission was 537 ng/ml. The toxic level is not reported for dogs, but is considered>60 ng/ml in people. The dog was discharged 24 hours after admission with no apparent residual effects.     

Necropsy of adult cattle

This article presents a brief overview of some examination techniques commonly used during necropsy of adult cattle. A few common diseases and their typical lesions are described and appropriate laboratory techniques to confirm or help deny the roles of specific agents are mentioned.     

Efficacy of topically applied ivermectin against Boophilus microplus (Canestrini, 1887) in cattle

Systemic efficacy of ivermectin applied topically was evaluated against the cattle tick, Boophilus microplus. Twenty cattle with induced infestations were randomly allocated to five groups of equal size based on the numbers of engorged female ticks which fell through the slatted floor of individual pens during the 3 days prior to treatments. Control cattle were non-medicated. Cattle in three groups were given ivermectin at 200, 500 or 1000 mcg kg-1 in a topical formulation applied along the backline from the withers to the rump; cattle in the fifth group were given ivermectin in an injectable formulation subcutaneously at 200 mcg kg-1. Individual 24-h tick collections were made three times weekly for 5 weeks after treatment. Engorged female B. microplus were incubated to determine effects on reproduction. Based on the numbers of engorged female B. microplus collected following treatments, overall efficacy of ivermectin applied topically at 200, 500 and 1000 mcg kg-1 was 50, 85 and 91%, respectively, whereas ivermectin given at 200 mcg kg-1 subcutaneously was 80% effective. The index of reproduction for ivermectin given topically was reduced by 84, 94 and 95%, respectively, and that for ivermectin subcutaneously was 94%. No significant differences (P greater than 0.05) were found for these variables between ivermectin given topically at 500 or 1000 mcg kg-1 versus 200 mcg kg-1 given subcutaneously.     

Effect of water content and storage temperature of gladiolus corms on flowering

Flowering of Gladiolus grandiflorus was affected by the previous growing conditions and post-harvest handling of the corms. Reducing the storage temperature of the May-harvested corms from 33 to 5 °C caused severe decreases in flowering, whereas a similar treatment given to July- or September-harvested corms did not reduce flowering. A 10% reduction in water content of summer-harvested corms immediately after digging had no deleterious effect on flowering.