FACTORS RESPONSIBLE FOR THE TOLERANCE OF BLACKCURRANTS TO SIMAZINE

Summary. Evidence is presented that blackcurrants show a considerable tolerance to simazine when the entire root system is exposed to a uniform concentration of the herbicide in sand and water culture. The tolerance of this species under field conditions does not therefore seem to be primarily due to root development being limited in the surface soil to which simazine is applied. Accordingly, experiments were carried out using simazine, labelled in the ring with ¹⁴C, to determine whether there were restrictions to the uptake of the herbicide by the roots and its translocation to the xylem sap and leaves, and whether there was extensive breakdown of simazine in the plant. The results of these experiments are compared with those on two susceptible species, barley and marrow.
Although simazine appeared to be metabolized to a greater extent in blackcurrants, and was less readily translocated from the roots, than in the susceptible species, a substantial proportion of the labelled material in the leaves was present as unchanged simazine. Studies on the effects of simazine on the rate of transpiration of detached leaves of the three species suggested that in blackcurrants there was a restriction to movement of the herbicide from the conducting tissue in the leaves to the mesophyll; this was confirmed by autoradiographs. It is suggested that this restriction, combined with partial breakdown of the herbicide in the leaves, may be responsible for the tolerance of blackcurrants to simazine.
Résistance du cassissier à la simazine     

Assessment of perceived farming risks,communication of risk management practices,and evaluation of their efficiency in Pacific white shrimp (Penaeus vannamei) farming—a survey-based cross-sectional study

Aquaculture International - Pacific white shrimp (Penaeus vannamei) farming is an important commercial aquaculture production system contributing substantially to the economic and societal...     

SnakeMap: four years of experience with a national small animal snake envenomation registry

SnakeMap is a national cloud-based, veterinary snakebite registry. It was designed to prospectively collect data of the clinical circumstances and temporospatial information on cases of snake envenomation in dogs and cats. We herein introduce the project and summarise the data from the first 4 years of SnakeMap. The registry is a veterinary community-based online database allowing case entry from veterinary hospitals across Australia. Registry data comprise hospital characteristics, patient characteristics, envenoming snake type, treatment and outcome variables, including time and geolocation of the snake bite. We present summative information on select key variables from the SnakeMap registry (1 July 2015 to 30 June 2019). Twenty-eight hospitals from 6 states/territories entered 624 cases into the registry, including 419 dogs (67%) and 205 cats (33%). Bite time was available in 216 animals of which 90 (42%) were reported to be bitten in the 3 hours between 03:00 pm and 05:59 pm; median bite to presentation interval was 60 (interquartile range [IQR] 30, 211) minutes in dogs and 95 (IQR 41, 238) minutes in cats. Bites occurred in the owner's yard in 356 dogs (85%) and 53 cats (26%). A snake venom detection kit was used in 172 cases (28%) and antivenom was administered in 523 cases (85%). Most animals (n = 534, 88%) survived to discharge (median hospitalisation of 25 [IQR 16, 62] hours). SnakeMap effectively collects relevant clinical data from dogs and cats with presumed snake bite and provides locally specific information on the epidemiology of snake envenomation in small animals.     

Vitamin D-dependent rickets in a Saint Bernard dog

Rickets diagnosed in a 12-week-old female St Bernard was attributed to an inborn error in vitamin D metabolism. Radiographically the physes were enlarged radially and axially, and metaphyseal bone adjacent to the physes was widened and cup-shaped. Serum biochemical abnormalities were hypocalcaemia, hypomagnesaemia, and hyperparathyroidism. Treatment was given with dihydrotachysterol, a synthetic sterol that is metabolised to a pharmacologically active analogue of 1,25 dihydroxycholecalciferol by the liver. This resolved the rachitic skeletal lesions completely in six weeks, as assessed radiographically, and maintained the serum calcium at the lower end of the normal range.     

Use of tilmicosin in a severe outbreak of respiratory disease in weaned beef calves

Severe respiratory disease, associated with seroconversion to bovine respiratory syncitial virus (BRSV), caused the death of two cattle and necessitated antibiotic treatment of 70 calves (rectal temperature of 39.6°C or greater) from a group of 96 (73%) during an 8-day period. Tilmicosin injection resulted in a reduction in median rectal temperature from 40.3°C to 39.2°C and 39.0°C for the first and second days after treatment. The rectal temperature was 39.5°C or lower in 72% (48 of 67) and 96% (64 of 67) of cattle 1 and 2 days after tilmicosin treatment, respectively. Ten cattle were re-treated with tilmicosin 6 to 16 days after the first treatment. Our study demonstrated that bovine respiratory syncytial virus infection could cause severe respiratory disease in a beef herd that had no previous history of BRSV-related disease. Secondary bacterial invasion after BRSV infection was controlled effectively by tilmicosin treatment but repeat antibiotic treatments were occasionally necessary due to bacterial re-infection of the respiratory tract.     

Control of clinical paratuberculosis in New Zealand pastoral livestock

This review summarises current control measures for clinical paratuberculosis (Johne’s disease; JD) in New Zealand pastoral livestock. Most New Zealand sheep, deer, beef and dairy cattle herds and flocks are infected by Mycobacterium avium ssp. paratuberculosis (Map). Dairy cattle and deer are mostly infected with bovine (Type II), and sheep and beef cattle with ovine (Type I) strains. Control in all industries is voluntary. While control in sheep and beef cattle is ad hoc, the dairy and deer industries have developed resources to assist development of farm-specific programmes.

The primary target for all livestock is reduction of the incidence rate of clinical disease rather than bacterial eradication per se. For dairy farms, a nationally instituted JD-specific programme provides guidelines for risk management, monitoring and testing clinically suspect animals. While there is no formal programme for sheep farms, for those with annual prevalences of clinical disease >2%, especially fine wool breeds, vaccination may be a cost effective control option. The deer industry proactively monitors infection by a national abattoir surveillance programme and farmers with an apparent high disease incidence are encouraged to engage with a national network of trained consultants for management and control advice. Evaluation of the biological and economic effectiveness of control in all industries remains to be undertaken. Nevertheless, opportunities exist for farmers, who perceive significant JD problems in their herds/flocks, to participate in systematic best-practice activities that are likely to reduce the number of clinical infections with Map on their farms, and therefore the overall prevalence of JD in New Zealand’s farming industries.     

Infection of oats and other cereals by oat chlorotic stunt virus in the field and laboratory

During 1992/1993 and 1994/1995, field experiments were carried out to investigate the infection of several cultivars of oats, other cereals and grasses, with oat chlorotic stunt virus (OCSV), which is provisionally identified as a member of the Tombusviridae . Under field conditions a high percentage of oat plants became infected when sown in infested soil and there was little difference in susceptibility between the oat cultivars compared. Although plants of other Poaceae such as winter wheat, winter barley and annual meadow grass also became infected, the percentage was low and the virus titre reached was much lower than in oats. In most infected plants the virus was localized within the roots, and only in a few plants did it spread systemically. This suggests that the virus was acquired through the roots, indicating further similarities between OCSV and members of the Tombusviridae . Several cereals, including oats, wheat, barley and maize, were infected by mechanical inoculation using an embryo-wounding technique; in the majority of cases virus infection only reached a low titre.     

Potassium and magnesium in some Kenyan soils: their mineral sources and release to Ca-resin

Five soil types from Kenya were examined for their ability to release K and Mg to crops by extracting them with a calcium-saturated cation exchange resin, and for the mineral sources of K and Mg. Amounts and rates of release of exchangeable, short- and long-term reserves of K and Mg were determined. This was done for K before and after one, two and 10 wetting and drying (WD) cycles, designed to mimic the effect of the local climate on K release. The order of decreasing K and Mg contents of the soils was Muguga > > Katumani > Kampi-ya-Mawe (KYM) ∼ Ithookwe ∼ Kwale. In the case of K, wetting and drying increased the exchangeable fraction in all of the soils. The Muguga, Ithookwe and KYM soils have the capacity to release a great deal of K in the long-term, but at very different rates; the Kwale soil has few reserves and fixes K on WD.
The K and Mg contents of the soils were closely related to the mica contents of the clay + silt fractions. Exchangeable and non-exchangeable K was released from soil micas primarily by ion exchange, with some contribution to non-exchangeable K from dissolution. Release of exchangeable Mg was primarily by ion exchange, whilst that of non-exchangeable matrix Mg was by dissolution of trioctahedral mica in the clay + silt and the sand fractions of the soils. Response would be expected only to K fertilizers and only with the Kwale soil. However, all the other soils should, in the interests of good husbandry, receive maintenance dressings of K and Mg at convenient times in the crop rotation.