Spider mite webbing. Part IV: The effect of acaricides on spinning by the carmine spider mite Tetranychus cinnabarinus (boisduval)

Cyhexatin, dienochlor and four experimental acaricides, U-25322 (1-benzoyl-3-phenylhydrazine), U-27415 1-benzoyl-3-(2, 4, 6-trichlorophenyl)hydrazine, U-42558 [N¹(4-chloro-o-tolyl) N²-methyl-N¹-(phenylthio)formamidine], and U-42564 [N²-methyl-N¹-(phenylthio)- N¹-(2, 4-xylyl)formamidine], at 125 mg litre-¹, induced spindown by the carmine spider mite, Tetranychus cinnabarinus (Boisduval). Cyhexatin caused the largest number of mites to spin-down, dienochlor the least. Spinning occurred only during the first 6 h after treatment. Mites spun the same average length of threads in response to all compounds. The pattern of spin-down was even and similar for all the compounds except dienochlor for which it was sporadic. Acaricide-induced spin-down is postulated to be an ‘all-or-nothing’ reaction.     

Development of crown and root rot disease of tomato under irrigation with saline water

ABSTRACT We studied the effect of water salinity on the incidence and severity of crown and root rot disease of tomato, as well as on the pathogen and on the plant's response to the pathogen. Irrigation with saline water significantly increased disease severity in tomato transplants inoculated with Fusarium oxysporum f. sp. radicis-lycopersici, and mineral fertilization further increased it. In one field experiment, disease incidence in plots irrigated with saline water (electrical conductivity [EC] = 3.2 +/- 0.1 dS m(-1)) and in those irrigated with fresh water (EC = 0.4 +/- 0.1 dS m(-1)) was 75 and 38%, respectively. Disease onset was earlier and yield was lower in plots irrigated with saline water. In a second field experiment, final disease incidence 250 days after planting, was 12% in plants which had been irrigated with saline water (EC = 4.6 +/- 0.1 dS m(-1)) and 4% in those irrigated with fresh water (EC = 1.2 +/- 0.1 dS m(-1)). Irrigation of tomato transplants with 20 mM NaCl did not inhibit plant development, but partial inhibition was observed at higher NaCl concentrations. Growth of the pathogen in culture or survival of conidia added to soil were not affected by saline water. Plants which were preirrigated with saline water were more severely diseased than those preirrigated with tap water. It was concluded that disease increases effected by saline water are associated with the latter's effect on plant response.     

Sensitivity analysis of optimal operation of irrigation supply systems with water quality considerations

A model for optimal operation of water supply/irrigation systems of various water quality sources, with treatment plants, multiple water quality conservative factors, and dilution junctions is presented. The objective function includes water cost at the sources, water conveyance costs which account for the hydraulics of the network indirectly, water treatment cost, and yield reduction costs of irrigated crops due to irrigation with poor quality water. The model can be used for systems with supply by canals as well as pipes, which serve both drinking water demands of urban/rural consumers and field irrigation requirements. The general nonlinear optimization problem has been simplified by decomposing it to a problem with linear constraints and nonlinear objective function. This problem is solved using the projected gradient method. The method is demonstrated for a regional water supply system in southern Israel that contains 39 pipes, 37 nodes, 11 sources, 10 agricultural consumers, and 4 domestic consumers. The optimal operation solution is described by discharge and salinity values for all pipes of the network. Sensitivity of the optimal solution to changes in the parameters is examined. The solution was found to be sensitive to the upper limit on drinking water quality, with total cost being reduced by 5% as the upper limit increases from 260 to 600 mg Cl l^–1. The effect of income from unit crop yield is more pronounced. An increase of income by a factor of 20 results in an increase of the total cost by a factor of 3, thus encouraging more use of fresh water as long as the marginal cost of water supply is smaller than the marginal decrease in yield loss. The effect of conveyance cost becomes more pronounced as its cost increases. An increase by a factor of 100 results in an increase of the total cost by about 14%. The network studied has a long pipe that connects two distinct parts of the network and permits the supply of fresh water from one part to the other. Increasing the maximum permitted discharge in this pipe from 0 to 200 m³ h^–1 reduces the total cost by 11%. Increasing the maximum discharge at one of the sources from 90 to 300 m³ h^–1 reduces the total cost by about 8%.     

The effect of farming practices on reducing excess nitrogen fertilizer use

A nitrogen balance model is used to investigate the adoption of a crop rotation and the limitation on the application of nitrogen fertilizer to reduce excess nitrogen. For a farmer initially planting corn continuously, the adoption of a soybeans-corn rotation will have a smaller compliance cost but it will not eliminate the excess application of nitrogen fertilizer under a relatively low nitrogen fertilizer to corn price ratio. An explicit limitation on nitrogen fertilizer use would be needed to achieve this objective. Limiting nitrogen fertilizer use on cropland susceptible to a high potential for leaching will have a smaller compliance cost than on cropland with a moderate potential for leaching.     

Efficient near-infrared polymer nanocrystal light-emitting diodes

Conjugated polymers and indium arsenide-based nanocrystals were used to create near-infrared plastic light-emitting diodes. Emission was tunable from 1 to 1.3 micrometers--a range that effectively covers the short-wavelength telecommunications band--by means of the quantum confinement effects in the nanocrystals. The external efficiency value (photons out divided by electrons in) is approximately 0.5% (that is, >1% internal) and is mainly limited by device architecture. The near-infrared emission did not overlap the charge-induced absorption bands of the polymer.     

RADIOGRAPHIC CHANGES IN TESTES OF BULLS INFECTED WITH BESNOITIOSIS

Ten beef bulls infected with Besnoitiosis were examined radiographically and pathologically. Eight of these were slaughtered soon after diagnosis; two were left for a six-month observation period. The radiographic findings were focal and branching-tree calcification of the testes. Histopathologic examination proved these calcifications to be necrotic sections of the seminiferous tubules. Radiography of the testes as a means of evaluating the fertility status of the infected bull is recommended.     

MULTIPLE CONGENITAL URINARY TRACT ABNORMALITIES IN A BITCH: A CASE HISTORY REPORT

A 2 1/2-month-old, female German Shepherd Dog was examined because of incontinence since birth. Multiple urinary anomalies which included left renal agenesis, right hydronephrosis and hydroureter and urinary bladder dysfunction were found by excretory urography. These abnormalities were confirmed at necropsy. In addition, vesicovaginal continuity with apparent absence of the urethra was also found     

The effect of potassium on yield,nutrient uptake and efficiency of teff (Eragrostis tef Zucc. Trotter) on vertisols of North Western Ethiopian Highlands

Vertisols are characterized by deficiency of nutrients and recently, potassium (K), a major plant nutrient in crops, is gaining attention because of crop removal, fixation by clay minerals and leaching. A field experiment was conducted during the 2015 and 2016 main cropping seasons to test the effect of potash fertilizer on Vertisols of East Gojjam at Gudalima and Dejen/Tik sites using teff crop. The K rates (applied as muriate of potash) were 0, 50,100, and 150?kg ha^?1. The experiment was laid out in a randomized complete block design in three replications. The results indicated that the plant height, panicle length, number of effective tillers, dry matter and grain yield of teff increased significantly (P?<?0.05) with applied K. The highest dry matter and grain yield (6966.4 and 2418.2 kg ha^?1, respectively) were obtained from the application of 100 kg ha^?1 KCl. Total uptake of N, P, and K were enhanced significantly with K treated plots than those without and K efficiency was improved due to the rate of K. The present study demonstrated the importance of K application to supplement NPS for optimum dry matter and grain yield of teff on Vertisols of the study sites.