A method for monitoringBemisia tabaci and timing spray applications against the pest in cotton fields in israel

A method for monitoring tobacco whitefly [Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae)] populations was developed and used for timing spray applications against this pest in cotton. It was found to be successful in tests in eight commercial cotton fields. A trap composed of a yellow plastic plate (15 × 20 cm) smeared on the upper side with a thin layer of glue, was attached to an iron pole which held the plate in a horizontal position above the plants. The traps were placed 400 m apart along the periphery of the field. The sticky plates were changed weekly and the adult whiteflies were counted. When the mean weekly catch per trap reached ~ 100–200 adults, spray applications were carried out. Following this treatment,B. tabaci populations remained low and sooty mould did not develop on the lint.     

Screening ofbacillus thuringiensis preparations for microbial control ofostrinia nubilalis in sweet corn

Bacillus thuringiensis Berliner (B.t.) preparations were bioassayed against larvae of the European corn borer,Ostrinia nubilalis Hübner, to determine their potency.B.t. serovar 3a3b,kurstaki (Dipel) was more potent thanB.t. serovar 1,thuringiensis (Bactospeine I);B.t. serovar 3a3b,kurstaki (Toarow CT) — in which the spores are inactive; or serovar 7,aizawai (ABG 6104). Another preparation of 3a3b,kurstaki (Bactospeine III), at concentrations of 0.5 and 1% sprayed on leaves of potted sweet corn seedlings and plants in the field, was active against larvae reared on an artificial diet in the laboratory. The pH of the corn leaf surface ranged from 6.9 to 7.5, before and after application.     

A Laboratory method for estimating survival of tobacco whitefly nymphs after insecticide treatment,based on honeydew excretion

A quick and easy method for estimating the number of surviving nymphs of the tobacco whitefly (TWF),Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), after spray applications was developed in the laboratory. The method is based on the number of honeydew droplets ejected by TWF immatures during 30 minutes. Since the nymphs ofB. tabaci feed on the lower leaf surfaces, the honeydew excreted falls downward. In this study infested cotton leaves were placed with their lower side up, forcing the nymphs to eject the honeydew droplet upwards. Inverted plastic petri dish covers were placed over infested cotton leaves and after 30 minutes the droplets deposited on the inner side of each cover were counted and the average number of droplets per nymph was calculated. To estimate the number of live nymphs on an infested cotton leaf, the number of droplets ejected during 30 minutes was divided by the average number of droplets per nymph (factor of 1.23).     

A comparison between mixed support kriging and block cokriging for modelling and combining spatial data with different support

Precision Agriculture - The paper proposes a geostatistical framework to solve the issues of heterogeneous support for spatial estimation. Apparent soil electrical conductivity (ECa) was measured...     

Honeydew staining techniques for estimating the live tobacco whitefly nymph population on cotton leaves

Techniques of staining the honeydew droplets excreted by nymphs of the tobacco whitefly,Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), were screened to select an effective means of estimating the number of nymphs on an infested cotton leaf. Indicators of pH and redox potential, absorbed on a cellulose acetate strip and on a water-sensitive paper (Ciba-Geigy), were used to stain the droplets. The water-sensitive paper provided the most practical means for rapid counting of the stained droplets for nymph estimation.     

Long‐Term Durum Wheat‐Based Cropping Systems Result in the Rapid Saturation of Soil Carbon in the Mediterranean Semi‐arid Environment

Climate, soil physical–chemical characteristics, land management, and carbon (C) input from crop residues greatly affect soil organic carbon (SOC) sequestration. According to the concept of SOC saturation, the ability of SOC to increase with C input decreases as SOC increases and approaches a SOC saturation level. In a 12‐year experiment, six semi‐arid cropping systems characterized by different rates of C input to soil were compared for ability to sequester SOC, SOC saturation level, and the time necessary to reach the SOC saturation level. SOC stocks, soil aggregate sizes, and C inputs were measured in durum wheat monocropping with (Ws) and without (W) return of aboveground residue to the soil and in the following cropping systems without return of aboveground residue to soil: durum wheat/fallow (Wfall), durum wheat/berseem clover, durum wheat/barley/faba bean, and durum wheat/Hedysarum coronarium. The C sequestration rate and SOC content were lowest in Wfall plots but did not differ among the other cropping systems. The C sequestration rate ranged from 0.47 Mg C ha⁻¹ y⁻¹ in Ws plots to 0.66 Mg C ha⁻¹ y⁻¹ in W plots but was negative (−0.06 Mg C ha⁻¹ y⁻¹) in Wfall plots. Increases in SOC were related to C input up to a SOC saturation value; over this value, further C inputs did not lead to SOC increase. Across all cropping systems, the C saturation value for the experimental soil was 57.7 Mg ha⁻¹, which was reached with a cumulative C input of 15 Mg ha⁻¹. Copyright © 2015 John Wiley & Sons, Ltd.