Molecular characterization of two distinct strains of blueberry scorch virus (BlScV) in northern Italy.

During blueberry scorch virus (BlScV) surveys of highbush blueberries in Italy between 2005 and 2010, we initially discovered infected orchards only in Piedmont. Since 2009, however, three infected orchards have also been found in Trentino, where a new host species, Vaccinium ashei, was found to be infected by BlScV. Molecular characterization of isolates during the study period suggests that two very distinct epidemics are now present in Italy: the Piedmont isolates belong to a new BlScV strain, whereas the Trentino isolates are almost identical to the Washington State strain.

Genetic diversity of Armillaria spp. infecting highbush blueberry in northern Italy (Trentino region).

Armillaria spp. are the causal agents of root rots of several woody plants, including highbush blueberry. Since 2003, highbush blueberry plants infected by Armillaria spp. have been found in Valsugana Valley, Trentino region, northern Italy. Our aim was to identify the Armillaria spp. involved in these infections, as well as possible sources of inoculum in blueberry fields. Samples of Armillaria spp. were collected from diseased blueberry plants in 13 infected blueberry fields, from bark spread along the blueberry rows, from infected trees in the vicinity of the fields, and from four forest locations. The identification of Armillaria spp. was accomplished using a species-specific multiplex polymerase chain reaction method and by sequencing the rDNA at a specific locus. The differentiation between genotypes was performed by using simple-sequence repeat analysis. Armillaria mellea and A. gallica were the most frequently observed species infecting blueberry in the Valsugana Valley. Three to eight Armillaria genotypes were identified in each blueberry field. No individual genotypes were found in more than one blueberry field. Two-thirds of the genotypes found colonizing trees in the immediate vicinity of infected fields and two-thirds of the genotypes found colonizing the bark spread in blueberry rows were also isolated from blueberry plants in the field, indicating that bark used as mulch and infected trees surrounding the fields may be important sources of inoculum.

Deltamethrin multifactorial activity toward carp larva mobility related to calcium, humic acids, and pH.

The toxicity of pyrethroid insecticide deltamethrin was assessed by the "escaping capability" of carp larvae out of a trap. Mobility was tested after 1, 4, and 12 hr exposure to eight deltamethrin concentrations in standard water and after 24 hr exposure to seven deltamethrin concentrations in 18 media derived from the combinations of pH levels of 6.9, 7.8, 9.0, calcium concentrations of 2 . 10(-4) and 2 . 10(-2) M, and humic acid concentrations on 0, 5 and 100 mg/liter. In standard water, a 1-hr exposure at 4 microg/liter deltamethrin increased the mobility, while a 4-hr 32 microg/liter exposure decreased it. After 24 hr without deltamethrin, mobility was reduced at pH 6.9 and 7.8 and 2 . 10(-4) M calcium. It was also reduced in 100 mg/liter humic acids, especially when the former pH and calcium conditions were used. Humic acid effects could partly result from a calcium concentration reduction in water, and darkness due to humic acid coloration could play a minor role. Increasing humic acid concentration, calcium concentration, and pH reduced deltamethrin activity. In 0 or 5 mg/liter humic acids the No Observed Effect Concentration was 1 microg/liter, and in 100 mg/liter humic acid it was 2 microg/liter. Compared to previous results on deltamethrin-induced lethality, the escape test appeared less reproducible, but was 2 or 4 times more sensitive.

Deltamethrin lethal multifactorial activity toward carp larva related to pH, calcium, and humic acid concentrations.

Acute 24-hr embryotoxicity of the pyrethroid insecticide delta-methrin toward carp larvae was tested in multifactorial combinations of three pHs (6.9, 7.8, 9.0), two calcium concentrations ([Ca] = 2 x 10(-4) and 2 x 10(-2) M), and three humic acids concentrations ([HA] = 0, 5, and 100 mg/liter). Lethal effects were determined and compared to the distribution and hexane extractibility of radiolabeled deltamethrin in the solution and on the vessel walls, either in the presence or in the absence of the larvae. As a function of the three combined factors tested, the no observed effect concentrations (NOECs) differed to a maximum by a factor of 8, while they differed by only a factor of 2 with pH alone, and by a factor of 4 with calcium or humic acids alone. No contact toxicity was observed with adsorbed deltamethrin on the vessel walls, on which adsorption and hexane extractibility was increased in the presence of larvae. The most plausible interpretation for the toxicological influence of the physicochemical factors tested on deltamethrin toxicity deals with the deltamethrin distribution in the medium for humic acids, changes in biological targets for calcium influence, and, for pH influence, degradation speed or one of the two other explanations.