Search

A field trial was conducted, under stressing conditions of agricultural drought, in order to evaluate the effect of combined inoculation with Bradyrhizobium sp. and Trichoderma harzianum on agroproductive variables of the hybrid Tifton 85 (Cynodon dactylon). The experimental design was control plot, with five replicas and three treatments: control fertilized with NH4NO3 (150 kg of N/ha), absolute control and inoculated treatment. The dry weight of the aerial part (APDW), inoculation efficiency index based on the APDW (IEIAPDW), stem length (SL) and flowering (Flow.), were evaluated. In the APDW the statistical superiority of the inoculated treatment (326,8 g/m²) over the absolute control (230,0 g/m²), was observed, although these two treatments, in turn, were lower than the fertilized control (492,4 g/m²). With regards to IEIAPDW, the inoculated treatment showed 42,1% more biomass than the absolute control. In SL there were no statistical differences between the inoculated treatment (28,9 cm) and the absolute control (27,0 cm), while the fertilized control (36,8 cm) surpassed both. There were no differences among treatments in flowering. It is concluded that, although there was no effect of the microbial inoculants on the flowering status of the crop, or on the stem length, a productivity of aerial biomass was obtained in the inoculated treatment higher than that of the absolute control. In general, the efficiency of the microbial inoculants used was proven. [ABSTRACT FROM AUTHOR]

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is the insect vector of huanglongbing (HLB), the most devastating citrus disease in the world. The objective of this study was to evaluate the efficacy of two species of commercially available predatory mites, Neoseiulus cucumeris (Oudemans) and N. barkeri (Hughes) (Acari: Phytoseiidae), against D. citri. The predatory mites were evaluated by (1) determining their prey stage preference under no-choice conditions by providing eggs, 1st and 2nd instar nymphs; (2) determining the functional and numerical responses of the predators to varying densities of eggs (from 2 to 32/leaf disk); and (3) evaluating the control effect of N. cucumeris on D. citri on caged trees of Citrus reticulata Blanco in the field, using 1 to 8 sachets (900 ± 100 adult mites per sachet) per tree. The results indicated that N. cucumeris consumed eggs of D. citri only, whereas N. barkeri consumed eggs and 1st instar nymphs. Both predators displayed a Type III functional response (sigmoid). A single female adult of N. cucumeris consumed significantly more D. citri eggs than N. barkeri. N. cucumeris could lay eggs when feeding exclusively on D. citri eggs. The field experiment showed that control effect on D. citri was significantly correlated with the number of N. cucumeris released. Two or more sachets released per tree could achieve significant control at an initial density of 30 adult D. citri (male: female = 1:1) per tree. Improvement of field control efficacy of N. cucumeris on D. citri is discussed. [ABSTRACT FROM AUTHOR]

A solid state formulation of Beauveria bassiana (Balsamo) Vuillemin has been developed for biological control of the Red Palm Weevil (RPW), Rhynchophorus ferrugineus (Olivier, 1790). Two kinds of bioassays (dry conidia and dipping) using 10 isolates from several coleopterans in Mediterranean environments, identified 2 RPW derived isolates (193 and 203) as most pathogenic to RPW larvae and adults (zero survival within first 4-5 d for dry conidia, and 14 and 23 d for dipping bioassays). Isolate 203 (5.1 × 108 ± 1.9 × 108 conidia g-1) was formulated with fragmented date seed into solid granules and tested in palms infested with RPW under semi-field conditions in Feb, Apr/May and Jun of both 2007 and 2008. Beauveria bassiana significantly reduced RPW adult survival with respect to controls in May 2007 and in the Apr/Jun 2008 experiments. Total RPW adult mortality was achieved within 30 days for all B. bassiana treatments, and was associated with increasing numbers of insects with signs of mycosis in 2008 experiments. Beauveria bassiana formulation reduced RPW multiplication in artificially infested palms compared to controls, and a positive correlation between numbers of larvae and time post-infestation was recorded. The suppression of RPW adult populations by B. bassiana persisted for at least 3 months under semi-field conditions. The Beauveria bassiana solid formulation, which induces great adult mortality and persistence in the field, could be applied as a preventive as well as a curative treatment for the integrated management of RPW. [ABSTRACT FROM AUTHOR]