Evaluation of different spray programmes and stem barriers for the reduction of fruit damage caused by the V back snout beetle, Phlyctinus callosus (Schönherr, Curculionidae)

Management strategies were evaluated for the reduction of fruit damage caused by the V back snout beetle, Phlyctinus callosus (Schönherr, Curculionidae). The evaluated strategies included three stem barrier treatments (Planttex, Ghries,  and Enviroband) and four spray programme treatments (different combinations and time of applications of Chlorphenapyr, Indoxacarb and Deltamethrin). Two trails were done on  the farm Vastrap (Du Toit Agric Western Cape) in the Witzenberg Valley (Ceres area), which included two different cultivars namely Braeburn and Pink lady.  The trials both had intermediate to low Snout Beetle pressure during the trial period. In both trails all the treatments performed significantly better than the untreated control for both leaf and fruit damage. Control of leaf damage in two of the stem barrier treatments (Ghries barrier and Environ band) was significantly better than two of the spray treatments (Indoxacarb, 2 weeks interval and Indoxacarb/Deltamethrin) in both trials. The control of leaf damage of the Indoxacarb 4 weeks interval treatment was inconsistent between the two trials, whereas control of leaf damage of the fourth spray treatment (Chlorphenapyr/Indoxacarb) did not differ significantly from the barrier treatments in both trials. The results on fruit damage between the two trials were not always consistent. In the Braeburn orchard the Indoxacarb 2 weeks interval treatment was the only treatment that gave significantly less control of fruit damage than the other treatments, whereas in the Pink lady orchard the Ghries and Environ band treatments gave significantly better fruit damage control than almost all of the spray treatments, with the exception of the Chlorphenapyr/Indoxacarb treatment. Due to inconsistencies between the two trials, and several treatments not differing significantly from each other, it is very difficult to draw clear conclusions from the results. The trials did, however, confirm previous findings that stem barriers tend to outperform spray treatments. There were also some other trends that were evident in both trials although these were not statistically in both trials, including (i) the Ghries barrier and the Environ band giving better control of both fruit and leaf damage than the Plantex barrier, (ii) the Indoxacarb 4 weeks treatment giving better leaf and fruit damage control than the Indoxacarb 2 weeks interval treatment and (iii) the addition of a Chlorphenapyr application prior to Indoxacarb applications improving the control of fruit and leave damage.