Tolerance of grapevine askari cultivar to injury caused by Lobesia botrana anthophagous generation using damage simulation

Dena County is one of the most important grape-growing area in the southwest of Iran. The dominant cultivar in this area is Askari and grapevine moth, Lobesia botrana (Denis & Schiffermüller, 1775), is major pest on this cultivar. The first generation of this pest has a high population and seriously damages the flowers. To investigate this cultivar’s tolerance to first generation injuries on flowers, a damage simulation experiment designed and carried out for two consecutive years. In the first step, the average number of bunch/tree and flower/bunch for each year calculated, accurately. Having these data, the experiments performed with seven treatments (removal of 0, 5, 10, 15, 20, 25, and 30 percent of flowers based on the calculated average number of flowers/bunch in each year) and four replications (each tree considered as one replication). At vintage time, harvested grape product weighed separately and analyzed for simple and combined analyses of variance. The results showed that Askari cultivar in Dena region had a good tolerance and could compensate completely for anthophagus generation damage to the blossoms so that no yield loss observed in the treatments. The ability to compensate for damage is achieved by reducing the natural shedding of flowers and increasing the berry’s weight. According to the obtained results, up to 30% removal of flowers on Askari cultivar in Dena region, there is no need for controlling the first generation, thinning the flowers also increases the quality of berry. However, it is necessary to study the higher levels of flower removal and then make a final decision about the damage threshold of first generation in the region.