Why Is the Bloom Season Important in an IPM Program?
Bloom season, which extends from red bud to petal fall, is the best time to manage several apricot pests. Because foliage is sparse at this time, you can get good spray coverage more easily than later in the season. You can avoid water quality problems associated with dormant-season sprays for peach twig borer by treating with low-toxicity insecticides (and mating-disruption supplements) at this time. Also, monitoring for pests, including the installation of pheromone traps, begins at bloom.
Monitoring and treatment for various pests should be timed based on an estimate of when a certain proportion of the flower buds are open. For example, peach twig borer is monitored during bloom. Also, the most important application for brown rot blossom and twig blight is when the maximum number of pollenizable flowers are open.
In years with high chilling, as many as 80% of the blossoms may reach full bloom at the same time. In low chilling years, the proportion may be below 50%.