Why is the bloom stage important in an IPM program?
Bloom stage, which extends from the popcorn tip stage to petal fall, is the best time to manage a number of almond pests. Generally, bloom stage activities occur in the period between early February to late April but dates may vary according to region, variety, and weather. Some of the key pests are present in the trees during bloom. Also, since foliage is sparse at this time, good spray coverage is easier to achieve than later in the season.
Mummy removal is a critical management tool for navel orangeworm. This task must be completed before bloom. A good time to treat peach twig borer is during bloom with well-timed treatments of Bt. Bt treatments during bloom have the least negative impacts on the environment and natural enemies. Applications must be timed to larval emergence from overwintering hibernacula.
Monitoring for many other insect pests begins soon after bloom. This includes setting out navel orangeworm egg traps and pheromone traps for San Jose scale and peach twig borer.
Various pathogens, including brown rot, anthracnose, leaf blight, and scab, require treatments at different stages of bloom, so timing of fungicide treatments is often based on an estimate of when a certain proportion of the flower buds are fully open such as, pink bud, full bloom or petal fall. Therefore, familiarity with bloom stages of almond is critical in disease management.
Estimating bloom stages is a matter of visual scanning of the orchard. Use the photos and descriptions below to familiarize yourself with the various bloom stages.