With apples in bloom throughout the region, now is a good time to assess your pest management program, including setting pheromone traps and planning for upcoming insecticide sprays.

Monitoring insect populations is important to determine the timing and frequency of pesticide applications. By far the most important insect to monitor is the codling moth, followed by the oriental fruit moth (OFM). Phenology models are useful tools for timing insecticide applications, but monitoring adults with pheromone traps is critical to determining the need for and frequency of applications. They also serve as a forewarning when chemical control fails, due to insecticide resistance or some other cause. While pheromone trapping for other lepidopterans is available (e.g., tufted apple bud moth, redbanded leafroller), these insects are usually controlled by insecticides applied for codling moth and/or OFM and monitoring is less important.

While several new pheromone lures have come on the market in recent years, we continue to recommend Trece CM L2 and OFM L2 for codling moth and OFM, respectively, because our recommendations for monitoring programs are based on research with these lures. Plus, they continue to perform well compared to other lures in current studies. Both lures are considered long-lasting and have a life of 12 weeks. We also recommend using Delta- or wing-style traps, although Delta traps (e.g., Trece Pherocon VI Delta, Scentry LPD) are much easier to use with their replaceable liners (sticky bottoms). Traps and lures can be purchased at Great Lakes IPM.

OFM adults begin to emerge near Green Tip, while codling moth initial emergence is during Bloom, so pheromone traps should be deployed at those times.

Several species of green fruitworms are sporadic pests that occasionally cause sufficient damage to justify chemical control. Larvae feed on small developing fruit, often when blooms are still on the tree, so an insecticide safe to bees is needed. Intrepid 2F (at 6 to 8 oz/acre) or a Bt (Dipel or Xentari at 1 lb/acre) are both safe options.

Because green fruitworms are considered sporadic pests, it is advisable to monitor their presence before making the decision to apply an insecticide. Fruitworm feeding on foliage precedes feeding damage on fruit, so the presence of feeding damage on new shoot growth leaves can be used as a guide for the need for control. Again, this is a sporadic pest that in most years is not a concern.

The two key pests to target at Petal Fall are the plum curculio and oriental fruit moth, and if rosy apple aphid was not controlled before bloom, a material active against aphids should also be considered. See the table below for Petal Fall insecticide recommendations.

Plum Curculio (PC): PC is a potential pest in virtually every apple (and peach) orchard in the southeast. Its oviposition and feeding scars inflicted between Petal Fall and the first cover spray cause cosmetic damage that is not suitable for the fresh market. The eggs laid in fruit do not hatch in apples on trees, but larvae can complete in fruit that fall to the ground. Most PC adults overwinter in wooded areas surrounding orchards, so the level of damage usually declines from the edge to center of the orchard. In our region, a single insecticide applied at Petal Fall provides the necessary level of control. Regardless of what insecticides were applied up to this point, an insecticide active against PC is highly recommended at Petal Fall.

Oriental Fruit Moth (OFM): Adult moths from the overwintering generation typically begin to emerge near Green Tip or shortly thereafter, with peak moth capture occurring near Bloom. The largest trap captures of the year occur at this time, although these large trap captures are often not indicative of their damage potential, because this generation usually has lower fecundity that those later in the season. Consequently, a single insecticide applied at Bloom will control the first generation.

There are two scenarios under which this first generation of OFM poses little threat to apples and insecticides can be avoided. 1) Mating disruption dispensers were placed in orchards before first generation adults emerged – no later than Tight Cluster. 2) Naturally low populations, which most often occur when mating disruption was used in previous years but not in the current year. "Low" means peak pheromone trap captures of less than 10 to 20 moths per trap per week between Tight Cluster and Bloom.

Rosy Apple Aphid (RAA): Rosy apple aphid overwinters in the egg stage on apple trees, with egg hatch occurring during the Pink stage of flower development. If an insecticide effective against RAA was applied between Tight Cluster and Pink, no additional control measures will be required. However, a RAA-effective insecticide was not applied before Bloom, Petal Fall is the last option for control. Usually, the pre-Bloom timing is more effective than a Petal Fall timing. Most neonicotinoids and aphicides with other modes of action (e.g., Sivanto Prime, Versys, Beleaf) applied before Bloom provide excellent RAA control. Pyrethroids also are effective, although some resistance does exist.

Based on your knowledge of insecticides applied before Bloom and when/if mating disruption dispensers were applied for OFM/CM, the table below can be used as a guide to select an insecticide to apply at Petal Fall.

Learn more about southeastern apple insect pests at the Apple Insect Management page.

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