Written by Elizabeth H. Beers, Washington State University, May 5, 2026
The Washington tree fruit industry has been experiencing some historically lean years in terms of returns on fruit, and many growers are keen to cut production costs where possible, but still produce a ‘money zone’ crop. Many factors go into this, and pest management is just one part. Costs associated with ag chemicals are a relatively small percentage of total variable costs (about 5%), so you can’t move the needle much on your total costs. But unlike cuts in some areas, failure to control certain pests can affect both your orchard and your neighbors, and haunt both of you for years to come.
So what are the most impactful pests of apple?
No. 1 on the list is codling moth. A runaway population can make the current year’s crop virtually unpickable, fly into neighboring orchards, and become firmly established as an internal problem in both. And this can land you on the Pest Board Case list, with possible legal and financial consequences. In addition, clawing back from a sizeable infestation may take several years, and many dollars to accomplish. The best strategy is never let it get out of control.
Essential codling moth controls
That said, there are always options for control, with widely varying associated costs; and clearly, your options are very different if you are organic or conventional. The first option in almost all cases should be codling moth mating disruption. This should be the foundation of your program, and additional control measures added as need and pressure dictate. Control of the first generation is critical: the potential for increase in population between 1st and 2nd generation is 2-10x, and the number at the end of the first generation must be as low as possible. Ideally, if first generation control is excellent, nothing more need be done in low pressure orchards. In moderate to high pressure orchards, and most organic orchards, control measures must continue through September, or when moths stop flying.
Both organic and conventional growers should consider using horticultural spray oil in as many sprays as possible, depending on the frequency of applications. Oil acts as both an adjuvant, an ovicide, and an oviposition deterrent to many pest species, including codling moth. These latter effects are not sufficient alone to provide adequate control, but the cumulative effect of multiple applications (along with the effect of the primary insecticide) will keep chipping away at the population. It’s relatively cheap insurance. You will, of course, need to be aware of the potential for phytotoxicity at high temperatures and repeated applications, but pour on as much as you dare.
Choosing ‘bang for your buck’ codling moth materials
For conventional growers, your choice of active ingredient (AI) will depend on the cost and the other pests present. The recent appearance of generic materials for our older, brand name products, could not come at a better time for growers on a tight budget. The same AI may be available from multiple companies at this point, so I’ll use the chemical name [with the most familiar brand name in brackets] to highlight this choice. My relative ratings are based on 2025 prices of brand name products, and the relative cost may have changed for the 2026 season. The first ‘value’ option for codling moth control is chlorantraniliprole (Altacor). This was one of the early diamide materials, and still looks good in my trials. The second is acetamiprid [Assail]; this was one of the first new larvicides introduced, and one of the few neonicotinyls with lep activity. Spinetoram [Delegate] is a spinosyn, again with the best lep activity of this class. Spinetoram was relatively expensive in 2025, but this may have changed. These three materials likely provide good control on a 14-day schedule in most orchards. Another diamide, cyantraniliprole [Exirel] was on the expensive side, but should also give a similar level of codling moth control.
A new codling moth material this year is isocycloseram [plinazolin, Zivalgo]. This is a new mode of action (Group 30) which can be used for rotations in resistance management. This has been comparable to our standard codling moth materials in all of my tests.
I’ll group the pyrethroids for convenience; I haven’t made head-to-head comparisons among them, and there may be differences in efficacy and longevity. Three possible codling moth pyrethroids are lambda-cyhalothrin [Warrior], esfenvalerate [Asana], and zeta-cypermethrin [Mustang Maxx]. We have traditionally avoided these materials because of their toxicity to predatory mites, and the tendency to disrupt mite biological control. But they may be the least expensive option, if this outweighs other considerations.
For organic growers, the options are relatively limited; with the exception of oil, none would be considered cheap. Codling moth virus is a mainstay in organic, but kaolin [Surround], biologicals, sterile moths and various sanitation measures may also merit a place in your program.
Non-target effects of Insecticides – bad news for IPM
Speaking of non-target effects, most insecticides come with at least a bit of baggage in this department. Oil and virus are pretty innocuous, allowing season-long use without negative consequences. Of the conventional materials, chlorantraniliprole [Altacor] generally has the fewest negative effects on natural enemies. Spinetoram [Delegate] is toxic to hymenopterous (wasp) parasitoids as well as predatory mites, while acetamiprid [Assail] was documented as having moderate disruptive effects in the field on mites. The pyrethroids (and perhaps Zivalgo, also) have a broader spectrum of activity, which often translates to more non-target effects.
Broad vs. Narrow Spectrum
But a broad spectrum of activity has its benefits also, if you have multiple pests you need to control, and can potentially do it with a single material. This is a savings (potentially) in material costs and in trips through the orchard – a cost which may exceed the cost of the material in the tank. Zivalgo has leafrollers, Oriental fruit moth, thrips and mites on its label, so if these warrant control, this material might be a good option (depending on timing). Exirel, Altacor, pyriproxyfen [Esteen], novaluron [Rimon] and Delegate all have dual activity on codling moth and leafrollers; Delegate also has thrips activity. Again, the timings need to align in order to get the full benefit. From a certain perspective, a pre-mix insecticide may functionally have a broader spectrum of activity; WSU generally does not recommend pre-mixes because it limits resistance management options, but it does have recommendations for a tank mix of a codling moth ovicide and larvicide at certain timings. If the pre-mix fills the functions of the tank mix (e.g., acetamiprid + novaluron [Cormoran], it meets the criterion.
Other direct and indirect pests
While codling moth is our key apple pest, there are other pests that should not be ignored in either the short or slightly longer run. Oriental fruit moth, if you are in an area prone to damage, is similar to codling moth in the type of damage and damage potential. If you are in an apple maggot quarantine area, there are specific rules regarding control of this pest. Two somewhat under-rated, but potentially devastating indirect pests are San Jose scale and woolly apple aphid. You can let them go for a year or so, but if you experience chronic, high levels, they can debilitate or kill your trees. Eventually. If you have a persistent thrips problem, and a cultivar where damage is visible, you may have to control this pest to get the packout you want. Campylomma and other true bugs (e.g., boxelder bug, stink bugs) can be locally important, but likely not a concern for most growers. Rosy apple aphid can be problematic in organic production, but is relatively cheap and easy to control with a neonicotinyl in conventional programs; just switching to acetamiprid [Assail] for codling moth in the first generation should take care of it. Most of the primarily foliar pests (mites, leafhoppers, leafminers, green apple aphid) can occur at higher levels without noticeable impact, at least in the short run.
Summary
In sum, if you are running a tight program, spend your money on codling moth control first and foremost, then the other direct pests. Resistance management is important in the bigger picture, but unless there is an imminent threat (as with granulosis virus), it can be deferred. We have the tools to restore the other parts of the IPM in the coming years if things get out of whack.
Contact
Betsy Beers
Professor and Entomologist / Extension Entomologist
Washington State University
ebeers@wsu.edu
509-293-8755
Fruit Matters articles may only be republished with prior author permission © Washington State University. Reprint articles with permission must include: Originally published by Washington State Tree Fruit Extension Fruit Matters at treefruit.wsu.edu and a link to the original article.
