In this Issue
- Codling moth: updated spray dates table for apple and pear
- Woolly apple aphid: watch for tufts of cottony areas on apple and treat early
- Peach twig borer: nearing end of first generation egg hatch in northern Utah
- Greater peachtree borer: treat lower trunks of peach and nectarine next week (for some areas)
- Western cherry fruit fly: continue protecting fruit up to harvest
APPLE, PEAR
Codling Moth
Be mindful that no treatment is needed between the end of first generation egg hatch and start of second generation
View a pdf of the spray timing table.
For northern Utah, the June heat has pushed the end of the first generation (cycle) of egg hatch to be around the end of this month. Our predictions are not “perfect” but, you do not need to apply a spray between the end of the first generation egg hatch and the start of the second, because there are no larvae present.
For the second generation, apply your next spray, or if you can tolerate higher injury or have a low codling moth population, apply your next spray at the start of “second generation peak egg hatch.”
And then from there on, you should continue to protect your apple or pear fruit until harvest or September 15, whichever is earliest.
Note that there are restrictions for some insecticides on how many times it may be used (check your label). We recommend switching to a product with a different active ingredient for the second generation treatment.
Treatment
Woolly Apple Aphid
Watch for tufts of cottony areas on apple trees.
Woolly apple aphid overwinters as nymphs on apple roots or in protected sites in the tree. They start feeding and reproducing in spring, but they are usually not visible in the canopy until June.
If left unmanaged, the young nymphs will crawl to new feeding sites (or are blown by the wind) over the course of the summer, to cover large areas in sticky, cottony masses. Older stages are less mobile.
The cottony appearance is actually very waxy and difficult for predators or insecticides to penetrate. In fact, woolly apple aphids are the most difficult aphid to manage due to their protection.
Treatment
It is important to catch woolly apple aphids early.
- Residential growers can use insecticidal soap plus 1% oil, aimed directly at the colonies. Ortho Flower, Fruit and Vegetable (acetamiprid) plus 0.5% oil is also effective.
- Commercial growers: At this time, one of the most effective options is Ultor, but it must be applied even before aphids are seen, at petal fall. Other options for treating the aphids directly: click here.
PEACH/NECTARINE, APRICOT
Peach Twig Borer
First generation egg hatch will be ending soon in certain locations
View a pdf of the updated spray timing table. Be sure to read the instructions at the top of the page, for how to read the table.
In most areas of northern Utah, the first generation egg hatch will be ending in the next few weeks. The start of the second generation egg hatch is then a few weeks after that.
For the second generation, with high-population areas, two cover sprays may be required. In low population areas, only one application is needed.
Pay attention to apricots, which ripen earlier. At this time of year, peach twig borer larvae will be entering fruit as they ripen.
Treatment
- Residential options are the same as codling moth (see above)
- Commercial growers
Greater Peachtree Borer
Updated dates for protecting lower trunk
As mentioned in our May 26 advisory, the greater peachtree borer is a moth, and adults lay eggs on the lower trunk. Spraying that area (10″ up from the ground plus exposed roots) with an insecticide will kill any eggs that are laid by the female moths. Otherwise, a larva will hatch and immediately bore into the tree trunk and feed on the inner bark and cambium.
The larvae stay within the lower trunk until the following spring. This is when people notice gumming mixed with frass at the base of the trunk, or even just below the soil line.
Newly planted peach and nectarine (and sometimes apricot, plum) are most susceptible and should be protected the first 3 to 4 years until bark thickens.
When to Treat
- Cache, Sanpete, Summit, Uinta, Wasatch counties: June 26 – 30 (one of the earliest dates ever!)
- Carbon County: June 22
- Davis County: June 19
- Iron County: June 19
- Utah County warmer areas – June 17 – 20
- Utah County cooler areas: June 23
- Weber County: June 18
Non-chemical Treatment Options
- Remove all weeds, grass, and excess soil from around the base of the tree. Heat and dryness reduce the survival of eggs and larvae.
- Avoid mechanical and rodent-caused injuries to trunks.
- Keep trees healthy with optimal nutrition and irrigation
Treatment
- Residential: permethrin, such as Hi Yield Farm and Garden Insect Control. Apply at the appropriate timing, and repeat once per month, with the last application in September. Spectracide Triazicide or GardenTech Sevin are also options but may last slightly less than 4 weeks.
- Organic options include products that contain either pyrethrin or azadirachtin (AzaSol, EcoGarden). They need to be applied weekly.
- Commercial: click here
CHERRY
Western Cherry Fruit Fly
Continue protecting fruits up until harvest
As mentioned in the May 26 advisory, the time to treat for the “worms in the cherry” is based on the development of your own tree. When the rosy blush forms, the female flies are able to penetrate the fruit skin and lay eggs inside. This has occured in most areas of the state.
Therefore, treatment should begin as soon as cherries develop a salmon blush color. Base this off the fruits in the sunniest location of the tree, which is often toward the top or on the outside edges.
Sweet cherries are near ripe in certain areas while tart cherries have a few weeks to go. If you need to spray your ripening cherries one last time before harvest, be mindful of the pre-harvest interval, whether you are a farmer or homeowner. More on this in the next advisory.
Treatment
Residential Conventional:
- Malathion (malathion): every 7 days
- Bonide Fruit Tree Spray & Plant Guard (lambda-cyhalothrin), GardenTech Sevin (zeta-cypermethrin), Spectracide Triazicide (gamma-cyhalothrin): every 14 days
Residential Organic:
- Fertilome / Gardens Alive / Bull’s Eye / Monterey (spinosad): every 7 days
Commercial Growers:
- Commercial growers, click here.