Current Insect and Disease Activity |
APPLES/PEARS |
| Codling Moth | 
| | In some very rare cases, codling moth larvae can attack peach fruit. If you see green fruit with "worms" inside them, it might not be peach twig borer. If the larvae are cream-colored with a brown to black head, that is codling moth. |
Most areas along the Wasatch Front are “in between” generations, with second generation egg hatch starting next week. So if your trees are due for a spray, wait until the start of the second generation. Cooler areas are just ending the first generation egg hatch.
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| Woolly Apple Aphid
Continue to check trees for this aphid that forms cottony-looking colonies on twigs and bark. The larger the colonies get, the more difficult it is to control. Remember from the last advisory that the aphids also feed on roots, which over the long term, can cause trees to be less vigorous.
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STONE FRUITS
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| Peach Silver Mite
 Peach silver mite is a microscopic eriophyid mite that feeds on the bottom of the leaves. It is a mite that has been around all season, but may become very noticeable later in the season when populations build to high numbers in the summer heat. Their feeding causes leaves to look silvery in appearance. Trees can tolerate high populations, but when there are more than 300/leaf (or when leaves start to droop and fall), a miticide or 0.5 - 1% horticultural oil application should take care of the problem. Alternatively, they can be treated in early spring (at budbreak) with oil.
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| Walnut Husk Fly
It is time to start treating black and English walnuts for walnut husk fly if you have not started already. Late peach varieties are secondary hosts, where they are growing near walnuts. Emergence is just beginning, with peak emergence toward the middle to end of August. Although adults end emergence and egg-laying in late September, the maggots feed for 3-5 weeks before dropping to the soil to pupate. Early feeding on young walnuts causes the nut to shrivel, turn moldy, and drop prematurely. Later feeding (late Aug. – Sept.) will not affect the kernel, but will result in a husk that is stained black and a hull that is difficult to separate from the nut. For the most part, treatment on walnuts is not necessary because the kernel is usually not damaged. To make husk removal easier, store infested nuts in a damp burlap bag for 2-3 days. The only insecticides registered for home use of husk fly on walnuts are spinosad (see products under codling moth in the spray options table) and GF-120. GF-120 is spinosad mixed with a bait. It comes in 1 gallon sizes only and is expensive (approximately $100). If using plain spinosad, consider adding about 4 to 6 tablespoons of molasses per gallon of water applied. The spray mix should be applied as large droplets, evenly spaced throughout the entire tree. It is not necessary to cover all the nuts, just to have large droplets. The spinosad+bait will attract the adults to feed, and then the insecticide kills the flies. (If using spinosad alone, good coverage is important.) Begin sprays now, continuing every 7 days until within 1 month of walnut harvest. Eggs laid later than this will not have time to develop and cause damage.
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| Spotted Wing Drosophila Update Cory Stanley, USU CAPS Coordinator  Spotted wing drosophila (SWD), an invasive vinegar fly that was introduced into the U.S. in 2009 and has since spread to at least ten states, was first detected in Kaysville, Utah last August.
This year efforts to monitor for this pest were increased as part of the Cooperative Agricultural Pest Survey (CAPS) program. So far, 66 SWD traps have been placed at 34 sites in Cache, Box Elder, Weber, Davis, Utah, and Washington counties. Trapping sites include areas where raspberries, sweet cherries, tart cherries, and peaches are grown, as well as fruit stands. Additional raspberry and fruit stand sites will be added in the coming weeks. Traps are baited with yeast and sugar solution, which is replaced weekly when trap contents are removed and examined for SWD presence. No SWD has been detected yet this year.
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Upcoming Monitoring/Insect Activity |
| Pest | Host | Appearance/Management | | Spider mite | all fruit trees | Populations build in hot, dry weather | | Codling moth | apple fruit | Second generation begins late July/early August | | Peach twig borer | peach, nectarine, apricot | Second generation egg hatch begins late July/mid-August | | Peach powdery mildew | peach | Look for powdery lesions (peach powdery mildew) or rust-colored lesions (apple powdery mildew) | | Cherry powdery mildew | cherry | Look for small white lesions on new foliage at shoot terminals | | Western cherry fruit fly | cherry | Adult flies will be emerging and laying eggs through September (after harvest) | |
Degree Day Accumulations and Insect Development |
| Click here for information on degree days. March 1 - July 20
| County
| Location | Codling Moth, 1st Generation
| Peach Twig Borer, 1st Generation | | DD
(post biofix) | % Moth Flight | % Egg Hatch | DD
(post biofix) | % Moth Flight | % Egg Hatch | | Box Elder | Perry | 1038 | 7 | 0 | 806 | 0 | 100 | | Tremonton | 768 | 100 | 94 | --- | --- | --- | | Cache | River Heights | 843 | 0 | 97 | 507 | 99 | 65 | | Smithfield | 791 | 100 | 95 | 463 | 98 | 58 | | Carbon | Price | 946 | 1 | 99 | 641 | 0 | 3 | | Davis | Kaysville | 991 | 4 | 99 | 794 | 0 | 99 | | Grand | Castle Valley | 1762 | 95 | 76 | 1362 | 81 | 29 | | Iron | Cedar City | 949 | 2 | 99 | 800 | 0 | 100 | | Salt Lake | Holladay | 993 | 4 | 99 | 804 | 0 | 100 | | West Valley City | 1128 | 16 | 1 | 939 | 3 | 0 | | West Jordan | 1028 | 6 | 100 | --- | --- | --- | | Tooele | Erda | 959 | 3 | 99 | 863 | 1 | 0 | | Tooele | 1034 | 7 | 0 | 964 | 4 | 0 | | Uintah | Vernal | 983 | 4 | 99 | 739 | 0 | 99 | | Utah | Alpine | 817 | 0 | 96 | 442 | 97 | 43 | | American Fork | 943 | 2 | 99 | 782 | 0 | 99 | | Genola | 1090 | 12 | 0 | 733 | 0 | 98 | | Goshen | 681 | 99 | 85 | 434 | 97 | 40 | | Lincoln Point | 994 | 4 | 99 | 861 | 1 | 0 | | Lindon | 1043 | 7 | 0 | 788 | 0 | 99 | | Provo | --- | --- | --- | 878 | 1 | 0 | | Payson | 967 | 3 | 99 | --- | --- | --- | | Santaquin | 957 | 3 | 99 | 528 | 99 | 71 | | West Mountain | 952 | 3 | 99 | --- | --- | --- | | Weber | Pleasant View | 1039 | 7 | 0 | 836 | 0 | 0 | | Wasatch | Heber City | 688 | 99 | 86 | --- | --- | --- | | Wayne | Capitol Reef | 907 | 1 | 98 | --- | --- | --- | |
Codling Moth - When to Spray
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| Continue to apply your chosen material(s) at the interval provided on the label. Make sure fruit is well protected during the period of greatest egg hatch. You do not need to spray between generations.
| County | Location | Keep Fruit Protected up To: (1020 DD) | Second Generation
(1120 DD) | Period of Greatest Egg Hatch: 2nd Generation (1320-1720) | | Box Elder | Perry | past | July 27 | Aug 3 - Aug 21 | | Tremonton | past | July 30 | Aug 10 - Aug 29 | | Cache | River Heights | July 27 | Aug 2 | Aug 10 - Aug 31 | | Smithfield | past | Aug 1 | Aug 9 - Aug 28 | | Carbon | Price | July 31 | Aug 2 | Aug 9 - Sept 3 | | Davis | Kaysville | past | July 25 | Aug 1 - Aug 18 | | Grand | Castle Valley | past | --- | --- | | Iron | Cedar City | July 23 | July 26 | Aug 3 - Aug 21 | | Salt Lake | Holladay | past | --- | July 27 - Aug 9 | | West Valley City | past | --- | July 27 - Aug 11 | | West Jordan | past | July 22 | July 29 - Aug 13 | | Tooele | Erda | July 26 | July 30 | Aug 3 - Aug 18 | | Tooele | past | July 25 | July 31 - Aug 16 | | Uintah | Vernal | July 23 | July 27 | Aug 4 - Aug 24 | | Utah | Alpine | July 26 | July 31 | Aug 9 - Aug 27 | | American Fork | past | July 27 | Aug 3 - Aug 20 | | Genola | past | July 21 | July 29 - Aug 14 | | Goshen | past | July 30 | Aug 10 - Aug 27 | | Lincoln Point | past | July 25 | Aug 2 - Aug 18 | | Lindon | past | July 21 | July 29 - Aug 13 | | Payson | past | July 25 | Aug 2 - Aug 18 | | Santaquin-West | past | July 25 | Aug 2 - Aug 19 | | West Mountain | past | July 24 | Aug 2 - Aug 18 | | Weber | Pleasant View | past | July 23 | July 30 - Aug 14 | | Wasatch | Heber City | Aug 8 | Aug 15 | Aug 25 - Sept 29 | | Wayne | Capitol Reef | past | --- | July 29 - Aug 13 | |
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Peach Twig Borer - When to Spray
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| End of egg hatch, where you should “keep fruit protected up to” is at 800 degree days. The second generation egg hatch (5%) starts at 1200 DD.
| County | Location | Keep Fruit Protected Up To: | Start sprays, 2nd Generation | | Box Elder | Perry | past | Aug 8 | | Cache | River Heights | Aug 2 | Aug 21 | | Smithfield | past | Aug 18 | | Davis | Kaysville | past | Aug 4 | | Grand | Castle Valley | past | July 15 | | Iron | Cedar City | past | Aug 4 | | Salt Lake | Holladay | past | July 29 | | West Valley City | past | July 29 | | Tooele | Erda | past | Aug 1 | | Tooele | past | July 29 | | Uintah | Vernal | July 23 | Aug 10 | | Utah | Alpine | Aug 3 | Aug 20 | | American Fork | past | Aug 5 | | Genola | past | Aug 7 | | Goshen | past | Aug 15 | | Lincoln Point | past | Aug 2 | | Lindon | past | Aug 3 | | Provo | past | Aug 1 | | Santaquin | past | Aug 14 | | Weber | Pleasant View | past | Aug 2 | |
Spray Materials - Commercial Applicators |
| The options provided below are not all-inclusive and are not endorsements of USU. Please check the label before mixing. | Target Pest | Host | Brand | Chemical | Amount
per acre | REI | Comments | | Codling Moth | apple | Altacor 35WDG | chlorantraniliprole | 3.0-4.5 oz | 4 h | re-apply based on product interval through each generation until harvest or Sept. 15 | | Assail | acetamiprid | 1.7-3.4 oz | 12 h | | Belt SC | flubendiamide | 5 oz | 12 h | | Delegate 25WG | spinetoram | 6-7 oz | 4 h | | Imidan 70W | phosmet | 3.5-5.3 lbs | 3 d | | Voliam Flexi | thiamethoxam +chlorantraniliprole | 4-7 oz | 12 h | | Woolly apple aphid | apple | Assail | acetamiprid | 1.7 oz | 12 h | apply post bloom only if scouting shows that this pest is present | | Beleaf | flonicamid | 2-2.8 oz | 12 h | | Calypso | thiacloprid | 2-4 oz | 12 h | | Clutch | clothianidin | 2-3 oz | 12 h | | Admire Pro; generics | imidacloprid | see label | 12 h | | Peach twig borer | peach, nectarine | Belt | flubendiamide | 3-4 oz | 12 h | reapply based on protection interval until harvest | | Altacor | chlorantraniliprole | 3.0-4.5 oz | 12 h | | Delegate | imidacloprid | 4.5-7.0 oz | 12 h | | Imidan | phosmet | 4.25 lbs | 12 h | | Voliam Flexi | thiamethoxam+ chlorantraniliprole | 4-7 oz | 12 h | | Greater peachtree borer | peach, nectarine, apricot | chlorpyrifos | Lorsban | see label | 4 d | Lorsban: max once/season; do not allow spray to touch foliage/fruit
Thionex: max twice/season | | endosulfan | Thionex | see label | 4 d | | esfenvalerate | Asana | see label | 12 h | | pemethrin | Pounce | 4-8 oz | 12 h | | Powdery mildew | peach | Adament | tebuconazole+ trifloxystrobin | 4-8 oz | 4 h | monitor fruit and leaves for powdery mildew and only apply if necessary; chance of fruit infection decreases after pit hardening | | Abound | azoxystrobin | 11-15 oz | 12 h | | Orbit, Tilt | propiconazole | 4 oz | 4 h | | Pristine | boscalid+ pyraclostrobin | 2-2.4 oz | 12 h | | Western Cherry Fruit Fly | cherry | Altacor | chlorantraniliprole | 3.0-4.5 oz | 4 h | start applications when fruit develops salmon blush color on top of yellow and continue until harvest | | Assail | acetamiprid | 5.3-8 oz | 12 h | | Delegate | spinetoram | 4.5-7 oz | 4 h | | GF-120 | spinosad+bait | 10-20 oz | 4 h | | Admire Pro; generics | imidacloprid | see label | 12 h | | Powdery mildew | cherry | Abound | azoxystrobin | 11-13 oz | 4 h | | | Pristine | boscalid+ pyraclostrobin | 10.5-14.5 oz | 12 h | | Quintec | quinoxyfen | 7 oz | 12 h | | Rally | myclobutanil | 2.5-6 oz | 24 h | | Rubigan | fenarimol | 6-12 oz | 12 h | |
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Spray Materials - Residential Applicators |
| Note that these treatments are only recommended if you know you have the particular pest in your trees. | Target Pest | Host | Chemical | Example Brands
| Comments | | Codling moth | apple, pear | Conventional | | acetamiprid: every 14 days
carbaryl: every 14 - 21 days
malathion: every 7 days
gamma-cyhalothrin: every 14 days
bifenthrin: every 14 days; pears only
hort. oil: lasts 5-7 days for killing eggs; use at beginning of each generation; apply at 1% rate only when temperatures are below 80; follow up with a different product
spinosad: every 7 days
codling moth virus can only be purchased online
| | acetamiprid | Ortho Max Flower, Fruit, and Veg. | | carbaryl | Sevin, Bonide Fruit Tree Spray, etc. | | malathion | Malathion | | gamma-cyhalothrin | Spectracide Triazicide | | bifenthrin | Ortho Max Lawn and Garden Insect Killer | | | | | Soft/organic | | | hort. oil (1%) | Many products | | spinosad | Green Light Lawn and Garden Spinosad; Gardens Alive Bull’s Eye; Ferti-Lome Borer, Bagworm, Leafminer & Tent Caterpillar; Monterey Garden Insect Spray; Natural Guard | | codling moth virus | Virosoft, Cyd-X | | Peach twig borer | peach, nectarine | Conventional | | see comments under Codling Moth
permethrin: every 14 days; this ingredient is becoming less available in stores
Surround: every 3-5 days; works to repel, not kill insects; only moderate control; must purchase online | | acetamiprid | Ortho Max Flower, Fruit & Veg | | carbaryl | Sevin, Bonide Fruit Tree Spray, etc. | | malathion | Malathion | | permethrin | Basic Solutions Yard & Garden, Bonide Eight | | | | | Soft/organic | | | spinosad | see ‘codling moth’ above | | kaolin clay | Surround | | Greater peachtree borer | peach, nectarine, apricot | permethrin | Bonide Eight, Green Light Borer Killer, Bonide Borer-Miner Killer, Enforcer Outdoor Insect Killer, Hi-Yield Broad Use Including Gardens; Lilly Miller Multi-Purpose Insect Spray | permethrin: apply every 14-21 days until mid-September in highly infested areas; apply twice (now and one month later) in low infestations
carbaryl: must be applied every 7 days | | carbaryl | Sevin, Bonide Fruit Tree Spray | | Aphids | all fruit trees | carbaryl | Bayer Advanced | start with a single application bifenthrin: pears only | | bifenthrin | Ortho Bug-B-Gone | | malathion | Bonide, Malathion | | neem oil | Green Light | | permethrin | Lilly Miller | | Powdery mildew | all fruit trees | bayleton | Bonide | do not apply lime sulfur when temperature is over 75 degrees F Neem oil and Kaligreen are organic options | | lime sulfur | Lilly Miller | | propiconazole | Ferti-Lome | | neem oil | Garden Safe | | potassium bicarbonate | Kaligreen | | Western cherry fruit fly | cherry | carbaryl | Sevin | start applications when fruit in sunniest locations develop a salmon blush malation: make sure cherry is on label
spinosad: every 7 days | | malathion | Malathion | | pyrethrin | Concern Multi-Purpose | | (Soft/Organic)
spinosad |
see above
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Precautionary Statement: Utah State University Extension and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed herein. |
USU Tree Fruit IPM Pest Advisories provide nearly weekly updates on current insect and disease occurrences, biology, and treatment recommendations for Utah. Updates run from mid-March through September.
