Tree Fruit IPM Advisory

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.

To subscribe to this advisory (link to this newsletter sent to your email inbox), click here.

Mating Disruption

pdf version

April 16, 2008 

In this Issue:

What to Look for/Do Now:

  • Pear psylla eggs in crevices under buds
  • Whitened terminal shoots of apple indicating overwintering powdery mildew
  • Identify San Jose scale-infested branches for later monitoring
  • Prune out fire blight in apple, pear
  • Prune out shothole cankers in peach, nectarine

Bud Stages

Although Mother Nature granted us a few warm days this past week, we are still behind on development and degree days by about 1-2 weeks.

Davis, Box Elder, Salt Lake, and Weber Counties:
Apples:  Green tip - 1/2" green
Apricots:  First bloom - Full bloom
Cherries:  Swollen bud
Peaches:  1/4" green - Pink
Pears:  Bud burst

Cache County:
Apples:  Silver tip
Cherries:  Swollen bud
Peaches:  Swollen bud
Pears:  Swollen bud

Grand County:
Apples:  Open cluster
Apricots:  Petal fall
Cherries:  Tight cluster
Peaches:  First bloom
Pears:  First bloom

Utah County:
Apples:  Green tip
Cherries:  Swollen bud
Peaches:  1/4" green
Pears:  Swollen bud - Bud burst

Insect and Disease Activity

Speckled Green Fruitworm: 

The speckled green fruitworm is the most common of the green fruitworms that occur in Utah and adult moths are emerging now.  They are stout, and reddish-brown in color.  It overwintered as a pupa in the soil and typically emerges in March to April to mate and lay eggs on both pome and stone fruit trees, as well as several ornamental species.  It can lay up to 300 eggs in one large cluster.  The eggs begin hatching during apple bloom or cherry petal fall. 

The young larvae feed on flowers and leaves while the older larvae can also feed on fruit (see above).  Damaged fruit can drop early or show deep sunken areas.  Injury looks similar to leafroller feeding, but is deeper.  There is just one generation per year.

Treatment:  Treatments used for other pests (codling moth, peach twig borer, etc.) will also take care of fruitworms.  Otherwise, use Bt (Foray, Dipel, etc.) or spinosad (Entrust, Success) at bloom during dawn or dusk.

Speckled green fruitworm fact sheet

Rosy and Green Apple aphids: 

Both of these aphids are beginning egg hatch now, but the green apple aphid (the most common aphid of apples) won’t increase significantly until the warmer summer months.  The rosy apple aphid is more of a problem in spring.  They inject a toxic saliva during feeding, causing curled leaves and stunted and deformed fruits (as shown above).  They migrate out of the apple orchard to weed hosts in late June and July.  Green apple aphids remain in the orchard for the entire season.

Treatment:  Delayed dormant (up to 1/2” green) oil (or oil plus Lorsban) will kill most overwintering eggs and emerging nymphs.

Apple aphid Fact Sheet

Peach Twig Borer

Peach twig borers spend the winter as a small larvae in galleries (hibernacula, shown below) within the tree cambium.  They emerge as leaves begin expanding to seek the first flush of new growth.   There they bore into the tip of shoots, causing the typical “shoot strikes.”  Later generations feed on the fruit. 

Treatment:  A pre-bloom application has been an effective means of controlling the overwintering larvae as they begin to stir.   This is a good time for control as it is made before bees and other pollinators are active.  Materials:  oil plus esfenvalerate (Asana for commercial; Ortho Bug-B-Gon or Ortho Max for residential), spinosad, malathion, sevin.

If twig borer was not a significant problem last year, then a pair of bloom-time applications of Bt at dusk (early bloom, and again at post bloom) are very selective, highly effective, and harmless to pollinators.

Some commercial growers also use mating disruption to help suppress peach twig borer, and is often used in conjunction with the delayed dormant and bloom-time applications.  It is most effective in orchards with low pest pressure, and in sites that are not adjacent to uncontrolled peaches.  Dispensers are hung at or just before biofix, or at 400-450 degree days (base 50) after March 1.

Peach twig borer Fact Sheet


Degree Days and Insect Development

Monitoring/Insect Activity

Pear psylla Adults active 31-99 DD; egg-laying at 40-126 DD (base 41)
San Jose scale Overwintering nymphs begin feeding at sap flow
Pearleaf blister mite Adults begin feeding at bud swell
Codling moth Hang traps at 100 degree days (base 50)
First flight at 190-260 DD
Rosy apple aphid  First egg hatch around 90 DD (base 50)
European red mite  First egg hatch around 135 DD (base 50)
Campylomma bug Egg hatch begins at first pink (apples)
White Apple Leafhopper Egg hatch begins at first pink

Degree Day Accumulations (March 1 - April 15)

County City Codling Moth, 
Peach Twig Borer
(base 50 F)
Western Cherry Fruit Fly
(base 41 F)
Box Elder Perry 50 165
Cache North Logan 30 105
  Providence 35 105
  Smithfield 30 105
Carbon Price 48 158
Davis Kaysville 61 202
Grand Castle Valley 174 380
Salt Lake SLC 32 115
  West Valley City 65 202
Tooele Erda 65 202
  Tooele 64 202
Utah Alpine 49 185
  Genola 72 228
  Lincoln Point --- ---
  Orem 58 190
  Payson 80 231
  Provo 58 190
  Santaquin 61 198
  West Mountain 62 167
Weber Pleasant View 28 122

Production Information

Using Mating Disruption to Control Codling Moth

The use of insect pheromones in orchards allows us not only to monitor for insect pests, but to manage them, as well.  Pheromones are chemicals that insects use to communicate with one another, and our interest is in the pheromones (of mostly moth species) that are released by females to attract males for mating.  These species-specific chemicals are synthesized and imbedded in a rubber lure to use on sticky traps to determine the presence and abundance of certain moth pests.  But when dispersed in large quantities over great distances, pheromones can also be useful in suppressing pest damage by preventing mating.  For the last 10 years, mating disruption (MD) has been a valuable tool for commercial apple and pear growers in suppressing codling moth damage.

Notice that “commercial growers” is written above.  That is because the use of mating disruption only works in orchards 10 acres in size or more, and the typical residential orchard is much smaller.  Mating disruption will not work on smaller orchards because it does not prevent mated females from neighboring locations from flying into the orchard.

How it Works

In a non-treated environment, the plume of “scent” that a female releases can be detected hundreds of yards away by males, and “hangs” in the air in such a way that the male can follow the scent through the plume, almost always zeroing in on the female.  When enough artificial sources of pheromones saturate the air, the probability of males finding females is significantly reduced.  They are unable to follow one specific plume, and wander for days.  When no mating occurs, injury to fruits is also reduced.

There are four theories presented by Michigan State University researchers of how males are prevented from finding females:

  1. Desensitization.  Imagine sitting in a room filled with cologne.  At first, you’re overwhelmed, but after several minutes, you grow “numb” to the smell and don’t notice it anymore.  This theory surmises that the moth’s brain is overloaded with information and can no longer process what to do about the pheromones.
  2. Sensory Imbalance.  The male moths cannot distinguish between the authentic and artificial pheromones.
  3. Camouflage.  The females’ pheromone is mixed with the artificial, and males are in essence “driving blind” to try and find the females.  They still sense pheromone, but cannot orient themselves to any particular direction. 
  4. Competitive Attraction or False-Plume Following.  The males are able to sense and follow various pheromone plumes for the duration of their lives.  But because there are so many plumes in a mating disruption treated orchard, they almost always are following the plume of an artificial dispenser. 

The competition theory holds the most weight in explaining how MD works.  The mating of males and females may not be completely disrupted, but is significantly delayed.  Eventually, some males will find females.  But by the time they meet (a delay of 2-3 days) the fecundity of the females is reduced by more than 50%.

Using Mating Disruption

Mating disruption programs should be considered as one tactic within the toolbox of pest management options.  In any orchard where there was codling moth injury in the past, supplemental cover sprays will be necessary.  You may wonder, “if I have to spray anyway, why pay for the mating disruption?”  It is a proven-effective component of an IPM program because, over time, it significantly reduces the overall target insect population.  (Getting all neighboring orchards of suitable size will speed this process along.)  Eventually, the number of sprays will be significantly reduced.  It is highly selective, and there are virtually no mammalian or environmental health risks.

The commercially available MD dispensers that are most commonly in use are placed in the orchard in a high number of points (200-400) per acre.  To prevent all mating, they should be hung in the orchard before biofix.  (Although it is imperative that growers get a biofix from a comparable, non-MD location to time supplemental sprays.)  These hand-applied dispensers should be placed as high as possible in each tree.

The standard brands (Isomate, Checkmate) utilize wires, clips, or circular twin tubes and are twist-tied or clipped directly onto branches.  These products last approximately 120 days, allowing for pest suppression for most of the growing season.  Isomate CTT (Pacific Biocontrol) is a more concentrated formulation and is applied at 200 points/acres. 

Results of Mating Disruption Studies at Washington State University

  • New products that are in the form of pheromone-impregnated flakes or fibers, (Suterra Checkmate CM-F, Sentry NoMate CM Fiber, Hercon Disrupt Micro Flakes CM) that are applied at high densities (20,000-40,000/acre) with specialized equipment do not perform as well as hand-applied dispensers.  More modifications are needed on these products.
  • As the density of hand-applied dispensers is reduced, the risk of crop injury increases.  Caution should be taken when reducing rates of hand-applied dispensers below the recommended rate per acre, especially under moderate to high pressure situations.
  • A new product (Trece Cidetrak) is the first hand-applied dispenser that is comparable to, or slightly better than, the industry standard (Isomate C-plus).  This may be a promising new product for Utah.  The pheromone in any mating disruption product breaks down in UV light, occurring more quickly in our high altitudes.  This product claims to break down more slowly than others.

Other Methods

  • “Attract and Kill” involves applying droplets of pheromone to foliage by hand (Last Call CM, Aptiv, Inc.) and also contain pyrethroids to kill attracted males.  Research in Utah showed poor results of this product, with close to 20% injury.
  • High-emission dispensers such as aerosol “puffers” (i.e., Puffer CM and Puffer OFM from Suterra LLC.) or polymer bags loaded with large doses of pheromone (i.e., MSTRS OFM from AgBio Inc., Ames, IA).  Not enough is known about these products in Utah.
  • A new wax product called SPLAT (ISCA Technologies) that is sprayed with specialized equipment at the rate of about 5 acres/hour, 100 drops/tree.  Not tested in Utah.

Monitoring in a MD Orchard

Growers should continue to monitor for codling moth during the season to evaluate the effectiveness of the mating disruption, and to determine if supplemental sprays are needed.  Two types of lures, a “megalure” (also called 10x) releases more pheromone than the typical lure so that it is still attractive to males.  Another lure called the DA-combo is a combination of the megalure and a synthetic pear ester.  The pear ester is easily distinguished from the pheromone by males and females, and both sexes are attracted to this lure.  Although research on action thresholds in Utah is ongoing, we currently recommend treatment when 5 moths have been caught with either type of lure.

In tree fruits, mating disruption pheromone materials are also available for other insects besides codling moth:  oriental fruit moth, peachtree borer, peach twig borer, and some leafroller species. 

 Bud Phenological Stages

 1/2-inch green Pink (open cluster)
1/4-inch green First bloom
Swollen bud  Bud burst
Swollen bud First bloom
First bloom  

Spray Materials - Commercial Applicators

For dormant and delayed-dormant timing

Target Pest Host  Chemical Trade Names  Amount per acre REI         Comments 
San Jose scale pome and stone fruits  hort. oil alone or with: 
lime sulfur

6-12 gal varies

12 h
2-14 d
good coverage essential; oil plus Esteem has shown good results
Aphids apple, cherry, peach hort. oil alone or with:

6 gal

4 pints

4 d
good coverage essential
Peach twig borer peach, nectarine, apricot hort. oil with:


6-8 oz
4-8 oz
3-7 oz

12 h
4 h
4 h
Pear psylla pear  hort. oil with: 
lime sulfur
kaolin clay

4-6 gal
3 qt
1 pint
11 gal
see label
2.5-5 oz
12 h

4 h
12 h
1 d
good coverage essential 

Surround (organic) must be applied up to 3 times before first bloom.
Pearleaf blister mite  pear  hort. oil with:
4 gal
4 pints
 4 h
12 h 
Coryneum blight (shothole) stone fruits

copper sulfate
fixed copper




COCS, Kocide 
Echo, Bravo


3-4 pints

6-8 lbs
1 d 

1 d

12 h

48 h
copper can be injurious to plant tissues; fixed copper less so.  Do not use after green tip stages.  Be sure tank is always agitated during sprays.
Fire blight apple, pear  fixed copper many  varies  1 d  do not apply copper after green tip stage because fruit russetting may result

 Spray Materials - Residential Applicators


Note that these treatments are only recommended if you know you have the particular pest in your trees.

Delayed-dormant timing

Target Pest Host Chemical Trade Name                                           Comments
San Jose scale, aphids pome and stone fruits hort. oil alone or with: 

Ortho bug-b-gone, Max
Bug stop, Spectracide
Peach twig  borer peach, nectarine, apricot hort. oil with:

Ortho products
Green Light
Pear psylla pear hort. oil with:
kaolin clay
Ortho bug-b-gone, Max
Bug stop, Spectracide
Best to treat before egg-laying and when adults are detected. 

Surround (organic) must be applied up to 3 times before first bloom.
Pear blister mite pear hort. oil with:
lime sulfur
Only a single application is needed
Coryneum blight (shothole) stone fruits copper sulfate
fixed copper

do not apply copper after green tip stage because fruit russetting may result

Precautionary Statement:  All pesticides have benefits and risks, however following the label will maximize the benefits and reduce risks. Pay attention to the directions for use and follow precautionary statements. Pesticide labels are considered legal documents containing instructions and limitations. Inconsistent use of the product or disregarding the label is a violation of both federal and state laws. The pesticide applicator is legally responsible for proper use.  Any mention of a pesticide brand in this document is not an endorsement by USU, and brand lists are not all-inclusive.