WVU Extension Service: The Orchard Monitor: Committed to the Integration of Orchard Management Practices
April 17, 2006

Upcoming Events


Pheromone Trap Counts Plant Pathology



April 27, 6:00 p.m. - Tree Fruit Grower Twilight Dinner and Meeting at Gourmet Central (in Hampshire Industrial Park), Romney, W. Va.  WVU Extension Specialists will discuss early-season insect and disease management strategies.  For more information contact the Hampshire County Extension Office at 304-822-5013.

May 2, 6:00 p.m. - Tree Fruit Grower Twilight Dinner and Meeting at Nob Hill Orchards, Gerrardstown, W. Va.  The orchard is located on Reunion Corner Road (Route 51/1), 1.7 miles from Route 51 at Gerrardstown.  Following dinner, seasonal updates will be provided by Extension Specialists from the WVU Kearneysville Tree Fruit Research and Education Center, and a tour will be provided by the orchard owners, George and Susanne Behling.  For more information contact the WVU KTFREC at 304-876-6353.

May 4, 7:00 p.m. - Spring In-depth Fruit Meeting at Virginia Tech's Alson Smith Agricultural Research and Extension Center, Winchester, Va.  The agenda will include seasonal updates by VA Tech Extension Specialists and a presentation on apple thinning.  For more information contact the Frederick County Extension Office at 540-665-5699.


Oriental fruit moth adults have been captured in pheromone traps for over two weeks, with biofix set on March 31 (11 days earlier than last year) at the WVU KTFREC.  Using a base temperature of 45F and upper temperature of 90F, degree days (DD) should be accumulated from biofix in order to properly time spray applications.  Pheromone traps should be monitored on a weekly basis to determine if control is needed.  Control of the first generation is justified where the pheromone trap capture exceeds 15 moths/trap/week in peach and 30 moths/trap/week in apple.  In peach, an application of pyrethroid, azinphosmethyl (Guthion), or Imidan is recommended at 170-195 DD (10-15% egg hatch, normally about shuck split).  A second application at 350-375 DD (55-60% egg hatch) may be needed if pest density is high.  In apple, control with an application of Assail or Calypso at 250-275 DD (25-30% egg hatch, normally petal fall), or Avaunt, azinphosmethyl (Guthion) or Imidan at 350-375 DD, (55-60% egg hatch).  Through April 16, 181 DD (12% egg hatch) have accumulated since biofix at the WVU KTFREC. Oriental fruit moth adult

Tarnished plant bug and stink bug adults overwinter under bark and leaves in woodlots, fence rows and rock breaks, and around alfalfa, other legumes or weeds that are seeded late in the summer or early fall.  They become active on warm spring days and begin feeding on peach and nectarine buds when they enter the pink stage of development.  Feeding injury from pink through petal fall causes bud, flower or fruit drop, and is usually of no consequence except in years of light crops due to winter freeze or spring frosts.  Feeding injury from shuck split until pit hardening results in fuzzless, corky, depressed areas and fruit deformity called "catfacing" injury.  Feeding on slightly larger fruits results in scarring injury, which is similar to catfacing injury but without deformity.

These pests are difficult to control because they are not  full-time residents on fruit trees, but move frequently between broadleaf weed hosts and fruit trees to cause injury.  Maintaining thorough and frequent spray coverage from shuck split until a few weeks after shuck fall is critical to minimizing fruit injury.  Pyrethroids (Ambush, Asana, Baythroid, Pounce, Proaxis, Warrior) are considered the most effective chemical class for control of these pests, but application after petal fall is more likely to result in mite outbreaks, and therefore they should be used with caution.  Other options include azinphosmethyl (Guthion), Imidan and Actara (higher rate).  Maintaining good broadleaf weed control will also reduce fruit injury from this pest complex.

Tarnished plant bug adultBrown stink bug adultCatfacing injuryScarring injury
Green peach aphid typically overwinters in this area as wingless females in protected places on the tree and in ground debris.  Aphid feeding on flower parts or on the underside of leaves is usually first observed during the late bloom to petal fall stage of peach and nectarine.  Infestations are often first detected on leaf clusters attached to the trunk or scaffold limbs in the lower part of the tree.  Feeding on leaves causes them to curl, become yellow, and drop prematurely from the tree.  Feeding on fruit may result in distortion, cracking and drop, especially on nectarine.  Provado and Actara are the most effective treatments and are recommended for control if more than an average of one colony per tree is found. Green peach aphid colony

Plum curculio is an important direct pest of both apple and peach, causing injury to developing fruit in the early postbloom period.  Adult beetles, which overwinter in hedgerows, trashy fields and woods, usually begin moving into orchards during the bloom stage.  Maximum activity occurs when temperatures reach 70F and above.  The primary injury results from egg-laying, consisting of a crescent-shaped scar on the fruit surface.  In apples that remain on the tree,   most   larvae   do   not  complete development as they are crushed by the expanding fruit.  Larvae successfully complete development in peaches and fallen apples.  Typically, most of the injury from this insect has occurred in apple blocks of mixed cultivars with a wide range in bloom periods.  Injury usually occurs on the earlier blooming varieties while waiting for the later blooming varieties to reach petal fall.  Recommended control options in peach include pyrethroids (Ambush, Asana, Baythroid, Pounce, Proaxis, Warrior), azinphosmethyl (Guthion), Imidan, Actara and Surround. In apple,  recommended options include azinphosmethyl (Guthion), Imidan, Avaunt, Assail, Calypso, Actara, and Surround.


Plum curculio adult

Plum curculio fresh egg-laying injury

European apple sawfly is a localized problem that has increased in some orchards over the past few years.  Adults begin emerging from the soil at pink and females deposit eggs in the calyx end of young apple fruit from bloom through petal fall. Tunneling by the hatching larva creates a large circular russeted scar that originates from the calyx.  The larva will typically leave the first fruit and tunnel to the core of a second fruit, consuming most of the flesh.  Frass (excrement) will protrude from these injured fruits which will later fall from the tree.  Where white visual traps have been used for adult monitoring, petal fall control is justified if the accumulated  prebloom and bloom capture reaches 3 or more per trap.  Where traps have not been used, control is recommended if fruit injury was observed last year.  Early petal fall timing usually provides effective control.  Where injury was severe last year, a bloom application is recommended.  Avaunt, Assail and Calypso may be used during bloom as long as bees are not foraging during application and sprays have sufficient time to dry before bees become active.  Petal fall options include these materials, or azinphosmethyl (Guthion), Imidan, Sevin, or Actara.

European apple sawfly injury on young appleEuropean apple sawfly injury on older appleEuropean apple sawfly larva in apple

Pheromone traps should be installed at this time for monitoring codling moth emergence, and during the last week of April for monitoring emergence of tufted apple bud moth, lesser peachtree borer, and dogwood borer.


March 20 0
March 27 29 0 0
April 3 155 920 38
April 10 105 1600 39
April 17 90 2820 224

RBLR = Redbanded leafroller; STLM = Spotted tentiform leafminer; OFM = Oriental fruit moth; CM = Codling moth; TABM = Tufted apple bud moth; DWB = Dogwood borer; LPTB = Lesser peach tree borer; PTB = Peach tree borer; AM = Apple maggot.


Apple scab.  We recorded one wetting period since the last newsletter on April 3rd. Infection period #2 occurred on April 8 and was initiated by 0.21 inches of rain and lasted for 14 hours at 49 F. Additional wet periods have been recorded but have not officially qualified as infection periods. On April 13, we recorded 0.09 inches of rain with a wet period lasting for 7.5 hours at 56 F (with 2 of these hours occurring at night). On April 16 - 17, we recorded a night-time wetting period of 8 hours at 53 F, followed by a day-time wet period of 6 hours at 49 F (estimated at the time of writing).

Table 1. Dates and conditions for apple scab infection periods at the WVU - KTFREC, 2006.

No. Date 2006 Hours/ degrees F
1. March 31 - April 1 10 hr/59 F
2. April 8 14 hr/49 F

The peak period of ascospore release usually occurs during the pink through petal fall stages of bud development, so now is the time to be using the most effective materials. Growers who suspect decreased effectiveness of the sterol-inhibiting fungicides (Nova, Rubigan, Procure) may want to consider using the strobilurin class of materials (Flint, Sovran, Pristine) for two applications at this time.

Fire blight.  Conditions favorable for fire blight occurred on April 14 and 15, if wetting occurred on those days. On April 14, we recorded 0.03 inches of rain and 2 hours of wetting at 60 F. We did not record any wetting on April 15, but wetting did occur in some locations. On April 16, we recorded 0.02 inches of rain; however temperatures were a few degrees below those that favor infection. The long range weather forecast predicts cooler temperatures through the end of the month, which should reduce considerably the risk for fire blight infections. Always be aware that fire blight risk can increase rapidly with warm temperatures and wetting. See our "Current Conditions" Web page for details that are updated at least three times weekly during the bloom period.

Streptomycin reminders: For best blossom blight control, apply Streptomycin just before an anticipated infection, then re-apply it in 4 days if high risk conditions persist. High risk occurs with any combination of three out of the following four criteria: 1) blossoms open, 2) bacteria present on blossom surface, 3) average temperature for the day of 60 F, and 4) sufficient moisture in the form of rain or dew. Note that infection of susceptible cultivars is very likely to occur if all four of these criteria are satisfied. Streptomycin applied after infection can provide acceptable control, however the level of control that is achieved declines with time and declines more rapidly as temperature increases.

Avoid alternate-row-middle programs for fire blight control. If this method is used and if infection conditions occur after the first half spray, follow immediately with the second half spray of streptomycin. Do not exceed 3 to 4 antibiotic sprays per year in order to minimize the chance that the fire blight bacterium will develop resistance to streptomycin. Make blossom treatments strictly on whether an infection is expected or has occurred, not on how severe that event might be.

Peach scab and Rusty spot.  The shuck split - shuck fall stage is the time to initiate fungicide applications for managing these diseases on peaches and nectarines. Follow instructions in the 2006 Spray Bulletin for the selection of spray materials for these diseases. For scab control, remember that Bravo is highly effective but is not labeled for applications after the shuck fall stage. Control of rusty spot will be facilitated by adequate control of powdery mildew in adjacent apple orchards.

Current Conditions.  Fruit producers with access to the World Wide Web can access a web page called "Current Conditions" that will provide daily (or "as-needed") updates on current disease and insect development issues.  The page should help to bridge the information gap between issues of The Orchard Monitor and provide the grower with the timely information that is needed for making good pest and disease management decisions.

To view the "Current Conditions" page, click here, or go to the WVU - KTFREC Home Page at: http://www.caf.wvu.edu/kearneysville/wvufarm1.html and select "Current Conditions" from the menu.


Trade and brand names are used only for the purpose of information, and the West Virginia University Extension Service does not guarantee nor warrant the standard of the product, nor does it imply approval of the product to the exclusion of others which may also be suitable. The West Virginia University Extension service assumes no responsibility in the use of hazardous chemicals.

Individuals requesting an accommodation at a meeting because of a disability should contact one of the Extension Specialists at the WVU Kearneysville Tree Fruit Research and Education Center at 304-876-6353 at least five days prior to the event.

Helping you put knowledge to work

P. O. BOX 609
PHONE:  304-876-6353
FAX:  304-876-6034
WEB:  www.caf.wvu.edu/kearneysville

The West Virginia University Cooperative Extension Service, U.S. Department of Agriculture, West Virginia County
Boards of Education and County Commissions Cooperating.  Equal Opportunity / Affirmative Action Institution

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