WVU Extension Service: The Orchard Monitor: Committed to the Integration of Orchard Management Practices
April 21, 2008

Upcoming Events


Pheromone Trap Counts Plant Pathology



April 24, 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 new pest management tools, and early-season insect and disease management strategies. Steve and Ruth Martin will discuss some fruit marketing web sites and their bramble plantings. For more information contact the Hampshire County Extension Office at 304-822-5013.

April 30, 6:00-8:00 p.m. – Meet the WV Commissioner of Agriculture candidates at West Virginia University, Room  1021 South Agricultural Sciences Building. Sponsored by the WVU Collegiate Farm Bureau and WV Farm Bureau. For more information contact wvufarmbureau@gmail.com or Cassie Brown at 304-588-2612.

May 1, 7:00-8:30 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 “fruit thinning strategies and other orchard management topics” by Dr. Rongcai Yuan.  For more information contact the Frederick County Extension Office at 540-665-5699.

May 6, 6:00 p.m. – Tree Fruit Grower Twilight Dinner and Meeting at Butler Farms, Inwood, W. Va. To reach the orchard, travel 1.7 miles south on Arden-Nollville Road from the junction with Tablers Station Road at Arden to the entrance on the right at the brown brick home, or travel 2.5 miles north on Arden-Nollville Road from Inwood to the entrance on the left. 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 our hosts, Bill and Todd Butler. For more information contact the WVU KTFREC at 304-876-6353.


Temprano (abamectin) from Chemtura was recently registered by the EPA for mite control on apple, pear, plum and prune. Containing the same active ingredient as Agri-Mek, Temprano is recommended as a preventative treatment for application within 2 weeks of petal fall at the rate of 10-20 fl. oz. per acre in combination with a horticultural spray oil. Temprano use restrictions include a seasonal maximum of 40 fl. oz. per acre, PHI of 28 days and REI of 12 hours.

Oriental fruit moth adult emergence was first detected at the WVU KTFREC on April 2, when two moths were captured in a single pheromone trap. No additional emergence was detected until April 10-11, when quite a few moths were captured in all traps. Biofix was set on April 10, which is 11 days earlier than last year and 10 days later than 2006.  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 appleIn peach, control options include Assail or Intrepid at 70-100 accumulated DD after biofix (1-3% egg hatch), then at 250-275 DD (25-31% egg hatch), if needed; or Imidan, Diazinon, pyrethroids (Ambush, Asana, Baythroid, Lambda-Cy, Mustang Max, Perm-UP, Pounce, Proaxis, Tombstone, Warrior), or Delegate at 170-195 DD (10-14% egg hatch, normally about shuck split), then at 350-375 DD (54-61% egg hatch), if needed.  In apple, control options include Rimon at 200-250 DD (15-25% egg hatch); or  Assail, Calypso, or Intrepid at 250-275 DD (25-31% egg hatch, normally petal fall); or azinphosmethyl (Guthion), Imidan, Diazinon, Delegate, or Avaunt at 350-375 DD, (54-61% egg hatch).  Through April 20, 121 DD (4% egg hatch) have accumulated since biofix at the WVU KTFREC.

Oriental fruit moth adult
EAS larval injury on young fruit EAS larval injury on older fruit

European apple sawfly 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, with options including Avaunt, Assail, Calypso, azinphosmethyl (Guthion), Imidan, Sevin, or Actara.

EAS larval tunneling in second fruit
Tarnished plant bug adultBrown stink bug adult

Tarnished plant bug and stink bugs overwinter as adults 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, Lambda-Cy, Mustang Max, Perm-UP, Pounce, Proaxis, Tombstone, 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 Beleaf, Thionex, Lannate, Imidan and Actara (higher rate).  Maintaining good broadleaf weed control will also reduce fruit injury from this pest complex.

Catfacing injuryScarring injury

Pheromone traps should be installed on May 1 for monitoring emergence of lesser peachtree borer in peach orchards.


March 17 0
March 24 6 0
March 31 31 17
April 7 98 376 2
April 14 74 2688 84
April 21 109 1152 376

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’ve recorded two additional infection periods since the last Orchard Monitor on April 7, 2008. On April 11 – 12, we had 16 hours of wetting at 62 F with 1.3 inches of rain. This infection period also may have been favorable for the rust diseases, although cedar-apple rust galls examined at this time were not fully mature. The second infection period on April 20 - 21 is still in progress, with rainfall amounts exceeding 4 inches at WVU-KTFREC, 1.5 inches at Three Churches, near Romney; 3 inches in Arden; and 2.1 inches at Ridgefield Farm. Wetting duration at WVU-KTFREC has exceeded 30 hours at an average temperature of 58 F. These conditions are highly favorable for apple scab and rust infections.

Apple scab ascospore maturity degree-day tracker: With a green tip estimate for March 31, 2008, estimated ascospore maturity is approximately 50% (90% confidence interval 21 to 80%) as of Monday, April 21, 2008.

Table 1. Dates and conditions for apple scab infection periods at the WVU - KTFREC, 2008.


Date 2008

Hours/ degrees F


March 31-April 1

17 hr/54 F


April 3-4

31 hr/46 F


April 11-12

16 hr/62 F


April 20-21

30+ hr/58 F

Cedar-apple rust and quince rust.  The wetting periods recorded on April 11 - 12 and April 20 - 21 were favorable for cedar-apple rust and quince rust infection.

Fire blight.  Warm weather on April 17 and 18 pushed apple development from the tight cluster stage into early bloom over the weekend of April 19 – 20. With rain beginning near midnight on April 20, and continuing through April 21, the Maryblyt model indicates that conditions were favorable for fire blight infection during the early hours of April 20. The 5-day forecast for April 22 – 26 shows a brief cooling trend followed by warmer temperatures (and high risk) later in the week, suggesting that later in the week may be a good time to apply streptomycin to protect newly opened blossoms. 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, especially if there is a history of the disease. 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. Try not to exceed 3 - 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 spray guide 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 control 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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