WVU Extension Service: The Orchard Monitor: Committed to the Integration of Orchard Management Practices
May 15, 2006

Upcoming Events


Pheromone Trap Counts Plant Pathology



May 18, 6:00 p.m. - Tree Fruit Grower Twilight Dinner and Meeting at Gourmet Central (in Hampshire Industrial Park), Romney, W. Va.  Following dinner, seasonal updates will be provided by Extension Specialists from the WVU Kearneysville Tree Fruit Research and Education Center.  For more information contact the Hampshire County Extension Office at 304-822-5013.

May 29. - West Virginia University Holiday.  The WVU KTFREC will be closed in observance of Memorial Day.

June 1, 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 internal worms.  For more information contact the Frederick County Extension Office at 540-665-5699. 

June 6,  6:00 p.m. - Tree Fruit Grower Twilight Dinner and Meeting at George S. Orr and Sons Orchard, Arden, W. Va.  Take exit 13 off I-81 and follow Route 15 (King Street) west for 1.7 miles. Turn left onto Arden-Nollville Road (Route 30), travel 2.3 miles to a right turn at Orr's Farm Market sign, and proceed mile to the farm market.  Following dinner, seasonal updates will be provided by Extension Specialists from the WVU KTFREC, and a tour will be conducted by Mike and Mark Orr.  For more information contact the WVU KTFREC at 304-876-6353. 

June 8,  6:30 p.m. - Joint PA, MD and WV Fruit Grower Meeting at Allenberg Orchards, Smithsburg, MD. From Jefferson County, take WV-480 north through Shepherdstown, crossing the Potomac River onto MD-34. In Sharpsburg, turn left onto N. Church Streeet (becomes MD-65, Sharpsburg Pike). Follow MD-65 north until you intersect I-70 (about 10 miles). Take I-70 east for 5 miles to exit 35 (Smithsburg/Boonsboro, MD-66). Follow MD-66 north (left) towards Smithsburg for 5 miles. At the intersection of MD-66 and Smithsburg Pike/Jefferson Blvd. (MD-64), turn right. Proceed on MD-64 for about 1.5 miles (around the town of Smithsburg, through an intersection with MD-77) to a right onto MD-491. Proceed to Barth Spring Lane just ahead on the right. From Berkeley County, take I-81 north to I-70 east to exit 35 (Smithsburg/Boonsboro, MD-66). Follow MD-66 north (left) towards Smithsburg for 5 miles. At the intersection of MD-66 and Smithsburg Pike/Jefferson Blvd. (MD-64), turn right. Proceed on MD-64 for about 1.5 miles (around the town of Smithsburg, through an intersection with MD-77) to a right onto MD-491. Proceed to Barth Spring Lane just ahead on the right. The agenda will include an orchard tour, followed by brief presentations by Extension Specialists from PSU, Univ. of MD, and WVU.  For more information contact the WVU KTFREC at 304-876-6353.


Rimon (novaluron) from Makhteshim Chemical Works, Ltd (distributed by Chemtura USA Corporation) was recently granted a federal label for the control of codling moth, Oriental fruit moth, leafminers, and various leafroller species, and suppression of plant bug and white apple leafhopper on apple. It was available for use last year in West Virginia under a Section 24(c) supplemental label. Rimon is an insect growth regulator (IGR) that interferes with the insect's ability to form chitin, thus disrupting the molting process. It has demonstrated activity against the egg and/or immature stages of insects, depending upon species, and will not kill adults. Route of insect entry is primarily through ingestion, with some contact activity. Rimon is available as a 0.83EC and applied at the rate of 20-40 fl oz/acre, with a maximum of 4 applications (150 fl oz/acre) per season. Applications should be initiated at the beginning of oviposition or egg hatch, depending upon species, based on degree day accumulations after biofix (first sustained moth capture in pheromone traps). Rimon has a 12 hour restricted-entry interval (REI) and 14 day preharvest interval (PHI).

Codling moth hatch of first generation eggs is expected to begin on May 20-21, based on degree day accumulations since biofix (April 26) and forecasted temperatures at the WVU KTFREC, which is about a week earlier than last year.  Control is justified to prevent fruit injury  in those orchard blocks where the pheromone trap catch has exceeded 5 moths/trap/week.  The best timing for spray applications, based on degree day (DD) accumulations after biofix, depends on the insecticide used. Some materials (Rimon, Intrepid, Assail, Calypso) perform best when applications are initiated before the beginning of egg hatch. The ideal timing to initiate applications is 50-150 DD for Rimon and 150 DD for Intrepid, Assail and Calypso.  Through May 14, 163 DD have accumulated since biofix at the WVU KTFREC. Applications of Avaunt, Azinphosmethyl (Guthion), Imidan, Diazinon, Carbaryl (Sevin) or CM granulosis virus (Cyd-X, Carpovirusine) should be initiated at 250 DD (3% egg hatch), which is expected to occur on May 23-24. An initial spray should be followed by a second complete application in about 14 days (7-10 days for CM granulosis virus), or three additional alternate-row-middle applications 5-7 days apart (3-5 days apart for CM granulosis virus).  A third complete application or two additional alternate-row-middle applications of CM granulosis virus will likely be needed, depending upon pest pressure and the length of the egg hatching period. Codling moth fruit injury

Lesser peachtree borer adults have been emerging for about two weeks.  Moths are active during the day, with mating and egg-laying occurring soon after emergence.  Female moths are attracted to damaged and previously infested trees, and deposit eggs in cracks or under bark scales of wounded sites.  Eggs hatch in seven to ten days and larvae burrow, feed and develop in the inner bark and cambium tissue for 40 to 60 days.  An infestation of lesser peachtree borer is almost always associated with previously damaged trees.  The problem tends to be more severe in older orchards that have a greater incidence of Cytospora canker, winter injury, and pruning and other mechanical wounds.  Infestation occurs in these damaged bark areas from the ground to a height of about eight feet.  Although the majority of injury occurs in the upper trunk and scaffold limbs, small diameter branches also may be infested.  Larval feeding enlarges the wounded area, which eventually results in complete girdling of the trunk, scaffold limb, or branch.   The primary and earliest impact is a gradual decline in production on damaged limbs, which when girdled will break under a fruit load.  With time, tree loss will occur from trunk girdling.  Lesser peachtree borer feeding can also afford entry for disease organisms, eventually resulting in limb and tree death. 

In addition to monitoring adult emergence with a pheromone trap, inspect wounded areas on the upper trunk, scaffold limbs and branches when moth flight is increasing to determine the average number of empty pupal cases per tree protruding from the bark.  Treatment is recommended if there are more than a total of two larvae or empty pupal cases per tree for each of two generations.  Good control of adults can be achieved with an airblast sprayer application of a pyrethroid insecticide (Ambush, Asana, Baythroid, Pounce, Proaxis or Warrior) when moth flight is peaking, as determined with pheromone traps.  This strategy is not recommended however if mites are already present in the orchard, since pyrethroid use will increase mite populations.  An alternative, and more effective strategy, is to control the larval stage in late May to early June (1st generation) with a pyrethroid (if no mites) or Endosulfan (Thionex), and/or in August (2nd generation) with Lorsban 4EC or 75WG applied with a handgun to thoroughly wet all wounded areas.  Lorsban is best used after harvest since spray contact with fruit is prohibited.  Blocks that receive a pyrethroid application should be monitored closely for mite outbreaks.

Lesser peachtree borer adult
Lesser peachtree borer larvae and wood injury
Lesser peachtree borer empty pupal case

Rosy apple aphid was not adequately controlled during the prebloom period  in some apple orchards this year, and will require additional control measures to minimize fruit injury. In general, green tip to tight cluster applications of organophosphates performed better than pyrethroids, with pink applications of neonicotinoids (Assail, Calypso) providing the best control. 

There are usually three generations of rosy apple aphid on apple, with the second generation occurring two to three weeks after petal fall, and the third generation occurring by mid to late June. Reproduction extends from pink to about the third week of June, with the maximum period of reproductive activity occurring during the last week of May and first week of June. With each succeeding generation of aphids, a larger percentage of alate (winged forms) are produced which migrate from apple to the summer host, narrowleaf plantain. Populations are normally highest in the inner and upper parts of the apple tree canopy. However, this year populations are more abundant in the inner, lower parts of the canopy in most orchards. 

To assess the incidence of rosy apple aphid, make a 3-minute examination of 5-10 trees per block and count the number of fruit clusters showing curled leaves with live aphids. Pay particular attention to the lower, inner region of trees. Apply Provado, Actara, Assail, Clutch or Calypso if an average of one or more infested fruit clusters per tree are found.

Rosy apple aphid infested fruit cluster


March 20 0
March 27 29 0 0
April 3 155 920 38
April 10 105 1600 39
April 17 90 2820 224 0
April 24 20 1064 239 2 0 0
May 1 14 293 224 7 5 0 2
May 8 4 120 85 47 40 0 35
May 15 1 57 29 20 34 7 25

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 two wetting periods since the last newsletter on May 1st. Infection period #4 occurred on May 8 - 9 and was accompanied by 0.18 inches of rain and lasted for 19 hours at 51 F. Infection period #5 was accompanied by 0.91 inches of rain and lasted for 25 hours at 56 F. Infection period #'s 4 and 5 were the first infection periods in our area to occur after the appearance of visible scab lesions, which were first observed at WVU-KTFREC on May 9. The first lesions were most likely due to infections that occurred during infection period #3 back on April 21-23.

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
3. April 21-23 34 hr/54 F
4. May 8-9 19 hr/51 F
5. May 11-12 25 hr/56 F
6. May 15 In progress

Cedar-apple rust and quince rust.  Weather conditions on April 21 - 23 were favorable for the rust diseases. Apple leaves that were 4 to 8-days old at the time of infection are most susceptible to the cedar - apple rust fungus and these leaves are now showing tiny rust lesions. The lesion on the upper leaf surface contains the pycniospore stage of the rust fungus. The pycniospores function as spermatia and when mated with a compatible mating type will lead to the formation of the aeciospore stage on the underside of the leaf later this summer. The aeciospores will infect eastern red cedar when weather conditions are favorable, and then about 18 months later, galls on cedar will provide the inoculum in spring 2008. Quince rust causes dark green lesions and puckering at the calyx end of infected fruits. Aeciospores of the quince rust fungus are produced on fruit and often are visible by mid-June.

Fire blight.  Conditions favorable for fire blight occurred on April 14, 21, and 23 as described in the last newsletter. We had a couple close calls with sporadic warmer temperatures in the past two weeks, although no new infection periods were recorded because wetting did not occur (check your records for May 4 and 5 - if you had wetting on those dates it is likely that a fire blight infection occurred). Generally cool conditions to date have made this a relatively easy fire blight season so far. See our "Current Conditions" Web page for details that are updated at least three times weekly during the bloom period.

Brown rot of stone fruits.  Here's something to think about. How would you manage brown rot if you could no longer rely on the sterol-inhibitor class of fungicides (Indar, Orbit, Elite) for disease control? This is what growers in some parts of New York and Georgia are dealing with this season, so it is potentially a problem on the horizon for us. There are a couple of things we can do to slow the development of resistance, including: 1) don't use this class of fungicides at both the bloom stage and the pre-harvest stage; this use pattern accelerates the selection pressure on the resistant individuals in the fungus population; 2) consider a different strategy at the pre-harvest stage, perhaps using a strobilurin class material (Flint/Gem or Pristine) at 10-days preharvest, then followed up with the SI material. The strobilurin materials can be applied two times consecutively. Alternatively, if conditions are not highly favorable for brown rot development, use of Elevate or captan+Topsin-M would provide effective control until the stronger materials were brought in closer to harvest.


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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