August 25, 2008
|Upcoming Events||Meeting Hosts & Sponsors||Pheromone Trap Counts||Plant Pathology|
September 1. – The West Virginia University Kearneysville Tree Fruit Research and Education Center will be closed in observance of Labor Day.
September 10, 8:00 a.m. – noon. – Chemical Evaluation Field Day at WVU’s Kearneysville Tree Fruit Research and Education Center. Pesticide Industry Representatives, Agricultural Research and Extension Personnel, Consultants and other interested persons are invited to tour research plots and obtain preliminary results from evaluations of acaricides, insecticides and fungicides on apples and peaches. For more information contact the WVU-KTFREC at 304-876-6353.
September 24, 10:00 a.m. – 3:00 p.m. – What’s Happening in Precision Agriculture Field Day at Drilake Farm, Charles Town, W. Va. For more information and to register (by September 22), contact Craig Yohn at 304-728-7413 x0 or by email at Craig.Yohn@mail.wvu.edu.
MEETING HOSTS & SPONSORS
2008 Fruit Grower Meeting Hosts
Bill and Todd Butler – Butler
Cristy Christie and Robert Cheves – Gourmet Central
Eli Cook – Spring Valley Farm and Orchard
Bill Gardenhour – Gardenhour Orchards
Mark and Laura Glascock – Glascock’s Farm
USDA Appalachian Fruit Research Station
2008 Fruit Grower Meeting Sponsors
Arysta LifeScience – Alan Kurtz
BASF – Gar Thomas
CBC (America) Corp. – Greg Stamm
Dow AgroSciences – Patti Webb
Durand-Wayland, Inc. – Ron Shrum
Gowan Company – David Pieczarka
Helena Chemical Company – Todd Metzger
Knouse Foods Coop., Inc. – Dave Cox
Suterra – Mark Shannon
UAP – Larry Dell
United Phosporus – John Miller
Valent USA – Hal Blackmore
Winchester Equipment Co. – Doug Rinker
Belt™ (flubendiamide) insecticide from Bayer CropScience received EPA registration in early August for use on pome and stone fruits for the control of Lepidopteran larvae (codling moth, lesser appleworm, green fruitworm, and leafrollers). Belt belongs to the phthalic acid diamide chemical class, and is primarily active through larval ingestion by causing a disruption of calcium balance in insect muscle cells, resulting in rapid paralysis. Formulated as a 4SC (suspension concentrate), application rate ranges from 3-5 fl oz per acre on pome fruits (100 GPA minimum spray volume), and 3-4 fl oz per acre on stone fruits (50 GPA minimum spray volume). Because Belt is chemically related to Altacor, these two products should not be rotated against successive generations of the same Lepidopteran pest in order to avoid the development of resistance. Restrictions include a seasonal maximum of 3 applications and 15 fl oz per acre on pome fruits and 12 fl oz per acre on stone fruits; restricted-entry interval (REI) of 12 hours; and pre-harvest interval (PHI) of 14 days on pome fruits and 7 days on stone fruits.
Tufted apple bud moth second generation egg hatch is estimated at 67% complete through August 24, based on an accumulation of 2716 degree days (DD) since biofix on May 4 at the WVU-KTFREC. The stage of development through August 24 based on DD accumulations is 3 days behind last year. Based on forecasted temperatures, second generation egg hatch is expected to reach completion about September 3. For most effective control of late season larvae, recommended options include Altacor, Belt, Delegate, Intrepid, Proclaim, Rimon, SpinTor, and pyrethroids (Asana, Battalion, Baythroid, Danitol, Decis, Lambda-Cy, Mustang Max, Proaxis, Warrior). Orchards should be inspected over the next few weeks for larvae and/or injury. In addition to causing surface injuries, late season larvae that are not controlled are often found feeding in the calyx end of fruits, which can result in load rejection by processors. Larvae inside the calyx may also survive the dump tank and packing process of fresh fruit, and can result in rejection of fruit loads if found in packed fruit.
Codling moth third generation egg hatch is just beginning, estimated at 3% complete through August 24, based on an accumulation of 2201 DD since biofix on May 2. Insecticides should be applied for third generation control this week, if not already completed, in those orchards where the pheromone trap capture has exceeded 5 moths/trap/week. Recommended control options include Altacor, Belt, Delegate, Azinphos-methyl (Guthion), Imidan, Assail, Calypso, Avaunt, Intrepid (12-16 oz/acre), Rimon, Cyd-X, Carpovirusine or pyrethroids (see above; considered less effective against codling moth than tufted apple bud moth). Although third generation larvae can cause fruit injury and result in processor load rejections, they do not mature enough to survive the winter, and thus do not contribute to the population next year. The progression of third generation egg laying and hatch, and the potential for late season fruit injury by larvae are dependent upon weather conditions. Not only do temperatures influence egg hatch and larval development, but also moth mating and egg-laying. Even though daytime temperatures may be warm enough for egg hatch and larval feeding, hours when nighttime temperatures drop into the mid-50’s like we’ve recently experienced would be too cool for mating and egg-laying.
Oriental fruit moth fourth generation eggs will be hatching throughout September. In addition to populations that may already exist in apple orchards, third generation moths emerging in peach orchards will move to adjacent apple orchards because most peach fruits will have been harvested and shoots are no longer succulent for entry by larvae. Therefore, be aware that an apple orchard with a low population up to this point, could experience late season fruit injury if adjacent to an infested peach orchard.
As with codling moth, the best approach for the remainder of the season is to monitor the male moth population with pheromone traps. Initiate and maintain insecticide applications, as described for codling moth, in those blocks where the trap capture exceeds 10 moths/trap/week. Recommended control options include the same materials as for codling moth (except for Belt, Cyd-X and Carpovirusine), plus sprayable pheromone (CheckMate OFM-F). Orchards with a history of late season injury would be good candidates to receive sprayable pheromone during the last application of the season to provide 4-5 weeks of control (mating disruption).
Stink bugs have become an increasingly important pest complex causing late season injury to apples that resembles the physiological disorder cork spot. The stink bug complex attacking apple consists primarily of three species (brown, dusky, and green stink bugs) that cause most of the injury during August until harvest by puncturing maturing fruit. In addition, adults of brown marmorated stink bug, an introduced species that has been a nuisance in homes, were observed two weeks ago on apple trees in a commercial orchard in West Virginia. Although the injury caused by stink bugs can be confused with cork spot, Dr. Mark Brown, USDA entomologist has found that it differs in three ways: 1) the edge of the depression on the fruit surface from stink bug feeding is gradual instead of abrupt as in cork spot; 2) the corky flesh is always immediately beneath the skin in stink bug injury, but may not be in contact with the skin in cork spot; and 3) a puncture is present from stink bug feeding that is visible with at least 40x magnification.
Orchards most likely to experience stink bug injury are those with poor weed control that are adjacent to woods and/or weedy borders. Stink bugs are very difficult to manage because: 1) they are highly mobile; 2) have a broad host range, including many crops and broadleaf weeds; 3) move frequently between weed hosts and fruit trees; and 4) are therefore not continually exposed to insecticide residues for long periods of time. Pyrethroids (see above) are likely to provide the most effective control, followed by Lannate, Beleaf, and organophosphates (Guthion, Imidan). Depending upon the situation, spraying the border rows adjacent to woods may provide sufficient control. Improved weed management will also reduce stink bug injury.
Be sure to consider the preharvest interval (PHI) in Table 1 below when selecting management options for control of the above insects.
Table 1. PHI for insecticides on apple.
a21 days if over 2 lbs/acre.
Lesser peachtree borer and peachtree borer larvae can be controlled on peach and nectarine trees in the postharvest period (not necessary if pheromone mating disruption dispensers were applied earlier for adult control). For lesser peachtree borer (LPTB), inspect wounded areas on the upper trunk, scaffold limbs and branches to determine the average number of empty pupal cases per tree protruding from the bark. Also inspect wounds for evidence of larvae or fresh (amber colored) gum exudates mixed with wood borings and sawdust-like frass (excrement). Control is recommended if there are more than a total of 2 larvae or empty pupal cases per tree.
For peachtree borer (PTB), inspect the base of trees for an exudation of gum containing frass and sawdust, and examine the soil at or near the base of trees for cocoons and empty pupal cases. Control is recommended for trees up to 3 years old if any evidence of PTB infestation is detected. In older orchards, an average of more than 1 cocoon and/or empty pupal case per tree would warrant treatment.
Chlorpyrifos (various 4E products and Lorsban 75WG available) is the preferred choice for postharvest control of either borer species. Most effective control is achieved with a handgun application. For LPTB control, thoroughly wet all wounds on the trunk, scaffold limbs and small branches. For PTB control, thoroughly drench the lower trunk, allowing the liquid to pool at the base of the trees.
PHEROMONE TRAP COUNTS
WEST VIRGINIA UNIVERSITY KTFREC
|DATE - 2008||RBLR||STLM||OFM||CM||TABM||DWB||LPTB||PTB||AM|
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
AM = Apple maggot (in a commercial orchard in Kearneysville).
Infection periods and general disease update. We’ve recorded one additional infection period since the last Orchard Monitor on August 11, 2008 (Table 1). Our disease pressure has been low for the past two weeks, with many locations needing rainfall to help settle the dust. Our lone infection period occurred on August 14, with 17 hours of leaf wetness at an average temperature of 66° F and 0.56 inches of rain. Other locations experienced less rainfall with this frontal system, while some experienced more. Total rainfall for August to date is 1.61 inches (average for the month is 3.9 inches). Some of you told me in June that August would be dry. Please call me regarding September. Thanks.
Accumulated wetting hours. As of August 25, 2008, we have accumulated 509 wetting hours. Accumulated wetting hours are useful for predicting the appearance of sooty blotch and fly speck on nonsprayed fruit. Sooty blotch and fly speck were first observed on nonsprayed fruit during the week of July 7th. Control failures with sooty blotch and fly speck on apple occur either because of poor spray coverage during the latter part of the growing season or because trees were left unprotected through more than 270 hr of accumulated wetting during the preharvest interval. Because fungicide protection on fruit is exhausted after 2 inches of rain, fungicide sprays may be needed in late August and September if heavy rains occur with more than 25 days remaining before fruit will be harvested. Twenty-five days is a "worst-case" scenario, based on experience, for accumulating 270 wetting hours. Maintaining fungicide coverage at normal, extended intervals will protect apple fruit from summer diseases as long as we have a dry weather pattern; in a wet weather pattern spray intervals should be shortened and fungicide rates increased.
Bitter rot epidemic. An outstanding example of how devastating this disease can be was observed during the second week of August. The outbreak occurred mainly in Empire apples, but was also observed on Honeycrisp. The Empire apples were planned as PYO, but approximately 50% of the fruit were already on the ground with bitter rot lesions, and about 25% of the fruit in the trees exhibited active bitter rot lesions. These will be on the ground in the very near future. This particular orchard has had problems in the past with non-abscised mummies in the trees. Fungicide "wash-off" events (2 inches of rain or greater) occurred on July 13 and July 23, and these will likely play a major role in determining why disease levels were so high at this site.
Table 1. Dates and conditions for infection periods at the WVU - KTFREC, 2008.
Hours/ degrees F
31 hr/68° F
11 hr/71° F
READ THE LABEL CAREFULLY AND USE THE CHEMICALS IN ACCORDANCE WITH LABEL CAUTIONS, WARNING AND DIRECTIONS. REQUEST A MATERIAL SAFETY DATA SHEET (MSDS) FROM THE MANUFACTURER FOR EACH PRODUCT YOU USE.
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
TREE FRUIT RESEARCH AND EDUCATION CENTER
P. O. BOX 609
KEARNEYSVILLE, WV 25430-0609
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