August 20, 2007

Mark & Karen Burkhart, Dave Cox, Gus White – Knouse Foods Cooperative, Inc.
Cristy Christie and Robert Cheves – Gourmet Central
Alan Gibson & Scott Beard – Ridgefield Farm and Orchard
Levels Fire Hall
J. D. Rinehart & family – Rinehart Orchards
Virginia Tech’s Alson Smith Agricultural Research and Extension Center 

Adams County Nursery, Inc. – Phil Baugher
Arden Equipment Repair, Inc. – LeRoy Shade
Arysta LifeScience – Alan Kurtz
BASF – Gar Thomas
Bayer CropScience – Rick Love
CBC (America) Corp. – Greg Stamm
Cerexagri-Nisso – John Miller
Chemtura USA Corporation – Raymond Choban
DuPont Crop Protection – Dave McAuliffe
Dow AgroSciences – Patti Schurr
Durand-Wayland, Inc. – Ron Shrum
Gowan Company – David Pieczarka
Knouse Foods Coop., Inc. – Dave Cox
Syngenta Crop Protection, Inc. – Chris Munsterman
UAP – Larry Dell
Winchester Equipment Co. – Doug Rinker

ENTOMOLOGY

Tufted apple bud moth second generation egg hatch is estimated at 63% complete through August 19, based on an accumulation of 2688 degree days (DD) since biofix on May 11 at the WVU KTFREC. The stage of development through August 19 based on DD accumulations is one day behind last year.   Based on forecasted temperatures, second generation egg hatch is expected to reach completion about Aug. 29. For most effective control of late season larvae, recommended options include Intrepid, Rimon, Proclaim, SpinTor, and pyrethroids (Asana, Battalion, Baythroid, Danitol, Decis, 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 estimated at 5% complete through August 19, based on an accumulation of 2258 DD since biofix on May 5. Insecticides should be applied for third generation control as soon as possible, if not already completed, in those orchards where the pheromone trap capture has exceeded 5 moths/trap/week. Recommended control options include  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).  Maintain spray intervals on a 2 week (complete) or 5-7 day (alternate-row-middle) schedule for as long as the trap threshold is exceeded. The percent of this generation that completes egg hatch, and the potential for late season fruit injury by larvae is 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, nighttime temperatures, especially in September, may be too cool for mating and egg-laying. 

Oriental fruit moth fourth generation eggs will be hatching during the remainder of this month and 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 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 during the past 5 or so years.  Because injury resembles the physiological disorder cork spot, it has probably occurred at low levels and been misdiagnosed for quite a few years.  Reasons for the recent increase in injury are not completely understood, but changes in chemistries used for pest management (substitution of Intrepid and neonicotinoids for organophosphates and Lannate) and possible resistance are believed to be contributing factors.  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.  Although the injury 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 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.

Insecticide	PHI (days)
Asana	21
Assail	7
Avaunt	14
Azinphos-methyl (Guthion)	14a
BT	0
Battalion	21
Baythroid	7
Calypso	30
Carpovirusine	0
CheckMate OFM-F	0
Clutch	7
Cyd-X	0
Danitol	14
Decis	21
Imidan	7
Intrepid	14
Lannate	14
Proaxis	21
Proclaim	14
Rimon	14
Sevin	3
SpinTor, Entrust	7
Warrior	21

^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

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.

PLANT PATHOLOGY

Infection periods.  We recorded two new infection periods since the last Orchard Monitor on August 6 (Table 2). Total rainfall for August is 1.62 inches (and increasing at the time of this writing) at KTFREC. In the two-week period from August 6 through August 20, we accumulated 41 additional wetting hours for a total of 368 (AWH = 487 last year at this time). Normal rainfall (65-year average) for August is about 3.9 inches.

Control failures with sooty blotch and flyspeck 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 for accumulating 270 wetting hours. Maintaining fungicide coverage at normal, extended intervals will protect apple fruit from summer diseases as long as we remain in the dry weather pattern we've been experiencing so far this season. Be prepared to change your fungicide strategy if our weather pattern changes significantly.

Table 2. Dates and conditions for infection periods at the WVU - KTFREC, 2007.

See our “Current Conditions” Web page for details that are updated at least three times weekly.

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.

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