WVU Extension Service: The Orchard Monitor: Committed to the Integration of Orchard Management Practices
July 28, 2008

Upcoming Events

Entomology

Pheromone Trap Counts Plant Pathology Horticulture

 

UPCOMING EVENTS

August 12, 6:00 p.m. – Twilight Fruit Growers Dinner and Meeting at Glascock’s Farm, 5381 Highland Ridge Road, Berkeley Springs, W. Va. To reach the farm from Martinsburg, take Route 9 West to Berkeley Springs; turn left onto Route 522 South and travel 2 miles to a left onto Winchester Grade Road; travel 5 miles to a left onto Eppinger Road; travel 1 mile to a T and turn right (continue on Eppinger Road); travel 1 mile to another T and turn right; travel mile to a brick home on the left. The agenda will include a fried chicken and corn-on-the-cob dinner, seasonal updates by WVU Extension Specialists, and a tour of vegetable and fruit production for direct marketing by hosts Mark and Laura Glascock. For more information contact the WVU-KTFREC at 304-876-6353. 

August 14, 4:00-7:00 p.m. – Twilight Fruit Growers Meeting at Virginia Tech’s Alson Smith Agricultural Research and Extension Center, Winchester, Va.  The agenda will include a tour of 2008 research plots, seasonal updates by VA Tech Extension Specialists and a catered supper.  For more information contact the Frederick County Extension Office at 540-665-5699.

ENTOMOLOGY

Oriental fruit moth hatch of third generation eggs continues and is estimated at 28% complete through July 27, based on an accumulation of 2290 DD since biofix of first brood moths on April 10 at the WVU-KTFREC.  Based on degree day accumulations since biofix, egg hatch at this time of the season is the same as last year. Refer to the July 14 issue of The Orchard Monitor newsletter for control options and timing in those apple and peach orchards where the pheromone trap capture has exceeded 10 moths/trap/week. 

Codling moth hatch of second generation eggs continues and is estimated at 54% complete through July 27, based on an accumulation of 1609 DD since biofix of first brood moths on May 2 at the WVU-KTFREC.  Based on degree day accumulations since biofix, egg hatch at this time of the season is estimated to be only one day behind last year. A second complete insecticide application approximately 2 weeks (300-400 DD) after the initial application, or up to four alternate-row-middle applications, 5-7 days apart, are recommended in those orchards where the pheromone trap capture has exceeded 5 moths/trap/week.  Options include Altacor, Delegate, Azinphosmethyl (Guthion), Imidan, Rimon, Intrepid, Esteem, Assail, Calypso, or Avaunt. CM granulosis virus (Cyd-X, Carpovirusine) is another option that is only recommended as a complete spray every 7-10 days for a total of 3-4 applications. 

Tufted apple bud moth adult emergence (second flight) has just begun.  This would be a good time to assess fruit injury from first brood larvae to aid in developing the specific program needed for second brood control.  In orchards with very little, if any, fruit injury and low second flight trap captures, a combination of Lannate plus organophosphate [Azinphosmethyl (Guthion) or Imidan], or BT would probably provide sufficient control of second brood larvae.  Higher levels of fruit injury and/or trap captures would require one or more applications of Altacor, Delegate, Intrepid, Rimon, SpinTor, or Proclaim to minimize second brood fruit injury.

All materials will perform best if spray applications are timed to coincide with egg hatch based on degree day accumulations.  For organophosphate + Lannate combinations, or BT, make two complete applications at 2280-2355 DD (10-20% egg hatch) and 2665-2740 DD (60-70% egg hatch), or four alternate-row-middle applications at 7-day intervals, beginning at 2210 DD (1% egg hatch).  For Altacor, Delegate, Intrepid, Rimon, SpinTor, or Proclaim make an initial complete application at 2355-2435 DD (20-30% egg hatch), and then again at 2665-2740 DD (60-70% egg hatch) where pest pressure is high.  If alternate-row-middle application of these materials is planned, begin at 2280 DD (10% egg hatch) and repeat at 7-day intervals for up to four applications, depending upon pest pressure.  Through July 27, 1982 DD have accumulated since biofix of first brood moths on May 4 at the WVU-KTFREC.  Based on forecasted temperatures, second brood egg hatch is predicted to begin on August 4.

Brown stink bug on peach

Stink bugs can pose a threat to peach and nectarine near harvest. Feeding on fruit often results in the exudation of gum in droplets or strings. Although this injury is usually of no direct consequence, it does provide a wound for the entry of brown rot that can result in significant losses under favorable environmental conditions. Occasionally, late season feeding may be expressed as darker green “water-soaked” areas on the fruit surface, which can result in downgrading. A third type of injury is often not evident until harvested fruit are brought out of storage, which consists of small, tan-colored, surface depressions with internal tissue breakdown. This injury can result in losses after fruit are shipped for sale. 

Pyrethroid insecticides, followed by Lannate and Beleaf, are considered the most effective control options to prevent this late season injury. The following days to harvest limitations should be considered when selecting these materials for stink bug management: Ambush [14], Asana [14], Beleaf [14], Lambda-Cy [14], Perm-UP [14], Pounce [14], Proaxis [14], Warrior [14], Baythroid [7], Tombstone [7], and Lannate [4 on peach, 1 on nectarine]. Pyrethroids are most likely to result in an increased mite population during harvest, and/or a higher incidence of overwintering mite eggs.

Gummosis and water-soaked injuries on peach

San Jose scale second generation crawler emergence should be monitored over the next 4-5 weeks in those blocks in which greater than 1% of the fruit was injured at harvest last season.  Monitor crawler emergence by wrapping black electrician’s tape (sticky side out) around tree limbs that are encrusted with dark scale coverings.  A thin film of petroleum jelly may be spread on the tape surface to enhance crawler capture.  An alternative approach is to cover the black electrician’s tape (wrapped with sticky side against the branch) with double sided cellophane tape.  Inspect the tape traps twice weekly for the bright yellow crawlers, and apply Esteem, Centaur (only one application per season), Diazinon or Provado as a high volume spray when emergence is first detected and again in 10-14 days.  Adequate coverage of the tops of trees is critical to control of this insect.

San Jose scale injury on apple

PHEROMONE TRAP COUNTS
WEST VIRGINIA UNIVERSITY KTFREC

DATE - 2008 RBLR STLM OFM CM TABM DWB LPTB PTB AM
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 0
April 28 33 392 329 3 0 0
May 5 12 114 210 19 3 0 1
May 12 1 114 138 14 16 0 12
May 19 1 37 51 30 31 1 38
May 27 0 17 78 31 36 7 36
June 2 0 448 20 24 46 4 16 0
June 9 46 1504 13 19 42 27 27 0
June 16 127 1520 13 15 2 17 24 1
June 23 88 1792 45 9 8 6 12 2
June 30 43 1344 65 6 1 12 9 2 0
July 7 25 456 57 6 0 21 3 2 0
July 14 12 512 43 13 0 9 7 2 0
July 21 21 576 28 31 1 20 1 2 1
July 28 44 340 12 26 2 8 5 2 2

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 and general disease update. We’ve recorded two additional infection periods since the last Orchard Monitor on July 14, 2008. Our disease pressure has been fairly low for the past two weeks, with some locations actually needing rain. On July 22, we had leaf wetting for 10 hours at 68 F with 0.10 inches of rain. On July 23, we had leaf wetting for 10 hours at 68 F with 0.18 inches of rain (this infection period is in progress at the time of this writing, so the details will probably change). Total rainfall to date for July is 4.24 inches (normal for the month of July is 3.3 inches). These most recent infection periods are favorable for the development of apple summer diseases. Looking ahead to August, normal rainfall (65-year average) for that month is about 3.9 inches. For the period beginning March 1, 2008, to the time of this writing, we are at 10.08 inches of above-normal rainfall.

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, 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.

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

No.

Date 2008

Hours/ degrees F

27.

July 4

8 hr/68 F

28.

July 4-5

19 hr/68 F

29.

July 5-6

12 hr/67 F

30.

July 6-7

12 hr/69 F

31.

July 7-8

14 hr/67 F

32.

July 13-14

19 hr/70 F

33.

July 22

10 hr/68 F

34.

July 23

10 hr/68 F

Accumulated wetting hours – threshold reached.  As of July 23, 2008, we have accumulated 392 wetting hours for a petal fall date of May 3 (last year at this time AWH = 258). Accumulated wetting hours are useful for predicting the appearance of sooty blotch on nonsprayed fruit. Symptom development for these diseases is highly dependent upon temperature and moisture conditions surrounding the fruit. The appearance of sooty blotch symptoms has been predicted with reasonable accuracy by using accumulated wetting hours (AWH). Visible signs of sooty blotch may appear following approximately 260 - 300 AWH (earlier in the season (260 AWH) if the disease was severe last year, later in the season (300 AWH) if not). The AWH threshold for making the decision to include Topsin-M in the spray program is 225 for high disease pressure and 275 for low disease pressure. Each of these threshold values presumes that 25 additional AWH will occur in the next 5 days after reaching the threshold. Sooty blotch was observed on nonsprayed fruit in research plots about 3 weeks ago (July 8) at the Winchester AREC.

HORTICULTURE

Perennial Weed Management.  This is a good time to apply systemic herbicides for perennial weed management in orchards.  A few perennial weeds noted during recent orchard visits were horsenettle, Virginia creeper, poison ivy, mugwort, and johnsongrass.  Most of these perennials should be actively transporting sugars to the storage organs currently, to ensure successful regeneration during the following year.   If systemic herbicides are applied at this time, the conducting vessels will transport the herbicide to these underground storage organs, hence providing better kill of these tissues.  Any glyphosate herbicide (several products) if applied at 2 to 3 lb active ingredient/acre should provide satisfactory control of these weeds.  The pre-harvest interval (PHI) of glyphosate in apple and pear is 1 day and can be broadcast applied on a calm day.  The PHI in peach, plum and nectarine trees is 17 days and can be applied only using a wick applicator.  Quality Metal Works (Tel: (309) 379-5311; website: www.qualitymetalworks.com/) manufactures wick applicators, but the shortest one they have in stock is 6’9” according to the manager (Ron).  It could be attached to an ATV or a tractor.  They would be able to manufacture shorter sizes (to make a pass on each side of trees), but it may take some time.  I have tested this weed wiper in pastures and hayfields, and it has worked well with 1 part glyphosate + 4 to 6 parts water depending on the herbicide formulation.  There is minimal drip if applied properly and on level ground.  The fluid may drip on one side if applied along slopes for a while.  This applicator also reduces the herbicide rate considerably per acre.  If you are broadcast-applying glyphosate to control broadleaf perennials, you may want to add 1- 2 pt of 2,4-D labeled for the crop to improve the control levels (do not add 2,4-D + glyphosate to the wick as the mixture may clog fabric pores of the wiper).  The herbicide sethoxydim (Poast) is also effective to control johnsongrass in non-bearing apples and pears (25 days PHI for other fruits).   Spot treat Poast 1.5 L at 2.5 pints product/A to control johnsongrass.   Apply when the grass reaches 18” tall.  Add a crop oil concentrate at 1 quart/A.  Repeat application is necessary if johnsongrass is well established.  Systemic herbicides work well when the growing conditions are optimal and where there is adequate amount of moisture in the soil.  With the frequent showers this summer, this may be a good time to apply such herbicides. (Rakesh S. Chandran, WVU Extension Weed Specialist and IPM Coordinator).


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


WEST VIRGINIA UNIVERSITY
TREE FRUIT RESEARCH AND EDUCATION CENTER
P. O. BOX 609
KEARNEYSVILLE, WV 25430-0609
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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