WVU Extension Service: The Orchard Monitor: Committed to the Integration of Orchard Management Practices
May 29, 2007

Upcoming Events NRCS - Tree Fruit IPM

Entomology

Pheromone Trap Counts Plant Pathology

 

UPCOMING EVENTS

May 31, 6:30 p.m. – Joint MD, PA, WV Twilight Fruit Grower Meeting at Rinehart Orchards in Smithsburg, MD. Take either I-81 north (Berkeley County) or MD-65 (Jefferson County via Shepherdstown and MD-34) to I-70 east. Take exit 35 – Smithsburg/Boonsboro off of I-70, then proceed north (left) for approximately 5 miles on MD-66 (Mapleville Road). Turn right at intersection of MD-66 (Mapleville Road) and MD-64 (Smithsburg Pike) at Cavetown (AC&T gas station on the right). Proceed on MD-64 for approximately 5.5 miles to intersection with MD-418 - Ringgold Pike (large dairy farm on right). Turn right onto MD-418 and proceed about 1.5 miles to a right turn onto Rinehart Road. Proceed to the packing house on the left at the corner of Rinehart and Mong Roads. The agenda will include a tour of the orchard and pesticide storage building by host J. D. Rinehart; summer insect management by Drs. Henry Hogmire and Greg Krawczyk; summer disease management by Drs. Alan Biggs, Anne DeMarsay, and Henry Ngugi; and small fruit culture and pest management by Dr. Joe Fiola. Recertification credits for pesticide applicator’s license will be provided. 

September 27-28. – Agri-tourism Conference at Lakeview in Morgantown, WV. More information will follow in a later issue of this newsletter.

NRCS - TREE FRUIT IPM PROGRAM

The WVU Extension proposal to obtain NRCS cost-sharing support for a Tree Fruit IPM Program in West Virginia, which was presented at the Winter Fruit Schools, was also presented at a meeting of the NRCS State Technical Committee in Morgantown on April 19. Since the meeting, no feedback on this proposal has been received from NRCS. If you support this proposal and wish to assist in moving it along, please contact Herb Andrick (Assistant Conservationist) at 304-284-7560 or at herbert.andrick@wv.usda.gov, and Rick Heaslip (Resource Conservationist) at 304-284-7579 or at richard.heaslip@wv.usda.gov.

ENTOMOLOGY

Lesser peachtree borer adults have been emerging for about 2 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. Control of the larval stage is recommended in late May to early June (1st generation) with a pyrethroid (if no mites) or Endosulfan (Thionex), and/or in August (2nd generation) with chlorpyrifos (Lorsban 4EC, Nufos 4EC, Lorsban 75WG) applied with a handgun to thoroughly wet all wounded areas. Chlorpyrifos 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 fresh wood injuryLesser peachtree borer larvae and wood injuryLesser peachtree borer empty pupal case

Tufted apple bud moth adults have been emerging since May 11 (biofix), which is 8 days later than last year.  First generation egg hatch is predicted to begin at 480 degree days (DD) after biofix, which should occur on June 3, based on an accumulation of 327 DD through May 28 and forecasted temperatures over the next week. 

The objective in controlling this insect is to apply sprays during the period of egg hatch, which are best timed by using DD accumulations (45F lower and 91F upper threshold temperatures) after biofix.  Options for controlling the first generation include Intrepid, SpinTor (Entrust), Rimon, Proclaim, BT, or an organophosphate insecticide [azinphos-methyl (Guthion), Imidan] with Lannate.  Intrepid, SpinTor (Entrust), Rimon, and Proclaim will provide the best control in most West Virginia orchards.  It is recommended that any of these products be applied as a complete spray at 585-640 DD (20-30% egg hatch, expected on June 7-9) or as two alternate-row-middle applications 7 days apart beginning at 530 DD (10% egg hatch, expected on June 5).  An additional application may be needed (in 14 days for complete, in 7 and 14 days for alternate-row-middle) in high pressure situations.  If using BT or an organophosphate in combination with Lannate, make complete applications at 530-585 DD (10-20% egg hatch) and 805-855 DD (60-70% egg hatch).  Alternate-row-middle applications of these materials should begin 50-75 DD earlier and be repeated every 7 days for a total of up to four applications, depending upon insect pressure.

Tufted apple bud moth adult female and maleTufted apple bud moth fresh egg massTufted apple bud moth older egg massTufted apple bud moth hatched egg mass

San Jose scale infestations continue to occur in some orchards.  Changes in pest management practices in recent years have increased the potential for this insect to become more of a threat.  Use of pyrethroids, which do not control scale, in place of organophosphates (Diazinon, Lorsban, Supracide) and decline in oil use have contributed to increased survival of overwintering scale in some orchards.  Most newer chemistries (Intrepid, SpinTor, Rimon, Proclaim) used during June and August are not effective against the crawler stage. 

Crawler emergence typically begins in late May to early June and should be monitored in those blocks that had at least 1% scale injury on fruit at harvest last year.  Crawler emergence can be detected by wrapping black electrician’s tape (sticky side out) around scale-infested branches.  A thin film of petroleum jelly may be spread on the tape surface to enhance crawler capture.  Inspect the tape traps twice weekly for the bright yellow crawlers.  On apple, apply Esteem, Centaur, Diazinon or Provado, preferably as a high volume spray, when crawlers are first detected and again in about 10 days.  San Jose scale may also infest peaches and can be controlled with Diazinon.  Adequate coverage of the tops of trees is critical to control of this insect.

San Jose scale crawler

Tape Trap for San Jose scale crawlers

Green aphids (spirea aphids) can be expected to increase on the terminals of apple trees over the next few weeks.  In most situations, low to moderate populations of these aphids can be tolerated without detrimental effects.  High populations can stunt the growth of young trees, and indirect injury can result when aphids excrete large amounts of honeydew which supports the growth of a sooty mold that discolors the leaves and fruit.  The accumulation of honeydew is influenced by the amount of rainfall (less under wet conditions).

Examine the foliage and fruit for buildup of honeydew, and monitor aphid abundance by sampling 10 actively growing shoots (not watersprouts) on each of 5-10 trees per block.  On each shoot, determine the number of leaves that have wingless aphids (winged aphids are black) and calculate the average number of aphid infested leaves per shoot across all trees sampled.  Also examine shoots and aphid colonies for the presence of aphid predators, such as ladybird beetle adults and larvae, and larvae of syrphid flies, aphid midges and green lacewings.

An insecticide application is recommended for green aphid control if an average of four or more infested leaves per shoot are found, and less than 20% of the aphid colonies have predators.  Materials for control include Provado, Actara, Assail, Calypso, Clutch, Lannate and Thionex.

Spirea aphid colonyLadybird beetle larva, pupa and adultSyrphid fly larva feeding on an aphidAphid midge larva feeding on an aphidGreen lacewing egg, adult and larva

Peachtree borer adult emergence monitoring with pheromone traps should begin at this time.  Control can be achieved with the installation of pheromone mating disruption dispensers at the beginning of moth flight or with an application to the base of trees of Thionex in late June to early July (21 day PHI) and/or chlorpyrifos (Lorsban 4EC, Nufos 4EC, Lorsban 75WG) after harvest.

Peachtree borer adult female and male

PHEROMONE TRAP COUNTS
WEST VIRGINIA UNIVERSITY KTFREC

DATE - 2007 RBLR STLM OFM CM TABM DWB LPTB PTB AM
March 19 0
March 26 2 0
April 2 121 3 0
April 9 54 28 1
April 16 23 93 0
April 23 18 640 68
April 30 22 1220 230 0 0
May 7 6 396 404 3 0 0 0
May 14 1 132 120 33 2 0 33
May 21 0 12 74 17 17 0 23
May 29 0 64 22 22 43 4 30 0

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


Apple scab. We recorded two new infection periods since the last Orchard Monitor on May 14. The first one occurred on May 16-17 and was accompanied by 0.31 inches of rain. With rain beginning at around 12:00 p.m., leaves were wet for 20 hours at an average temperature of 58 F. The second infection period occurred on May 18-19 and was accompanied by 0.22 inches of rain. Wetting duration was 22 hours at an average temperature of 50 F. Primary scab lesions on nonsprayed trees was visible on May 14 from the April 26-27 infection period. Total rainfall for May has been about 1.3 inches in most locations. The 65-year average for May is 3.8 inches.

Table 1. Dates and conditions for apple scab infection periods at the WVU - KTFREC, 2007.

No.

Date 2007

Hours/ degrees F

1.

March 23-25

44 hr/50 F

2.

April 11-12

18 hr/ 47 F

3.

April 14-15

24 hr/44 F

4.

April 26-27

18 hr/52 F

5.

May 10-11

14 hr/63 F

6.

May 12-13

8 hr/60 F

7.

May 16-17

20 hr/58 F

8.

May 18-19

22 hr/50 F

Fire blight. Recognizing early fire blight symptoms is important for good disease management. Catching fire blight early allows you to focus your efforts on quick removal of a limited number of infections before the disease gets well established and more difficult to remove. Look for darkened blossom centers, dark green and water-soaked fruit pedicels, and bacterial ooze droplets on fruit pedicels. There is a moderate amount of fire blight in some commercial orchards.

Summer fungicide programs.  Excellent control of our summer disease complex can be achieved with well-timed fungicide sprays. Timing is one of the most important aspects of effective disease management. As always, read the labels for more detailed information about these materials.

1. EBDC fungicides (Dithane, Manzate, Penncozeb, Polyram): Will provide excellent control of summer diseases when combined with Captan, Ziram, or Topsin-M. EBDC’s can be applied up to 77 days before harvest when using the extended application schedule at the 3 lb per acre rate. Early use of these materials provides the foundation for managing summer diseases for the remainder of the season.

2. Topsin-M: Highly effective against sooty blotch, fly speck, and the Botryosphaeria rots (black rot and white rot). In wet growing seasons, the spray interval should not be longer than 14 - 21 days, or 2 inches of rain. Adjust the rates of Topsin-M toward the high end of the rate range (10 oz per acre) when disease conditions are highly favorable. Use Topsin-M in mixtures with protectant fungicides to help prevent the emergence of fungal strains resistant to Topsin-M.

3. Protectant fungicides (Captan, Ziram, Sulfur): Captan and Ziram applied by themselves or in combination will provide adequate control of summer diseases if applied often enough at the proper rates (6 to 8 lb per acre total). Spray intervals should be 21 days under moderate disease pressure, and should be shortened to 10 - 14 days under prolonged, highly favorable conditions. The 8 lb per acre rate also is preferred under highly favorable conditions. Sulfur by itself is only fair, at best, in limiting these diseases. However, sulfur and copper are the only choices for organic spray programs. Under extreme disease pressure, the addition of Topsin-M at a "half rate" improves control of Botryosphaeria rots and sooty blotch and fly speck. Where scab is well established, captan (8.0 lb. per acre) is the better choice to limit secondary infections.

4. Strobilurin fungicides (Sovran, Flint, and Pristine): These fungicides are very effective for controlling fly speck and sooty blotch and could be used as substitutes for Topsin-M + protectant (captan or ziram) sprays during summer. If strobilurins were used to control scab at tight cluster and pink, then they should not be used again prior to second cover. Strobilurins suppress sporulation of scab lesions, so their use at this time may be beneficial if your control of primary scab hasn’t been completely effective, although that hasn’t been a problem so far this year. If strobilurins were applied at petal fall and first cover, then additional summer applications would need to be delayed until July or August because of the requirement for intervening applications with some other class of fungicides. The strobilurins have residual activity against fly speck, although recent research suggests that the residual activity is not equivalent to that provided by Topsin-M. Fruit treated with Pristine prior to harvest may exhibit lower levels of blue mold and gray mold in storage. When calculating the tree-row-volume rate of the strobilurins, do not use less than the lowest per acre rate on the label (i.e., never use less than 2 oz. of Flint, 4.0 oz. of Sovran, or 14.5 oz of Pristine per acre).

Summary. Control of early-season diseases with a program that includes an EBDC material, alternated with the strobilurin fungicides, provides a solid foundation for controlling summer diseases. The most flexible program for controlling sooty blotch and fly speck is ziram or captan + Topsin-M, and optionally alternated with two applications of the strobilurin fungicides. This program may need to be modified if other summer diseases occur at moderate to high levels. For example, the combination of ziram + Topsin-M is rated as only "good" (rather than "excellent") against white rot and black rot, and is only "fair" against bitter rot. Alternating applications of ziram + Topsin-M or captan + Topsin-M with full rates of ziram or captan alone will improve your management of the summer rots. Remember that management of diseases with fungicides is improved if other cultural practices that reduce inoculum and improve coverage are employed. Good disease management may require some flexibility in application timing and rates of materials.

Accumulated wetting hours.  As of May 29, 2007, we have accumulated 53 wetting hours from a petal fall date of May 4 (last year at this time AWH = 121). 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.

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.

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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