WVU Extension Service: The Orchard Monitor: Committed to the Integration of Orchard Management Practices
April 11, 2005

Upcoming Events

Entomology

Pheromone Trap Counts Plant Pathology Horticulture

 

UPCOMING EVENTS

April 12, 7:00 p.m. - Spring In-depth Fruit Meeting at the Alson Smith Research and Extension Center, Winchester, Va.  Mr. David Kocka, Wildlife Biologist, will discuss "Dealing with Nuisance Wildlife".  Dr. Jim Schupp, Horticulturist at the Penn State University Fruit Research and Extension Center, will discuss "Update on Chemical Thinning of Apples".  For more information contact Cyndi Marston at 540-665-5699 or at cmarston@vt.edu.

April 26, 7:00 p.m.
- Spring In-depth Fruit Meeting at the Alson Smith Research and Extension Center , Winchester , Va. Dr. Mike Orzolek from Penn State University will discuss "High Tunnel Production of Sweet Cherries".  Nic Ellis, Ph.D. student at the Penn State University Fruit Research and Extension Center , will discuss "Effects of Apple and Peach Host Crops on Dispersal of Oriental Fruit Moth".  For more information contact Cyndi Marston at 540-665-5699 or at cmarston@vt.edu.

April 28,  6:00 p.m. - Tree Fruit Grower Twilight Dinner and Meeting at Gourmet Central (in Hampshire Industrial Park ), Romney, W. Va.   Extension Specialists will discuss horticultural issues and use of new chemistries for insect and disease management.  For more information contact the Hampshire County Extension Office at 304-822-5013.

May 2 & 3 - West Virginia Farmland Protection Workshop at Canaan Valley Resorts.  Workshop is free, but registration must be received by April 15.  Canaan Valley State Park is offering a package deal which includes lodging the night of May 2, dinner May 2 and breakfast May 3 for $101.  For more information and to register contact Debbie Hovatter at Canaan Valley Institute (800-922-3601 or Debbie.hovatter@canaanvi.org).  

ENTOMOLOGY

Dimethoate was removed from the VA, WV and MD Spray Bulletin for Commercial Tree Fruit Growers based on information that registration was going to be cancelled on fruit crops.  Dimethoate 400 (Loveland Products, Inc.) and Dimethoate 4EC (Drexel Chemical Co) are still registered, at least through 2005, in West Virginia for insect control on both apple and pear.

Lorsban 75WG is a new formulation of chlorpyrifos from Gowan Company that has replaced the 50W formulation.  Performance of this new formulation has been equal or superior to the 4E and 50W formulations.  Especially noteworthy are its low odor and improved rainfastness compared with 4E and 50W formulations.  Lorsban 75WG is registered for prebloom insect control on apple; for the control of peachtree and lesser peachtree borers on peach, nectarine and cherry; and as a preplant tree dip for peachtree borer control on peach and nectarine.  Registration is pending for control of trunk borers on apple.

Rosy apple aphids that hatched from overwintering eggs are all wingless females called stem mothers that become adults by the pink stage of apple bud development.  Whereas the newly hatched nymphs have a dark green color, adults are purplish or dusty gray.  A single stem mother is capable of curling a leaf, and it is from within this protected shelter that numerous live young are produced.  Rosy apple aphid must be controlled before petal fall in order to prevent fruit injury.  To monitor aphid abundance, make a 3-minute examination of 5-10 trees per block at the prepink stage and count the number of fruit spurs showing curled leaves with live aphids.  An insecticide application is recommended before petal fall if an average of one or more infested fruit clusters per tree are found.  The neonicotinoid materials (Actara, Assail, Calypso) are considered the most effective option.  To avoid hazard to bees, Actara should be applied  before full pink, whereas Assail and Calypso may be applied from pink through bloom if sprays are allowed to dry before bees begin foraging in the orchard.   Other options include pyrethroids (Ambush, Asana, Danitol, Decis, Pounce, Proaxis, Warrior), Dimethoate or Thionex.  Although Danitol also has activity against mites, all pyrethroids increase the potential for higher mite populations because of their greater toxicity to predators. Rosy apple aphid colony

Tarnished plant bug adults overwinter under bark and leaves in woodlots, fence rows and rock breaks, and around alfalfa, other legumes or weeds that are seeded late in the summer or early fall.  They become active and fly to apple trees near the tight cluster stage.  Feeding on apple buds before bloom usually results in early bud abscission and is rarely a problem, whereas feeding from bloom to shortly after fruit set results in a deeply sunken dimple in the side or calyx end of the fruit. 

A white visual, non-UV reflecting sticky trap has been useful for monitoring tarnished plant bug populations and for making decisions regarding management in apple orchards.  Where these traps are installed at green tip, prebloom control is recommended if the cumulative capture averages 2.4 per trap by tight cluster or 4.1 per trap through late pink.  Control options include pyrethroids (Ambush, Asana, Danitol, Decis, Pounce, Proaxis, Warrior), Actara, Assail, Calypso, Dimethoate, Thionex, or Carzol.

Tarnished plant bug adultTarnished plant bug apple injuryWhite visual trap

PHEROMONE TRAP COUNTS
WEST VIRGINIA UNIVERSITY KTFREC

DATE - 2005 RBLR STLM OFM CM TABM DWB LPTB PTB AM
March 21 0            
March 28 3 0            
April 4 17 9 0            
April 11 73 720 3            
DATE - 2005 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 tree borer; AM = Apple maggot.

PLANT PATHOLOGY


Apple scab. We recorded one wetting period last week on April 7 - 8 for 14 hours at 58 F. Rain initiated the wetting period at night and was over by daybreak, and because ascospore release is reduced during darkness, this wetting period was probably insignificant in low inoculum orchards (although there aren't too many of these anymore after the 2003 and 2004 growing seasons). This wetting period will be recorded as our first apple scab infection period for the 2005 growing season.

Table 1. Dates and conditions for apple scab infection periods at the WVU - KTFREC, 2005.

No. Date 2005 Hours/ degrees F
1. April 7 - 8 14 hr/58 F

It is important to avoid early infections on sepals, as these are difficult to detect and can provide conidial inoculum throughout the early part of the growing season. Copper applied last week would have provided adequate protection during this infection period. Copper sprays, even at the low label rate, will provide scab protection similar to that provided by a mancozeb fungicide applied at 3 lb/acre. However, copper does not provide back action against scab. The relatively new AP-type fungicides, Vangard 75WG and Scala 5SC will provide about 48 hours of back action. These products should be used in a tank mix with a protectant material, preferably one of the EBDC's or captan (3 ounces of Vangard or 5 fluid ounces of Scala, combined with the 3-lb. rate of mancozeb 75DF, Polyram 80DF, or captan).

Powdery mildew spores are first available at about the tight cluster stage of bud development. For best mildew control, fungicide applications should begin at tight cluster and continue until terminal growth stops in midsummer. The spray interval is generally 10 days from tight cluster through petal fall, when leaf tissue is developing rapidly, and is lengthened to 14 days after petal fall. Excellent powdery mildew control can be expected when Nova, Rubigan, or Procure are used on a 7 to 10 day interval for scab control. The strobilurin fungicides, Sovran and Flint, also provide good control of powdery mildew. (Deciding how to configure sprays of SI's and strobilurins should depend upon other disease concerns, particularly the rust diseases, and whether or not your orchard contains scab that is resistant to the SI's). Severity of powdery mildew is directly related to the amount of overwintering inoculum in shoot and blossom buds and the length of the spray interval. Check blocks of highly susceptible cultivars (Jonathan, Ginger Gold, Rome Beauty, Stayman Winesap, Idared, Paulared, Granny Smith) to determine the amount of overwintering inoculum. Where mildew is a problem, maintaining shorter spray intervals (not over 7 days) more effectively reduces mildew infection than increasing fungicide rates. On highly susceptible cultivars, special mildew sprays applied between the regular sprays from pink through the cover sprays is the most economical way to effectively manage the disease and prevent a repeated buildup of mildew for the following year. These extra spray applications will easily pay for themselves with increases in yield and quality. When the protectant fungicides mancozeb, Polyram, captan, and Ziram are being used for scab control, the addition of sulfur will usually provide good control of mildew. The SI fungicide Bayleton may also be a good choice if more aggressive mildew and rust activity is needed (Bayleton is not effective against scab).

W.Va. growers to benefit from fungicide resistance assessment pilot project. Researchers at West Virginia University, University of Massachusetts, and Cornell University have received funding for a cooperative project to develop and implement site-specific management of resistance (SMOR) for the control of apple scab. The goal of the project is to determine the feasibility of implementing a fee-based site-specific assessment of individual orchards for sensitivity to the various classes of at-risk fungicides (benzimidazoles, Dodine, SI's, strobilurins, and AP's). With this information, growers can make better informed decisions and reduce the risk of economic losses from control failures related to fungicide resistance. Orchards from five growers will need to be sampled in 2005. These orchards and five additional ones will be sampled in 2006 and 2007. The project will run from 2005 through 2007. In order to participate, you will need to provide some trees that are not sprayed prior to petal fall, as well as access to spray records to determine fungicide use history. Scabbed leaves will be collected in May and June, and assessments of scab incidence, level of disease at harvest, and fungicide resistance will be provided by the researchers. Please contact Dr. Alan Biggs at abiggs2@wvu.edu or 876-6353 if you are interested in participating in this project. The number of participants is limited to 10 due to the limited amount of sampling that can be financed with the grant funds.

Current Conditions: Fruit producers with access to the World Wide Web can access a web page called "Current Conditions" that will provide daily (or "as-needed") updates on current disease and insect development issues.  The page should help to bridge the information gap between issues of The Orchard Monitor and provide the grower with the timely information that is needed for making good pest control decisions.

To view the "Current Conditions" page, click here, or go to the WVU - KTFREC Home Page at: http://www.caf.wvu.edu/kearneysville/wvufarm1.html and select "Current Conditions" from the menu.

HORTICULTURE

Small fruit.  Pruning should be completed on brambles and blueberries. Nitrogen (ammonium nitrate) fertilization on established bramble plantings should be as follows:  Fall bearing red raspberries should receive 100 lbs. per acre.  Summer bearing red raspberries and both types of blackberries should receive 70 lbs. per acre, while black raspberries should receive 50 lbs. per acre.  These amounts should be split with one half the recommended rate applied in the spring and the other half before July 1.

If you prefer to apply nitrogen on a per foot of linear row basis, Table 2 below may be of use to you.  Keep in mind the amounts (lbs.) of N indicated should also be split into two applications as noted above.

Table 2.   Nitrogen (lbs.) for application per foot of linear row.

 

Bramble Type

 

Year

     Irrigated

   Non-irrigated

Loam

Clay

Loam

Clay

Primocane-fruiting annual fall crop only

 

   1

     2

   1.5

     2

   1.5

   2

   4.5

     4

     4

     3

   3+

   6.5

     6

     5

   4.5

Summer-bearing red, thornless blackberries

 

   1

     2

   1.5

   1.5

   1.5

   2

     3

   2.5

   2.5

     2

   3+

   4.5

    4

     3

   2.5

Summer-bearing black and purple raspberries, thorny blackberries

   1

   1.5

   1.5

     1

     1

   2

   2.5

    2

     2

   1.5

   3+

     3

   2.5

   2.5

     2


















Bramble yields.  Year three yields for the 12 varieties of red raspberries and blackberries at the WVU Fruit Center ranged from poor to excellent. Table 3 below presents the data collected last summer; note the actual yield data in grams were extrapolated to show potential pounds per acre.

Table 3.   Bramble yields at WVU-KTFREC in 2004.

 
Variety


First Pick  - Last Pick

Yield
10 berries (gms)  

Yield
(gms)

Yield
Acre (lbs.)

Thorny Blackberries

Chickasaw  

6/23 - 8/16

106.6

15,636*               

9,900

Illini Hardy

7/1 - 8/16

40.8

12,724*               

8.131

Kiowa   

6/23 - 7/21

44

5,188*

3,290

Thornless Blackberries

Chester

7/9 - 8/25

58.5

25,034*                

15,979

Triple Crown

7/6 - 8/20

68.3

11,670*               

7,453

Arapaho

7/1 - 7/16

31.5

904*               

580

Summer Red Raspberries

Encore

6/21 - 7/21

42.7

11,544**

1,179

Latham

6/23 - 7/1

14.3

1,546**

158

Tulameen

Insufficient Data

-

-

-

Primocane Red Raspberries

Polana

7/1 - 10/18

28.2

7,172**

733

Autumn Bliss

6/28 - 10/18

29

14,804**

1,513

Heritage

7/1 - 10/18

26

48,605**

4,765

* Harvest taken from 10 foot randomly selected section of the row.
** Harvest taken from all plants in a 70 foot row.

 


























Thoughts on Weed Control in Orchards for 2005.  As I prepare this we are still a few days away from April and there has been little movement of fruit buds in orchards.  The season has thankfully been slow to develop so that should give everyone time to prepare.  Hopefully, that will also give you time to get spring herbicides on early enough.  It has been my experience here in PA that too often growers are late in applying their spring pre-emergent materials.  They seem to rely on adding paraquat or glyphosate in a tank mix with their pre-emergent materials.  The burn down agents they believe will take care of existing weeds that germinated in the winter, and the pre-emergent will control any weeds as they germinate.

There are some advantages to this approach.  It allows the grower a chance to scout the orchard to identify what weed seedlings are present.  Second, by delaying the application weed control may carry further into the fall.  Third, you may be past the heavy spring rains that can wash herbicides too deep.  While all pre-emergent materials need to get down to the germinating zone in the soil, some residual material on the soil surface can also help to prevent seedlings on the surface from germinating.  Lastly, there have been indications that some vegetation under the tree in the early season may keep insects out of the trees and avoid some damage.

There are some potential disadvantages.  First, if the existing vegetation is too dense the pre-emergent may not reach the soil surface. Second, if it does reach the soil surface it may not be in time to prevent the seedlings from emerging.  Third, this approach can lull growers into complacency where you entirely miss the weed seedling germination period because of heavy dependence on the burn-down material.  Fourth, it may reduce yields by allowing weed competition during the critical period immediately after fruit set.

This winter, I tried to suggest that growers need to try fall applications of herbicides after the crop is harvested but before the ground freezes.  The main advantage is providing a cleaner surface over winter and extending the window of late spring application.

Another point to consider this growing season is to walk the orchard in mid-summer to look for spots of problem perennials or escapes (skips) that are emerging.  Quick action in mid-summer will prevent a small population of a weed developing into a larger headache later.  This usually means an application of paraquat for annual escapes and glyphosate for perennials.  When treating with glyphosate be sure to note on the label the correct timing for the weed you are trying to control.  For example, Canada thistle applications should be made at early flower bud whereas bindweed applications should be made at full flower.  Note also the rates may vary by weed species.

This spring a new material is available for the weed control arsenal. Chateau is currently labeled for application to all nonbearing tree fruit that have been established at least a year in the field unless the trunks are protected by a nonporous wrap.  The material has both pre- and some post-emergent activity.  Do not allow material to drift onto the tree foliage.  Chateau may also be used to maintain bare ground on non-crop areas of orchards and may be especially useful around fence rows.  Growers may find this last option a useful way to experiment with how well the material works.

Scouting hint: Place a pane of glass on bare soil. Then return in a few days. This will give you advance notice on which weeds will be emerging in the next few days.

Source: (from Leslie Huffman, Ontario Ministry of Agriculture and Food)  (Submitted by Rob Crassweller, PSU, Dept. of Horticulture).


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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