WVU Extension Service: The Orchard Monitor: Committed to the Integration of Orchard Management Practices
March 22, 2004

Upcoming Events Sponsors Spray Bulletin Entomology Plant Pathology Horticulture

 

UPCOMING EVENTS

April 6, 6:00 p.m. - Tree Fruit Grower Twilight Dinner and Meeting at the WVU Kearneysville Tree Fruit Research and Education Center , Kearneysville, W. Va.   Extension Specialists will discuss early-season insect and disease management strategies and horticultural issues. For more information contact the WVU KTFREC at 304-876-6353.

April 6, 7:00 p.m. - Spring In-depth Fruit Meeting at the Alson Smith Research and Extension Center , Winchester , Va.   Dr. Gary Puterka, USDA Research Entomologist, will discuss "Orchard Pest Management Using Surround".  For more information contact Cyndi Marston at 540-665-5699 or at cmarston@vt.edu.

GROWER MEETING SPONSORS

The following fruit industry support companies and representatives have contributed to a Grower Meeting Fund to cover expenses at fruit schools and grower meetings.  Please let them know that you appreciate their support as we do.

Adams County Nursery, Inc. - Phil Baugher
BASF - Gar Thomas
Bayer CropScience - Rick Love
CBC (America) Corp. - Greg Stamm
Cerexagri - John Miller
Dupont Company - John R. Clawson
Durand-Wayland, Inc. - Ron Shrum
Gowan Company - David J. Pieczarka
Green, Inc. - Elizabeth White
Helena Company - Todd Metzger
Knouse Foods Coop., Inc - Dave Cox
Winchester Equipment Co. - Doug Rinker

SPRAY BULLETIN

The 2004 Virginia/West Virginia/MarylandSpray Bulletin For Commercial Tree Fruit Growers may be picked up at the WVU KTFREC or obtained by mail for $14.50 each.  A check (payable to West Virginia University) should be sent to the WVU KTFREC, PO Box 609, Kearneysville, WV 25430-0609. The Spray Bulletin is also available on the Web as PDF files at: http://www.ext.vt.edu/pubs/treefruit/456-419/456-419.html.

ENTOMOLOGY

The following products have received EPA registration or had label changes since last season.

Calypso 4F (thiacloprid) from Bayer CropScience is the newest member of the neonicotinoid class of chemicals (following Provado, Actara, and Assail) to receive registration on apple and pear.  It has broad-spectrum activity, similar to Assail, against sucking insects (aphids, leafhoppers, leafminers, mirid bugs, and pear psylla), European apple sawfly, plum curculio, codling moth, Oriental fruit moth, and apple maggot.  Rate of application is 2-4 oz/acre for aphids, leafhoppers, leafminers, and mirid bugs; 4-8 oz/acre for the other fruit pests.  The season maximum is 16 oz/acre.  Calypso has a 12 hour restricted-entry interval (REI), and at least 30 days must elapse between the last application and harvest.

Zeal 72WDG (etoxazole) from Valent is an acaricide for the control of European red mite and twospotted spider mite on apple, pear, strawberry, and all non-bearing tree fruits.  This is the first acaricide with activity as an insect (mite) growth regulator.  It has translaminar movement and acts as an ovicide, inhibits molting of larval and nymphal mite stages, and sterilizes adults.  Rate of application is 2-3 oz/acre with a maximum of one application per year.  Zeal has a 12 hour REI and spray-to-harvest interval of 28 days on apple and pear; 1 day on strawberry.  Due to its mode of action as a growth regulator, Zeal will not provide rapid knockdown of mites, and at least 7-10 days is usually required to see a reduction in mite abundance.  Therefore, it is recommended for application in the early season  as a  preventative approach, or at a low mite threshold.

MEC-OFM Phase V is a sprayable pheromone manufactured by 3M Canada and marketed by Certis USA for the control (mating disruption) of Oriental fruit moth on pome and stone fruits.  The material may be applied in one of two methods based on grower practice.  As a Full Rate Single Application (FRSA), 1.7-2.5 oz/acre is applied once at the beginning of moth flight for each generation.  As a Low Rate Frequent Application (LRFA), 0.3-0.7 oz/acre is applied as an alternate-row-middle (ARM) application 7-10 days apart throughout the flight period.  MEC-OFM Phase V is recommended for low to moderate populations in blocks of at least 5 acres in size.  Supplemental control with insecticides may be needed for high populations.  Monitor performance with pheromone traps and assessment of fruit injury.

Provado 1.6F (imidacloprid), which has been available under a Section 18 Emergency Exemption label for aphid control on peach and nectarine for the past 4 years, is now registered on all stone fruits for the control of aphids, green June beetle, Japanese beetle, rose chafer, San Jose scale, leafhoppers, and tarnished plant bug.  Rate of application is 4-8 oz/acre, with a maximum of 24 oz/acre/year on apricot, nectarine and peach; 40 oz/acre/year on cherry, plum and prune.  Provado has a 12 hour REI and may be used up to harvest of apricot, nectarine and peach, and until 7 days of harvest on cherry, plum and prune.

Actara 25WDG (thiamethoxam) was registered earlier this month by Syngenta for use on all stone fruits for the control of leafhoppers, aphids, cherry fruit fly, plum curculio, stink bugs and tarnished plant bug.  Rate of application is 2.0-2.75 oz/acre for leafhoppers; 3.0-4.0 oz/acre for aphids; and 4.5-5.5 oz/acre for other pests.  Use is limited to one application prebloom and/or one application postbloom, with a maximum of 8 oz/acre/year.  Actara is highly toxic to bees exposed to direct treatment or to residues on blooming crops and weeds.  Do not apply Actara between swollen bud and petal fall stages.  Actara has a 12 hour REI and a 14 day spray-to-harvest interval.

Guthion 50W (azinphosmethyl) has undergone label changes on new product that will be marketed this year.  Plums have been removed from the label.  The maximum amount of formulated product permitted per acre per season has been lowered for all tree fruits as follows:  apples - 8 lbs; pears - 6 lbs; cherries - 3 lbs; nectarines and peaches - 4.5 lbs.  In addition, the REI is now 14 days for apples, pears, nectarines and peaches; 15 days for cherries.  The spray-to-harvest interval has been extended to 30 days for U-pick, and there are numerous buffer zone restrictions.  Old product may be used according to its label, so be sure to check and follow the label of the product you are using.

Pyridaben, which has been sold as Pyramite 60WSB, will now be marketed as Nexter 75WSB by BASF.  The new rates of application are 4.4-5.2 oz/acre for European red mite; 8.8-10.7 oz/acre for twospotted spider mite; and 6.6-10.7 oz/acre for pear psylla.

Lorsban 75WG is a new  formulation of chlorpyrifos that will be marketed by Gowan Company as a replacement for the 50% wettable powder formulation that will be phased out.  Described as an encapsulated dry EC, this unique formulation has performed equal to or better than the 4E and 50W formulations.  The 75WG formulation has low odor and rainfastness is significantly greater than either the 4E or 50W formulations.

Rosy apple aphid is the most important aphid species on apple because of its potential to cause significant fruit injury, which was experienced in many orchards last year.  For many growers, this insect was the most abundant and problematic pest of the 2003 season.

This aphid species overwinters as shiny jet black eggs, less than 1/16 inch long and oval in shape, on the bark of spurs and shoots.  These eggs cannot be distinquished from those of apple grain aphid, which are much more numerous on apple.  Eggs of apple grain aphid are the first to hatch, and young aphids (nymphs) of this species can often be found clustered on buds at silver tip.  Eggs of rosy apple aphid begin to hatch about a week later (green tip), with hatch usually complete by the -inch green stage.  Young nymphs of both species tend to be dark green in color, but rosy apple aphid can be distinguished by its longer antennae (half the length of the body) and cornicles ("tail-pipes").  Antennae of apple grain aphid are less than half the length of the body and cornicles  are very short, barely swollen discs.

Upon egg hatch, nymphs of both species move to the tips of buds to feed on emerging green tissue.  As the buds open aphids move inside to continue feeding on leaf and fruit bud clusters.  Feeding of apple grain aphid is of no consequence, but nymphs and adults of rosy apple aphid cause leaf curling and fruit distortion.
The first opportunity to control aphids is when nymphs are clustered on the bud tips (green tip to -inch green) where they are exposed to spray contact.  Effective options at this time include pyrethroids (Asana, Ambush, Danitol, Pounce, Warrior), organophosphates (Lorsban, Supracide), Aza-Direct or Esteem.  Pyrethroids perform better under cooler conditions, whereas organophosphates are more effective under warmer temperatures. Aza-Direct is listed by the Organic Materials Review Institute (OMRI) as an option for organic production.  Esteem, which only effects development of eggs and immature stages, must be applied before aphids reach the adult stage.
The availability of the newer neonicotinoid chemistries (Actara, Assail, Calypso) provides growers with more flexibility and more effective control in high pressure situations.  Actara at 4.5 oz/acre would be most effective from tight cluster to early pink.  Since Actara is toxic to bees exposed to direct treatment or residues on blooming crops, it should not be applied from full pink through bloom, or within 5 days of placing beehives in the orchard.  Assail (1.1-1.7 oz/acre) and Calypso (2-4 oz/acre) would provide very effective control from tight cluster through bloom.  Although direct contact with these materials is toxic to bees, residues are not.  Delaying application of neonicotinoids until pink to bloom would also provide control of tarnished plant bug, mullein bug, European apple sawfly and early egg hatch of Oriental fruit moth (Assail and Calypso only).  However, effective control of all of these additional pests would require higher rates of application for both Assail (2.5-3.4 oz/acre) and Calypso (4-8 oz/acre).  See pages 41-42 of the 2004 Spray Bulletin.

If injury from San Jose scale was detected on fruit at harvest last season, a dilute application of oil, Lorsban, Supracide or Esteem is recommended at delayed dormant.  Oil will also provide control of overwintering eggs of European red mite, and will typically maintain mite populations below threshold into June when applied at 2 gal/100 gal dilute at the -inch green stage or 1 gal/100 gal dilute at the tight cluster stage.

Pheromone traps should be installed at this time for monitoring of Redbanded leafroller and the beginning of April for monitoring of Oriental fruit moth.

Rosy apple aphid nymphs

San Jose scale fruit injury

European red mite overwintering eggs

PLANT PATHOLOGY

General Disease Conditions for Spring, 2004: Moist and seasonable winter conditions with snow cover were favorable for overwintering of our important plant pathogens. Normal amounts of moisture are forecasted for spring 2004, so look for normal development of the organisms that cause diseases. Apple scab ascospores will mature near the green tip stage of bud development. This means that if you had a problem with scab last year, and many of you did, you should be ready for the early scab infection periods. This will be a year in which the initial inoculum is very high in some orchards, so good fungicide coverage will be essential to minimize the risk of losses due to scab.

Fire blight bacteria overwinter in cankers or at the ends of pruning cuts where blight was cut, from the previous season. A good way to reduce the risk of a severe fire blight outbreak is to make a late dormant application (no later than 1/4 inch green on fresh-market fruit) of a copper-containing material (i.e. Bordeaux mixture, C-O-C-S, Kocide, Tenn Cop 5E, just to name a few) that acts to kill a large percentage of the bacteria on the plant surface (and provides some early-season protection against apple scab). Although this spray does not eliminate the possibility that fire blight could become epidemic in 2004, in some years it may reduce considerably the amount of inoculum available for blossom infections. This dormant application is recommended where fire blight was present in 2003 and on young trees of susceptible apple cultivars such as Gala, Fuji, York, Jonathan, and Rome Beauty (whether fire blight was present last year or not), or on any cultivar on M.9, Mark, and M.26 rootstock.

Given that the bacterium moves easily from unsprayed blocks to adjacent sprayed blocks, it may be useful to apply copper to blocks (or rows) of less susceptible trees that are adjacent to blocks of more susceptible trees. Most copper formulations are compatible with oil. Streptomycin should be applied to blossoms of susceptible apple and pear cultivars when weather conditions favor infection.

Read pages 69-72 in the 2004 Spray Bulletin for additional information on fire blight biology and management. Monitor our WWW Site for up-to-date information on the disease.

Apple scab ascospores should be abundant this spring. Look for apple scab ascospores to mature near the green tip stage of bud development. This means that if you had greater than 0.5% leaf infection when you assessed foliage prior to leaf fall in 2003, then you should be ready to spray for the earliest scab infection periods. 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. Where pre-leaf fall leaf assessments indicated 1% or higher leaf infection, sanitation practices (urea application or flail mowing leaf litter) are unlikely to delay the onset of significant scab infection, and early spraying is advised.

Phytophthora root rot can be managed with mefanoxam (Ridomil Gold EC and Ridomil 5G) and will aid in the control of crown, collar, and other root rots caused by Phytophthora spp. on both bearing and non-bearing apple trees. Ridomil 5G can be used in nonbearing orchards only. Applications should be made on a preventative schedule before symptoms appear, especially in orchards where conditions are favorable for disease development. For best results, make one application at the time of planting or in the spring before growth starts. Make another application in the fall after harvest.

Dipping the roots of nursery-grown trees into a solution of the fungicide Aliette prior to planting may reduce inoculum on infested rootstocks. To use, thoroughly mix Aliette at a rate of 3.0 lbs./100 gallons of water, in the desired volume of water and dip the entire root system for 30 to 60 minutes in the mixture prior to planting in the field.

Organic Apple Research: WVU researchers have a 3-year grant to study organic approaches to apple pest and disease management with the main goal being to reduce the risks inherent in organic production. We are looking for grower cooperators to host research plots and to serve on an advisory committee. If you are interested in either or both of these roles, please contact WVU-KTFREC (304-876-6353 or email abiggs2@wvu.edu).

HORTICULTURE

Hormones and Pruning.  Even though the pruning season is essentially over, here are a few bits of information which may shed some light on what goes on when trees are pruned.

Characteristically there are five plant growth hormones:  auxins, cytokinins, gibberellins, ethylene and abscisic acid.  The importance and impact of  these hormones can be diverse.

Auxins play an important role in stem elongation, stimulate ethylene production, and stimulate root formation.  Most importantly, they play an intricate role in apical dominance.  The time and concentration when synthetic auxins such as NAA and IBA are applied  determines the effects on leaf or fruit drop or leaf growth.  Heading cuts compromise the effect of auxins and enhance the effect of cytokinins for a period of time.

Cytokinins have an important role in cell division which in turn promotes lateral bud development and bud enlargement.  Another function of cytokinins is the delay of senescence or tissue death.

Gibberellins or gibberellic acid (GA3) functions primarily to promote cell elongation in soft tissue.  Gibberellin also plays an intricate role in seed germination.  However, when applied in combination with IAA (natural auxin), there is a significant increase in the vascular tissues of the plant.  This provides potential for greater intake of water and nutrients.

Ethylene is well known for its fruit ripening effects.  Ethylene also promotes leaf drop, minimizes stem elongation, promotes fibrous root development, releases buds from dormancy and stimulates bud growth.

Abscisic Acid is the one hormone known distinctively as an inhibitor.  Abscisic acid, ABA, is generally a growth retardant.  ABA causes leaves, stems, fruits and flowers to drop, mainly stimulating dormancy.  The presence of ABA, however, also allows the plant to maintain moisture in times of stress.

Plant growth hormones in combination with one another can manipulate the size, shape, and vigor of your trees.  When pruning dormant trees it's important to know what's going on within the tree.  Generally, when pruning cuts are not made correctly the outcome can be observed during the growing season.  Summer pruning may correct dormant pruning errors.

 Source: Tree Fruit News of Central New York, January, 2004.

Free Resource Helps Farmers Transition to Organic Agriculture. Over the last decade, organic acreage has more than doubled in the U.S. as interest among farmers and consumers has soared. Now, a new guide can help farmers convert their farms to organic production. Transitioning to Organic Agriculture, a 32 -page bulletin from the Sustainable Agriculture Network (SAN), highlights how farmers can work with nature to increase profits while protecting the environment.

John Vollmer, a North Carolina tobacco and small grain farmer, knew that tobacco farming faced a bleak future in the 1990s. Heartened by emerging research on organic farming, Vollmer tried growing organic strawberries.

"My main goal was to keep the farm in the family for the next generation," says Vollmer, who received a grant from the Sustainable Agriculture Research and Education (SARE) program to test growing specialty crops like lettuce in a former tobacco greenhouse. Both his lettuce and his acres of strawberries proved successful, prompting him to grow more fruit and vegetables using mostly organic practices.

Vollmer's story is one of many woven throughout the bulletin, which lays promising strategies to convert successfully, including typical organic farming production practices. "This is the most comprehensive material on organic transition available," said Brad Brummond, a county extension agent from Walsh County, ND.  "It includes research and testimonials from organic farmers and covers all aspects of organic production."

Beyond providing information on how to design profitable rotations and build healthy soils, the bulletin also addresses:

.  Controlling weeds and pests
.  Organic production economics
.  Considerations for livestock
.  Innovative marketing ideas
.  Federal certification standards
.  Start-up ideas

Transitioning to Organic Production is available at www.sare.org/bulletin/organic. Those without web access may call (301) 504-5236 for a print copy.  Please provide your name, address and phone number and specify the title when placing your order.  Transitioning to Organic Production and other SAN bulletins are available to agricultural educators in quantity at no cost.

Source: Country Folks Grower, March, 2004.


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 an Extension Meeting because of a disability should contact one of the Specialists at the WVU Kearneysville Tree Fruit Research and Education Center at 304-876-6353 at least 5 days prior to the meeting date.


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/wvufarm1.html

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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