WVU Extension Service: The Orchard Monitor: Committed to the Integration of Orchard Management Practices
March 28, 2005

Upcoming Events Grower Meeting Sponsors 2005 Spray Bulletin Fruit School Presentations


Plant Pathology Horticulture



March 29, 7:00 p.m. - Spring In-depth Fruit Meeting at the Alson Smith Research and Extension Center, Winchester, Va. Dr. Keith Yoder, Virginia Tech Plant Pathologist, will discuss "Early Season Disease Management Dealing with Shifts Toward Fungicide Resistance", and "Prospects for Improved Summer Disease Control".  For more information contact Cyndi Marston at 540-665-5699 or at cmarston@vt.edu.

April 5, 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 horticultural issues and how to use new chemistries for improved early season insect and disease management.  For more information contact the WVU KTFREC at 304-876-6353.

April 12, 7:00 p.m. - Spring In-depth Fruit Meeting at the Alson Smith Research and Extension Center, Winchester, Va. For more information contact Cyndi Marston at 540-665-5699 or at cmarston@vt.edu.


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
Green, Inc. - Elizabeth White
Helena Company - Todd Metzger
Knouse Foods Coop., Inc. - Dave Cox
National Fruit Product Co., Inc. - Jim Robinson
UAP - Larry Dell
Uniroyal Chem./Crompton Co. - Ray Choban
Winchester Equipment Co. - Doug Rinker


The 2005 Virginia/West Virginia/Maryland  Spray Bulletin For Commercial Tree Fruit Growers may be picked up at the WVU KTFREC or obtained by mail for $8.50 each.  A check (payable to West Virginia University) should be sent to the WVU KTFREC, PO Box 609, Kearneysville, WV 25430-0609.


Presentations that were made at the 2005 Fruit Schools in Romney and Kearneysville are now available on our web site.  To view the presentations, go to our home page at:  www.caf.wvu.edu/kearneysville/wvufarm1.html  Click on the link to the Fruit School presentations in the upper left corner of the home page, which will take you to a menu of the presentations which are pdf files.  Adobe Reader, available at:  www.adobe.com/products/acrobat/readstep2.html, is needed to view these files.


CheckMateŽ OFM-F
sprayable pheromone was recently registered in West Virginia by Suterra LLC for mating disruption of oriental fruit moth on pome and stone fruits.  The product should be applied at 1.32 fl oz (39 ml) to 2.93 fl oz (87 ml) per acre, with a maximum of 22 fl oz (649 ml) per acre per year.  Initiate application at the beginning of moth flight as determined with pheromone traps and retreat as needed based on trap capture.  Monitor product performance with pheromone traps and by visual inspection for terminal and fruit injury.   Supplemental insecticide applications may be needed in moderate to high pressure situations.  Use in sprayers equipped with piston, diaphragm, or centrifugal pumps only.  Do not use in sprayers equipped with roller or gear pumps as they will damage the product's controlled release system.  The REI is 0 hours and the product may be applied up to the day of harvest.

Pear psylla adults overwinter in or near pear orchards.  When daytime temperatures exceed 50°F, adults return to pear trees, mate and begin laying eggs (pale cream to yellow-orange colored) in crevices on fruit spurs.  The use of oil during the dormant to white bud stage delays egg-laying because females do not like to lay eggs on oily surfaces.  Oil application shortens the length of the egg-laying period, resulting in a population with a more uniform age structure which makes management easier.  Oil can be used from dormant to the white bud stage, but the rate should be gradually reduced from 3% (dormant) to 2% (green cluster bud) to 1% (white bud).  An effective strategy is to make two applications of oil at 2% each, the first at dormant to bud swell and the second at the green cluster bud stage.  An insecticide to kill adults should be combined with oil, especially with the second of two oil sprays.  Pyrethroids (Asana, Ambush, Danitol, Pounce, Proaxis, Warrior) are a good option to combine with oil.  Actara, Assail, or Calypso at green cluster bud, or Esteem, Assail, or Calypso at white bud are newer products that are excellent options for prebloom psylla control. Three prebloom applications (dormant-green tip, green cluster bud and white bud) of Surround have also provided very good control of overwintering adults.  Surround should not be tank-mixed with oil.

Pear psylla adult

Pear psylla eggs

Rosy apple aphid is the most important aphid species on apple because of its potential to cause significant fruit injury. 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 page 47 of the 2005 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

General Disease Conditions for Spring, 2005.  Moist and seasonable winter conditions with occasional snow cover were favorable for overwintering of our important plant pathogens. Normal amounts of moisture are forecasted for spring 2005, so look for normal development of the organisms that cause diseases.

Apple scab ascospores will mature near the green tip stage of bud development and should be abundant this spring. This will be yet another year in which the initial inoculum is very high in some orchards, so good fungicide coverage beginning early will be essential to minimize the risk of losses due to scab. A general guideline for monitoring would be if you had greater than 0.5% leaf infection when you assessed foliage prior to leaf fall in 2004, 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. In high inoculum orchards, even when sanitation practices are employed, early spraying is advised.

Some area orchards experienced poor scab control with the SI fungicides last year (Nova, Rubigan, and Procure). If you suspect that you have resistance to this class of fungicides, you will need to consider other options for management of the early-season diseases. Consider a copper application at silver tip to green tip; mancozeb-captan combinations from half-inch green through tight cluster; use Scala or Vangard when 48-hour after-infection activity is needed, or to work around the incompatibility of captan and oil; consider using Flint or Sovran at tight cluster and pink, or at pink and bloom, but keep the spray interval at 7 days and limit consecutive applications of these materials to two; use the SI fungicides plus captan or plus mancozeb at petal fall and first cover for best control of mildew and cedar-apple rust infections.

Fire blight. 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, see above). Although this spray does not eliminate the possibility that fire blight could become epidemic in 2005, in some years it may reduce considerably the amount of inoculum available for blossom infections. Copper application is recommended where fire blight was present in 2004 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.

Phytophthora root rot can be managed with mefanoxam (Ridomil Gold EC and Ridomil 5G) which 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.


Winter Injury to Fruit Buds

The weather has been anything but predictable in the recent past. Last year due to some extreme temperatures, several fruit growers experienced loss caused by mid-winter injury to fruit buds.

Apple trees are considerably cold tolerant, surviving temperatures as low as -30°F, whereas stone fruit trees are more susceptible to winter injury at temperatures of -10 to -15°F.

However, the most destructive injury does not come during the frigid winter months. Winter injury is much more extreme when warmer air in mid-February induces growth activity, and is then followed by an extreme cold chill in March.

The most common form of injury occurs to the flower buds, the fruiting buds. Leaf buds are usually not injured unless whole twigs are killed. Flower buds, once initiated can also experience freezing injury. The more they begin to open, the more susceptible they are to cold temperatures. Peaches in full bloom can be injured by 25°F, whereas just before they begin to open, they can survive 20-23°F (Childers 1961).

If the season has experienced such dramatic fluctuations in temperature, growers are advised to evaluate the extent of cold injury to the fruit buds that occurred in their orchards. Using a single-edge razor blade, fruit buds can be dissected vertically and visually examined. Undamaged buds will be uniformly juvenile, greenish throughout, while cold damaged buds will be browned to varying degrees in the center.

The degree of browning will vary depending on the amount of damage. Slight browning may not indicate severe damage, however, if the discoloration occupies most of the flower bud, it is likely fruit set will not occur. The flowers may still bloom, however, since the reproductive parts have been damaged they will not initiate fruit production.

Wait until warm temperatures arrive above freezing to evaluate the possibility of damage. This can ensure proper diagnosis, as browning will be more obvious. In order to correctly identify the degree of loss, be sure to randomly sample throughout the tree canopy for the most accurate results.

Source: "Tree Fruit News of Central New York", Cornell Cooperative Extension of Oswego County, February, 2005.

What's the Risk in NOT Replanting Orchards and Vineyards?

One of the most important management decisions facing fruit growers is whether or not to replant an existing orchard or vineyard with a new planting system. A new system may mean a different variety, rootstock, or training system, or some combination of these changes. Many growers feel a sense of inertia about making such a major investment, which can cost from $3,000 to $10,000 per acre. Growers who are hesitant about renewing their stock of trees or vines often cite the following risks:

But have you considered the fact that the decision not to renew your stock of trees or vines also carries with it a set of substantial risks?

The Risks of Not Renewing Orchards and Vineyards

Risk #1. As consumers' preferences change, growers face the risk that existing varieties will not have a market, or will be priced below direct costs of production. Examples of this abound, consider Rome apples for fresh market, or Aurore grapes for wine.

Risk #2. The yields of old training systems are lower than that of the newer systems being adopted by other growers. As the new higher yielding systems come into bearing they will drive down the price. The early adopters make a profit at first, but growers with the old system cannot cover costs. An example here is the high-density plantings that are now nearly universally planted, resulting in higher yields and often in higher quality fruit.

Risk #3. Old systems are less efficient than newer systems, in that their production costs are higher, and they may not be adaptable to new technology. As an example, certain grape training systems can be more readily adapted to mechanized pruning technology. In the orchard, dwarf trees are more efficient to harvest and more attractive to harvest crews, who can pick faster and earn higher piece rate.

Risk #4. An old planting becomes more difficult and more costly to manage as the trees age. Either pruning costs become too high, or the quality of fruit too low for profitable production.

Risk #5. The combined effect of the first four risks is that many older growers, especially, fail to reinvest in replanting as they near retirement. The resulting risk is that the farm's key productive asset, the orchard or vineyard becomes less profitable and thus of less value to the prospective buyer, or to the son, daughter, or partner who wants to transition into the operation. In any event, the loss of asset value on the balance sheet ultimately reduces the grower's retirement earnings. (Of course, if the site is really a poor one for fruit production, the grower will lose by sinking money into a poorly performing asset. That too can reduce the health of the balance sheet.)

My Advice About Replanting

Twenty-four years of experience with the New York fruit industry has convinced me of the folly of standing pat with old plantings. Growers need to constantly assess new varieties, rootstocks, planting densities, and training systems. Many apple growers are now considering other crops, especially peaches and sweet cherries, given the low apple prices of recent years. Besides the potential for greater profits, these other crops provide diversification that helps to reduce variability in income over time.

Replanting ought to be a continuous process. The speed at which orchards and vineyards can or should be renewed depends upon many factors, such as net worth of the grower, market conditions, and the availability of new technology. A good rule of thumb for apples, as well as for juice grapes or low-end American or hybrid wine grape varieties, is that growers can replant up to five percent per year. Total non-bearing orchards of more than 15% can cause cash flow difficulties. Growers with high debt to asset ratios need to be more conservative, as even 5% per year may cause serious cash flow problems.

In conclusion, there are significant risks involved in replanting. But the risk of not replanting is the risk of winding up with an uneconomical and undesirable orchard or vineyard.

Article from" Tree Fruit News of Central New York", Cornell Cooperative Extension of Oswego County, by Jerry White, Dept. of Applied Economics and Management, Cornell University, January 2005 issue.


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.

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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
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