WVU Extension Service: The Orchard Monitor: Committed to the Integration of Orchard Management Practices
May 23, 2005

Upcoming Events


Pheromone Trap Counts Plant Pathology Horticulture



May 26, 6:00 p.m. - Tree Fruit Grower Twilight Dinner and Meeting at Gourmet Central (in Hampshire Industrial Park), Romney, W. Va.  Following dinner, seasonal updates will be provided by Extension Specialists from the WVU Kearneysville Tree Fruit Research and Education Center.  For more information contact the Hampshire County Extension Office at 304-822-5013.

May 30. - West Virginia University Holiday.  The WVU KTFREC will be closed in observance of Memorial Day.

June 7, 6:00 p.m. - Tree Fruit Grower Twilight Dinner and Meeting at Butler's Orchard, Inwood, W. Va.  To reach the orchard, travel 1.7 miles south on Nollville-Arden Road from the junction with Tablers Station Road at Arden to the entrance on the right at the brown brick home, or travel 2.5 miles north on Nollville-Arden Road from Inwood to the entrance on the left.  Dinner will be followed by a presentation on hire reporting requirements by Susan Mace, Program Coordinator with the West Virginia New Hire Reporting Center, seasonal updates by Extension Specialists from the WVU KTFREC, and a tour of the orchard by hosts Bill and Todd Butler.  For more information contact the WVU KTFREC at 304-876-6353.

June 9, 6:30 p.m. - Joint PA, MD and WV Twilight Fruit Growers Meeting at Barr Orchards, Smithsburg, Md.  The agenda will include an orchard tour, pest management update by Henry Hogmire, a two-prong approach to orchard weed control by Rob Crassweller, and an "ask the experts" question and answer session.  WV growers will receive 4 credits for Pesticide Applicator Recertification.  To reach Barr Orchards from Jefferson County, take WV-480 north through Shepherdstown, crossing the Potomac River onto MD-34.  In Sharpsburg, turn left onto N. Church Street (becomes MD-65, Sharpsburg Pike).  Follow MD-65 north until you intersect I-70 (approx. 10 miles).  Take I-70 east for 5 miles to exit 35 - Smithsburg/Boonsboro (MD-66).  Follow MD-66 north (left) towards Smithsburg for 5 miles.  At the intersection of MD-66 and Smithsburg Pike/Jefferson Blvd. (MD-64), turn right.  Proceed on MD-64 for about 4 miles, to a left onto Gardenhour Road (look for a big apple shaped sign for Gardenhour Orchards).  You'll cross a small bridge at Gardenhour Orchards where the road turns to the right, then forks; take the left-hand fork onto Durberry Road.  Follow Durberry Road for about 1.3 miles (past a sign for Barr Orchards on your left at a sharp curve in the road) to a long driveway that crosses a stream on your right (look for CREP hardwoods in grow tubes); turn right and proceed to buildings.  From Berkeley County, take I-81 north to I-70 east to Exit 35, Smithsburg/Boonsboro (MD-66), and proceed as above.  For more information contact the WVU KTFREC at 304-876-6353.


CentaurT Insect Growth Regulator from Nichino America, Inc. was recently registered by the EPA and WV (April 20) for use on peaches and pome fruit.  Formulated as a 70WP, Centaur is labeled for the control of scales, leafhoppers, and pear psylla.  The active ingredient, buprofezin, acts as a chitin biosynthesis inhibitor, and therefore has primary activity on the nymphal stages of these pests.  Although adult insects are not controlled, there is some reduction in egg laying and viability of eggs.  Insect uptake of Centaur is primarily through contact, with some vaporization for a period of time after application.  Centaur is to be applied at 34.5 oz/acre, with a maximum per year of one application on apple, and two applications on pear and peach.  The product has a 12 hour REI and 14 day PHI.

Codling moth hatch of first generation eggs should begin this weekend, based on degree day accumulations since biofix (May 6) and forecasted temperatures at the WVU KTFREC.  Control is justified to prevent fruit injury  in those orchard blocks where the pheromone trap catch has exceeded 5 moths/trap/week.  If using Intrepid, Assail, Calypso, or Rimon, the first application is recommended just before egg hatch begins, at 150 degree days (DD) after biofix, which occurred last Friday. If using azinphos-methyl (Guthion), Imidan, Diazinon or Avaunt, make the first application at 250 DD after biofix (3% egg hatch). Through May 22, 167 DD have accumulated since biofix at the WVU KTFREC, with 3% egg hatch predicted to occur on May 31, based on forecasted temperatures.   An initial spray should be followed by a second complete application in about 14 days, or three additional alternate-row-middle applications 5-7 days apart.

Codling moth fruit injury

Lesser peachtree borer adults have been emerging for about 10-12 days.  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.  Good control of adults can be achieved with an airblast sprayer application of a pyrethroid insecticide (Ambush, Asana, Pounce, Proaxis or Warrior) when moth flight is peaking, as determined with pheromone traps.  This strategy is not recommended however if mites are already present in the orchard, since pyrethroid use will increase mite populations.  An alternative, and more effective strategy, is to control the larval stage in early June (1st generation) with a pyrethroid (if no mites) or Endosulfan, and/or in August (2nd generation) with Lorsban 4EC applied with a handgun to thoroughly wet all wounded areas.  Lorsban 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 larvae and wood injury

Lesser peachtree borer empty pupal case


March 21 0            
March 28 3 0            
April 4 17 9 0            
April 11 73 720 3            
April 18 51 896 42            
April 25 34 1372 186            
May 2 7 256 89 0 0 0 0    
May 9 8 140 53 15 7 0 0    
May 16 5 94 163 32 76 0 18    
May 23 2 15 23 21 131 1 24    

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.


Apple scab.  We recorded three new apple scab infection periods since the last Orchard Monitor was published on May 9th. On the weekend of May 14 - 15, we experienced 15 hours of intermittent wetting at an average temperature of 64 F. Wetting events during this period were localized and the presence of favorable conditions should be assessed on an individual basis. Where conditions were favorable for scab, they were favorable for rust infection, also. Much needed rain occurred during the period May 19 - 21, with 18 hours of wetting at 54 F followed by 16 additional hours of high relative humidity and local showers. Unsettled weather continued on May 21 - 22 with 13 hours of wetting at a cool 48 F. The current weather forecast for May 23 - 24 suggests that conditions favorable for scab will continue. Visible scab lesions have been reported (May 10th) from Frederick County, Virginia.

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
2. April 22 - 23 33 hr/52 F
3. April 30 - May 1 19 hr/57 F
  May 10 Lesions observed in northern Virginia
4. May 14 - 15 15 hr/64 F
5. May 19 - 21 18 hr/54 F
6. May 21 - 22 13 hr/48 F

Fire blight. Conditions favorable for fire blight occurred on April 20th, if wetting occurred on the 19th or 20th. Symptoms from that infection would have been visible on or around May 14. The weekend of May 14 - 15 also experienced weather favorable for fire blight infection on both days, and symptoms from that infection are still several days away from being visible. For this past weekend (May 19 - 22), conditions were borderline in much of our region with only few remaining open blossoms and temperatures just slightly below 60 F. Our data show that fire blight infection probably did not occur, however variation in local conditions may have resulted in an infection on May 19 if you had open blossoms and your temperatures were slightly higher than ours on the 18th and 19th. Our data can be viewed from our "Current Conditions" page at our Web site.

Powdery mildew. Prior to the recent spate of wet weather, conditions were very favorable for powdery mildew development. Secondary lesions were observed in Hampshire County on April 28th. In locations where mildew is a problem, susceptible varieties should be protected until shoot growth hardens off and terminal buds are set. Excellent mildew control can be achieved with the sterol-inhibiting fungicides (Nova, Rubigan, and Procure) and the strobilurin fungicides (Flint and Sovran).

Powdery mildew occurs wherever apples are grown. In some areas of the country it is a major foliar disease. In other areas, it is only a minor problem. Economic loss from mildew varies with climatic conditions, cultivar susceptibility, and orchard or nursery management practices. Apple leaves, blossoms, and fruit can be infected. Infections on leaves first appear as whitish, felt-like patches of fungal mycelium and spores, most commonly on the lower surface. These lesions may appear as yellowish spots on the upper surface or may spread to the upper surface and cover the entire leaf with a white, powdery mass of spores and mycelium. Infections along the leaf margin often result in leaf curling or crinkling. Severely infected terminals are stunted, have shortened internodes, and are covered with a silver-gray mat of mycelium that may persist through the dormant season.

Fruit infections are common on severely infected trees. Apple blossoms emerging from infected buds may give rise to small, russetted fruit. When apples are infected during bloom, their growth is stunted, and a fine network of russetted cells that may merge into a solid patch covers their surface, and is visible at harvest.

The powdery mildew fungus overwinters on apple as mycelium in dormant buds infected during the previous growing season. Conidia produced on overwintering mycelium initiate the primary infections in the disease cycle. Conidia infect young leaves, blossoms and fruit, which in turn provide inoculum for secondary cycles as new leaves, shoots and fruit develop. Leaves are susceptible for only a few days after they emerge. Conidia germinate readily over the range of 50 to 78 F (optimum 68 to 72 F) at relative humidity as low as 70%. Germination is slower at temperatures below 50 F, and no germination takes place in free water or at high temperatures (above 86 F). Conidia from overwintering mycelium can be found as early as the tight cluster stage and are released during early bloom. Infection that causes fruit russet occurs from about 3 weeks before to about 3 weeks after bloom. Infection of lateral and fruit buds occurs within a month after they are formed, apparently before the protective bud scales suberize. After bud infection, the mycelium is quiescent until budbreak the following spring. The percentage of terminal buds infected can be especially high when growth resumes in late summer following terminal bud set.

Management of powdery mildew depends upon cultivar susceptibility, the desired market quality of the fruit, and the importance of other diseases to be controlled. The main strategy is the timely application of effective fungicides. Excellent powdery mildew control can be expected when Nova, Rubigan, or Procure are used on a 7 to 10 day interval for scab control. Highly susceptible cultivars include Jonathan, Baldwin, Cortland, Ginger Gold, Idared, Rome Beauty, Stayman Winesap, and Granny Smith. Less susceptible cultivars include Delicious, Golden Delicious, Winesap, York Imperial, and Nittany. The practice of interplanting cultivars of different susceptibilities in an orchard often results in applications based on the need of the most susceptible cultivar, or more commonly, poor mildew control on the susceptible cultivar. Supplementary sprays may be required on highly susceptible cultivars to reduce inoculum for infection of less susceptible cultivars and other hosts (rusty spot on peach). Fungicide applications to control mildew should be made from the tight cluster stage until terminal growth ceases in midsummer. The interval between sprays is generally 7 days during the stages of rapid leaf development before petal fall, and 12 to 14 days during the postbloom period.


Strawberry Plasticulture Review

Let's review what makes a good strawberry plasticulture planting.  Strawberry cultivars are vegetatively propagated because their seeds are not true to type.  Using plug transplants is the best method to establish a high quality planting.  The advantage of a plug is it's not subject to digging damage which results in transplant shock.  Research has shown that large crowned transplants produce higher early season yield than small crowned transplants.  Plugs can be purchased from commercial suppliers which have had their stock inspected and approved free of disease and insects.  Also, growers may want to grow their own plugs.  If you are planning on producing your own plugs, purchase tips from a reliable source.  By using your own tips you are another generation further from the original cultivar.  Sanitation and having the proper equipment may be the deciding factor to purchase and not try and grow your own plugs.  If disease is in your planting, it will carry over to the daughter plants.  Establishing a plasticulture planting is very expensive so consider all the options and alternatives before planting.

The following planting specifics and background information is from Dr. Joseph Fiola, Specialist in Small Fruit, University of Maryland.


High density, annual, strawberry production systems utilized in California, Florida and North Carolina have increased profitability over conventional matted-row plantings.  The late summer planted system includes raised beds, black plastic mulch, trickle irrigation and plants spaced on staggered double rows.  Establishment costs are higher, but production is earlier (when crop value is highest) and of greater quality.  Labor costs are typically reduced as there is no need for blossom removal, setting daughter plants or hand weeding, and fruit is more easily and efficiently harvested from the beds.  The short growth period (plant late August, harvest mid May) allows efficient land use for double cropping possibilities and ease of rotation.  By planting late in the summer, the plant directs energy into branch crowns and flower buds instead of runners and avoids the heat, drought and weed and disease pressure of midsummer.

Dedicated growers in certain locations have found high profitability in utilizing this system.  However, potential limitations of the system include:  high establishment costs, including plastic, plant costs (high density), trickle irrigation and floating row covers as well as winter injury reducing growth and fruiting.  Research is being conducted to make this system practical in more limiting Northern climates.

Specifics of the Planting System

There are many critical parameters of the system, all of which are important to optimal production and efficiency.  Since this is an integrated system, all of the components are important and any "weak link" or exclusion of a component can lead to failure.

Location:  This system has given highest yields at locations with a long growing season.  A limitation of the system is the risk of low yield due to a restricted period available for growth in the fall in some locations and/or seasons.  Floating row covers become even more critical as sites become more marginal.  Select fields protected from Westerly winds and with a Southern exposure.

Prepare soil:  Work the soil well to make beds, including plowing, disking and roto-tilling.  Fumigation is highly recommended to control weeds and diseases, especially where strawberries or solanaceous crops were previously planted. 

Fertilization:  Sample and have soil tested by the local County Agricultural Educator to determine specific nutritional needs.  Generally, broadcast and work into beds 60 lb actual nitrogen/A, depending on soil type, as a 10-10-10 fertilizer.  An additional 30 pounds of N/A is then added through the trickle in the early spring.

Prepare bed with black plastic mulch:  Raised beds (24-30" width; wider if less in height) are prepared on 4-5' row centers.  Center crowned, firm beds, with tight black plastic are a necessity.  Trickle irrigation is installed while laying the plastic.

Plants:  The best current option for plant type is the use of transplant "plugs" ($130.00/1000) which are propagated from actively growing runner tips.  Plugs can be purchased directly or to save money, one can purchase tips ($55.00/1000) and produce transplant plugs in a greenhouse.  A list of nurseries which supply plugs and runner tips, and/or directions for propagating from tips is available through Cooperative Extension.  Dormant and/or fresh-dug plants may be an option in some areas.

Cultivars:  The current primary choice for cultivar for this system is 'Chandler'.  Although they are not typically a problem with this system, 'Chandler' is susceptible to Red Stele (Phytophthora) and Verticillium wilt.  'Allstar' had yield and fruit size comparable to 'Chandler' in replicated trials and is definitely worth a trial on heavy soils where Red Stele may be a severe problem.  'Idea', 'Marmolada' and 'Jewel' have performed well in observation trials and may warrant limited testing.

Plant spacing:  The best in-row spacing is 12 inches on a staggered double row.  The quantity of plants per acre depends on row center distance (example: 60' (5') centers x 12 x 12 within = 17,400/A).

Planting date:  Optimal planting date and spacing must be determined to allow for ample time to produce sufficient vegetative growth before flower bud initiation.  In Northern areas, mid to late August planting of plugs is necessary.  Early applied floating row covers may help compensate for slightly later planting dates.

Row covers:  Floating row covers (FRC) are considered an integral part of the system in the Northeast for improved growth in the fall, winter protection, frost protection and earlier fruiting.  Remove the FRC at the first signs of bloom to allow for bee pollination.

Our area has heavier soils and a shorter growing season than the major plasticulture growing areas. 

Source: George Perry, Extension Agent, Schuylkill County and Dr. Joseph Fiola, Specialist in Small Fruit, University of Maryland.

Look up for Guidance

If you want to know what nutrients to add to your orchard's soil, don't bother with the soil itself. Focus on the leaves.

Occasionally, University of California Cooperative Extension Farm Adviser Bill Coates will encounter a well-meaning tree fruit or nut grower who's having a problem in an orchard and supplies Coates with a lab report on a soil sample. Unfortunately, the report is of limited use to Coates. "If the grower gives me a copy of their soil analysis, I usually discard a lot of it because it doesn't have much value," he says.  It's not that soil samples have no importance. In fact, they are crucial to take before planting so that the land can be prepared. It's just that it's the tree that sets the crop, not the soil.

"Why do I encourage leaf analysis more often than soil analysis for tree crops? Leaf analysis is the most accurate method of determining the nutrient status of fruit and nut trees," says Coates, the adviser on fruit and nut crops to growers in San Benito, Santa Cruz, Santa Clara, and Monterey Counties. "You can find out what is actually getting into the tree in acceptable as well as excess or deficient concentrations."

Soil analysis can be useful for determining pH, lime, or gypsum requirements, as well as changes in certain elements through soil layers, but it doesn't tell you what the tree is utilizing. In fact, if a grower isn't careful, he can actually be misled by a soil analysis, no matter how thorough it is.

That's because some types of nutrients may be present in the soil in sufficient quantities, but can't be used by the trees because of insolubility, competing nutrients, weakened root systems, drought, and a host of other causes.

Common problems.  The most common deficiencies in Coates' region, the Central Coast of California, are nitrogen, zinc, potassium, and iron. Occasionally manganese and magnesium may also be deficient. Excess may include chloride, sodium, and boron - all of which may cause leaf burn. Manganese can also be in excess in apple leaves when associated with measles in acid soil conditions. But it's important to note that leaf analysis cannot diagnose all nutrient problems, says Coates. Iron cannot be accurately measured by leaf analyses, for example. "for iron, I rely on visual symptoms of chlorosis: green veins with yellow leaf blades," he says.  More severe cases will have the leaves completely bleached out, followed by dieback."  One additional consideration is that if trees have been sprayed with foliar nutrient sprays such as zinc, you will not get an accurate leaf analysis for the element.

One of the most vital nutrients is nitrogen, but because of that it is also one of the most overused. Nitrogen will make trees take off, but can cause problems later with the fruit, Coates says.  Excess nitrogen, even if it's only just above the recommended levels, can hurt fruit quality.  For example, excess nitrogen can increase bitter pit in apples and brown rot in stone fruit.

"You also start running into delayed or uneven ripening, or excessive vegetative growth," says Coates.

Source: Article by David Eddy, Senior Western Editor, American/Western Fruit Grower, May 2005.

Additional information on tissue/leaf analysis will be provided in a future issue of The Orchard Monitor.


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

P. O. BOX 609
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

Top of PageUp One LevelAgriculture & Natural Resources DevelopmentWVU Extension ServiceWest Virginia University