WVU Extension Service: The Orchard Monitor: Committed to the Integration of Orchard Management Practices
August 1, 2005

Upcoming Events


Pheromone Trap Counts Plant Pathology



August 2, 6:00 p.m. - Twilight Fruit Growers Dinner and Meeting at Jefferson Orchards, Kearneysville, W. Va.  The orchard is located on State Route 9, 1.5 miles east of Kearneysville.  Following dinner, seasonal updates will be provided by WVU Extension Specialists and a tour will be conducted by host Ron Slonaker.  For more information contact the WVU KTFREC at 304-876-6353.

August 11, 6:00 p.m. - Twilight Fruit Growers Meeting sponsored by the Timber Ridge Fruit Farm, Gore, Va.  The meeting will begin with a catered dinner at the Bethel Church pavilion.  Take I-81 to Route 37 to Route 50 West.  Follow Route 50 West for approximately 12 miles to Route 610 (Parishville Road).  Turn left onto Route 610 (Parishville Road) and stay on the hard surfaced road for approximately 2 miles to Bethel Church on the left.  Dinner will be followed by an orchard tour and updates by VA Tech Extension Specialists.  To make a meal reservation, contact Cyndi Marston at 540-665-5699 or at cmarston@vt.edu by August 5.


Tufted apple bud moth adults (second flight) have been emerging since the third week of July, which is about one week later than last year.  Based on degree day accumulations since biofix of spring brood moths (2137 DD through July 31), hatch of second generation egg masses is expected to begin the middle of this week and continue for the next 4-6 weeks.  Larvae of this generation typically cause greater fruit injury than those of the first generation because: 1) the egg hatching period is usually more prolonged for this generation than the preceding one; 2) it is more difficult to obtain thorough coverage at this time of the season because the tree canopy is more dense and the larger size of clustered fruit provides better protection of larvae from spray contact; 3) some orchards are not sprayed after mid-August, when a substantial portion of egg masses have yet to hatch; and 4) the use of equipment and labor for peach harvest may prevent the proper timing of spray application in apple orchards. 

Control is best achieved by using degree days (DD) to time spray applications to coincide with egg hatch, so that larvae are killed before they cause fruit injury.  Intrepid,  SpinTor and Rimon are considered to be the most effective materials.  It is recommended that these products be used as two complete applications at 2355-2435 DD (20-30% egg hatch) and 2665-2740 DD (60-70% egg hatch) where pest pressure is high.   If alternate-row-middle applications are planned, a total of four sprays are recommended at 7-day intervals, beginning at 2280 DD (10% egg hatch).  A single complete application, or two alternate-row-middle applications would be sufficient in lower pressure situations.  Other control options, considered to be less effective, include Avaunt, BT, or an organophosphate [azinphos-methyl (Guthion), Imidan] in combination with Lannate.  When using these products, make two complete applications at 2280-2355 DD (10-20% egghatch) and 2665-2740 DD (60-70% egg hatch), or four alternate-row-middle applications at  7-day  intervals, beginning at 2210-2245 DD (1-5% egg hatch).  Pyrethroid insecticides (Asana, Danitol, Proaxis, Warrior) are also an effective option.  Because they can result in an increase in the motile stages and/or overwintering eggs of European red mite, pyrethroids should be limited to the last application of the season.  This strategy may not prevent the detrimental consequence of pyrethroid use, but it could reduce the severity of the mite increase.  Be sure to check the preharvest intervals when selecting products for use.

Tufted apple bud moth fresh egg mass

Tufted apple bud moth egg mass near hatch

Tufted apple bud moth hatched egg mass

Oriental fruit moth third generation egg hatch is estimated at 39% complete on peach through July 31, based on an accumulation of 2374 DD since biofix on April 11.  A second insecticide application may be warranted this week at 2450-2500 DD (50-56% egg hatch), depending upon pest density (pheromone trap capture greater than 10 moths/trap/week) and proximity to harvest.  Control options [days to harvest] include azinphos-methyl (Guthion) [21], Imidan [14], Intrepid [7], Lannate [4 on peach, 1 on nectarine], and carbaryl (Sevin) [3]. 

On apple, initiate applications (above materials, or Avaunt, Assail, Calypso, Clutch or Rimon) about 7 days after exceeding a trap threshold of 10 moths/trap/week, and maintain spray intervals on a 2 week (complete) or 5-7 day (alternate-row-middle) schedule for as long as this condition continues. 

Codling moth second generation egg hatch is estimated at 74% complete through July 31, based on an accumulation of 1739 DD since biofix on May 6.  A second insecticide application should have been made at 1550-1600 DD (45-53% egg hatch), or 10-14 days after the first application, in those orchards where the pheromone trap capture has exceeded 5 moths/trap/week.  Options include azinphos-methyl (Guthion), Imidan, Intrepid, Avaunt, Assail, Calypso, Clutch or Rimon.

San Jose scale second generation crawler emergence should be monitored over the next few weeks in those blocks in which greater than 1% of the fruit was injured at harvest last season.  Monitor crawler emergence by wrapping black electrician's tape (sticky side out) around tree limbs that are encrusted with dark scale coverings.  A thin film of petroleum jelly may be spread on the tape surface to enhance crawler capture.  An alternative approach is to cover the black electrician's tape (wrapped with sticky side against the branch) with double sided cellophane tape.  Inspect the tape traps twice weekly for the bright yellow crawlers, and apply Esteem, Centaur, Diazinon or Provado as a high volume spray when emergence is first detected and again in 10-14 days.  Adequate coverage of the tops of trees is critical to control of this insect.

San Jose scale fruit injury

San Jose scale tape trap


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    
May 31 0 0 5 4 108 2 14 0  
June 6 0 52 10 9 144 1 14 0  
June 13 34 1280 9 23 132 0 37 3  
June 20 121 704 6 7 50 17 28 0  
June 27 135 1728 14 1 9 13 13 3 0
July 5 122 1312 30 8 1 15 11 2 0
July 11 34 640 7 13 2 14 4 0 1
July 18 17 1280 9 17 1 8 2 0 4
July 25 12 416 9 36 2 25 1 0 2
August 1 15 463 39 20 8 15 4 0 4

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.


Infection periods.  We recorded several rain events since the last Orchard Monitor was published on July 18th. However, in most cases, rapid drying afterwards resulted in wetness durations too short to qualify as infection events, therefore only one new wetting event (July 25th) has been added to the table below. Nevertheless, wetting hours continued to accumulate with the rain and dew periods. Total rainfall at WVU - KTFREC for July 18 - 31, 2005 was 0.61 inches; total rainfall for the month was 3.23 inches.

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

No. Date 2005 Hours/ degrees F
8. June 2 - 3 33 hr/60 F
9. June 6 - 7 12 hr/64 F
10. June 9 - 10 13 hr/70 F
11. July 5 - 6 18 hr/68 F
12. July 8 18 hr/66 F
13. July 13 - 14 15 hr/71 F
14. July 15 7 hr/72 F
15. July 16 10 hr/74 F
16. July 16 - 17 14 hr/74 F
17 July 25 6 hr/72 F

Accumulated wetting hours: Threshold warning - threshold exceeded.  As of August 1, 2005, we have accumulated 275 to 321 wetting hours, for petal fall dates of May 14 and May 7, respectively. Signs of flyspeck were first observed on July 20th at WVU - KTFREC (between 244 to 290 AWH depending on whether accumulations began on May 14 or May 7, respectively).

Apple Fruit Rot Basics: Black rot is a common disease of apple and pear and occurs throughout the eastern apple growing area. The black rot fungus causes frogeye leaf spot, fruit rot, and limb cankers. Fruit infection can occur early in the season, as soon as the bud scales begin to loosen. Sepal infection is the most common form of early-season infection. Symptoms first appear as minute red specks that later turn purple and are bordered by a red ring. After a few weeks the entire sepal lobe is affected and turns dark brown. Sepal infections result in blossom end rot later in the season. Infections occurring after petal fall begin as reddish flecks that develop into purple pimples, 1 mm or less in diameter. These lesions do not enlarge rapidly until the fruit begin to mature. Infections that occur on more mature fruit are often black, irregularly shaped, and surrounded by a red halo. As the lesions enlarge, they form a series of concentric rings alternating from black to brown. The lesions remain firm and are not sunken. The optimum temperature for fruit infection is 68 to 75 F, with 9 hours of wetting required for infection to occur.

White rot, or Bot rot, has been reported to cause fruit losses of up to 50% in the southeastern U.S. Fruit lesions usually become noticeable 4 to 6 weeks before harvest, although infections may have occurred earlier in the season. Lesions begin as small, often circular, slightly sunken, brown to tan spots, which may be surrounded by a red halo (or a dark purple to black halo on red-skinned apple cultivars). As lesions expand in diameter, the rotted area extends in a cylindrical pattern toward the core. In more advanced stages, the core becomes rotted. When fruit rot under warm conditions, rotted fruit are clear tan to light brown, soft, and watery. Under cooler conditions, rotted areas are usually firmer and deeper tan, and resemble black rot. Although wounds are not required for infection to occur, infection of wounded fruit can occur in only 2 hours at 82 F. Golden Delicious is very susceptible to this disease. Twig and limb infections are usually associated with periods of hot, dry weather. The canker phase of the disease is most common on Rome and Delicious, but can occur on all cultivars.

Bitter rot lesions on apple fruit vary in appearance depending upon when during the season infection occurs. Fruit infections can occur as early as bloom and appear as minute gray-brown flecks, which usually do not develop further until fruit begin to ripen. Fruit infections occurring a month after petal fall begin as small, round, slightly sunken areas which are light to dark brown in color and are sometimes surrounded by a red halo on mature fruit. As lesions enlarge, they usually remain circular and they may become sunken or saucer-shaped. Secondary spores (conidia) are produced around the initial point of infection. Under moist, humid conditions, the conidial spore masses appear creamy to pink to orange in color. Under dry conditions, spore masses appear crystalline. Active lesions may first be noticed when they are smaller than the size of a dime, but the characteristic pink/orange spores are not usually evident until the lesions are about the size of a quarter. Decay lesions extend in a cone-shaped pattern toward the core, a trait best seen by cutting the apple in half through the decayed area and observing the V-shaped lesion. The rotten flesh is brown and more watery than would be expected with black rot. White rot lesions appear more cylindrical when the fruit is cut open. Other decays commonly seen in the orchard at this time of year are usually initiated at bird pecks or insect injuries. If decays occur on fruit where the skin has not been damaged, bitter rot is the most likely cause.

Fruit are susceptible to the bitter rot fungus right up until harvest, and can become infected with as little as 5 hours of wetting at 79 to 82 F. At 80 F, lesions can develop and produce spores within 11 days of inoculation. Unprotected fruit exposed to high inoculum levels may develop many small dark spots, which initially give the fruit a peppered appearance. Epidemics can develop rapidly during prolonged warm, wet weather, and losses can be extensive. The most severe epidemics usually occur when the early season is warm and wet and primary infection occurs early, providing abundant secondary inoculum.

Summer disease integrated management includes many things in addition to adequate spray coverage and proper timing of spray applications. Consider the following:

1) prune to improve spray coverage and drying time;
2) remove prunings, cankers, dead wood, and vines from the orchard;
3) remove mummies when feasible;
4) optimize tree nutrition to help wounds and cankers heal;
5) reduce cork spot to prevent bitter rot build up;
6) control fire blight to reduce rot fungus build up;
7) prevent insect injury to fruit to reduce rot;
8) remove brambles and volunteer trees from rock ledges;
9) frequently monitor orchard blocks most prone to disease; and
10) try to stay ahead of problems.

See our "Current Conditions" Web page for details that are updated at least three times weekly.


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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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
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