May 30, 2006
|Upcoming Events||Farm Bill Feedback||Pheromone Trap Counts||Plant Pathology|
June 1, 7:00 p.m. - Spring In-depth Fruit Meeting at Virginia Tech's Alson Smith Agricultural Research and Extension Center, Winchester, Va. The agenda will include seasonal updates by VA Tech Extension Specialists and a presentation on internal worms. For more information contact the Frederick County Extension Office at 540-665-5699.
June 6, 6:00 p.m. - Tree Fruit Grower Twilight Dinner and Meeting at George S. Orr and Sons Orchard, Arden, W. Va. Take exit 13 off I-81 and follow Route 15 (King Street) west for 1.7 miles. Turn left onto Arden-Nollville Road (Route 30), travel 2.3 miles to a right turn at Orr's Farm Market sign, and proceed ¾ mile to the farm market. Following dinner, seasonal updates will be provided by Extension Specialists from the WVU KTFREC, and a tour will be conducted by Mike and Mark Orr. For more information contact the WVU KTFREC at 304-876-6353.
June 8, 6:30 p.m. - Joint PA, MD and WV Fruit Grower Meeting at Allenberg Orchards, Smithsburg, MD. From Jefferson County, take WV-480 north through Shepherdstown, crossing the Potomac River onto MD-34. In Sharpsburg, turn left onto N. Church Streeet (becomes MD-65, Sharpsburg Pike). Follow MD-65 north until you intersect I-70 (about 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 1.5 miles (around the town of Smithsburg, through an intersection with MD-77) to a right onto MD-491. Proceed to Barth Spring Lane just ahead on the right. From Berkeley County, take I-81 north to I-70 east 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 1.5 miles (around the town of Smithsburg, through an intersection with MD-77) to a right onto MD-491. Proceed to Barth Spring Lane just ahead on the right. The agenda will include an orchard tour, followed by brief presentations by Extension Specialists from PSU, Univ. of MD, and WVU. For more information contact the WVU KTFREC at 304-876-6353.
June 22, 6:00 p.m. - Tree Fruit Grower Twilight Dinner and Meeting at Shanholtz Orchards, Romney, WV. Following dinner, seasonal updates will be provided by WVU Extension Specialists and an orchard tour will be conducted, which will include studies underway for weed control and pheromone mating disruption for codling moth and Oriental fruit moth. For more information contact the Hampshire County Extension Office at 304-822-5013.
FARM BILL FEEDBACK
A Web-based farm bill feedback form has been launched by the U.S. House of Representatives' Agriculture Committee to help members learn what is important to producers around the country.
Chairman Bob Goodlatte made the announcement Monday, May 8. He emphasized the importance of receiving the form's information because "farm bill policy directly impacts the lives of America's farmers and ranchers." He also was quoted as saying, "By having a Web-based feedback form, producers everywhere will have the opportunity to provide the committee with their thoughts and input about future farm policy."
Combined with field hearings now being conducted, the forms will help committee members analyze the current farm policy as they prepare to reauthorize the 2002 Farm Bill, which expires September 2007. However, the information provided by the Web-based forms will be viewed only by members of the House Committee on Agriculture and will not be part of the Congressional Record.
To access the feedback form, click on the Farm Bill Feedback icon on the committee's Web site (www.agriculture.house.gov). Or you may go directly to the form (www.agriculture.house.gov/inside/feedbackform.html).
Tufted apple bud moth adults have been emerging since May 3 (biofix), which is 5 days earlier than last year. First generation egg hatch is predicted to begin at 480 degree days (DD) after biofix, which should occur on June 2, based on an accumulation of 370 DD through May 29 and warmer temperatures expected this week.
The objective in controlling this insect is to apply sprays during the period of egg hatch, which are best timed by using DD accumulations (45ºF lower and 91ºF upper threshold temperatures) after biofix. Options for controlling the first generation include Intrepid, SpinTor (Entrust), Rimon, BT, or an organophosphate insecticide [azinphos-methyl (Guthion), Imidan] with Lannate. Intrepid, SpinTor (Entrust) and Rimon will provide the best control in most West Virginia orchards. It is recommended that any of these three products be applied as a complete spray at 585-640 DD (20-30% egg hatch, expected on June 6-9) or as two alternate-row-middle applications 7 days apart beginning at 530 DD (10% egg hatch, expected on June 4). An additional application may be needed (in 14 days for complete, in 7 and 14 days for alternate-row-middle) in high pressure situations. If using BT or an organophosphate in combination with Lannate, make complete applications at 530-585 DD (10-20% egg hatch) and 805-855 DD (60-70% egg hatch). Alternate-row-middle applications of these materials should begin 50-75 DD earlier and be repeated every 7 days for a total of up to four applications, depending upon insect pressure.
Oriental fruit moth hatch of first generation eggs is complete and the second flight of moths has just begun. Orchards should be inspected for shoot injury at this time in order to evaluate the effectiveness of first generation control measures.
There are various options for controlling the second generation. One strategy that could be targeted against adults is pheromone mating disruption, with various hand applied dispensers (Isomate-M100, Isomate CM/OFM TT, Disrupt OFM) and a sprayable pheromone (CheckMate OFM-F) available. A second strategy is to control larvae with insecticides beginning after mid-June in those orchards where the pheromone trap catch exceeds 10 moths/trap/week.
San Jose scale infestations continue to occur in some orchards. Changes in pest management practices in recent years have increased the potential for this insect to become more of a threat. Widespread use of pyrethroids, which do not control scale, in place of organophosphates (Diazinon, Lorsban, Supracide) and decline in oil use have contributed to increased survival of overwintering scale in some orchards. Most newer chemistries (Intrepid, SpinTor, Rimon) used during June and August are not effective against the crawler stage.
Crawler emergence typically begins in late May to early June and should be monitored in those blocks that had at least 1% scale injury on fruit at harvest last year. Crawler emergence can be detected by wrapping black electrician's tape (sticky side out) around scale-infested branches. A thin film of petroleum jelly may be spread on the tape surface to enhance crawler capture. Inspect the tape traps twice weekly for the bright yellow crawlers. On apple, apply Esteem, Centaur, Diazinon or Provado, preferably as a high volume spray, when crawlers are first detected and again in about 10 days. San Jose scale may also infest peaches and can be controlled with Diazinon. Adequate coverage of the tops of trees is critical to control of this insect.
Green aphids (spirea aphids) have increased on the terminals of apple trees, and will continue to be abundant for the next 3-4 weeks. In most situations, low to moderate populations of these aphids can be tolerated without detrimental effects. High populations can stunt the growth of young trees, and indirect injury can result when aphids excrete large amounts of honeydew which supports the growth of a sooty mold that discolors the leaves and fruit. The accumulation of honeydew is influenced by the amount of rainfall (less under wet conditions).
Examine the foliage and fruit for buildup of honeydew, and monitor aphid abundance by sampling 10 actively growing shoots (not watersprouts) on each of 5-10 trees per block. On each shoot, determine the number of leaves that have wingless aphids (winged aphids are black) and calculate the average number of aphid infested leaves per shoot across all trees sampled. Also examine shoots and aphid colonies for the presence of aphid predators, such as ladybird beetle adults and larvae, and larvae of syrphid flies, aphid midges and green lacewings.
An insecticide application is recommended for green aphid control if an average of four or more infested leaves per shoot are found, and less than 20% of the aphid colonies have predators. Materials for control include Provado, Actara, Assail, Calypso, Clutch, Lannate and Thionex.
Peachtree borer adult emergence monitoring with pheromone traps should begin at this time. Control can be achieved with the installation of pheromone mating disruption dispensers at the beginning of moth flight or with an application to the base of trees of Thionex in late June to early July (21 day PHI) and/or Lorsban after harvest.
PHEROMONE TRAP COUNTS
WEST VIRGINIA UNIVERSITY KTFREC
|DATE - 2006||RBLR||STLM||OFM||CM||TABM||DWB||LPTB||PTB||AM|
|DATE - 2006||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.
Infection periods. We recorded one wetting period since the last newsletter on May 15th. Infection period #6 occurred on May 15 and was accompanied by 0.33 inches of rain and lasted for 11 hours at 55° F. Infection period #'s 4 and 5 were the first infection periods in our area to occur after the appearance of visible scab lesions, which were first observed at WVU-KTFREC on May 9. The first lesions were most likely due to infections that occurred during infection period #3 back on April 21-23. Rust lesions initiated during that infection period also are visible. Intermittent showers and significant dews occurred during the period May 25 - 28 and resulted in significant accumulation of wetting hours (see more below). Our total rainfall for the month of May is 1.57 inches at WVU-KTFREC, 1.27 inches at Orr's Farm Market, and 1.36 inches at Butler's Farm Market. Our thanks to these growers for hosting our Davis weather machines.
Table 1. Dates and conditions for apple scab infection periods at the WVU - KTFREC, 2006.
|No.||Date 2006||Hours/ degrees F|
|1.||March 31 - April 1||10 hr/59 F|
|2.||April 8||14 hr/49 F|
|3.||April 21-23||34 hr/54 F|
|4.||May 8-9||19 hr/51 F|
|5.||May 11-12||25 hr/56 F|
|6.||May 15||11 hr/55 F|
Summer fungicide programs. Excellent control of our summer disease complex can be achieved with well-timed fungicide sprays. Timing is one of the most important aspects of effective disease management. As always, read the labels for more detailed information about these materials.
1. EBDC fungicides (Dithane, Manzate, Penncozeb, Polyram): Will provide excellent control of summer diseases when combined with Captan, Ziram, or Topsin-M. EBDC's can be applied up to 77 days before harvest when using the extended application schedule at the 3 lb per acre rate. Early use of these materials provides the foundation for managing summer diseases for the remainder of the season.
2. Topsin-M: Highly effective against sooty blotch, fly speck, and the Botryosphaeria rots (black rot and white rot). In wet growing seasons, the spray interval should not be longer than 14 - 21 days, or 2 inches of rain. Adjust the rates of Topsin-M toward the high end of the rate range (10 oz per acre) when disease conditions are highly favorable. Use Topsin-M in mixtures with protectant fungicides to help prevent the emergence of fungal strains resistant to Topsin-M.
3. Protectant fungicides (Captan, Ziram, Sulfur): Captan and Ziram applied by themselves or in combination will provide adequate control of summer diseases if applied often enough at the proper rates (6 to 8 lb per acre total). Spray intervals should be 21 days under moderate disease pressure, and should be shortened to 10 - 14 days under prolonged, highly favorable conditions. The 8 lb per acre rate also is preferred under highly favorable conditions. Sulfur by itself is only fair, at best, in limiting these diseases. However, sulfur and copper are the only choices for organic spray programs. Under extreme disease pressure, the addition of Topsin-M at a "half rate" improves control of Botryosphaeria rots and sooty blotch and fly speck. Where scab is well established, captan (8.0 lb. per acre) is the better choice to limit secondary infections.
4. Strobilurin fungicides (Sovran and Flint): These fungicides are very effective for controlling fly speck and sooty blotch and could be used as substitutes for Topsin-M + protectant (captan or ziram) sprays during summer. The best timing for Sovran and Flint in summer sprays remains to be determined. If Sovran or Flint were used to control scab at tight cluster and pink, then they should not be used again prior to second cover. Sovran and Flint suppress sporulation of scab lesions, so their use at this time may be beneficial if your control of primary scab hasn't been completely effective. During early summer, good spray coverage is still possible, whereas dense foliage, fruit clustering, and limbs drooping under heavy crop loads often compromise spray coverage in late summer. However, if Sovran or Flint is applied at petal fall and first cover, then additional summer applications would need to be delayed until July or August because of the requirement for intervening applications with some other class of fungicides.
Sovran has a 30-day preharvest interval and the label indicates that it should not be used as the last spray of the season. This prohibition was based on the assumption that growers might apply Sovran for scab control starting at green-tip, and using it both to end the season and begin the following season would compromise resistance management. Flint has a 14-day preharvest interval. Both Flint and Sovran have residual activity against fly speck, although recent research suggests that the residual activity is not equivalent to that provided by Topsin-M.
Summary. Control of early-season diseases with a program that includes an EBDC material, alternated with the strobilurin fungicides, provides a solid foundation for controlling summer diseases. The most flexible program for controlling sooty blotch and fly speck is ziram or captan + Topsin-M, and optionally alternated with two applications of the strobilurin fungicides. This program may need to be modified if other summer diseases occur at moderate to high levels. For example, the combination of ziram + Topsin-M is rated as only "good" (rather than "excellent") against white rot and black rot, and is only "fair" against bitter rot. Alternating applications of ziram + Topsin-M or captan + Topsin-M with full rates of ziram or captan alone will improve your management of the summer rots. Remember that management of diseases with fungicides is improved if other cultural practices that reduce inoculum and improve coverage are employed. Good disease management may require some flexibility in application timing and rates of materials.
Accumulated wetting hours. As of May 30, 2006, we have accumulated 121 wetting hours, for a petal fall date of April 27. Accumulated wetting hours are useful for predicting the appearance of sooty blotch on nonsprayed fruit. Symptom development for these diseases is highly dependent upon temperature and moisture conditions surrounding the fruit. The appearance of sooty blotch symptoms has been predicted with reasonable accuracy by using accumulated wetting hours (AWH). Visible signs of sooty blotch may appear following approximately 260 - 300 AWH (earlier in the season (260 AWH) if the disease was severe last year, later in the season (300 AWH) if not). The AWH threshold for making the decision to include Topsin-M in the spray program is 225 for high disease pressure and 275 for low disease pressure. Each of these threshold values presumes that 25 additional AWH will occur in the next 5 days after reaching the threshold.
See our "Current Conditions" Web page for details that are updated at least three times weekly.
Update on apple scab and fungicide resistance. (Wolfram Koeller and Diana Parker, Plant Pathology Department, Cornell University, Geneva, NY, from the 5/22/2006 issue of Scaffolds Fruit Newsletter). (Note to WV cooperators on this project - we still have not received any data from the samples that we've submitted for testing in 2005 and 2006; the findings reported here pertain to samples collected in New York). What started out as an "easy" scab season in our Station orchards here in Geneva turned around to be a serious problem. Following a heavy 3-day infection period at tight cluster, 90% of clusters had scab lesions at petal fall, and the performance of fungicides in our orchard trials confirmed previous experiences. Starting the scab program at half-inch green rather than at green tip and responding to the infection at tight cluster with a post-infection spray provided no or poor control of cluster leaf scab. Dithane at its low mixture rate, but also when mixed with Captan, failed to control cluster leaf scab. As expected for an orchard with resistance to the SI fungicides, Nova, even in combination with Dithane, performed poorly. The performance of the strobilurin Flint was also poor, showing one more time that the strobilurins Flint and Sovran are starting to lose their post-infection edge. Both Scala and Vangard provided adequate post-infection activity, but we will have to wait until harvest to find out whether and how this post-infection advantage can be carried over to good control of fruit scab at harvest. We have continued our sensitivity testing of the apple scab fungus during the 2005 season, and the not so "pretty" picture we found a year earlier has been confirmed. Resistance to the SIs Nova, Procure and Rubigan is by now quite common (in New York) rather than a rare occasion here and there. Resistance to Syllit is unpredictable. We found that, once an orchard had developed resistance to dodine, this resistance was stable for more than 30 years, even after orchards had been replanted. We have not yet discovered an orchard totally immune to the strobilurins Flint and Sovran. But, sensitivity shifts toward resistance are obvious. These sensitivity shifts have eroded the post-infection power of the strobilurins. They remain very effective in a protective mode. The APs Scala and Vangard remain a "hard nut to crack". We found that in SI-resistant orchards their potency was diminished before they ever were used. We also found that their post-infection advantage in the early scab season provided little advantage in the control of fruit scab at harvest.
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
TREE FRUIT RESEARCH AND EDUCATION CENTER
P. O. BOX 609
KEARNEYSVILLE, WV 25430-0609
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