October 13, 2008
|Upcoming Events||NRCS-EQIP Programs||Pheromone Trap Counts||Plant Pathology|
November 18, 9:00 a.m. -2:30 p.m. – Specialty Crop Tour for Mid-Atlantic Young Growers. This tour will include visits to Musselman’s Greenhouses, Kuhn Orchards, and Twin Springs Fruit Farm in Cashtown, PA. A head count is needed for lunch (sponsored by the Adams County Fruit Grower Association) by November 3 by contacting Tara Baugher (firstname.lastname@example.org; 717-334-6271) or Alan Michael (email@example.com).
December 9-11. – Great Lakes Fruit, Vegetable and Farm Market Expo at the DeVos Place Convention Center, Grand Rapids, MI. For more information go to www.glexpo.com or call 269-424-3990.
January 16-17. – Future Harvest-CASA’s 10th Annual Conference at the Frederick Holiday Inn and Conference Center, Frederick, MD. For more information go to www.futureharvestcasa.org.
January 27-29. – Annual Meeting of the Virginia and West Virginia State Horticultural Societies at the Holiday Inn Select, Richmond, VA. For more information contact Katy Trenary at 304-263-1027 or at firstname.lastname@example.org, or Liz White at 540-667-9101 or at email@example.com.
February 3-5. – Mid-Atlantic Fruit and Vegetable Convention at the Hershey Lodge and Convention Center, Hershey, PA. For a copy of the program and registration form go to: www.shaponline.org. For questions or more information contact Maureen Irvin at 717-677-4184 or at firstname.lastname@example.org.
NRCS-EQIP PROGRAMS - 2009
Three NRCS-EQIP Cost-Share programs (listed below) are available for West Virginia tree fruit growers in 2009. The sign-up deadline for applications is October 31, 2008.
Integrated Pest Management (IPM). West Virginia commercial tree fruit growers can receive a 75% cost-share to support the use of advanced IPM practices. A minimum of 3 acres (150 trees) of bearing apple or peach trees must be enrolled for 3 years in order to participate. The possibility of shorter term (< 3 years) contracts is being investigated.
Practices and cost incentives include:
Growers currently with IPM contracts
Deer Fence. A 75% cost-share of $5.02 per linear foot is being provided for materials and labor for construction of a 10 ft. high deer fence.
SmartSpray Technology. A 75% cost-share is being provided towards purchase and installation of a SmartSpray system on newly purchased or existing airblast sprayers, for those participating in the above IPM program.
New Sprayers Existing Sprayers
6 sensor system - $11,437.50 6 sensor system - $14,025.00
8 sensor system - $12,937.50 8 sensor system - $15,525.00
10 sensor system with tower - $14,032.50 10 sensor system with tower - $16,620.00
How to sign up. Contact your local Natural Resources Conservation Service (NRCS) office and make arrangements to complete an application by October 31, 2008. You can find your local NRCS office in the phone book under United States Government – Agriculture Dept. – Natural Resources Conservation Service. Or go online at: www.wv.nrcs.usda.gov/about/ and click on “Find a Service Center” on the left to access the directory.
For more information, contact
Henry Hogmire (876-6353, email@example.com); Alan Biggs (876-6353, firstname.lastname@example.org);
or Rakesh Chandran (293-6131 x4225, RSChandran@mail.wvu.edu).
2008 pest summary. Internal worms [codling moth (CM), oriental fruit moth (OFM)] continue to present the greatest management challenge to West Virginia fruit growers. Quite a few growers used the newly registered products, Delegate and Altacor, for internal worm control. In addition, some growers who are participating in an NRCS-EQIP IPM program had their first experience in the use of hand-applied pheromone mating disruption dispensers for management of these pests. Overall, these programs performed very well, especially when considering that many sites were high pressure situations. CM was responsible for almost all of the injury in the various fruit samples that we examined, which occurred from mid-July through early September. Biofix (beginning of moth flight) was 11 and 3 days earlier in 2008 vs. 2007 for OFM and CM, respectively. Despite an earlier biofix, seasonal development of these pests was behind last year by 1-5 days from June 1 to August 1 and 5-8 days on Sept. 1 because of cooler temperatures.
Rosy apple aphid was generally well managed by most growers during the prebloom period, with fewer postbloom problems requiring rescue treatments than last year.
European red mite populations exceeded threshold and required treatment in only a few orchards. The generally cooler temperatures as compared with last year (9 vs. 30 days >90° F) and more abundant rainfall (28.6 vs. 12.4 inches from April through August) helped to slow build up of mite populations this year. Most of the problem situations occurred earlier in the season, May and June, resulting from a high population of overwintering eggs and lack of oil or other early season preventative acaricide application.
Leafrollers [tufted apple bud moth (TABM), redbanded leafroller (RBLR)] were well managed in most orchards, with many growers continuing to use Intrepid during the egg hatching periods. In addition, growers who used Rimon, Delegate or Altacor for internal worm control benefited from good control of leafrollers with these products as well.
Japanese beetle populations were generally much lower overall than last year. The drier conditions last year, especially during July (1.8 vs. 6.2 inches of rain), undoubtedly had a negative impact on the establishment and survival of larvae feeding on grass roots, resulting in fewer adults to emerge this year.
Stink bug populations of our traditional species (brown, dusky, green stink bugs) were significantly lower than last year. For the past few years we have been baiting common mullein (a preferred stink bug host) with pheromone lures to collect brown stink bugs for laboratory studies. Even though common mullein plants thrived this year with the abundant rainfall, we collected very few brown stink bugs as compared with the past few years. However, the brown marmorated stink bug (BMSB), an introduced species that has become a nuisance in homes in the fall, has become much more abundant. Introduced into the U.S. from Asia, adults of BMSB were first identified in Allentown, PA in 2001, and have been increasing in West Virginia since 2004. Known as a pest of fruit trees and legumes in its native China, South Korea, Japan, and Taiwan, BMSB has been found feeding on fruit in PA and NJ during the past few years, and was observed feeding on fruit in commercial apple and peach orchards in WV this year. Whereas our traditional stink bug pests develop on various weed species and feed on fruit as adults, BMSB is more likely to lay eggs on fruit trees, resulting in fruit damage by both nymphs and adults. Therefore, BMSB could become more problematic because of its potential for greater abundance on fruit trees. At the present time, BMSB is being treated the same as our traditional stink bug species for management purposes, with pyrethroids considered to be the most effective control option.
PHEROMONE TRAP COUNTS
WEST VIRGINIA UNIVERSITY KTFREC
|DATE - 2008||RBLR||STLM||OFM||CM||TABM||DWB||LPTB||PTB||AM|
|DATE - 2008||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 (in a commercial orchard in Kearneysville).
Peach leaf curl control that is virtually 100% effective can be achieved by a single fungicide application during the dormant season. A dilute application should be made under calm conditions anytime after most (no less than 90%) of the leaves have fallen and before hard freezing weather sets in. Thorough coverage of each bud is essential for controlling the leaf curl fungus. If leaf curl was severe in your peach or nectarine blocks in this year, make fungicide applications this fall and next spring before bud swell. Treatments with copper compounds are recommended where bacterial spot has been a problem. In orchard blocks that have been intensively scouted and where the grower knows with certainty that the disease is entirely absent from the block for a period of two or more years, this spray can be omitted until the disease begins to recur. See the 2008 Spray Bulletin for fungicides and rates of application.
Bacterial spot of stone fruits. Bacterial spot (caused by Xanthomonas arboricola pv. pruni) is a serious disease of peach, nectarine, apricot, almond, and plum. It can severely devitalize trees by defoliation and it reduces yield and quality of harvested fruit. Most varieties developed in more humid areas of the country possess fair to good tolerance to the disease. Varieties developed in drier areas of the country are frequently too susceptible to grow successfully in humid areas. Bacterial spot is of most concern in regions with annual rainfall greater than 20 inches per year. Some of the new white peaches developed in California are especially susceptible.
Bacterial spot attacks the fruit, leaves, and current season's twigs. Fruit infections appear as tiny purple to black flecks on the fruit surface of peaches, and as water-soaked spots on nectarines and other smooth skinned Prunus spp. Later, the skin is "broken" and the flesh beneath the spot becomes sunken. Early season infections result in very deep lesions in the flesh, and infections within 30 days of harvest result in circular, yellowish spots on the fruit surface. The leaf spots are always angular as a result of being restricted by the veins of the leaf. Initially, the spots appear as water-soaked angular spots that are generally only visible when viewed with a light source behind the leaf. In about three days, the lesion becomes visible with reflected light. Within one to two weeks, the center of the lesion is "walled off" by the leaf and drops out, resulting in a shothole or tattered appearance. Leaf lesions are much more common at the distal ends of the leaves and around major leaf veins. This occurs because the water film is thicker in such areas and these regions of the leaf dry more slowly. Leaves with as few as two to three lesions turn yellow and fall. Under heavy disease pressure, only the youngest leaves remain on the tree. Captan fungicide spray injury is often mistakenly diagnosed as bacterial spot, but can be distinguished by the more circular shot holes that develop on young leaves, many of which may be damaged on only one side of the mid-vein. Two types of cankers appear on the twigs. Summer cankers appear in midseason as irregularly shaped, dark, slightly sunken lesions on the current season's twigs. Spring cankers develop as darkened blisters in the early spring near the twig tip of the past season's growth. The injury to the tip is so extensive that the terminal bud fails to open, resulting in a number of dead tips on the tree.
Leaf scars on current season's woody tissue are infected in late fall as the leaves fall from the tree. The bacteria multiply within the twigs during periods with favorable temperature and the bacteria ooze out of natural openings in the spring during periods of wetness. The bacterium requires water congestion for infection to occur. Since newly emerged leaves contain no air spaces between the cells, these leaves are immune to infection. Thus, leaf and fruit infections generally do not occur until around petal fall and shuck split, respectively. Bacteria exude from the cankers for a period of about 30 days and also exude from leaf and fruit lesions throughout the season. A dry period from petal fall and extending for about three weeks greatly reduces the potential for spread.
There are no established treatment thresholds for bacterial spot. However, since infections occur only when the leaves are wet and the amount of disease increases exponentially, base your decision to begin a protective treatment program on three factors: 1) if the disease on this site in the past affected the quality of more than five percent of the fruit; 2) if the incidence of initial lesions in the current season is considered "common" (i.e., 20 percent or more leaves show lesions); and 3) whether new lesions have developed in the last week. Protective treatments need to be continued until two to three weeks before harvest, but can be safely suspended during periods of extended dry weather.
Management. The most effective means of disease management is avoiding the selection of highly susceptible cultivars. Some peach varieties are more susceptible than others, but virtually all commercially grown peach varieties can be infected. Some of the most susceptible varieties include: Autumnglo, Autumn Lady, Blake, Elberta, Halehaven, July Elberta, Jersey Queen, Jerseyland, Kalhaven, Suncling, Suncrest, Sunhigh, Ran Cocas, Redcrest, Rio-Oso-Gem, and Sweet Sue.
Varieties with the highest resistance include: Belle of Georgia, Biscoe, Candor, Comanche, Dixired, Earliglo, Early-Free Red, Emery, Encore, Garnet Beauty, Harbelle, Harbinger, Harbrite, Harken, Late Sunhaven, Loring, Madison, Norman, Ranger, Redhaven, Redkist, Redskin, Sentinel, and Sunhaven. Most apricot varieties are susceptible (Goldcot, SH-50, & SH-7), and many nectarine varieties are also susceptible.
Locating new plantings of peach and nectarine (apricot and plum, also) near orchards of highly susceptible cultivars ultimately leads to a build up of the disease in the more resistant cultivars. Chemical sprays may help to reduce the levels of fruit and leaf infection. To be effective, spray applications must be applied before symptoms occur. The first spray is usually a copper compound applied just before tree growth resumes in the spring. This is followed by weekly applications of an antibiotic beginning at petal fall (alternating applications of antibiotic and copper may be effective, also, although many stone fruits are sensitive to copper and injury from copper may be difficult to distinguish from damage caused by the pathogen). The 3-week period following petal fall is critical for early-season fruit infection and establishment of inoculum on new foliage. Rainfall during this period is favorable for infection. Spray programs do not provide complete control of the disease and, in some years, may not provide control that is commercially acceptable. For this reason, the best strategy is the selection of resistant cultivars in areas where the disease is endemic.
The current strategy for controlling bacterial spot is to reduce inoculum levels using copper starting in the fall and/or at late dormant with 2 lb (a.i.) of metallic copper. Where inoculum was high during the growing season, a copper application in the fall may be justified to help prevent leaf scar infections and reduce bacterial overwintering. This application at this time will also provide control of leaf curl. I would also make the copper application again in spring before bud break. In areas where the disease is severe every year, copper applications are continued during the bloom period, up to petal fall, but rates are significantly reduced to avoid phytotoxicity. I don’t think bloom applications are necessary in West Virginia orchards.
After petal fall, apply Mycoshield (or FlameOut (both contain 17W oxytetracycline and are interchangeable)) in weekly intervals or rotate oxytetracycline with copper (Tenn-Cop 5E) applied at low rates throughout the season. Despite this very aggressive spray program, chemical sprays may not be totally effective on highly susceptible cultivars in years when conditions for bacterial spot are very favorable. Timing of spray applications is critical. Applications are most effective if applied prior to a rain but with enough time for drying. The "low rate" formulations of copper, such as Tenn-Cop 5E, are best used post bloom in cover sprays rather than in the pre-bloom or dormant sprays. Rates of Tenn-Cop 5E range from 4 – 8 fl oz/A applied in 100-125 gallons of water/A. Tenn-Cop 5E can be alternated with Mycoshield/FlameOut 17W on a 7-14-day interval depending on frequency of rainfall, and is used at 0.75 – 1.25 lb/A. The label reads that it can be used a maximum of 6 times in the post bloom cover spray period. Any fixed copper can be used during the dormant period.
Remember that copper is protective and not curative, so to be effective it must be present prior to occurrence of conditions for infection (i.e., the presence of moisture such as rainfall or dew). This also means that good spray coverage of the tree is essential. When a rate range is provided, use the higher rate on highly susceptible varieties or in orchards where bacterial spot has been damaging or weather conditions are very favorable for disease.
Mycoshield and FlameOut. There currently are no post-shuck split chemical alternatives that are as effective as Mycoshield or FlameOut (think of FlameOut as a generic Mycoshield) for controlling bacterial spot on peaches – without causing phytotoxicity. Without question, either of these products should be your first choice when bacterial spot pressure is high or when treating highly susceptible varieties. Mycoshield was registered for use on peaches in the early 1980s. No other products have shown efficacy comparable to Mycoshield, nor have any been registered for use on peaches since the registration of Mycoshield.
Some cautions on copper. There are many factors that affect the efficacy of copper for the control of bacterial plant pathogens. The most important property contributing to the biological activity of copper is its ability to exist in what is termed the "free" or "ionic" state. In nature, copper almost always is combined with other elements or minerals. When conditions become such that copper exists in the ionic or in the free copper state, it is very reactive. It is this reactive nature that gives copper the ability to kill bacteria. Also, it is this reactiveness that is responsible for phytotoxicity. The amount of copper in the ionic state is greatly influenced by pH of the solution (e.g. droplet of water on the leaf). More acidic (pH below 7.0) solutions have more free copper and are more bactericidal, but are potentially more phytotoxic. In contrast, more basic (pH greater than 7.0) solutions have less free copper and are less bactericidal, but have less potential for phytotoxicity. The goal is to achieve a balance between these two extremes.
Copper-containing materials have been used on peaches for many years and their use may be increasing. It should not be forgotten that peaches can be very sensitive to copper and if improperly used serious phytotoxicity can occur. Be sure that the correct rate of copper is used and that sprayers are correctly calibrated. Phytotoxicity is more likely to occur when conditions are slow drying (more than 20 minutes) and cool (less than 55F). Injury to leaves most often appears as discoloration, shot-hole formation, and defoliation.
Some older ideas: Captan tank-mixed with Dodine (Syllit 65W). This is a combination that was evaluated in the 1960s and 1970s, and the recommendation remains on the Syllit 65W label. It is recommended for use when bacterial spot pressure is light to moderate. This hopefully is the situation in orchards where the early season copper spray program was followed. Data from the average of seven experiments (1961—1971) using this chemical combination showed about 50% of the bacterial spot incidence of the non-sprayed check. In these experiments, the Captan-plus-Syllit sprays were started at petal fall or shuck split, without any earlier sprays for bacterial spot. In years with frequent rainfall, newly emerged leaves can be infected earlier than petal fall, thus providing an abundant source of bacteria for fruit infection starting at shuck split. Therefore, this spray combination may be even more effective if earlier copper sprays have been applied. The rate listed on the Syllit 65W label is 0.5 lb-plus-1.0 lb Captan 50WP per 100 gal. Some leaf "shot-hole" has been observed with this combination, but this has not resulted in significant defoliation. This combination also provides peach scab control (if sprays are applied at the proper time for scab control and at least 4.0 lb of Captan 50WP is used).
Zinc-containing materials. Different forms of the metal zinc have been evaluated, often formulated as zinc sulfate. Disease control obtained has been less than that using copper products, and there remains the risk of phytotoxicity from zinc, which also responds to pH (similar to that described for copper). The fungicide Ziram contains metallic zinc, sold under the brand names Ziram 76DF and Ziram Granuflo. Each of these products contains 16.25% metallic zinc. This is approximately 2.6 oz of zinc per pound of material. The use rate is 4—8 lb per acre, and one should not exceed 72 lb per acre per year. Both of these formulations are labeled for use on peaches up to 14 days before harvest, BUT neither has bacterial spot listed on the label. Ziram has been occasionally evaluated during the last 20 to 30 years, with some indication of bacterial spot suppression. No foliar or fruit injury has been observed with the use of Ziram. However, Ziram should not be relied upon for adequate peach scab control.
General recommendations. The focus should be on preventing bacterial spot from starting. The optimal time to use Mycoshield is at late shuck split to the start of shucks off and then for the following 3 to 4 weeks on a 7 to 10-day schedule if weather conditions remain wet. Wet can be defined as having at least one measurable rainfall per week or heavy dews that result in several hours of leaf wetness. Do not use less than 0.75 lb of material per acre in an attempt to "stretch" the use of Mycoshield by using low rates.
Disease control is most effective when chemicals are applied within a 24-hr period prior to anticipated rainfall but with a sufficient time period for the pesticide to dry. In wet or rainy seasons, additional applications of Mycoshield may be needed on a 10 to 14-day schedule and can be applied up to 3 weeks before harvest. If wet weather continues for the few weeks after shuck fall, continue Mycoshield applications on a 7 to 10-day interval.
If at all possible, insecticide and fungicide application should be conducted only when foliage is dry. Spraying when the foliage is wet can further distribute the bacteria.
Once pit hardening occurs, at which time fruits apparently become less susceptible, evaluate the bacterial spot situation on fruit as well as the foliage. If few or no lesions are observed, but weather conditions remain favorable for disease, consider alternating a low rate of copper or a Syllit 65W-plus-Captan application with Mycoshield. Also, focus the use of Mycoshield on the most susceptible varieties.
If you do not have or choose not to use Mycoshield, continue to apply the reduced rates of copper sprays, carefully monitoring for injury before each application until a point is reached that injury is considered too great to continue the use of copper. Switch to Syllit 65W-plus-Captan sprays at this time. (Information contained in this article was gleaned from articles by Dr. Dave Ritchie, North Carolina State University; Dr. Phil Brannen, University of Georgia; and Dr. William Turechek, USDA-ARS).
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.
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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
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