October 18, 2004

ENTOMOLOGY

2004 pest summary.  The insect of the year award in area orchards for 2004 goes to periodical cicada. Brood X, which was active from mid-May until the third week of June, was most abundant in Berkeley and Hampshire Counties, with generally much lower levels throughout most of Jefferson County.  Injury was most severe on non-bearing trees, and on bearing trees the greatest impact was observed on peaches where numerous branches bearing fruit were broken, resulting in fruit loss.  As expected, pyrethroids provided the best control of periodical cicada.  Of this group, Danitol was found to be significantly more effective than Asana and Warrior in testing conducted in an area orchard. Of the neonicotinoid chemical class, Assail provided more effective control than Calypso and Actara.  Of the two materials evaluated that are OMRI certified for organic production, Surround was superior to Aza-Direct.  Rosy apple aphid, which was the most troublesome insect in 2003, was much less abundant in 2004, as were most foliage pests including spirea aphids, white apple leafhopper, rose leafhopper and spotted tentiform leafminer.  Potato leafhopper was quite abundant in some orchards, as was European red mite where pyrethroids were used for cicada control in the absence of preventative measures.  Japanese beetles were very abundant over a prolonged period in 2004. Biofix (first trap capture) of oriental fruit moth, codling moth and tufted apple bud moth was almost identical to 2003.  However, because of warmer temperatures in 2004, development based on degree days was 15-17 days earlier by June 1 and 12-14 days earlier by July 1 and for the remainder of the season.  Populations of oriental fruit moth and codling moth and the fruit injury they cause were higher than in 2003, resulting in a significant number of fruit loads that were rejected by processors.

PHEROMONE TRAP COUNTS
WEST VIRGINIA UNIVERSITY KTFREC

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.

PLANT PATHOLOGY
 
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 2004, 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 that the disease is virtually absent from the block for a period of two or more years, this spray can be omitted until the disease begins to recur. See page 77 of the 2004 Spray Bulletin for fungicides and rates of application.

Phytophthora root rot can be managed with mefanoxam (Ridomil Gold EC and Ridomil 5G) and 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. Ridomil should not be expected to revitalize trees showing moderate to severe disease symptoms. Ridomil is not registered for use as a preplanting dip treatment. 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. Ridomil is highly specific and will not control other agents causing similar tree decline symptoms, including but not limited to other fungal root rots, graft union necrosis (tomato ringspot virus) and vole damage.

Apple scab urea application. A 5% solution of urea (46-0-0) in water may be applied to apple trees as leaves begin to fall in the autumn (42 lb. urea in 100 gal. water, applied at 100 gallons/acre). This should be done as late as possible to prevent the urea from being translocated into the tree. However, it should be early enough to have most of the leaves still on the tree. Note that trees sprayed with urea may defoliate more quickly than unsprayed trees. Urea may also be sprayed on the leaves on the ground, after all the leaves have dropped. The ground spray can also be done in the spring.

HORTICULTURE

Rootstock  Project

The interest in high density plantings has prompted the development of a dwarf apple rootstock trial here at the WVU Tree Fruit Research and Education Center.  At this point we have identified nearly a dozen varieties to be planted using at least two or three different rootstocks if available from the nurseries.  If you are interested in recommending a variety for the trial please contact me soon. 

Varieties being considered at this time are:  Cameo; Gold Rush; Jazz; Pacific Rose; a Gala cultivar; September Wonder; a Splendor cultivar; Hampshire; Pink Lady and  Fonota.  Let me hear from you regarding this project.

Honeycrisp...

"an apple with an attitude"

Dr. Keith Yoder coined the above tongue-in-cheek description for Honeycrisp.  Following are some random comments for your consideration from a recent article by Win Cowgill and Jon Clements in the October, 2004 issue of American Fruit Grower.

•    Growers have a love-hate relationship with this apple!  During the honeymoon, strong demand and returns are padding the love nest.
   

•    Honeycrisp is probably one of the more difficult apples to grow and pack successfully.
   

•    Only the best sites will do for Honeycrisp and even there you'll have problems.
   

•    Orchards that grow highly colored McIntosh are good candidates for Honeycrisp.
   

•    Calcium sprays from fruit set until harvest to control bitter pit.  Growers should strive to apply 12 to 14 pounds of calcium per acre in multiple foliar applications.
   

•    Soft scald has been a real problem with Honeycrisp.
   

•    Don't pick too early or too late; fruit should be pre-conditioned at 50-60 F for several days before being placed in cold storage; storage temperatures should be no colder than 35-40 F.
   

•    Honeycrisp is moderately susceptible to fire blight.  An aggressive fire blight control program is required.
   

•    Honeycrisp has some scab resistance.
   

•    Honeycrisp is not a vigorous cultivar.  The young tree must be grown strongly before cropping to avoid stunting. Careful rootstock, tree spacing and planting system selection helps.
   

•    Growers clearly favored vigorous, semi-dwarf rootstocks such as M.7, MM.106 and G.30 for new plantings.
   

•    Harvest management must include extra cautious handling.
   

•    Essential to allow Honeycrisp trees to grow for several years and fill the system space before cropping too heavily.
   

•    Many professionals feel Honeycrisp will never be a high tonnage-per-acre apple.  Growers should be happy with 500 bushels per acre.
   

•    Careful chemical and hand thinning of young trees and aggressive chemical thinning of older trees is recommended to achieve a crop where fruit quality and yield are in balance and biennial bearing is avoided.
   

•    Background color is not a particularly good indicator of maturity.  Measuring starch content can be a better indicator of maturity with a target starch index of 5 to 6.
   

•    Give serious thought to your site before planting then follow production and harvesting recommendations. 

Transitioning to Organic Production 

Transitioning to organic production from conventional production systems can be difficult.  During the transition phase the farming system is undergoing many changes in physical, chemical and biological properties.  The transition phase is typically accompanied by reduced yields until the farming system reaches a new equilibrium.  Further, crops produced during this phase cannot be marketed as "organic".  As a result growers must be prepared to operate with the reduced yields and resulting  reduced income.  Below are some tips for the transition period adapted from Zinati (2002).  Keep in mind that factors such as location, soil type, pest pressure, and environmental factors may affect the impact and implementation of these tips. 

1. Select land with a high nutrient status, good soil structure and low pest pressure to initiate the organic production systems on your farm.  A grower can transition separate fields at different times to organic production.  A pre-transition phase may be introduced to deal with high pest pressures in a particular strategy for transitioning a specific field (see tip 8). 

2. Include legumes in the crop rotation to supply nitrogen to the soil and reduce pest pressure.  Different legumes add differing amounts of N to the soil.  Crop production guides often include N values for different legume crops used as green manures. 

3. Start the transition by planting a crop with low nitrogen needs. This strategy will provide more time for adding nitrogen to the soil using other fertility management tools including green manures and compost. 

4. Use green manures, animal manures and compost to increase soil organic matter, enhance water infiltration, reduce soil erosion and increase overall soil fertility. 

5. Alternate cool season crops with warm season crops to break weed cycles.  Weeds are typically listed as the major pest problem by organic producers.  This is one strategy for their management. 

6. Use timely disking and over-seeding as other strategies for managing weeds. 

7. Experiment on a small scale before adopting a pest management strategy on a large scale.  Risks will be reduced in the event the strategy fails.

8. While a three year transition period is required for organic certification, a pre-transition phase may help alleviate decreased yields during the transition phase.  A pre-transition phase may be useful for fields with high pest pressure.  During a pre-transition phase conventional pest management may be used along with organic methods to reduce pest pressures.  Once pest pressures are reduced, organic pest management methods can be implemented. 

Source: The Vegetable and Small Fruit Gazette, February, 2004

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.

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