Facts for Fancy Fruit 96-05        
 April 24, 1996
 
 ****************************************************
 Facts for Fancy Fruit is a newsletter for commercial and advanced amateur fruit
  growers developed in the Purdue University Department of Horticulture with
  regular contributions from the specialists in the Departments of Entomology and
  Botany and Plant Pathology, and from other agents & specialists on campus.  If
  you have questions, or are are interested in receiving this newsletter
  electronically, contact Bruce Bordelon (bb@hort.purdue.edu).
 ****************************************************
 Crop Conditions
 Weather
 Risks of Freezing Temperatures
 Save the Bees
 Apple Nutrition
 Apple Scab Resistance to Sterol Inhibitor Fungicides
 Fire Blight
 EBDC Fungicides
 Peach Scab
 Apple Growth Regulators
 Tree Training
 Codling Moth
 Grape Flea Beetle Reminder
 Prevent Gound Water Contamination with Pesticides
 New Thinning Guide Available for Apple Growers
 Commercial Spray Guides Available on the Internet
 Coming Meetings/Events
 ****************************************************
 Crop Conditions:  Spring has finally arrived in Indiana.  Fruit crops are
  beginning to develop quickly following last weeks warm temperatures and recent
  rainfall in some areas.  Apples are at pink to early bloom in the south, at
  tight cluster to pink throughout central part of the state, and at half inch
  green to tight cluster in northern areas.  Peaches are at petal fall to shuck
  split in the south.  Grapes are at full budswell to 1 inch shoots in the south,
  and at early to full swell in central and northern areas.  Blueberries are at
  pink tip in the south and budbreak in the north.  Mummy berry mushrooms should
  begin showing up with the next warm spell.  Strawberries are nearing bloom in
  the south, and just beginning to push in central and northern areas.  Fruit
  crops have not endured any significant damage from the recent cold temperatures
  because of they delayed development.  Most crops are still about two weeks
  behind normal.  
 	In areas where there was a drought in the fall of 1995, return bloom is light
  in many orchards that carried a full to heavy crop in 1995.  The dry fall last
  year coupled with a heavy crop resulted in less (or no) fruit bud formation for
  the 1996 crop.  This has been seen most on Red Delicious but could be observed
  on a number of other varieties not usually considered to be strong biennial
  bearers.  Where the 1995 crop was adequately thinned, the problem should be
  minimized.  Hail has been a problem in some central Indiana orchards.  Where
  hail marks break the epidermis, care should be taken to protect against
  fireblight and fungal problems.
 	Peach buds have been mostly killed in central Indiana.  However Dick Hayden has
  seen a few live buds in the Purdue orchards - not enough to warrant spraying. 
  Growers in more southern areas might want to check again before they write off
  the crop completely.
 	The blueberry crop appears fair at this point.  Some varieties had a very low
  fruit bud set last summer due to the heat and drought.  Jersey looks a little
  better than other varieties.  
 
 Weather:  (From Purdue Crop and Weather meeting minutes, April 19)  Temperature
  and precipitation trends for the past two weeks:  Few places in Indiana
  received over an inch of rain in the past two weeks.  Most places received .5
  to .7 inches of moisture, less than one half of normal.  Temperatures were 4 to
  6 degrees below normal which is a continuation from March.  Soil temperatures
  are not yet consistently over 50 degrees at the 4 inch depth.  The low
  temperatures is 40 degrees for bare soil and 45 degrees under sod.  The most
  frequently asked question this spring has concerned wind and wind damage.  This
  likely stems from the large number of systems moving through the state in
  response to the position of the jet stream. - Ken Scheeringa
 
 Weather Outlook:  (From Purdue Crop and Weather meeting minutes, April 19)  The
  current movement of systems through Indiana is expected to continue as the jet
  stream continues to flow through the Ohio Valley.  Two more systems are
  expected to move through by next week-end.  One system will move through
  northern Indiana next Wednesday with colder temperatures moving in on Thursday.
   Temperatures on Thursday will decline into the 30's but no freezing
  temperatures are expected.  The second system will move through central Indiana
  next Saturday.  With the resulting precipitation, soil moisture levels are
  expected to increase significantly.
 	The 6 to 10 day forecast is for below normal temperatures throughout the state
  and above normal precipitation in southern Indiana with normal rainfall in
  northern part of the state.  The 30 day forecast for the month of May is for
  normal temperatures and normal precipitation in Indiana  -- and most of the
  country.  The 90 day forecast (May, June, and July) is for near normal
  temperature and precipitation.  - Tom Priddy, UK 
 
 Risks of Freezing Temperatures:  Spring has apparently finally arrived in
  Indiana.  Frosts and freezes are always a major hazard in fruit production. 
  Both tree fruit and small fruit are highly susceptible to freezing injury
  during the pre-bloom, bloom, and early post-bloom periods.  Freezing
  temperatures occurring during these times may result in yield reduction, fruit
  deformity or russeting, foliage injury and twig killing.  Air temperatures of
  32ûF are seldom damaging to fruit crops, but when temperatures reach 28ûF for
  1/2 hr or more, damage to fruit and flowers can be expected.  Because of the
  cool, dry conditions of the past few weeks, fruit crop development is about two
  weeks behind normal.  The delay in fruit crop development should help plants
  avoid potential frost/freeze damage as the chances of damaging frosts are
  diminishing.  
 	Weather records from past years provide statistical probabilities of weather
  events.  The ÒaverageÓ frost free date for an area is when there is a 50%
  probability that a frost will occur after that date.  That 50% probability
  equates to number of years; i.e. in 50 out of 100 years a frost would occur
  after the ÒaverageÓ frost free date.  
 	According to weather records, the probabilities of a 28ûF damaging frost on or
  about April 24 are: 10% in Southwest Indiana, 10-25% in Southcentral, 25-50% in
  the Brookville area of Southeast Indiana, but less than 10% along the Ohio
  River near Jeffersonville and Madison, 25-50% in East Central, 25% across
  Central Indiana, 10-25% in West Central, 25-50% in Northeast, 50% in North
  Central, and 25-50% in Northwest Indiana.  
 
 SAVE THE BEES:  Do not apply insecticides or miticides during bloom since these
  pesticides are toxic to bees.  Those bees that are not killed by direct contact
  in the orchard often carry the pesticide back to the hive where it may kill the
  brood.  Remove bees from the orchard as soon as adequate pollination has been
  achieved, and certainly before the petalfall spray is applied.  With current
  concerns about survival of bees over the winter and resulting low bee
  populations, be extra careful, please.
 
 Apple nutrition:  In blocks or varieties where buds and/or spurs are weak, the
  use of foliar fertilizers may be desirable.   Application of nitrogen and/or
  boron in the pink, petalfall and first cover sprays can be useful to help the
  spur leaves get off to a better start.   These are the leaves that most affect
  fruit set and early development of the fruit.  Without active cluster leaves
  fruit set is uncertain at best.  
 	Solubor can help to improve fruit set, so in orchards where boron is low,
  growers may want to add Solubor to both the pink and petalfall sprays at 1 lb.
  per 100 gallons or a maximum of 2 pounds per acre.  Check compatibility with
  pesticides, especially NOVA (apparently the water-soluble pouch is not
  compatible with solubor).  Do not over-fertilize with boron since excesses can
  be injurious and can only be corrected with time.
 	Foliar nutrition with nitrogen is not a substitute for ground fertilization,
  but where trees are weak or spur foliage damaged, urea (spray or feed grade
  that is less than 2% biuret) may be applied in pink and petalfall at 2-3 lbs.
  per 100 gallons, but not to exceed 12 lbs. per acre.  Calcium nitrate can also
  be used for these applications at about the same rate;  and could be helpful
  when calcium is being applied in the cover sprays for bitter pit and/or cork
  spot control.   Check compatibilities with pesticides carefully, or apply
  separately.  See the 1996 ID 168 and the Revised ID 60 for additional
  suggestions.
 
 Apple Scab Resistance To Sterol Inhibitor Fungicides:   In a recent edition of
  Scaffolds Fruit Journal, Drs. Wayne Wilcox and Wolfram Koller make the
  following points in regard to apple scab resistance to sterol inhibitor
  fungicides (Nova, Rubigan, etc.):  Òthe anti-resistance strategies weÕve been
  preaching for years (maintain full SI rates, tank mix with a protectant, get
  good coverage, donÕt cheat on the intervals) really do work.  Or, conversely,
  not following them really can get you in trouble.Ó  Wilcox and Koller further
  point out that:  Òwe are probably somewhere between a resistance ÒwatchÓ and a
  resistance ÒwarningÓ in our commercial industry.  That is, we have not reached
  the stage where resistance is imminent, but we appear to be moving in that
  direction if we donÕt watch out.  The threat is real, and should be treated as
  suchÓ.
 
 Fire Blight:   Bloom + Warm Weather + Rain = Fire blight!  An old refrain but
  one that needs repeating at this time of year.  Blossom sprays protect only
  those flowers that are open at the time of treatment.  Thus, the protective
  value of an application made too early can be lost quickly with the opening of
  many new flower buds.  Paul Steiner points out the rate of flowers opening on a
  Jonathan apple is approximately 1 percent per 1.5 DD>40¡F so that in just one
  or two warm days nearly 20% more buds may open.  This poses a risk of
  approximately one unprotected flower per spur.  Think about it!
 
 EBDC Fungicides:  The label for EBDC fungicides (Dithane, Manzate, Penncozeb,
  Polyram) on apples allows growers to choose one of two schedules:  either
  pre-bloom use at the high rate of 1.5 - 2 lbs/100 (6 lbs/acre)  OR the low rate
  of 3 lbs/acre (max 21 lbs/year) up until 77 days to harvest.  See product
  labels for full details.  We suggest growers calculate the 77 days to harvest
  date for each of their major cultivars and make their final application of EBDC
  on that date to take full advantage of the excellent control the EBDC
  fungicides provide for sooty blotch and flyspeck.  In the Lafayette area this
  would make July 20th the final spray date assuming harvest occurs October 4th
  (unless I counted my days wrong).
 
 Peach Scab:  Early shuck-split and shuck-fall sprays are critical for peach scab
  control.   The first spray should be applied about one week after petal fall. 
  Do not wait until the shucks have slipped to begin this program. Continue to
  spray on a 10 day interval until 40 days before harvest. See  ID-168, "1996
  Indiana Commercial Tree Fruit Spray Guide", for further information.
 
 Apple Growth Regulators:  Promalin for Red Delicious "apple stretching" may be
  worth considering if your fruit must compete with western fruit on "type" or
  shape.  Applications should be made during early bloom, and timing is critical.
   Apply when most of the Red Delicious king blooms have opened.  Promalin has
  some thinning properties, which is not a problem where bloom is good.  Where
  the bloom is light, do not use Promalin.  Follow label directions closely
  concerning timing and precautions. The amount of water applied per acre is also
  somewhat critical.  Results have been best where about 100 gallons per acre has
  been applied.  Additional suggestions are given in ID 60.
 	"Provide" is a growth regulator that in Illinois tests has been shown to reduce
  the amount of russetting on Golden Delicious.  Provide is a mixture of GA4 and
  GA7.  The label calls for three or four sprays at 7-10 day intervals beginning
  in late bloom to petalfall.  The rate is 10 to 13 ounces per acre applied in
  about 100 gallons of water.  The total amount that can be applied per acre per
  year is 40 ounces.  This program may reduce, but cannot be expected to
  eliminate russet.  In the midwest the degree of russet varies with the weather.
   The 30 day period after bloom is the critical period for the beginning of
  russetting.  Growers who have been troubled with rusty Goldens may wish to try
  Provide.
 	Accel is benzyladenine (BA) with a very small amount of Gibberellic Acid(GA). 
  Used according to label it has improved average fruit size, and thinned
  moderately.  Used in combination with Sevin, thinning has been enhanced on
  certain varieties.  Do not use in combination with NAA since more than usual
  pygmy fruits may be produced.  Accel is expensive, but where fruit size is
  critical, it may be cost-effective. Note that for 1996 the label rate has been
  increased to 30 grams active ingredient per acre.   Follow label instructions
  carefully.  If you try Accel, do it on a limited scale.   
 
 Tree Training:   Training of young apple trees to orient scaffold limb angles to
  45-60¡ from the vertical is best done by the end of bloom.  The degree of
  spreading depends on the spacing/rootstock combination.  The wider the spacing,
  the more shoot growth is necessary to fill the allotted space.  Thus the angle
  to which the scaffolds are trained should be smaller, i.e., more vertical.  
 	Where tree spacing is close and the rootstock is more dwarfing, the angle of
  scaffolds should be larger to promote early fruiting.  Do not train scaffolds
  completely to the horizontal, since that will stop extension shoot growth, and
  promote undesirable vertical growth from the top of the scaffolds.  A 60¡ angle
  is about right to promote fruiting and minimize the vegetative growth.  Limb
  spreaders and rubber bands are useful tools to accomplish this task.
 	Training crotch angles must be done by the time the shoots are 4-5 inches long,
  which will usually occur by mid May, depending on when the trees were planted. 
  Select the 5-6 most desirable shoots per tree and train to near horizontal with
  toothpicks or clothespins about the time that shoot growth reaches 4 inches
  long.
 	Training helps to bring trees into production earlier, while pruning promotes
  vegetative growth at the expense of production.  therefore prune as little as
  possible until the trees come into production.  Obviously, corrective pruning
  must be done to eliminate little problems before they become big problems. 
  Time spent training young trees is probably the most worthwhile time spent in
  the season.
 
 Codling Moth:  Codling moths, the proverbial Ôworm in the appleÕ, will soon be
  emerging from overwintering sites and moths will mate and begin laying eggs.
  Codling moths are one of the primary insects that apple growers must control to
  produce marketable fruit. The strategy for preventing the newly hatched larvae
  from entering the fruit is to have a lethal dose of insecticide present when
  the eggs hatch. Codling moths usually are controlled well by routine cover
  sprays of broad spectrum organophosphate insecticides such as Imidan or
  Guthion. However, control can often be improved by using pheromone traps and
  the accumulation of heat units to better time the application of the
  insecticide. You may hear the terms heat units and degree days used
  interchangeably, but I will stick to heat units to avoid confusion.
 	Pheromone traps baited with codling moth lures should be placed in the orchard
  at bloom. Traps should be checked daily and catches recorded. When the third
  moth is caught in a trap, start to monitor the accumulation of heat units.
  Insect development is driven mostly by temperature, so we want to use heat unit
  accumulations to predict when the eggs will begin to hatch. There are several
  ways to measure heat units but the simplest uses daily high and low
  temperatures.
 	To monitor the accumulation of heat units, follow these steps daily.
 1. Find the high and low temperature (Fahrenheit) for the day.
 2. Add the high and low temperatures together and divide by 2 to get the average
  temperature for the day.
 3. Subtract 50 from the average daily temperature to get the dayÕs heat units.
  Codling moths donÕt develop below 50 F, so we are only interested in
  temperatures above their developmental threshold.
 4. Add the dayÕs heat units to the previous total to get the updated accumulated
  heat units. (On the first day you will be adding to zero.)
 
 	When you have accumulated 250 heat units, it is time to spray. The eggs will
  have developed to the point where they are almost ready to hatch, so if you put
  on a spray at this time, you will have the maximum amount of residue present to
  control the young larvae before they enter the fruit.
 
 Example: LetÕs say that you catch the third moth in your pheromone trap on May
  8. The next day, you check the newspaper and find that the high temperature on
  May 8 was 82 degrees and the low was 64. When you add 82 and 64 together you
  get 146 and when you divide that by 2 you get 73. Subtract 50 and you
  accumulated 23 heat units on May 8. If the high and low on May 9 were 74 and
  56, you would accumulate 15 heat units. Adding the heat units from the two days
  gives you 23 + 15 = 38. If on May 10, the high was 56 and the low was 42, the
  average temperature would be 49, so no heat units would be accumulated for that
  day.
 
 	Second generation moths will begin to fly about 30 days after petal fall.
  Because there are relatively few pests attacking apples at this time, the
  second generation may provide the best opportunity for reducing the number of
  sprays necessary. Be sure to replace your pheromone lure for the second
  generation.
 
 Grape Flea Beetle Reminder:  Grapes are in the various stages of bud swell to
  early shoot growth across the state, depending on location and cultivar. 
  Development progressed rapidly over the past few days as temperatures reached
  the 70s.  Insect activity has also increased.  Scout vineyards for flea beetle
  or climbing cutworm damage and control if necessary.  Left uncontrolled these
  pests can cause considerable reduction in yield.  Incidence often occurs in
  outer rows adjacent to fence rows or woods making spot spraying an option. 
  Damage from flea beetles usually decreases as buds break and shoots become 1/2
  inch or longer.  Sevin or Penncap-M will provide excellent control of this
  insect.  Refer to the label or ID-169 for complete recommendations.
 
 Prevent Ground Water Contamination with Pesticides:   Ways to prevent 
  contamination include:   
 1.  Read all pesticide labels carefully.   Many labels contain ground water
  information.  Read the label before you buy the pesticide, before it is mixed
  and applied, before it is stored, and before disposing of excess pesticide or
  the container.
 2.  Avoid mixing pesticides near wells, streams or other natural water sources. 
  Inspect wells regularly for leaks and be sure that surface drainage is away
  from the wellhead.   
 3.  Measure and apply pesticides carefully, to stay within the per acre label
  rate.  This will avoid excess application and decrease potential environmental
  contamination.  Concentrate spraying can be accompanied by a reduction in per
  acre rate of application, which will further reduce potential for contamination
  without affecting pest control.
 4.  Use care in disposing of leftovers.  Ideally, measure materials closely, so
  that there are no leftovers.   Rinse pesticide containers thoroughly three
  times, putting the rinsate into the sprayer,  and dispose of containers
  carefully, according to label instructions.
 
 New Thinning Guide Available for Apple Growers:  (This information is from
  Apple-crop mailing group, apple-crop@orchard.uvm.edu)  The first new thinning
  manual published in nearly two decades for commercial apple growers in the
  Midwest and Eastern United States is now available.  The Apple Thinning Guide
  is authored by Phil Schwallier, Michigan State University district horticulture
  marketing agent.  His district includes the "Ridge" fruit growing area north of
  Grand Rapids that produces over 40% of Michigan's apple crop.  "I felt that
  thinning is very complicated and a confusing necessary practice that growers
  were always unsure of what to do," said Mr. Schwallier.  "Much of the confusion
  was over all the factors that influence fruit set and thinning.  I've tried to
  condense the thought process into steps that need to be considered by growers
  before, during and after thinning."  The recent release of some new thinning
  materials including Sevin XLR and Accel have further confused the issue.  Mr.
  Schwallier reviews how these materials and the older materials work to help
  growers understand the thinning response to them when used alone or in tandem.
  "Understanding what thinning materials are available and how they work will
  help growers make decisions on which ones to use and when to use them," Mr.
  Schwallier said.  "Knowing the responses that can be expected from different
  varieties will greatly increase the success of thinning."  The in-depth book
  looks at the factors that involve fruit set and thinning, and reviews variety
  sensitivity to help serve as a guide to thinning decisions with an eye on
  thinning that will help growers meet the needs of today's marketplace.  "The
  current thinking is to thin earlier and more aggressively starting at petal
  fall," Mr. Schwallier said.  "The manual encourages growers to thin earlier for
  successful thinning and return bloom, and aggressively for larger fruit size." 
  To make the subject easier to understand there are many colorful graphics,
  tables, charts and check off lists.  Sections of the book include an
  introduction, thinning windows, thinning factors, weather factors, apple
  thinning rates and timing, and thinning materials.  The tables cover thinning
  and fruit set factors, and varieties and thinning rates.  The charts include
  fruit set and thinning planner, the fruit set evaluation checkoff and a final
  pre-spray checkoff.  The fruit set and thinning planner combine the factors
  that influence fruit set and response to thinning, including predicted set,
  bloom factors, weather conditions, pollination factors, grower management
  factors and tree and orchard factors.  The final pre-spray checkoff is designed
  to be used by growers just before making any thinning applications and
  considers weather conditions for the next five days, predicts thinning response
  and makes recommendations on the thinning action.  "This is something all apple
  growers will find useful during this important decision time," Mr. Schwallier
  said. "This manual will help growers thin aggressively and early to provide the
  best success of annual fruit production and fruit quality." The Apple Thinning
  Manual is available from The Great Lakes Publishing Company, P.O. Box 128,
  Sparta, Michigan 49345. Cost is $10 plus $1.50 for postage and handling for
  each book. For more information call (616) 887-9008.  
 
 Commercial Spray Guides Available on the Internet:  For those of you who donÕt
  have a copy of ID-168, Indiana Commercial Tree Fruit Spray Guide, and ID-169,
  Indiana Commercial Small Fruit & Grape Spray Guide, these publications are now
  available electronically.  You can access them at the following URL (address):
  http://www.agcom.purdue.edu/AgCom/Pubs/menu.htm
 
 Facts for Fancy Fruit Available Electronically:  We hope to have all 1996 issues
  of Facts for Fancy Fruit available through the Plant & Pest Diagnostic Clinic,
  and Horticulture worldwide web homepages in the near, but until then we can
  send you the electronic version of the newsletter by email.  If you would like
  to receive the electronic version, send an email message to Bruce Bordelon at
  bb@hort.purdue.edu and I will see that your address is added to the list.
 
 Coming Meetings/Events:
 
 May 6 --- LaPorte area fruit growers twilight tour.  6:30 p.m. Sunacre Fruit
  Farm, LaPorte Co., 8711 N. 300 E. Rolling Prairie, IN. 4.2 miles N of Hwy 20 on
  300 E.  Contact Walt Sell (219-326-6808 Ext. 271)
 
 June 19 --- Southeast Indiana Fruitgrowers Summer Tour. Apple Junction,
  Batesville, IN. Contact Karen Witt (317-647-3511) or John Ewart
  (812-926-1189).
 
 June 22 --- Indiana Horticultural Society Summer Meeting.  Dave McAfee's County
  Line Orchards.  Hobart, IN.  Program details later.  Contact Dick Hayden,
  765-494-1301.
 
 June 23-25 ---   International Dwarf Fruit Tree Association Summer Tour. 
  Central MI.  Contact Dick Hayden, 765-494-1301.
 
 September 15, 1996 --- Ohio Valley Harvest Festival.  Louisville, KY. Contact
  Roy Ballard (812-948-5470).
 
 
 ****************************************************
 Bruce Bordelon, 1165 Dept. of Horticulture, Purdue University, West Lafayette,
  IN 47907-1165, 765/494-1298, e-mail: bb@hort.purdue.edu
 
 Dick Hayden, Professor Emeritus, 1165 Dept. of Horticulture, Purdue University,
  West Lafayette, IN 47907-1165, 765/494-1298, e-mail:
  Dick_Hayden@hort.purdue.edu
 
 Paul Pecknold, 1155 Dept. of Botany & Plant Path., Purdue University, West
  Lafayette, IN 47907-1155, 765/494-4628, e-mail: Pecknold@btny.purdue.edu
 
 Rick Foster, 1158 Dept. of Entomology, Purdue University, West Lafayette, IN
  47907-1158, 765/494-9572, e-mail: Rick_Foster@entm.purdue.edu
 
 
 Disclaimer:  Reference to products in this publication is not an endorsement to
  the exclusion of others which may be similar.  Any person using products listed
  in this newsletter assumes full responsibility for their use in accordance with
  current label directions of the manufacturer.  
 

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