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August 2004


The similarities between you and your orchard are many.  To be at peak performance you need a certain amount of rest, drink and nutrition.  Your orchard is no different!  A lot of blocks are working hard with big crops on them this year.  I’ve had a number of calls asking what can I do to help size my fruit?   Three weeks prior to harvest is a tough time to solve that issue.  Start NOW working on next year’s fruit size.  For the first month or so of each spring, your trees depend on stored reserves. The condition that the tree goes dormant in is the same one it wakes up with!  During the first month fruit goes through cell division.  The rest of the season is spent enlarging those cells.  The more cells to fill, the larger the fruit.  If cell division is limited by nutrition, your fruit size will be also.  


Soil Fertilization

The most common approach to fertilizer timing has been to make an application in the late fall.  Harvest is done, hunting is over, too early to start the honey do’s, too early to prune, why not spread a bit of fertilizer?  Research has shown that uptake and movement into the tree of a dormant application is greatly reduced and subject to winter leaching (recovery of soil-applied N by fruit trees typically ranges from 25-35%, Khemira, 1995).  Moreover, a late fall application will not be available till late, (too late) in the spring, past the cell division period when soil temps warm up.  A dormant application contributes most toward summer vegetative growth.  Consider a different timing.  Mid-August to mid-September most terminal growth has ceased, the temps are still warm and the tree is maintaining a high rate of respiration.  Fertilizer applied at this time, followed by a light irrigation will quickly be moved up into the tree.  It’s then stored, ready for cell division the next spring.   The “sweet spot” to aim for is the period when the tree is between it’s summer work and winter sleep.  Be cautious about late maturing varieties, they stay active later in the season.


Fall Foliar

Trees move nutrients from the leaves back into the buds and wood prior to leaf drop.  Research in California shows that a foliar spray of urea on peach begins to move into the leaf within two hours, with over 80% of the applied N moving into the leaves within 24 hours.  The efficiency of N recovery through a foliar urea application is four-fold greater than through soil application.   This nitrogen is mobilized and moved into other plant parts such as shoots and buds within one week. It remains there until spring when it is available for early use during cell division!  Give me a call to talk about rates.  Urea is known to enhance the uptake of other micronutrients when sprayed in combination.  Adding zinc, boron, manganese or any other element your tree requires will help boost bud strength.  No detrimental effects have been found on winter hardiness, quite the opposite,  research has shown that healthy buds with good nutrient reserves are the most winter hardy.



When you choose a material to apply via the foliage, choose wisely!  The material must be soluble and able to pass through the plants many barriers.  Insoluble mineral salts, all oxides, most hydroxides, phosphates, and some sulfates cannot be efficiently absorbed by the plant.  Applications with these formulations simply “paint” the outside of the plant.  That’s the reason  many elements are formulated as chelates.  The mineral molecule is surrounded by organic molecules to form a protective coat that the plant will absorb.   Once inside, the coat is shed and the mineral becomes available to the plant.   Grand Mesa Discount has chosen to handle Metalosate, Albion Labs line of foliar nutrition products.  They are a highly soluble material formulated around an amino acid chelate.  Amino acids are the basic building blocks of protein and are found in all living things.  Plants recognize amino acids as a food source and will readily absorb them.



Did you have problems with Coryneum blight this year?  If you did, starting this fall will go along way towards a clean crop next year.  The first autumn rains can start the spread of the disease.  Infection can also take place in the dormant season if proper moisture and temperature conditions occur.  Spores, spread primarily by splashing water can remain viable several months when dry.  The key to control is PREVENTION.  This is especially true is your farming with organic standards.  Establishing a protective barrier with copper is vital to keep Coryneum from germinating and spreading.  Good sprayer coverage is important! The disease usually starts low inside the tree where moisture persists, so be sure and target this area.  The most common application timing is at 50% leaf fall.  It’s not necessary to wait for that to happen.  If we have a wet September you could be behind by the time leaf fall occurs.  How aggressive you need to be with rates and applications depends on if you need to clean up a problem or are just performing routine maintenance.


While pest damage is still fresh in you mind, or in the bin, take a moment to think about the following.


Controlling any pest is a matter of:


  • Using the proper material properly.  Choose a material that will do the job.  Is resistance an issue?  Use a high enough rate to do the job or change classes.  Is it a special need and/or timing material?  Buffering, spreader, temperature, life stage issues? 

  • Proper timing of your application.  All pests have an optimum time to control them.  Do you know that timing for each pest in  your orchard?

  • Good coverage.  Have you ever walked behind your sprayer and looked at your coverage, looked at all the dry areas in your tree?  Water volume is not the issue!  I’ve seen dry spots behind a 300 GPA application.  According to Kevin Day, University CA farm advisor, “Excessive speed is probably the biggest roadblock to thorough spray coverage”.  An air blast sprayer must move the “resident” air from inside the tree before it can replace it with spray laden air.  According to Day, “sprayers should never travel over two miles per hour.”  I’ll bet that if I were to drive two mph in a race I would lose to every sprayer in the county!   Gempler’s has water sensitive 2” X 3” cards that you can hang throughout your tree.  Make a pass with your sprayer and you can quickly see what kind of coverage you have.



If you’re having trouble with control, then one of the above is the cause.  Don’t assume you know the answer.  Work your way down the list.


“Wisdom is what’s left after we’ve run out of personal opinions”  -Cullen Hightower

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