North American Fruit Explorers mailing list at ibiblio

["Dennis Norton" <dmnorton@royaloakfarmorchard.com>]

Several factors can affect fruit uptake of calcium in the spring (10 to 45 days after petal fall). High levels of nitrogen, potassium, and magnesium all reduce the fruit uptake of calcium. This is because nitrogen favors shoot growth over fruit growth. Potassium and magnesium compete with calcium because they are all positively charged ions. High levels of available water will increase fruit calcium if shoot growth is not excessive. In general, lessening shoot growth increases calcium uptake by the fruit. Increasing root growth results in increased uptake of calcium. Finally, maintaining a high photosynthetic rate will increase calcium in the fruit as long as shoot growth is not excessive.  Spray calcium as late in the season as practical, but start early in the first or second cover. The addition of small amounts of calcium to many sprays seems to be more effective than several large dosage sprays of calcium alone. Growers should apply calcium 6 to 8 times and the total amount of calcium should not exceed 20 pounds to the acre. Raising the calcium content of the fruit is not easy. Essentially only the calcium which is absorbed through the waxy cuticle is used by the fruit. Other benefits from calcium are increase fruit firmness in storage and increased storage life. There may also be some benefit in disease resistance from increasing cell wall strength and cell membrane integrity.

You do not want to use calcium chloride used for sidewalks.  Calcium chloride has a typical analysis of 34% calcium and 66% chloride. This high chloride content is not desirable for several reasons. When calcium chloride is applied, free calcium and chloride ions are present in solution. Sodium ions that may be present on leaves and fruit, from soil residues or irrigation water, may combine with this chloride forming sodium chloride (NaCl, common table salt). When salt deposits form on the surface of leaves and fruit, they dry out fruit and leaf tissues causing fruit finish to deteriorate by enhancing sunburn on the fruit surface and blackening of lenticels in certain varieties. Another disadvantage of calcium chloride is related to simple chemistry that occurs when it is dissolved in water, even the small amounts that may be present on leaves and fruit from condensation, respiration, and transpiration. By a process known as hydrolysis, free hydrogen ions in water react with chloride ions to form hydrochloric acid (HCl), a very strong acid, on the surface of leaves and fruit, which may manifest itself in reduced fruit finish, increased russet, and burned lenticels. This hydrolytic reaction is the reason calcium chloride has poor compatibility with many tank mixed chemicals.

But the low price of calcium chloride is a distinct advantage----it is one of the least expensive forms of calcium on the market. But there is definitely a tradeoff of price vs. consequence. While it is less expensive out of the bag, it is more costly in terms of fruit damage resulting from its high chloride content.  Calcium products that do not contain chlorides have been introduced into the industry and range widely in terms of solubility, analysis, and price. Nutrient Technologies has introduced TECH-GRO MIRA-CALSP, a powder completely soluble in water with an analysis of 30% Calcium and contains no salt product. It is effective in boosting calcium levels, contains no chlorides, nitrates, sulfates, or phosphates, and its price is competitive with any other non-chloride based calcium product currently available for use by the tree fruit industry.  An analysis can be found at http://agr.wa.gov/PestFert/Fertilizers/FertDB/prodinfo.asp?pname=1391 as well as the manufacturer phone number.  Hope this helps. 

Dennis Norton
Royal Oak Farm Orchard
http://www.royaloakfarmorchard.com

----- Original Message -----

From: O'Barr, R. D.

To: North American Fruit Explorers

Sent: Wednesday, February 01, 2006 5:26 PM

Subject: Re: [NAFEX] Fertilizing and calcium

Calcium moves downward slowly. Nitrogen moves down about like the water, potassium a little slower, and phosphorus very slowly; i.e., about 1 inch per year.

Large trees with deeper roots can be fertilized sooner than young trees without as much loss due to leaching.

Calcium Chloride is used to spray tomatoes as a foliar nutrient spray.

Topgun

----- Original Message -----

From: mauch1@aol.com

To: nafex@lists.ibiblio.org

Sent: Wednesday, February 01, 2006 1:40 PM

Subject: [NAFEX] Fertilizing and calcium

How early can fertilization be done?  Is there a loss of effectiveness?

 

Can the calcium chloride used for sidewalks be used for fruit sprays?

 

Thanks,

 

Chris Mauchline
SE PA, zone 6
40° 5' N 75° 51'W
~650 ft elevation

---

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