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March 2004


I don’t know of a subject that draws more debate or varied opinions than that of calcium sprays.  “It’s a must in my program!” “That calcium you sold me didn’t do a thing!”  So what do the experts say?  I read back through my collection of literature on calcium.


It functions in plant cell elongation and division, structure and permeability of cell membranes, nitrogen metabolism, and carbohydrate translocation.  Considered a secondary or micro-nutrient even though the concentration of calcium in the plant is as great as nitrogen or potassium.  Since calcium is part of the cell wall and acts as the cement that binds the cell walls together it is one of the most significant factors of firmness and storage life of fruit.


Water, containing elements and organic compounds, moves through the xylem up the tree. Stomates, which are small openings on the undersides of leaves, allow gases to move in and out of the leaf. Water evaporates from the stomatal openings in the process of transpiration, causing sap to be pulled through the xylem and into the leaf. This transpiration pull is responsible for the movement of water, containing nutrients, into the leaf and fruit.

                Calcium moves very slowly in the tree and it may take more than a year for calcium to move from the roots to the leaves. Leaves transpire far more water than do fruit (stomates vs lenticels). Anything that reduces transpiration, such as high humidity, very low light levels, or drought stress, slows the movement of calcium up the tree. Because most transpiration occurs in the leaves, calcium moves preferentially into shoots and leaves, rather than into the fruit.


The cell division period is critical for Ca levels in the fruit.  Early in the season prior to rapid shoot extension the fruitlet can

accumulate Ca on an equal basis with other demands in the tree.  Once the tree gets cranked up the Ca gets sucked right by the fruit.  As fruit enlarges there’s no additional internal Ca supply!  The concentration of Ca in the fruit declines for the remainder of the season.


There are several reasons that calcium deficiency symptoms show up in fruit: 

  • Quite often excess nitrogen is the cause.  In an attempt to boost yields the first solution always seems to be ….. more N! A big shot of N causes the plant to grow faster than calcium can be moved within the plant. Nitrogen is translocated through the plant approximately 20 times faster than calcium.  The increase in growth magnifies the problem. 

  • As a rule, the larger the fruit the less the Ca concentration.

  • Excessive soil applications of K or Mg compete with Ca uptake, reducing it.

  • Lack of adequate soil moisture, especially during the 1st half of the season when growing roots take up Ca.


So what’s the solution?  Pay attention to your overall program.  Don’t get too aggressive with vigor, don’t let the orchard suffer for water and keep your nutritional program within bounds.  If you do decide to supplement with Ca, keep in mind the early window during bloom and immediately post bloom before rapid shoot extension starts.  Later in the season, applications of Ca must contact the fruit to be effective.  Give me a call to discuss the different formulations of calcium available.



It seems like each year something sneaks up and reduces your pack out.  Euschistus conspersus otherwise know as “Stink bug” is good at doing just that. I heard several speakers at the Portland entomology conference comment that it’s hard to find a tougher pest to keep tabs on. Populations tend to follow cycles, building up to damaging levels once every few years.  Unfortunately there isn’t a pheremone available to monitor them with.

  • Stink bug overwinters as an adult on host plants on the orchard floor or outside of the orchard.

  • Eggs are present from March – June

  • Nymphs present from May – August

  • Diapausing adults cause the damage

  • Most stinkbugs are found in border vegetation.  Start your inspections there.

  • Manage broadleaf weeds in the groundcover.  Don’t let them flower and seed. 

  • Common Mallow is the favorite host (worst to have in the orchard).  Hosts for both stink bug and lygus include bindweed, pigweed, yellowfoxtail, white clover, alfalfa and lambsquarter.

  • One presentation (in Portland) dealt with using cut pears as a monitoring tool.  Starting in mid-season a slice approximately 30% of a pear was cut off the side.  This cut fruit was monitored for the presence of bugs or damage.  It was found that the cut fruit was 4 times more likely to have damage or adults present than on other uncut pears in the orchard.  But I don’t have pears you say….what about hanging a few cut pears where you’re getting damage?  As they dry and wither it would be necessary to replace them.  It might just work as a monitoring tool to give you a heads up.

A sweep net is probably the best tool available for finding stink bugs.  Check border vegetation and the covercrop for their presence.  Pay attention to when the native vegetation dries down in the summer.  A key objective is to keep them from moving into the trees.  Early morning while the temps are cool is the best time to look. 


Another peach pest that ranks right up there with Stink bug is Lygus bug.

  • Damage from Lygus resembles that caused by Stink bug.  Small, bluish green spots on the surface.  The damage from Lygus is shallower than that of Stink bug because the piercing mouthparts of Lygus are shorter than those of Stinkbugs. 

  • Adults overwinter in plant debris on the soil.

  • 1st and 2nd instar nymphs are tiny, light green, and may be mistaken for aphid.  Their ability to move rapidly distinguishes them.

  • Adults cause the damage to fruit.

  • Damage tends to be worse in orchards near uncultivated areas or adjacent to preferred hosts such as alfalfa.

  • Spring conditions favoring lush weed growth support greater populations of lygus with the potential for increased fruit damage.

With both of these pests your orchard management may be a big factor in determining whether you have damage or not.  Ground cover management is critical.  The weeds you allow, the presence of legumes, your mowing timing and allowing the cover to dry out all can have an impact on bug populations and resulting fruit damage. 



If you have a block of apples that’s too vigorous or just isn’t fruiting well, here’s a program worth considering.  For the last several years I’ve been watching a couple of blocks of Gala and Fuji that have received Apogee treatments.  The effects have been dramatic.  The overall vegetative growth is reduced, but more importantly there’s an increase in fruiting wood developed.  Apogee is a plant growth regulator that inhibits production of giberellin within the plant causing a reduction in cell elongation.  It is EXTREMELY critical that the first application be applied when the longest shoots on the tree are between 1 and 3 inches long.  You need to be ready, it occurs sooner than you think!  Neither Apogee nor it’s ability to reduce excessive growth is translocated to unsprayed parts of the tree.  It works only where it’s applied.  This characteristic allows you to target specific portions, or the entire tree for growth reduction.   I plan on making handgun applications to a block of trellised fuji this season.  I’m going to target the very top of the tree.  I hope to achieve 3 goals.  Reduce pruning, increase fruiting and increase sunlight in the lower portion of the tree.  Calcium in the tank with Apogee will inactivate the material.  Don’t mix them!  Other insecticides and fungicides are compatible.   Regulaid is recommended as an adjuvant as well as Amonium Sulfate on an equal weight basis with the Apogee (put the Apogee in the tank last).  The rate is variable depending on the vigor and variety of the tree.  The higher the rate the greater the effect.  Additional applications will probably be required and should be timed just as shoot growth resumes.


“Thus the metric system did not really catch on in the States, unless you count the increasing popularity of the nine-millimeter bullet” – Dave Barry


“I’d rather be a could-be If I cannot be an are; because a could-be is a maybe who is reaching for a star.  I’d rather be a has-been than a might-have-been, by far; for a might-have-been has never been, but a has was once an are.”  - Milton Berle



Questions on rates, timing or material choices?

Give me a call!


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