Pollen BankPollen Bank


Pollen viability depends on boron and calcium. When pollen is deficient or contains an excess of those nutrients, then its sexual performance is diminished.

First, we measure viability in the absence of Bor Ca (Control).
Second, we measure viability in the presence of B or Ca using at least 3 concentrations for each nutrient.

Results are usually reported within 24 hours after receiving the samples.


When to, Where to & How to !

To obtain a BoCal™ pollen bioassay, gather a minimum of 400 flowers (total) from 4 trees at each of 5 locations in your orchard, or in a manner similar to how you routinely take a soil leaf or hull sample. If different soil types, water sources or other anomalies exist in an orchard, take samples from separate blocks within a field. Early in the bloom (<1%) season, gather flowers at “popcorn stage” stage of development -- petals extended and almost open. Place them in a paper bag with 2 moist (not dripping wet) paper towels. Do not mix flowers from different varieties.

On the bag, indicate (A) your ranch, (B) block, (C) variety, (D) name and (E) phone number of who to contact when results are completed. Place the flowers in a box along with a sealed plastic bag containing ice or a small frozen gel-pack (keep ice and flowers separate). Mail or ship the samples next day air to our facility (UPS or FedEx):


We will inform you of the results, usually within 24 hours after receiving samples. Be prepared to correct deficiencies if they exist (over). We will send you a hard copy of the results within a week for your records.


The BoCal™ pollen bioassay is a novel approach to measure boron and calcium sufficiency in flowers – two essential elements critical for the reproductive needs of plants. The method utilizes pollen taken from flowers produced during early bloom. It is based on how pollen vitality responds to supplemental boron or calcium under laboratory conditions. Although the basic methodology has been in use for more than a half century, its use as a diagnostic tool to evaluate the boron and calcium status of flowers is new.

Key advantages are that a pollen bioassay can be performed early in the season, before fertilization and flower set occurs, when there is time to amend a nutrient deficiency or, equally important, eliminate unnecessary fertilizer applications. Another significant advantage is that the bioassay measures “available” boron or calcium, not total quantities. The pollen bioassay simply takes the guesswork out of boron and calcium management during bloom.


1. Obtain a BoCal™Analysis using popcorn stage flowers sampled from a field or orchard you want tested. Sample as early in the bloom (<1%) period as possible. Immediately send them off for analysis. BoCal results are reported within 24 hours after arrival at our lab. Then…
2. Take Action if a nutrient deficiency is detected. Be prepared to apply a foliar application of Boron and/or Calcium to remedy that condition. How much you might need depends on the degree of deficiency and your routine nutrient program protocol.
3. Do Nothing if the nutrient level is within +/-10% of optimum, because Boron or Calcium can become toxic to pollen when too much is present in a flower. Reminder: many commercially available fertilizers contain B and/or Ca, so be aware of what you apply during bloom. Do not make a good situation bad.
4. Do Nothing if the nutrient status is rated as excessive, because a toxic level will become worse. Presently, allowing time to pass without any input of B or Ca is the only remedy for this category. Accordingly, pay special attention to the ingredients of fertilizers you may apply at bloom and petal fall. Don’t make a bad situation worse.
5. Do Nothing to your standard nutrient testing procedures (soil, leaf, petiole, hull analyses). They are necessary to monitor the vegetative needs of tree growth. The BoCal pollen bioassay is specifically intended for the reproductive phase of crop development: everybody falls into this category.