Mainstay Calcium is the only soil applied calcium on the market that is highly plant available. This provides a unique opportunity to sharply improve calcium nutrition during cell division in permanent crops. In pome fruits, the uptake or “absorption” phase (depicted below) occurs from fruit set through 6 weeks. This is when fruitlets are actively transpiring and using water and nutrients delivered by the xylem. Without supplemental application, soil calcium availablility is often poor. Fruit will not receive enough calcium during this critical time to prevent quality problems such as bitterpit, cork spot, stem bowl cracking, etc. Targeted applications of Mainstay Calcium during cell division are the key to reducing or eliminating calcium related crop loss.
The Uptake Curve
Note that calcium uptake just after fruit set is rapid and strong (see graph). As cell division draws to a close, the curve begins to flatten. Ideally applications should target the steepest part of the curve.
Typical cell division rates are a total of 5 to 10 gallons per acre divided into weekly or biweekly applications. Application through drip irrigation is most often a weekly schedule. Spray down applications are typically a bi-weekly schedule. Use higher rates on susceptible varieties and hotter sites with a history of condition problems. Note that heavy crops are less likely to have calcium related problems while lighter crops may require more aggressive rates.
Calcium is taken up just behind the root tip on actively growing roots. Early root growth is dependent on soil temperature 55 – 60 degrees. Roots close to the surface start growing first so applications should be intended for the top 1’ of the soil profile.
Early season soil applications should be timed with irrigation to water them in.
Mainstay Calcium moves freely in the soil solution. When applied to coarse soil smaller more frequent applications produce better results. In loamy soil, less frequent but higher volume applications work well.
An acidic imbalance in soil pH can severly limit air/water relations, root growth and calcium availability. Correcting pH with lime is an essential component of plant health and optimal calcium uptake.
Each cultivar has its own calcium requirement. For example, most apples and pears will partition xylem supplied calcium effectively during cell division. Mainstay Calcium applications just during this six week period are often sufficient. Honeycrisp is less effective at partitioning calcium to the fruit. Mainstay Calcium applications on Honeycrisp should be emphasized during cell division but continued season long, particularly on warmer sites.
N, Mg, K
High levels of these three nutrients when plant available in the soil will require increased rates of calcium to offset.
High vigor will increase the likelihood of calcium disorder risk. Higher rates of calcium may be required to offset.
Zinc and Boron
These elements play a critical roll in cell division and calcium uptake and utilization. Triplex Micro and Triplex Zinc are reacted to remain plant available in the soil and can be added to applications of Mainstay Calcium.
Intensive Mainstay Calcium decreases fruit drop and crop loss in Honeycrisp as depicted below.