About Sysstem-Cal in apples

Phil Schwallier<schwalli@msu.edu>, and Amy Irish-Brown, Michigan State University Extension -

Sysstem-Cal is a foliar fertilizer that contains calcium and copper as well as phosphite.

The Sysstem-Cal formulation links calcium to phosphite for rapid absorption and translocation into the plant. When this product is added to the spray solution at 2 qt/100, it lowers the pH to near 2.5. Sysstem-Cal can be mixed with Apogee and not reduce the Apogee activity as other calcium products can. Apogee has on its label, “do not mix with any calcium products” because this combination will lead to less vegetative growth control as the Apogee gets tied up by the calcium. The situation with Sysstem-Cal is different and it can be safely combined with Apogee.

Sysstem-Cal has also been shown to increase the activity of some other PGR’s including NAA, Promalin, and MaxCel. In preliminary trials, the combination of Sysstem-Cal and thinning PGR’s (NAA and MaxCel) increased the thinning activity similar to thinning combinations of Sevin + NAA or Sevin + MaxCel. This does appear very promising as an additional approach to thinning. More research trials are needed to confirm Sysstem-Cal can be a reliable replacement for Sevin with these thinners.

Sysstem-Cal has 4% calcium included in the product. We are currently not aware of data that suggest mature fruit will have higher calcium levels, but suspect Sysstem-Cal will help fruit calcium levels. Sysstem-Cal is a strong acidifier and may have impact on other materials in the tank and perhaps on the tree. More experience is needed and growers who add it to their tanks are encouraged to leave check trees for comparison.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).

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