(1) Other plant nutrients when mentioned in the labeling shall be registered and guaranteed. Guarantees shall be made on the elemental basis. Sources of the elements guaranteed and proof of availability shall be provided to the department upon request. Except those guarantees for those water soluble nutrients labeled for ready-to-use foliar fertilizers, ready-to-use specialty liquid fertilizers, hydroponic or continuous liquid feed programs and guarantees for potting soil, the minimum percentages which will be accepted for registration are as follows:

Element	Minimum Concentration %
Calcium (Ca)	1.00
Magnesium (Mg)	0.50
Sulfur (S)	1.00
Boron (B)	0.02
Chlorine (Cl)	0.10
Cobalt (Co)	0.0005
Copper (Cu)	0.05
Iron (Fe)	0.10
Manganese (Mn)	0.05
Molybdenum (Mo)	0.0005
Nickel (Ni)	0.001
Sodium (Na)	0.10
Zinc (Zn)	0.05

Guarantees or claims for the above listed plant nutrients are the only ones which will be accepted. Proposed labels and directions for use of the fertilizer shall be furnished with the application for registration upon request. Any of the above listed elements which are guaranteed shall appear in the order listed immediately following guarantees for the primary nutrients of nitrogen, phosphate, and potash. When directions for use render the product ineffective (as a fertilizer) the department will not register the product.

(a) A warning or caution statement may be required on the label for any product which contains micronutrients in water soluble form when there is evidence that a micronutrient may be harmful to certain crops or where there are unusual environmental conditions.  

EXAMPLES OF WARNING OR CAUTION STATEMENTS:

(i) Directions: Apply this fertilizer at a maximum rate of (number of pounds) per acre for (name of crop).

CAUTION: Do not use on other crops. The (name of micronutrient) may cause injury to them.

(ii) CAUTION: Apply this fertilizer at a maximum rate of (number of pounds) per acre for (name of crop). Do not use on other crops; the (name of micronutrient) may cause serious injury to them.

(iii) WARNING: This fertilizer carries added (name of micronutrient) and is intended for use only on (name of crop). Its use on any other crops or under conditions other than those recommended may result in serious injury to the crops.

(iv) CAUTION: This fertilizer is to be used only on soil which responds to (name of micronutrient). Crops high in (name of micronutrient) are toxic to grazing animals (ruminants).

(v) CAUTION: (Name of micronutrient) is recommended for all crops where (name of micronutrient) may be deficient; however excessive application to susceptible crops may cause damage.