Question
Dear Jim, I am familiar with the types and brand names of iron sulfate sources.  I have read in your post about oak iron chlorosis also that these are commonly available.  I also read a more detailed treatment by USU forrestry extension, as well as a U of M(MN)article, all mentioning these are commonly available.  I have to disagree, I cannot find them anywhere within a 1000 mile radius!  I am in Fargo, ND.  Agriculture is king here, but no fertilizer supplier, landscaper, nursery, etc. can offer more than chelates or tiny amounts of iron sulfate for outrageous prices.  I need something like a 50# bag if I am going to fill holes around the drip lines...help!?!

Answer
Here is one source.  http://www.ironite.com/

Chlorosis is typically associated with one of three site conditions--a soil with a pH above 7 (an alkaline soil), a heavy soil containing a high percentage of clay, or a site where there has been extensive soil fill or removal, compaction, or construction injury that has damaged the root system. I would try getting the pH tested and alter it first--the sulfur products work well for this.

Some commonly available sources of iron and sulfur.

Source  Trade name Content (% iron)   
 Inorganic iron:      
 Ferrous sulfate Iron sulfate  20.5   
 Ferrous sulfate Ionate 10.0   
 Ferrous sulfate  Bandini 7 iron 7.0   
 Ferrous sulfate Ironite  4.5   
 Acidified mining residue Iron-Sul  20.0   
      
 Iron Chelates:      
 FeEDTA Sequestrene 12.0   
 FeEDTA  Hampene Iron 9.0   
 FeDTPA  Sequestrene 330 10.0   
 FeEDDHA  Millers Ferriplus 6.0   
 FeEDDHA Sequestrene 138 6.0   
 FeHEDTA Che-Gro Iron  5.0   
 FeHEDTA Versonol Ag Fe  5.0   
      
 Sulfur:  %sulfur   
 Elemental sulfur Elemental sulfur (powder form)  90.0   
 Elemental sulfur Degra-Sul (prill form) 90.0   
 Elemental sulfur Agri-Sul (prill form) 90.0