What Formula Is Best to Directly Inject Iron Chelate Into Trees?

Iron Chlorosis Sick Call

• There are many reasons for iron deficiency. Your soil might have large amounts of ash or limestone or you might have applied too much fertilizer containing high amounts of phosphorous. The soil pH, which measures the soil’s acidity or alkalinity, may be too high for your species of tree. The soil may also contain too much salt or not enough iron. If you insert powder or capsules containing liquid soluble iron into the tree or have an arborist inject it by needle, the treatment is good for two to four years.

The Nature of the Medicine

• Of the numerous types of iron chelates, two forms are typically inserted or injected into trees. Iron citrate, also called ferrous citrate, has one atom of iron and two anions of citrate, derivatives of citric acid. Anions are negatively charged atoms that attach themselves to positively charged atoms. Ammonium ferric citrate is a green or reddish brown powder that is frequently used to add iron to food. You can buy usually buy these chemicals in a form suitable for treating iron chlorosis in trees at larger garden supply centers or suppliers of agricultural chemicals.

Inserting in Holes

• To implant ferrous citrate powder, bore 3/8- to 1/2-inch-wide holes slanting downward 1 to 2 inches deep in the tree’s white sapwood . Start 1 to 3 feet above the ground and spiral the holes downward, spacing them 2 to 4 inches apart with one hole for each inch of trunk diameter. Place 0.8 gram of ferrous citrate in holes 2 inches apart on trees with trunks up to 4 inches wide. Place 1.8 grams of ferrous sulfate in holes spaced 3 inches apart in trees with trunks from 4 to 12 inches wide. Place 2.8 grams of ferrous citrate in holes 4 inches apart on trees with trunks larger than 12 inches wide. Seal the holes with asphalt, grafting wax, glazing compound or putty. Instead of measuring tiny amounts of ferrous citrate powder, you can insert plastic capsules containing liquid ammonium ferric citrate into the holes. The capsules are sold in sizes appropriate for various-sized trees and have slotted sides to release the iron into the sap. Their beveled heads help prevent the tree from bleeding sap so the wound typically closes within one year. Apply these in late spring or early summer.

Arborists Bearing Needles

• You should hire an experienced arborist to inject iron chelate into a tree trunk. Commercial liquid solutions for injection under pressure come in small plastic canisters and are injected into the tree in a pattern similar to boring holes in the trunk. The wounds made by injection heal more quickly than drilled holes because they are smaller and there are no plastic capsules left in the holes.