The following article was provided by George H. Snyder from the University of Florida/IFAS, Everglades Research and Education Center.

Slash pines (Pinus elliottii) are common in south Florida urban landscapes. Their presence in housing developments may pre-date the home/apartment construction. At times, the tree foliage (needles) may develop a yellow cast (chlorosis), and eventually the tree may die. Foliage color was improved by injecting iron chelates into the root flare of affected trees.

In south Florida, slash pines, Pinus elliottii, grow from near sea level to higher elevations in a wide range of conditions, from wet sites to well-drained sandy soils and rocky limestone outcrops, and a south Florida variety has been identified (Carey, 1992). They often are found in urban areas either as landscape plantings, or as trees that existed prior to urban development.

While slash pines commonly grow for several hundred years, yellowing (chlorotic), dying, and dead trees often are seen in urban settings. Speculation on reasons for their demise in urban settings include root disturbance and filling in over the roots during development, diseases, insects, and increases in soil pH which induce iron and manganese deficiencies (Gilman and Watson, 2014). This study only deals with iron deficiency.

Fig. 10. Slash pine, Pinus elliottii, Tree 7, prior to iron chelate treatment
on 25 Jan. 2018 (left), and on 23 May 2018 (right).