Tree Nutrition

Magnolia (Magnolia grandiflora) decline can be reversed


Splotchy yellowing foliage that becomes sparse over time is the principal symptom.

Splotchy yellowing foliage that becomes sparse over time is the principal symptom.

Although the Southern magnolia (Magnolia grandiflora) is a native tree in north and central Florida, sometimes severe nutrient deficiencies can occur in our urban soils. The magnolia nutrient deficiency symptoms are often seen as sparse, yellowing foliage. In extreme cases trees have continued to lose foliage until they finally die.

The sequence of photos below was taken since 2008 in a yard in Ponte Vedra Beach, Florida. The yard was receiving regular fertilizer applications from a reputable lawn service. The fertilizer was a high nitrogen turf mix (16-4-8). Yet the tree was in severe decline.

Leaf tissue analysis showed a severe manganese deficiency. Sometimes this deficiency is seen in combination with potassium and magnesium deficiences.

The leaf tissue analysis was the key to solving the problem. A soil test may not have provided enough information about the deficiency because the deficient nutrients may have been present in the soil but unavailable for the tree. The leaf tissue analysis tells us what nutrients are in the plant.

In severe cases too much foliage has been lost over the past several years. The tree can no longer make sufficient food for itself through photosynthesis and is slowly dying. Photo taken in 2008.

In severe cases too much foliage has been lost over the past several years. The tree can no longer make sufficient food for itself through photosynthesis and is slowly dying. Photo taken in 2008.

I have found the leaf tissue analysis to be very helpful in correcting nutrient deficiencies not only in magnolias but also for citrus trees and palm trees. And I will only recommend fertilizer for a live oak if a leaf tissue analysis indicates fertilizer is needed.

 

 

 

 

 

 

 

 

The recovery is slow and gradual. Some of the smaller dead branches and branch tips will not recover. Photo taken in 2009.

The recovery is slow and gradual. Some of the smaller dead branches and branch tips will not recover. Photo taken in 2009.

 

 

 

 

 

 

 

 

 

Interior branches are filling out. Foliage density is increasing. Some of the old dieback is still visible. Photo taken in 2010.

Interior branches are filling out. Foliage density is increasing. Some of the old dieback is still visible. Photo taken in 2010.

 

 

 

 

 

 

 

 

 

Tree foliage density is good. Some old dead branch trips are still visible. Customer not concerned about removing the dead branche tips. Photo taken 2011.

Tree foliage density is good. Some old dead branch trips are still visible. Customer not concerned about removing the dead branche tips. Photo taken 2011.

 

 

 

 

 

 

 

 

 

Tree is back to normal. Tree symetry still needs improvement due to earlier branch dieback. Photo taken in 2012.

Tree is back to normal. Tree symetry still needs improvement due to earlier branch dieback. Photo taken in 2012.