Manganese deficiency of Fraser and balsam firs

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.  

Samples of both Fraser and balsam firs submitted to the lab in recent weeks showed signs of poor growth and development. (view photos) The outermost, newest needles of each branch were extremely chlorotic.  The symptoms progressed from very chlorotic to almost a bronzing of the needles.  There were no plant pathogens or insects detected.  These symptoms are indicative of a micronutrient deficiency often called pH induced chlorosis.  This occurs when essential micronutrients, usually manganese and iron, are unavailable for uptake when the soil pH exceeds a critical level and shows very poor and unsatisfactory growth results.     

Soil and tissue nutrient tests confirmed our suspicion of manganese deficiency in both the Fraser and balsam firs.  Both soil and tissue tests are recommended to distinguish between soil nutrient availability and plant uptake problems induced by high soil pH.

The discolored firs were generally found in soils with a pH from 6.8 to 7.4 along with low soil phosphorus and potassium.  The optimal pH range for Fraser and balsam fir is 5.0 to 6.0 and 5.0 to 6.5, respectively.  Very poor and unsatisfactory growth will result if the soil pH level nears or exceeds the upper end of these ranges.  Fraser fir is especially sensitive to fluctuations in soil pH across the landscape.  Tissue tests confirmed manganese deficiency as the most limiting factor in the tissue of the Fraser and balsam firs (Tables 1 and 2).  This deficiency was induced by high soil pH – not by low soil manganese.

Table 1.  Recommended nutrient sufficiency range for Fraser fir*.

Nutrient in Tissue

Optimal Range for Fraser Fir

Nutrient Content of Fraser Fir Submitted

Nitrogen

1.50 - 2.00%

1.44

Phosphorus

0.20 - 0.60%

0.16

Potassium

0.60 - 0.80%

0.60

Magnesium

0.10 - 0.20%

0.13

Calcium

0.45 - 0.60%

0.61

Sulfur

0.08 - 0.20%

0.10

Boron

18 - 30 ppm

16

Zinc

18 - 75 ppm

20

Manganese

30 - 300 ppm

7

Iron

40 - 300 ppm

83

Copper

5 - 10 ppm

19

* There may be updated guidelines for high-performing Fraser fir.                   

Table 2.  Recommended nutrient sufficiency range for Balsam Fir*.

Nutrient in Tissue

Optimal Range for Balsam Fir

Nutrient Content of Balsam Fir Submitted

Nitrogen

0.90 - 2.10%

1.39

Phosphorus

0.10 - 0.26%

0.14

Potassium

0.28 – 1.08%

0.56

Magnesium

0.06 - 0.16%

0.14

Calcium

0.29 – 1.39%

0.61

Sulfur

0.11 - 0.22%

0.12

Boron

15 - 35 ppm

19

Zinc

46 - 50 ppm

32

Manganese

740 - 1600 ppm

8

Iron

35 - 120 ppm

69

Copper

3 - 8 ppm

6

* There may be updated guidelines for high-performing balsam fir.      

Unfavorable soil pH is the principal factor that limits plantings of certain conifers, so proper site selection is very important.  Adjustments in nutrient status and pH are more easily done before planting.  After planting, soil amendment may still be the best long-term approach for satisfactory growth of the trees and will obviously depend on the date of harvest.  Soil pH may be lowered to appropriate levels by the addition of sulfur or very acidic fertilizers.

Foliar applications of soluble manganese sulfate can be a rapid way to help alleviate manganese deficiencies.  These applications are temporary and provide a quick fix of the problem.  With this in mind, multiple applications of manganese sulfate would be needed during the year.  Foliar applications of manganese sulfate should be made three, six and nine weeks after bud break.  Manganese sulfate should be applied at 0.5 to 1.0 lb. manganese per acre.  Be sure to check the percent manganese content and specific supplier recommendations for the product that you are using.

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