ARCHIVE: Fertiliser Manual (RB209)

Leaf Analysis for Top and Soft Fruit

Leaf analysis is an essential technique for general monitoring of nutrient status and the diagnosis of nutritional disorders. Separate samples should be taken in a similar manner from good and poor areas of growth so that the results can be compared.

In addition, knowledge of leaf nutrient concentrations has proved useful for assessing the nutritional status of crops. Satisfactory ranges for optimal growth and cropping are given in the table below. Where analysis results are to be compared to these standards, it is essential that a representative sample is taken, in the correct way and at the correct time.

Because there are seasonal and other factors which influence leaf nutrient concentrations, leaf analysis must be interpreted carefully. Leaf nutrient levels can also vary between varieties. Where there is sufficient information, the standard ranges take account of differences between varieties.

Leaf analysis can be used to provide a more complete guide to the adequacy of the orchard fertiliser programme than can be obtained from soil analysis alone. Where leaf nutrient levels are below the satisfactory range, an increase in fertiliser use can be considered. However, before making a change, the cause of the problem should be further investigated to ensure that other factors such as soil compaction or disease are not involved.

Where the leaf nutrient level is consistently above the satisfactory range for several years, there is justification for a reduction in fertiliser use. In particular, high levels of nitrogen and potash can have adverse effects on apple storage quality and application rates can often be reduced to advantage.

A high manganese level indicates a need to check soil pH, as it is often associated with increased soil acidity, but can also result from use of foliar feeds or fungicides containing manganese.

Leaf analysis – satisfactory nutrient ranges of major nutrients expressed as elements

Crop

Leaf sampling

Nitrogen

Phosphorus

Potassium

Magnesium

Sulphur

  

  positiona

(N)

(P)

(K)

(Mg)

(S)

 

% in dry matter

Apple
Coxb

1

2.6-2.8

0.20-0.25

1.2-1.6

0.20-0.25

0.20-0.40

Bramley

1

2.4-2.8

0.18-0.23

1.2-1.6

0.20-0.30

 
Cherries

1

2.4-2.8

0.20-0.25

1.5-2.0

0.20-0.25

0.13-0.84

Pears
Comice

1

1.8-2.1

0.15-0.20

1.2-1..6

0.20-0.25

0.17-0.26

Conference

1

2.1-2.6

0.15-0.20

1.2-1.6c

0.20-0.25

 
Plums

1

2.0-2.6

0.15-0.20

1.5-2.0

0.20-0.25

0.20-0.70

Blackcurrants

2

2.8-3.0

0.25-0.35

1.5-2.0

0.15-0.25

 
Raspberries

3

2.4-2.8

0.20-0.25

1.5-2.0

0.30-0.35

 
Strawberries

4

2.6-3.0

0.25-0.30

1.5-2.0

0.15-0.20

0.10-0.20

Vines

5

2.0-3.0

0.25-0.30

1.2-1.6

0.20-0.30

 
Blueberries

6

1.8-2.0

0.08-0.40

0.4-0.7

0.13-0.25

0.12-0.20

a. Leaf sampling position:
   1 Mid third extension growth, sampled mid-late August.
   2 Fully expanded leaves extension growth, sampled prior to harvest.
   3 Fully expanded leaves non-fruiting canes, sampled at fruit ripening.
   4 Lamina of recently matured leaves, sampled at fruit ripening.
   5 Leaf opposite basal fruit cluster, sampled at full bloom.
   6 Fully expanded leaves between late July and mid August
b. For Gala and Braeburn follow Cox, however, typical average for Gala is 2.3% N and P content is less than in Cox.
c. Yield benefits are achieved at 1.6 % K

Leaf analysis – satisfactory nutrient ranges of micronutrients

Micronutrient

Deficiency

Optimum

High

 

mg/kg in dry matter

Manganese (Mn)

20

30-100

100a

Boron (B)b

15

20-40

40c

Zinc (Zn)

10

15-30

50

Copper (Cu)

5

7-15

15

Iron (Fe)

<45

45-250

 
a. Manganese concentrations above 100 mg Mn/kg indicate that the soil is becoming acid. Check the soil pH.
b. Fruit analysis is the most reliable diagnostic technique for boron deficiency. Optimum levels are 1.5 to 4.5 mg B/kg fresh weight. Below 1.5 mg B/kg indicates deficiency.
c. Excess boron levels can promote premature ripening and senescence in fruit.

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