0 DR FAULKNER’S FUNKY KEYS TO ASSIST IN THE DIAGNOSIS OF PLANT NUTRIENT DEFICIENCIES

As we have discovered, identifying plant nutrient deficiencies can be quite tricky. Seems even the experts disagree with each other a lot.

However the following is an attempt to gather together the most likely symptoms of deficiency for each of the essential plant elements and present them in a usable and practical format for diagnosis.

IMPORTANT: This guide is not intended to be infallible and you should always follow up with further tests if you want to be sure of the possible deficiency that you have diagnosed!

To make as user friendly as possible, the information has been split up into three keys:

Mostly older leaves affected...... Use Key One

Mostly younger leaves affected...... Use Key Two

Both older and younger, or medium aged leaves affected...... Use Key Three

KEY 1: MOSTLY OLDER LEAVES ARE AFFECTED

1 Leaves fairly uniformly coloured, not patchy or localised chlorosis...... 2

1*Leaves not uniformily coloured, chlorosis patchy or in discrete areas...... 5

2Leaves dark coloured, not pale yellowish green...... 3

3Leaves developing purplish, reddish or orange tints...... PHOSPHORUS

3* Leaves bronzy, stunted, very branched club roots may be present...CHLORINE

2*Leaves pale uniformly green or yellowish...... 4

4No necrotic spotting...... NITROGEN

4*Necrotic spotting present, leaves sometimes cupped or rolled..MOLYBDENUM

5Obvious interveinal chlorosis present...... MAGNESIUM

5*Interveinal chlorosis not present...... 6

6Yellowish along edges of leaves with burnt scorched leaf margins..POTASSIUM

6* Chlorotic and/necrotic leaf lesions present, leaves bronzy, stunted, club roots may be present CHLORINE

KEY TWO: MOSTLY YOUNGER LEAVES ARE AFFECTED

1 Growing points (buds at tips) severely affected and dying...... 2

1* Growing points not affected, remains alive...... 3

2Leaves chlorotic, leaves twisted and brittle, die back at tips...... BORON

2*Leaves not chlorotic, hooked tips then turn brown/black and die.....CALCIUM

3 Leaves uniformly chlorotic (not interveinal)...... 4

3*Leaves with definite interveinal chlorosis...... IRON

4 Leaves abnormally blunt, rounded, stunted: “mouse ear” appearance....NICKEL

4* Leaves stuntedbut normal shape...... 5

5 Leaf tips not affected...... SULPHUR

5* Leaf tips withered and/or dying back...... COPPER

KEY THREE: BOTH OLD AND YOUNG, OR MEDIUM AGE LEAVES ARE AFFECTED

1 Interveinal chlorosis with mottled pattern, often speckled or spotty appearance MANGANESE

1* Interveinal chlorosis well defined, stunted growth, often rosette appearance of stunted leaves at shoot tips ZINC

SUPPLEMENTARY NOTES:

  • Deficiencies of sulphur, nickel and chlorine are extremely rare in natural soils. These deficiencies are most likely to occur in artificial growing media or in hydroponics systems.
  • Deficiency of calcium is linked to blossom end rot in tomatoes and bitter pit in apples.
  • Deficiency of boron is linked to canker in beetroots and hollow stem in brassicas.
  • Deficiency of molybdenum is linked to whiptail disease in brassicas, especially in cauliflowers.
  • Deficiency of molybdenum in legumes may manifest as nitrogen deficiency, as the molybdenum is needed by nitrogen fixing micro organisms.
  • Remember deficiency symptoms for one element can actually be caused by excess of another. Preferably have a proper soil and leaf tissue analysis conducted by a laboratory before applying anything, especially trace elements. Remember the golden rule: “If in doubt, leave them out!”
  • Remember also that deficiencies can be related to pH levels: a good motto to adopt is: “Check the soil pH first before applying extra minerals because they may be there, just unavailable to the plants.”

1