Magnesium (Mg) deficiency.
Magnesium
deficiency will exhibit a yellowing (which may turn
brown) and interveinal chlorosis beginning in the older
leaves. The older leaves will be the first to develop
interveinal chlorosis. Starting at leaf margin or tip
and progressing inward between the veins. Notice how the
veins remain somewhat green though as can be seen in
figure 15.
Notice how in Figure 16 and 17 the leaves
curl upwards like they're praying? They're praying for
Mg! The tips may also twist.
This can be quickly
resolved by watering 1 teaspoon Epsom salts/gallon of
water. Until you can correct nutrient lockout, try
foliar feeding. That way the plants get all the nitrogen
and Mg they need. The plants can be foliar feed at
teaspoon/quart of Epsom salts (first powdered and
dissolved in some hot water). When mixing up soil, use 2
teaspoon dolomite lime per gallon of soil.
If the
starting water is above 200 ppm, that is pretty hard
water, that will lock out mg with all of the calcium in
the water. Either add a 1/4 teaspoon per gallon of epsom
salts or lime (both will effectively reduce the lockout
or invest into a reverse osmosis water filter.
Mg
can get locked-up by too much Ca, Cl or ammonium
nitrogen. Don't overdo Mg or you'll lock up other
nutrients.
