Even if enough Fe is in the soil, deficiency can occur under the following conditions: poorly drained soil, high Ca, high Mn, high pH, high P, high heavy metals, oxygen deficiency. Deficiency symptoms General: Yellow or white areas on youngest leaves. Older leaves remain green.
Bt corn is a variant of maize that has been genetically altered to express one or more proteins from the bacteria Bacillus thuringiensis. The protein is poisonous to certain insect pests and is widely used in organic gardening. The European corn borer causes about a billion dollars in damage to corn crops each year.
Corn is perhaps the most completely domesticated of all field crops. Its perpetuation for centuries has depended wholly on the care of man. It could not have existed as a wild plant in its present form. Corn is often classified as dent corn, flint corn, flour corn, popcorn, sweet corn, waxy corn, and pod corn. The remainder of this discussion will be concerned only with dent corn, which is the major type cultivated in the United States.