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.
The Bt corn can produce unpredictable toxins and allergens into food plants and therefore into the final product. Also the Bt corn can be considered unstable as the number of copies of an inserted gene changes through later generations of the Bt corn. The low tillage is also a prime spot for a monoculture in the fields. A monoculture is where all of the crops are the same, so with this it is a perfect situation for weeds.
Frost or Freeze Damage to Corn. According to the USDA Soil Survey of Craven County, 5 of 10 years will have temperatures at or below 32O F past April 2nd but only 2 of 10 years will have temperatures this low after April 14th. There is only a 10% probability of having temperatures at or below 28O F past April 6th. Thus, the most probable last frost/freeze event is likely to occur about mid-April in most years. These periodic cold temperatures may cause significant leaf tissue damage to corn but may or may not cause significant yield loss.