Certain crops are more susceptible to aflatoxin formation than others; maize (corn) and peanuts are two key staples that are prone to extensive contamination. Other staples such as rice and cassava may also be contaminated. Contamination can occur at all stages of  crop production: harvest,  storage and processing.  Farming and storage practices which affect temperature, humidity, and insect damage to crops can significantly impact aflatoxin levels. Irrigation and pesticide use, timing of harvest, drying techniques, and storage environment are all important. Irrigation and pesticide use reduce stress on the plant thereby decreasing susceptibility to Aspergillus growth.  However, irrigation can also provide moisture that the fungus needs to grow. Time of crop harvest, drying techniques, and storage conditions all affect moisture content; lower moisture content decreases continued Aspergillus growth. Processing techniques and insects can physically spread the toxin.18