Impact of weeds compared to insects, diseases

By Barry Tickes, UA Area Agriculture Agent

There are many different types of pests that affect crops grown in Arizona. The three types of pests most often cited as the source of most problems are insects, diseases, and weeds.

These are the same types of pests that are cited as causing the major agricultural pest problems across the U.S. and worldwide.

The relative importance of these types of pest problems differ in Arizona from the rest of the U.S. and worldwide.

In terms of pesticide use, worldwide herbicides account for 36 percent of total usage, insecticides 25 percent, fungicides 10 percent, and other products (nematicides, rodenticides, etc.) at 29 percent.

In the U.S., herbicides accounted for 44 percent, insecticides 10 percent, fungicides 6 percent, and others products at 40 percent.

In Arizona, however, insecticides account for 58 percent, herbicides 17 percent, and fungicides 12 percent.

This is only an indirect measure of the relative importance of these three areas of pest management and may be heavily influenced by the amount of pesticides used.

For example, it is common to spray for insects five or more times per season while it is uncommon to spray for weeds more than twice. Nonetheless, weeds are the predominant pest problem in agricultural areas across the U.S. and worldwide.

Contact Tickes: (928) 580-9902 or btickes@ag.arizona.edu