Why is “wave behavior” of EM field not observed at small frequencies? In Feynman’s lectures on Physics : Volume 1, there is a table in Chapter 2 : Basic Physics that lists various frequencies in the electromagnetic field and relates them to the observed behavior (in the far right column):
 
This suggests that even at significant frequencies of oscillation of charges, i.e., at 100 Hz, “field behavior” of the EM field is seen and that “wave behavior” is seen only after the frequencies reach $10^5$ Hz. 
Is it not true that even a small frequency of oscillation of charge should set up a wave in the EM field and that “field behavior” is seen only when charges are absolutely stationary? Also, what exactly is meant by “field behavior”?
 A: "Waves behavior" are the phenomena of interference and diffraction. For humans, this is noticeable when the wavelength is on the human scale: meters, maybe kilometers. 
For sound this means frequencies higher than a few cycles per second. When it is slower, we call these variations just changes in the atmospheric pressure. In oceans, the tides are too slow to be treated as water waves. In electromagnetism, human scale corresponds to frequencies of 100 MHz (FM broadcast). 
Really slow variations (AC power, the teacher waving a charged rod), are much better dealt with using quasistatic models where wavelength can be disregarded.
A: You should take the words "rough behavior" with a grain of salt, I mean is very rough. Fundamentally electromagnetism or radiation is a field theory. The full description is given by QED (quantum electrodynamics) so at any frequency, radiation IS described as a field, i.e. for the case of EM a 4-vector field $A_\mu$ which is defined at all times at every point in space, hence called a field. We identify its particle behavior as the excitation modes of this field. More specifically a field can be decomposed as a sum of modes (or waves if you wish) this modes are identified as particles depending on the context and energy scale, that was perhaps what Feynman was trying to convey with such table. 
The short answer is then that the more localized the energy is, the closer you are to dealing with particle behavior, namely a defined trajectory and no interference/diffraction phenomena. An example of this is given by particle-like excitations such as solitons. Or the spontaneous emission of light from an atom as an example of localization and particle behavior. 
