Decline of naled residue on filter paper was studied after exposure to
ultra-low volume droplets in a settling chamber. Naled-treated filter
papers were stored under 3 treatment scenarios: 1) in a dark environm
ental chamber at an average relative humidity (RH) of 46.9% and temper
ature of 24 degrees C, 2) in a dark environmental chamber at an averag
e RH of 87.7% and temperature of 24 degrees C, and, 3) in direct sunli
ght in the field. Decline of naled followed first order kinetics in al
l cases; consequently, half-life of naled under each treatment was det
ermined from the slope of each line. Half-life (+/-1 SD) of naled was
8.17 +/- 1.24, 4.81 +/- 1.18, and 1.37 +/- 0.24 h, for treatment scena
rios 1, 2, and 3, respectively. In each test, a significant (P < 0.05)
decline in naled residue occurred between initial assessment and 4 h
postapplication. The half-life of each treatment scenario was signific
antly (P < 0.05) different from that of the other 2 scenarios, indicat
ing that both humidity and sunlight affect naled degradation rates.