Carbon
nanotechnology is a growing research field with applications
in electronics, medicine, and engineering. The application of carbon
nanomaterials in agriculture has also been explored because of population
growth and resource depletion. In this research, fungicide pyraclostrobin
(Pyr) was successfully loaded on multiwalled carbon nanotubes (MWCNTs)
via a physisorption process, with drug loading up to 16.64% (w/w).
Compared with the 97% Pyr technical concentrate (97% Pyr TC), prepared
Pyr-loaded MWCNTs had a longer period of sustained release (360 h).
The indoor bioassay results showed that the MWCNTs carrier had a certain
fungicidal activity against Pyricularia oryzae, and the EC50 of Pyr-loaded MWCNTs against P. oryzae was 0.054 mg/L, which was close to that
of 97% Pyr TC (EC50 = 0.065). The nanoparticles could be
widely and uniformly distributed on the surface of mycelium and absorbed
by the roots of rice. There is a synergistic effect between the carrier
and drug molecules. The results of pot experiments showed that the
efficacy of the drug-loaded system against rice blast was 86.16% at
a concentration of 300 mg/L, which was comparable to the control effect
of commercial preparation 9% pyraclostrobin microcapsule suspension
(9% Pyr CS). In addition, compared with 97% Pyr TC, its acute toxicity
to zebra fish was reduced to 1/80, and the nanocarrier had no negative
effect on the germination of rice seeds and the growth of rice seedlings.
To sum up, these results suggest that MWCNTs are expected to be a
vehicle choice for pesticide delivery systems.