Plant Protect. Sci., 2006, 42(1):26-33 | DOI: 10.17221/2693-PPS

Influence of droplet spectra on the efficiency of contact fungicides and mixtures of contact and systemic fungicides

Martin Prokop¹, Karel Veverka²

¹ State Phytosanitary Administration, Brno, Czech Republic

² Division of Plant Medicine, Research Institute of Crop Production, Prague-Ruzyně, Czech Republic

The effects of droplet spectra, spray volume, and the addition of an adjuvant to the spray solution against Phytophthora infestans were evaluated using contact fungicides, mixtures of contact and systemic fungicides, and a contact fungicide + an adjuvant. Six droplet spectra, ranging from VMD = 183 µm to VMD = 939 µm, were used. The spray volumes were 300, 450 and 600 l/ha for the contact fungicides, and 300 l/ha was used for the mix of contact with systemic fungicides. No significant differences in efficiency were observed between different droplet spectra when used for the mix of contact with systemic fungicide treatments. However, the efficiency of treatments with a contact fungicide significantly increased with smaller droplet spectra. The larger droplet spectra required larger spray volumes for greater efficiency. The addition of the adjuvant (pinolene, 96%) to the spray solution of the contact fungicide caused the efficiency to be similar for all droplet spectra. The effect of droplet spectra is more pronounced in contact compounds. The translocation of the systemic compounds and the ability of the surfactant to improve the coverage with contact compounds may be the main mechanisms that counteract the effects of larger droplet spectra and lower leaf coverage.

Keywords: Phytophthora infestans; fungicides; water volume; droplet size; droplet density

Published: March 31, 2006  Show citation