SEDL / STP / STP1347-EB / STP14158S

Spray Retention is Affected by Spray Parameters, Species, and Adjuvants

Bruns, DE
Former Graduate Research Assistant and Professor, North Dakota State University, Fargo, ND

Nalewaja, JD
Former Graduate Research Assistant and Professor, North Dakota State University, Fargo, ND

Pages: 13    Published: Jan 1998

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Abstract

Spray retained by soybean, [Glycine max (L.) Merr. var. Ozzie], common lambsquarters [Chenopodium album (L.)], and redroot pigweed [Amaranthus retroflexus (L.)] was determined using a dye spectrophotometric method for water sprays (without pesticides) varying volume, droplet size, and adjuvants. Spray retained based on leaf area generally was greater for small than large droplets and more for surfactants than for oil adjuvants. Surfactants, Tergitol® 15-S-9 and Tergitol® 15-S-30, enhanced spray retained more for common lambsquarters than redroot pigweed or soybean. The oil adjuvants, methylated canola oil (MCO), canola oil (CO), and petroleum oil (PO) generally reduced spray retained by redroot pigweed, but generally increased spray retained by common lambsquarters compared to water spray alone. Spray retained by soybean was also increased by oil adjuvants, except for PO applied in droplets from an 8004 nozzle. Spray retained decreased as spray volume increased from 160 to 320 L/ha for surfactants and 80 to 160 L/ha for CO and MCO. Species retained more spray as oil adjuvant concentration increased from 0.25 to 4% v/v. However, retention decreased when Tergitol® 15-S-9 and 15-S-30 increased from 1 to 4%. The results of the present research with a water carrier demonstrate that optimization of spray retention requires a consideration of adjuvants, species, and spray parameters.