SEDL / STP / STP1478-EB / STP46607S

Spray Retention Models for Arable Crops

Forster, W. A.
Executive Director, Senior Technical Officer, Technical Officer, and Research Director, Plant Protection Chemistry, NZ, Rotorua,

Kimberley, M. O.
Scientist, ensis-Forests, Rotorua,

Steele, K. D.
Executive Director, Senior Technical Officer, Technical Officer, and Research Director, Plant Protection Chemistry, NZ, Rotorua,

Haslett, M. R.
Executive Director, Senior Technical Officer, Technical Officer, and Research Director, Plant Protection Chemistry, NZ, Rotorua,

Zabkiewicz, J. A.
Executive Director, Senior Technical Officer, Technical Officer, and Research Director, Plant Protection Chemistry, NZ, Rotorua,

Pages: 10    Published: Jan 2008

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Abstract

A model has been developed explaining 92 % of the variance in spray retention by individual plants. The effects of formulation and plant morphology were represented as a logistic function, because this can accommodate retention close to 100 or 0 % whereas an additive model cannot. All inputs for the current model, except for the plant morphology factor, Mp, could be readily measured. Mp could be estimated by a linear regression relating Mp to the leaf surface roughness, as determined by the contact angle of a droplet of 50 % acetone on the leaf surface. The use of a logistic function, and inclusion in the model of total plant area, plan area, and contact angle to account for plant morphology, has provided an improved, practical, easily used universal agricultural spray retention model needing few inputs.