The purpose of the study was to test the control of Florida Wax Scale (FWS) in citrus by potassium nitrate in comparison with broad-spectrum insecticides.
The trial included the following treatments: organophosphate (13L in 3500L water/ha), KNO3 (4%) + surfactant (Triton B-1956) 0,05% sprayed in 3500 L/ha and the control. These treatments were carried out on a 34 ha, 20 years old, citrus grove in the southern coastal plain of Israel.
Control of FWS by potassium nitrate + surfactant was nearly as good as organophosphate pesticides and statistically significantly better than the untreated control (Figure 1).
In addition, in a citrus grove at Yesodot (southern coastal plain) in Israel, thinning the invading generation of FWS larvae at low population densities by a combination of a nutritional spray of 4% potassium nitrate with 2% spray oil, once a year, obviated the necessity to control the pest by any other means during 7 years.
Figure 1. Effect of treatments on the mean number of live Florida Wax Scale per twig (square root transformed values) in days after spraying.