The behaviour of copper deposits from low and ultra low volume sprays on tomato foliage and their control of early blight
1985
Mabbett, T.H. | Phelps, R.H.
Inorganic copper fungicides such as cupric hydroxide provided good control of tomato early blight when applied at low and ultra low dosages using, respectively, a low volume mistblower and a fan-assisted ULV sprayer. ULV application at 0.2 kg Cu++ in 17 litres/ha application methods while LV mistblowing at 1.23 kg Cu++ in 350 litres/ha provided a real reduction in dosage for an established method of appliction. ULV application was more efficient than LV application and the high tenacity of ULV deposits indicated in the field and demonstrated under the effects of simulated rainfall appeared to be the key factor accounting for the higher recovery of copper applied by this method. The reduced recovery (percent) with increased dosage for both LV and ULV methods was related to the greater adherence than coherence of particulate copper fungicides and indicated the futility of striving to achieve "thick" deposits, irrespective of method used. Indications were that deposits of between 0.6 and 1.0 ug Cu++/cm2 as provided by ULV application of at least 0.2 kg Cu++/ha was the minimum necessary to control this disease, particularly during the wet season
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