Planta Daninha (2003) 21, S93-S98

E. Negrisoli, D. Martins, Velini. D.E. and W.L.B. Ferrera (2003)
Degradação de diquat em condições de caixa d'água com e sem plantas de egéria
[Diquat degradation under small-tank conditions with and without egeria plants]
Planta Daninha 21 (special issue), S93-S98
Abstract: Egeria is considered to be the most important aquatic weed in Brazilian reservoirs since it causes great damage to navigation, fishing and power generation. The objective of this work was to study diquat degradation under small-tank conditions with and without Egeria densa and Egeria najas and in soil. This trial was carried out at Unesp (Brazil), 1999. The plots consisted of reservoirs with 300-liter water capacity, plus 20 cm soil and 5 cm sand on the bottom. Twenty branches of each Egeria species were planted. The treatments consisted of applying 6 ppm diquat (Reward) under three different conditions: (i) reservoirs with water only, (ii) reservoirs with water and soil, and (iii) reservoirs with water plant and soil. The concentration was measured spectrophotometrically (308 nm), obtaining the following curve: herbicide concentration (ppm) = 0.7418 + 50.95391* A, where A= absorbance reading. The correlation coefficient was 0,9956648. Diquat half-life was 29 days after application, under condition (iii). Under condition (ii) Diquat half-life was 23 days after application. Under condition (i) its half-life was 18 days after application.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: Portuguese)
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Research topic(s) for pests/diseases/weeds:
control - general
health/environmental effects of pesticides

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Egeria densa (weed)		Brazil (south)
	Egeria najas (weed)		Brazil (south)