Kaolin and potassium soap with thyme essential oil to control Monosteira unicostata and other phytophagous arthropods of almond trees in organic orchards
2015
Marcotegui, Aránzazu | Sánchez-Ramos, Ismael | Pascual, Susana | Fernández, Cristina E. | Cobos, Guillermo | Armendáriz, Ignacio | Cobo, Ana | González-Núñez, Manuel
Monosteira unicostata (Mulsant & Rey) (Hemiptera: Tingidae) is an important pest of almond trees in the Mediterranean region requiring alternative control methods for organic farming. Kaolin and potassium salts of fatty acids combined with thyme essential oil (PSTEO) have shown high efficacy for the control of this insect in laboratory assays. Field studies were conducted during two consecutive years to test the feasibility of these products applied at the maximum field recommended concentrations to control this pest and other arthropods that damage almond trees. In 2009, two kaolin applications reduced the abundance of M. unicostata approximately by half, whereas in 2010, identical applications reduced the abundance by a third. This produced a damage reduction of 26 and 11 %, respectively. Concerning PSTEO, a 40 % reduction in M. unicostata abundance was obtained in 2009, producing a 14 % damage reduction, whereas no significant effect was observed in 2010. The effect of the treatments on M. unicostata was only observed at the lower part of the trees. Other phytophagous arthropods of almond trees, such as Cicadellidae, Aphididae, Bryobia rubrioculus (Scheuten) (Acari: Tetranychidae) and Phyllonorycter corylifoliella Hübner (Lepidoptera: Gracillariidae), were also negatively affected by kaolin treatments, but PSTEO had no effect on herbivorous arthropods other than M. unicostata. Kaolin could be useful to control M. unicostata in the field, but repeated applications might be required to achieve good tree coverage and pest control. PSTEO appears more limited in its efficacy.
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