Efficacy and Selectivity of Potassium Bicarbonate Salts against Cacopsylla pyri on Pears.

In recent years, the control of pear psyllid in northern Italy has not been particularly problematic, due to the presence of two insecticides (abamectin and spirotetramat) specifically for this pest, and due to the adoption of integrated pest management. However, the withdrawal of these two specific insecticides is imminent and, therefore, it has become necessary to find alternative control tools. More recently, potassium bicarbonate, known for its fungistatic activity against many phytopathogenic fungi, has also shown some activity against some insect pests. In the present study, the efficacy and possible phytotoxicity of potassium bicarbonate were tested in two field trials on second generation Cacopsylla pyri by spraying two different salt concentrations (5 and 7 kg ha-1), with or without polyethylene glycol as an adjuvant. Spirotetramat was used as a commercial reference. The results showed that potassium bicarbonate could positively control the number of juvenile forms (with a mortality percentage of up to 89% at the infestation peak), even though spirotetramat was still more effective. Therefore, potassium bicarbonate appears to be a sustainable integrated tool for psyllid control, especially in the wake of the imminent withdrawal of spirotetramat and other insecticides currently used on this pest.

Insecticidal activity and fungitoxicity of plant extracts and components of horseradish (Armoracia rusticana) and garlic (Allium sativum).

To avoid environmental pollution and health problems caused by the use of traditional synthetic pesticides, there is a trend to search for naturally occurring toxicants from plants. Among the compounds discussed for anti-fungal and insecticidal activity, the natural extracts from garlic and horseradish have attracted considerable attention. The objective of this study is to determine the insecticidal and anti-fungal activity of Armoracia rusticana and Allium sativum L. extracts against larvae of Aedes albopictus (Skuse) and some pathogenic fungi. For the insecticidal test, horseradish and garlic extracts were prepared from fresh plants (cultivated in Emilia Romagna region) in a solution of ethanol 80 % and the two different solutions were used at different concentrations (for the determination of the lethal dose) against the fourth instar mosquito's larvae. The fungicidal test was carried out by the agar plates technique using garlic and horseradish extracts in a 10 % ethanol solution against the following organisms: Sclerotium rolfsii Sacc., Trichoderma longibrachiatum, Botrytis cinerea Pers., Fusarium oxysporum Schlecht. and Fusarium culmorum (Wm. G. Sm.) Sacc. The first results demonstrated that the horseradish ethanol extracts present only a fungistatic activity against Sclerotium rolfsii Sacc., Fusarium oxysporum Schlecht. and F. culmorum (Wm.G. Sm) Sacc. while garlic extracts at the same concentration provided a good fungicidal activity above all against Botrytis cinerea Pers. and S. rolfsii. A. rusticana and A. sativum preparations showed also an interesting and significant insecticidal activity against larvae of A. albopictus, even if horseradish presented a higher efficacy (LC50 value of 2.34 g/L), approximately two times higher than garlic one (LC50 value of 4.48 g/L).