Efficiency of inorganic fungicides against the formation of Erysiphe necator chasmothecia in vineyards

Abstract

BACKGROUND A reduction in chasmothecia, an important inoculum of grape powdery mildew (Erysiphe necator Schwein.), is essential for disease control in vineyards; the use of fungicides during the formation of chasmothecia on vine leaves, late in the growing season, may accomplish this. Inorganic fungicides, such as sulphur, copper, and potassium bicarbonate, are very useful for this purpose because of their multisite mode of action. The aim of this study was to evaluate chasmothecia reduction using different fungicide applications late in the growing season in commercially managed vineyards and in an exact application trial. RESULTS Chasmothecia on vine leaves were reduced in commercial vineyards by four copper (P = 0.01) and five potassium bicarbonate (P = 0.026) applications. The positive effect of potassium bicarbonate was also confirmed in the application trial, where two applications showed lower chasmothecia numbers than the control (P = 0.002). CONCLUSION The application of inorganic fungicides reduced the amount of chasmothecia as the primary inoculum source. Potassium bicarbonate and copper are of further interest for disease control as these fungicides can be used by organic and conventional wine growers. The application of these fungicides should be carried out as late as possible before harvest to reduce chasmothecia formation and, consequently, the potential for powdery mildew infestation in the subsequent season. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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

“…These preliminary data indicate that this known fungicide might also be used as an insecticide even at high rates of application with no phytotoxic effects on pear plants. This is one of the few records of the potential use of potassium bicarbonate as an insecticide, alongside its known fungicide activities in pears and other crops [ 9 , 10 , 11 , 12 , 13 ]. The only reported evidence thus far has concerned coleus plants, Solenostemon scutellarioides , infested by the citrus mealybug, Planococcus citri [ 14 ].…”

“…Recently, an alternative strategy has been applied, based on the use of mineral salts [ 7 ]. Among these, potassium bicarbonate is mostly known as an inorganic fungicide (with fungistatic activity [ 8 ]), registered for use in agricultural and greenhouse cropping systems for the control of various plant pathogens [ 9 , 10 , 11 , 12 , 13 ], including S. vesicarium (S. Civolani, based on personal communication). Even though the effects of this fungicide have not been properly evaluated against insect pests, some activity has been observed in regard to citrus mealybug, Planococcus citri [ 14 ].…”