An acetonic extract of Nicotiana tabacum leafs against pseudococcinide insects as pests on coffee shrubs in horticulture

Insects of the pseudococcinean subfamily are pests of numerous useful and ornamental plants. In the greenhouse of an educational and scientific horticulture holding, young 20cm-sized Coffea arabica shrubs were parasitized with mealybugs belonging to the genus Planococcus. The infestation was easily detectable by white, cottonwool-like colonies at the bottom of the leafs and the shoot, additionally the plants looked viscid round the colonies caused by secretions of the mealybugs, what in turn often favoured secondary infestations by mould. The infestation symptomatics were documented photographically.

An acetonic extract from dried powdered leafs of tobacco plants (Nicotiana tabacum, Solanaceae) was mixed with water in different dilutions (1:2, 1:5, 1:10, 1:50) and daily applicated to the affected coffee shrubs by means of a customary sprayer until the colonies could no longer be seen. While the 1:2-dilution had stopped the infestation after three days, plants daily attended with the 1:5 and 1:10-dilution were parasite-free after a week. The 1:50-dilution showed no success and was stopped after four weeks.

These experiments may supplement the spectrum of plant protection strategies with the use of compounds from natural source, in this case against a hardbitten plant parasite whose wax exudations aggravate the moistening with hydrophilic solvents.