Question: how to eradicate mealybug?
Good morning I have a problem with my old and large rosemary, grown in pots, I noticed that it was attacked by mealybug, I cut the infested branch but I would like to disinfect it since I use it what kind of insecticide can I give? Looking forward to a welcome response, I offer greetings
Cochineal on Rosemary: Answer: Cochineal
traditionally, an insecticide called white oil is used against mealybug; it is a very refined mineral oil, practically it is the oil you put in the engine of the machine (in broad lines), but very refined, so that it remains on the plant as little as possible, and that it is not phytotoxic, that is harmful to foliage. This type of insecticide is also used in organic agriculture, but only in the spring, until March. In addition to this, white oil often has an effect only by contact, and not on insect eggs, and therefore it is often mixed with insecticides, all always in the early spring period.
There are also commercially available mineral oils that can be used for summer treatments, it is clearly indicated on the label; since you intend to use this product on a plant that you will use for cooking, also carefully read the so-called time of shortage: that is, the period within which the product remains active on the plant, and therefore during which the rosemary cannot be used. Depending on the product used, the shortage time generally ranges from one week to 15-20 days.
In place of mineral oils, ie derived from petroleum, there are also other types of oils on the market, useful against cochineal, such as neem oil or resinous plant oil; these insecticides are much less toxic than mineral oil; but also in this case it would be good to use the product in a not very hot period, or until early spring.
Instead of using large quantities of chemicals on rosemary, while containing the mealybug, you can prune it well, thus removing most of the insects, and then begin to vaporize, in the evening, a little water on the crown, as the mealybugs do not they love humidity and strong insolation. A sunny position, and some additional watering, in addition to the vaporizations, should decrease the number of insects. If you then manage to remove most of the remaining insects with a cotton swab dipped in alcohol, the infestation of mealybugs may become more contained; clear that it depends on the size of your rosemary.